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TRANSPORT FOR LONDON
RIVER CROSSINGS: EAST OF SILVERTOWN CROSSINGS SUPPORTING TECHNICAL DOCUMENTATION
This document contains information relevant to the following options:
Woolwich
Ferries
Bridges
Tunnels
Gallions Reach
Ferries
Bridges
Tunnels
Belvedere
Ferries
Bridge
Tunnels
GALLIONS REACH MARINE ASPECTS STUDY
(REPORT G) Halcrow
17 May 2013
This document builds previous work to develop and refine the ferry land-based infrastructure design as well as carrying
out an estimation of boarding and alighting times for the various ferry
options. The report also considers and compares the hydrodynamic impacts of
bridges, tunnels and ferries.
The highway engineering elements of the land-based infrastructure design is
reported separately in Report F.
Report ref 472413/62/001 version 004
Gallions Reach River Crossings (Task 102) Marine Aspects
Document: 472413/62/001 Version: 04
Preliminary Design Report
Transport for London
July 2014
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tel 01793 812479 fax 01793 812089 halcrow.com
Halcrow Group Limited is a CH2M HILL company
Halcrow Group Limited has prepared this report in accordance with the instructions of client xxx for the client’s sole and specific use.
Any other persons who use any information contained herein do so at their own risk.
© Halcrow Group Limited 2014
Gallions Reach River Crossings (Task 102) Marine Aspects
Preliminary Design Report
Transport for London
July 2014
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
Document history
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
Transport for London
This document has been issued and amended as follows:
Version Date Description Created by Verified by Approved by
01 24/04/13 First Issue for TfL comments TA/MG TA MG
02 17/05/13 Final Issue TA/MG NK MG
03 15/07/13 Minor amendment following
TfL comments
MG MG MG
04 01/07/14 Minor clarifications to Section
2.1 and executive summary only
MG MG MG
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
Contents
1 Executive Summary 6
2 Introduction 9
2.1 Background 9
2.2 Scope of the Preliminary Design 10
2.3 Definitions 10
3 Information Sources 11
3.1 Provided by TfL 11
3.2 Other Sources 12
3.3 Added Value 13
4 Geotechnical Considerations 14
4.1 Review of Available Information 14
4.2 General Overview of Conditions on the River Banks (Chain Ferry Option) 14
4.3 General Overview of Conditions in the River 17
4.4 Advice and Comment on the Feasibility of Piling 18
4.5 Advice and Comment on the Feasibility of Solid Slipway Structures 18
4.6 Advice and Comment on the Feasibility of Cofferdams 19
5 Preliminary Infrastructure Design for Propeller Driven Ferry 20
5.1 Design Parameters 20
5.2 Standards Used 20
5.3 Design Considerations and Assumptions 21 5.3.1 Vertical Geometry 21
5.3.2 Horizontal Geometry 22
5.3.3 Pontoons 22
5.3.4 Linkspans 25
5.3.5 Approach Structures 26
5.3.6 Berthing Dolphins 26
5.3.7 Pontoon Restraint Dolphins 26
5.3.8 Number of Lanes 27
5.3.9 Existing Flood Defences 28
5.3.10 Ancillary Infrastructure 28
5.3.11 Passive Provision for Third Vessel 29
5.4 Construction Considerations 30 5.4.1 Constructability 30
5.4.2 Closures/Diversions 30
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
5.4.3 Utilities 30
5.4.4 Programme 31
5.5 Proposed Operational Procedures 31 5.5.1 Maintenance 32
6 Preliminary Infrastructure Design for Chain Ferry 33
6.1 TfL Design Parameters 33
6.2 Standards Used 33
6.3 Design Considerations and Assumptions 33 6.3.1 Vertical Geometry 33
6.3.2 Horizontal Geometry 34
6.3.3 Design of Slipways 34
6.3.4 Chains and Chain Tensioners 35
6.3.5 Number of Lanes 36
6.3.6 Existing Flood Defences 37
6.3.7 Ancillary Infrastructure 37
6.3.8 Passive Provision for Third Vessel 37
6.4 Construction Considerations 38 6.4.1 Constructability 38
6.4.2 Closures/Diversions 39
6.4.3 Utilities 39
6.4.4 Programme 40
6.5 Proposed Operational Procedures 40 6.5.1 Maintenance 41
7 Estimates of Alighting and Boarding Times 43
7.1 Propeller Driven Ferry 43 7.1.1 Two lanes – Assumptions for Alighting Model 43
7.1.2 Two lanes – Results of Alighting Model 43
7.1.3 Two lanes – Assumptions for Boarding Model 44
7.1.4 Two lanes – Results of Boarding Model 45
7.1.5 Four lanes – Assumptions for Alighting Model 46
7.1.6 Four lanes – Results of Alighting Model 47
7.1.7 Four lanes – Assumptions for Boarding Model 47
7.1.8 Four lanes – Results of Boarding Model 47
7.1.9 Six lanes – Assumptions for Alighting Model 48
7.1.10 Six lanes – Results of Alighting Model 48
7.1.11 Six lanes – Assumptions for Boarding Model 48
7.1.12 Six lanes – Results of Boarding Model 49
7.1.13 Summary of Overall Alighting and Boarding Time 50
7.2 Chain ferry 50 7.2.1 Assumptions for Alighting Model 51
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
7.2.2 Results of Alighting Model 51
7.2.3 Assumptions for Boarding Model 52
7.2.4 Results of Boarding Model 52
7.2.5 Summary of Overall Alighting and Boarding Time 54
7.2.6 Additional Traffic Lanes 54
7.3 Validation of Alighting and Boarding Time Estimates 55
8 Discussion of Alternatives 56
8.1 Re-use of Existing Woolwich Ferry Vessels 56
8.2 Alternative Linkspan Arrangement for Propeller Ferry 57
8.3 Self-Beaching Propeller Ferry 58
9 Hydrodynamic Impact Assessment 60
9.1 Hydrodynamic Features 60 9.1.1 Flow rates 60
9.2 Ferry 60 9.2.1 Effect on Water Level 61
9.2.2 Effects on Tidal Propagation 62
9.2.3 Effects on Flow Distribution 62
9.2.4 Effects on Sediment Transportation 62
9.2.5 Effects on Environment 63
9.2.6 Effects on Navigation 63
9.3 Revised Chain Ferry (Piled Slipway) 63 9.3.1 Effect on water level 64
9.3.2 Effects on flow distribution 64
9.3.3 Effects on sediment transportation 64
9.3.4 Effects on Environment 65
9.3.5 Effects on Navigation 65
9.3.6 Construction phase 65
9.4 Bridge (Concrete Box Girder) 65 9.4.1 Effects on Water Level 65
9.4.2 Effects on Flow Distribution 66
9.4.3 Effects on Sediment Transportation 66
9.4.4 Effects on Environment 66
9.4.5 Effects on Navigation 66
9.4.6 Construction Phase 66
9.5 Bridge (Steel Arch) 67 9.5.1 Effects on Water Level 67
9.5.2 Effects on Flow Distribution 67
9.5.3 Effects on Sediment Transportation 68
9.5.4 Effects on Environment 68
9.5.5 Effects on Navigation 68
9.5.6 Construction Phase 68
Gallions Reach River Crossings – (Task 102) Marine Aspects
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9.6 Immersed Tunnel 68 9.6.1 Effects on Water Level 68
9.6.2 Effects on Flow Distribution 69
9.6.3 Effects on Sediment Transportation 69
9.6.4 Effects on Environment 69
9.6.5 Effects on Navigation 69
9.6.6 Construction Phase 69
9.7 Bored Tunnel 69
9.8 Conclusions 69
10 Environmental Issues 71
10.1 Comparison of Ferry Types 71
11 Risk Assessment 74
11.1 Significant Risks 74
11.2 Retired Risks from Previous Study 75
11.3 Construction (Design and Management) Regulations 2007 75
12 Cost Estimates 76
12.1 Assumptions 76
12.2 Risk and Optimism Bias 76
12.3 Summary of Ferry Options 77
13 Conclusions and Recommendations 78
13.1 Summary of Infrastructure Options 78
13.2 Recommendations 79
Appendices
Appendix A List of Figures, Tables and Graphs
Appendix B Glossary of Abbreviations
Appendix C Preliminary Design Drawings
Appendix D Environmental Summary Table
Appendix E Risk Register
Appendix F Designer’s Risk Assessment
Appendix G Cost Estimates
Appendix H Outline Construction Programmes
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1 Executive Summary There are currently only a handful of crossings of the River Thames in East London.
Transport for London (TfL) is investigating the possibility of a new crossing at
Gallions Reach to provide additional road‐based connectivity in this area. A series of
work packages have been commissioned to develop preliminary designs for
alternative crossing schemes.
Halcrow was commissioned by TfL in March 2013 to undertake work in connection
with the marine aspects of the preliminary design packages, including development
of ferry infrastructure proposals and hydrodynamic impact assessment of all crossing
options.
The design of infrastructure for two ferry options has been considered by Halcrow; a
pontoon and linkspan arrangement for a propeller driven ferry and a slipway
arrangement for a chain ferry. Each option has been developed to a level which
presents workable solutions, given the information currently available, with outline
cost estimates and construction programmes. In some cases, amendments to the
feasibility design have been necessary where new information has been available or
greater consideration of structural forms has been undertaken. A review of available
geotechnical information has resulted in the conclusion that a solid slipway for a
chain ferry is impractical due to the large amount of unsuitable, possible
contaminated, material that would need to be removed to reach adequate conditions
for the foundations. For this reason, the alternative option of a piled slipway has been
progressed instead.
Each infrastructure proposal is accompanied by an explanation of the likely
construction methodology and suggested operational procedures. These factors will
need further development throughout a more detailed design phase but certain
assumptions have been necessary at this stage to determine the most appropriate
preliminary designs. The underlying assumption regarding operation of a new ferry
service at Gallions Reach is that TfL requires a minimal level of staffing.
As part of the examination of operational procedures, Halcrow has developed robust
estimates of boarding and alighting times for each ferry type. These will dictate the
frequency of service and the hourly capacity of the crossing, which can then be
compared to other crossing options. It is noted that a ferry service would not be able
to provide the same capacity as a fixed crossing but a cost benefit analysis by TfL may
yield a positive result for such a substantially less expensive option. In summary, the
time taken to turn around the ferry varies depending upon the number of traffic lanes
provided. The complete boarding and alighting operation can take between 10 and 15
minutes for both options. It is noted, however, that berthing of a propeller driven
ferry requires a higher level of skill and will take longer than berthing of a chain ferry
which grounds on its slipway.
A significant aspect of the infrastructure design for a propeller driven ferry is the use
of pontoons for the ferry to berth to. TfL raised the possibility of using
decommissioned vessels from the Woolwich Ferry service as pontoons. Whilst this
would be commendable from a sustainability perspective, the idea has been
discounted due to the logistical problem of maintaining a service at Woolwich until
the new service opens and the likely cost of converting the old ferry vessels into
pontoons. It is possible to have a propeller driven ferry terminal without pontoons.
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Such a system would employ a mechanically operated linkspan which follows the
level of the tide. Unlike the current Woolwich operation, linkspans would not have to
be lowered and raised at each berthing and advancements in technology would result
in much lower energy consumption. Development of this solution is outside the
scope of this task and TfL is not currently in a position to investigate it further. The
main principles are detailed in this report for completeness should TfL wish to give it
further consideration in future. An alternative system using a self‐beaching propeller
driven ferry is also discussed at the request of TfL. This option has several similarities
to a chain ferry in terms of slipway infrastructure, but it is discounted as a viable
alternative on the grounds that it is less advantageous. The particular regime of
currents and tides in the River Thames would require the installation of berthing
dolphins and a higher level of crew skill.
The marine aspects task for TfL also includes hydrodynamic impact assessment for
all crossing options. Halcrow has worked with other consultant teams to determine
the effect of various bridge and tunnel crossing options as well as the two types of
ferry terminal described above. A number of factors have been considered in this
assessment including the effects on currents, sedimentation and the river
environment. With the exception of a bored tunnel, which is not anticipated to have
any significant effect upon the river above it, the infrastructure for a propeller driven
ferry is assessed as having the least hydrodynamic impact. This is primarily due to
the smaller cross sectional blockage caused by piles as opposed to large bridge piers
or a dredged channel for an immersed tube tunnel.
Environmental issues associated with a ferry crossing of the River Thames at Gallions
Reach have been considered using industry standard general topic headings. The
most significant environmental impacts arise from energy use, biodiversity and
visual impact. The overall environmental impact of each type of ferry infrastructure
are similar, though each option has different primarily impacts; a propeller driven
ferry has a greater effect upon energy consumption and visual impact whereas a
chain ferry affects biodiversity and hydrodynamic processes to a greater extent.
Community links and transportation connections are improved by the introduction of
a ferry service, though frequency of service is a key consideration. Although boarding
and alighting times for each ferry option are similar, a chain ferry is expected to
provide a more frequent service, largely due to a faster berthing time.
A risk register has been developed using the “live” risk register produced by
Halcrow for a previous feasibility study. The risk rating for each risk item has been
revisited to reflect the more advanced level of design development. Where
appropriate, certain risks have been retired and others have been added as new
design considerations have been introduced. The most significant risks relate to
planning and procurement, particularly legal processes.
With the exception of poor ground conditions which has resulted in the discounting
of a solid slipway for chain ferries, the highest ranking specific design related risks
are in connection with safety. A chain ferry in particular carries the inherent risk of
regular tidal washing of the slipway which would, without regular cleaning, result in
a slippery surface. Another difficulty with a chain ferry is the segregation of
pedestrians and cyclists from vehicles where the location of the ferry on the slipway
can vary between each crossing. The most significant risk for a propeller driven ferry
is the hazard to other river users that the terminals and ferries present.
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Outline cost estimates are included in this report for comparison of the ferry
infrastructure options with each other and with fixed crossings being developed by
other consultants. The propeller driven ferry infrastructure varies in cost between
approximately £24million and £38million depending upon the number of traffic lanes
used, which determines the number and size of structural components. A chain ferry
slipway is sized to accommodate the width of two ferries and any change in the
number of traffic lanes is only reflected in the cost of highway connections to the top
of the slipways, which is outside the scope of this task. As a result, an estimate of cost
for the chain ferry option is approximately £20million.
In conclusion, the recommended approach to the delivery of a possible ferry crossing
at Gallions Reach is that of a chain ferry using a piled slipway. The major benefits of
this option over a propeller driven ferry are a lower construction cost, fewer
operatives and faster turnaround times. It is considered that a four‐lane highway
approach will provide the best compromise between highway construction cost, land
take, manageability of vehicle movements and alighting and boarding times.
The elimination of a solid slipway for geotechnical reasons has not mitigated
environmental and hydrodynamic impacts down to a similar level as the
infrastructure for a propeller driven ferry and this is a major disadvantage that
remains for such an option. It will be essential to develop an operational regime that
ensures safety through the management and/or segregation of motorised and non‐
motorised users and regular cleaning of tidal deposits from the slipways.
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2 Introduction
2.1 Background
Transport for London (TfL) has commissioned a series of studies into crossings of the
River Thames at Gallions Reach. Access across the river in this area of East London is
currently provided by the Blackwall Tunnel and the ageing Woolwich Ferry service.
TfL is investigating options for providing additional road‐based connectivity in this
area. To provide evidence to support decision‐making, this report assesses the
feasibility, issues and costs of a number of crossing options at Gallions Reach.
The alignment of each crossing at Gallions Reach is within a safeguarded zone for the
previously proposed Thames Gateway Bridge and links the London Boroughs of
Newham in the north with Greenwich in the south.
Figure 1 Location of Gallions Reach (Google Maps, 2013)
Crossing types considered include:
Bridge structure;
Bored / immersed tube tunnel(s); and
Ferry for vehicles, pedestrians and cyclists.
TfL requires development of preliminary designs for each crossing type to allow the
decision making process to progress towards selection of a preferred option.
Gallions Reach
crossing area
Existing Woolwich Ferry Thames Barrier
London City Airport
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2.2 Scope of the Preliminary Design
TfL commissioned Halcrow in March 2013 to undertake the marine aspects package
from the studies into a River Thames crossing at Gallions Reach. This involves the
following key tasks:
Design development of ferry infrastructure; and
Assessment of the likely effects of all crossing options on the hydraulic
regimes of the river.
This work builds upon a study undertaken by Halcrow in 2009/10 which considered
the feasibility of a possible ferry replacement of the existing Woolwich Ferry service
with a new ferry at Gallions Reach. In order to develop ferry options further,
Halcrow is required to establish principal dimensions of the structural components of
terminals associated with a propeller driven and a chain driven ferry.
Each type of ferry terminal will be developed to consider the following aspects:
Safe access and waiting areas for pedestrians and cyclists;
Interface with highway access designs;
Control room/staff accommodation/maintenance facilities;
Treatment of the existing flood defence wall; and
Any effect on utilities from proposed infrastructure.
Design parameters for the size and capacity of each type of ferry have been provided
by TfL in consultation with renowned ferry expert Bill Moses MBE PhD MA. The
design vessels are larger with higher capacity than those in the previous feasibility
study and the preliminary design is to take account of this in an estimation of the
likely boarding/alighting times in conjunction with variations in the number of traffic
lanes to be used.
TfL would pursue a Transport and Works Act 1992 (TWA) Order for construction of
the chosen option and the preliminary design shall include sufficient information to
input into the engineering aspects of this.
In addition to the preliminary design, the brief requires an outline cost estimate, risk
register and construction programme for each ferry option to enable TfL to determine
the likely benefit in relation to the whole‐life cost.
The nature and extent of hydrodynamic effects from temporary and permanent
works in the river associated with ferry infrastructure, bridge construction or
immersed tube tunnel shall be described and compared. These comparisons will also
inform TfL’s decision on a preferred option for further development.
2.3 Definitions
For the avoidance of doubt, the term “linkspan” in this report is used to describe an
articulating structure that links the ferry to a fixed structure, or that links a pontoon
with the shore. It does not include the fixed approach structures or pontoons that are
considered as part of the preliminary designs for a propeller driven ferry.
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3 Information Sources Halcrow has made use of a number of information sources in the development of
preliminary designs for ferry infrastructure and the hydrodynamic analysis of all
relevant crossing options. TfL provided a package of reports and drawings from
related studies and Halcrow has made contact with other organisations to obtain
further data as necessary.
3.1 Provided by TfL
TfL has provided several documents from previous studies as listed in Table 1 below.
This information has been reviewed by Halcrow as part of the preliminary design
study.
Date Title Information included
February
2010
Halcrow Group Limited
Woolwich Ferry Replacement
and Gallions Reach Ferry
Feasibility Study:
Final Report
(TB/TFFS/REP/002)
Feasibility of a replacement ferry
service at Woolwich and/or new ferry
service at Gallions Reach;
Environmental and hydrodynamic
impacts of options;
Cost estimates and constructability
considerations.
May 2012 Mott Macdonald
Gallions Reach River Crossing
Study, Tunnel Engineering;
(298348/MNC/TUN/001)
Feasibility of a fixed crossing of the
River Thames at Gallions Reach;
Environmental impacts of options;
Cost estimates and constructability
considerations.
August
2011
Mott Macdonald
New Thames River Crossing,
Extended Phase 1 Ecological
Assessment
Assessment of ecological features in
Gallions Reach area;
Recommendations for further
ecological surveys.
October
2011
Mott Macdonald
Thames Benthic Ecology
Survey Report
Results of marine ecology and intertidal
benthic survey of Woolwich and
Gallions Reach areas;
Assessment of impact of ferry terminal
options;
Recommendations for further surveys.
December
2012
MARICO Marine
Woolwich Ferry Replacement
Project, Navigational Risk
Assessment for Different Types
of Ferry Systems at Gallions
Reach
Analysis of the risks to vessel
navigation through the Gallions Reach
area created by new ferry infrastructure
in the river.
December
2008
Halcrow Group Limited
Drawing TBTGRC‐P2‐TGB‐006
(rev 4)
Clearance constraints (air draft for river
vessels and headroom for aircraft) for
proposed Thames Gateway Bridge (not
needed for this study).
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Date Title Information included
July 2012 TfL Roads Directorate, Traffic
Design Engineering (TDE)
Proposed highway access
designs
Drawings of highway alignment
designs at the north and south sides of
the safeguarded corridor;
Queuing/stacking arrangements for
waiting ferry users.
September
1985
Halcrow Group Limited
East London River Crossing –
Interpretative Report Vol. 1 to 3
Referred to as part of geotechnical
information review.
April 1992 Halcrow Group Limited
East London River Crossing –
Supplementary Interpretative
Report
Referred to as part of geotechnical
information review.
Soil Mechanics Limited
Thames Gateway Bridge Site
Investigation – Location 1
Factual Report on Ground
Investigation
Report No A7028 – 1
Referred to as part of geotechnical
information review.
July 2007 Mortimore, R
Thames Gateway Bridge
Boreholes; Chalk Core Logging
Report 1D0101‐G0G00‐00543
Referred to as part of geotechnical
information review.
Table 1 Documentation received from TfL
3.2 Other Sources
In addition to the information provided by TfL, Halcrow has made use of a number
of other data sources as summarised in Table 2 below:
Date Title Information included
April
2013
Halcrow Group Limited
Task 95 – Tunnel Engineering
and Highway Engineering
(version 1.0)
Referred to in hydrodynamic impact
assessment.
April
2013
Atkins
Gallions Reach Fixed Link
Bridge Concept Engineering,
Options Study Report (rev 1.0)
5118859/060/001
Referred to in hydrodynamic impact
assessment.
March
1978
FHWA Bridge Division
HDS‐1: Hydraulics of Bridge
Waterways
Referred to in hydrodynamic impact
assessment.
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Date Title Information included
June 2010 Lloyds Register Marine
Consultancy Services London
Woolwich Free Ferries:
Operational Cost Estimate ( rev
0 and rev 1)
Referred to in discussion of alternatives
– existing Woolwich vessels are
considered to be sound.
April
2013
Discussion with
representatives of Torpoint
Ferry
Drawings, photographs and advice
from operator of Torpoint chain ferry.
July 1999 Maritime and Coastguard
Agency
Merchant Shipping (Counting
and Registration of Persons on
Board Passenger Ships)
Regulations 1999
Referred to in operational procedures.
December
2007
Halcrow Group Limited
N Burt and R Dobiecki
Technical Note P3‐T291
Overview of the results from
Site Investigation Contract 01‐
2007
Referred to as part of geotechnical
information review.
Halcrow Group Limited
Technical Note P3‐T289
EGGS Bridge Pier 5 ‐ Pile
Group Assessment
Referred to as part of geotechnical
information review.
Table 2 Other sources of information used in this task
3.3 Added Value
Halcrow has developed a comprehensive understanding of the Gallions Reach area
and the process of procuring a crossing in this location through several years of
working with TfL on the Thames Gateway Bridge (TGB) and Woolwich Ferry
Replacement projects. Where appropriate, existing Halcrow knowledge has been
used and refreshed as necessary. In some cases, this knowledge is outside the scope
of the current task, but is included to provide additional support to proposals where
it is considered to be of note.
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4 Geotechnical Considerations As part of this task, Halcrow has carried out a review of available geotechnical
information provided by TfL and from its own experience on the former East London
River Crossing (ELRC) and TGB schemes. This review has informed the preliminary
design process.
4.1 Review of Available Information
A number of site investigation (SI) campaigns were undertaken for the proposed
Thames River crossing, in the past, for the original scheme (ELRC) and the
subsequent one, namely TGB. There were three SI campaigns investigating the route
of the ELRC dating back to 1980, then 1983 and final one was conducted in 1990. To
supplement this information and provide specific and current information a further
SI was carried out in 2007 for the TGB scheme. The plan of the most relevant
exploratory locations is shown on the TfL drawing No: TBTGTA/P3/ASI/011.
The TGB SI scope focused predominantly on specific structures:
intermediate piers of the river bridge;
unfinished viaduct to the north of the river bridge (EGGS bridge); and
a communications tower for the PLA in Woolwich Arsenal.
Hence it does not provide a site wide coverage; however, it offers very detailed
analysis of Chalk Formation in the river channel as logged by Professor R.
Mortimore.
The ELRC site investigations encompassed the whole of the approach road network
as well as the main river crossing. Many of the exploratory locations are relatively far
from the site of the currently proposed ferry schemes hence bear little relevance for
the design.
The two river crossing options proposed, for two different types of ferry operation,
will require two different types of load/off‐load structures as one, propeller driven
ferry, will need deeper water for berthing and the other, chain ferry, would in essence
load/off‐load in the dry. In other words, the structures required for the propeller
driven ferry will be located in the river channel and require piled or deep foundations
and the structures for the chain ferry are proposed at the river bank and mudflats
utilising contained earthworks by means of embedded retaining walls.
As the ELRC SI campaigns were more extensive on land, and the TGB one focused on
soil strata in the river channel, the former was used predominantly for the
geotechnical assessment of the chain ferry option and the latter one for the propeller
driven ferry option, as it offers an assessment of the chalk classification.
4.2 General Overview of Conditions on the River Banks (Chain Ferry Option)
The geological profile on both banks, North and South, in general comprises:
Made Ground and very soft to firm Alluvial Clay, including distinctive sub‐layers of
peat, which overlie course grained River Terrace Gravel underlain by White
(formerly Upper) Chalk. The chalk was proven to nearly ‐90mOD during the ELRC SI
campaigns.
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The superficial Made Ground layer was formed by raising river banks in recent
history. This layer just below the existing ground surface is predominantly granular
and comprises: building rubble, furnace slag and ash, glass, plastic and timber. The
basal part of this layer is predominantly made up of reworked alluvial clay which has
been mixed with the manmade material mentioned previously.
The Alluvial Clay is very soft becoming soft and in places firm (probably due to
desiccation). It is of high to very high plasticity and contains traces and pockets of
organic matter and peat. At depth, inclusions of bands and pockets of sand as well as
occasional chalk gravel were observed. As the Made Ground is absent from mudflats,
in the river channel, a superficial layer of underconsolidated very soft silty clay of
very recent (Holocene) river deposits is present at the surface, which predominantly
plots below the A Line on the plasticity chart suggesting that this material is
predominantly silt of high plasticity.
Peat is predominantly soft friable and probably fibrous as most of the Atterberg Limit
results plotted below the A‐line. Due to the fibrous nature of the Peat, it is considered
inappropriate to estimate effective shear strength characteristics of the material. The
nature of Peat is probably one of the main reasons for the high (apparent) undrained
shear strength measured.
River Terrace Gravel underlies Alluvial Clay over most of the site including the river
channel. The formation predominantly comprises medium dense slightly to very
sandy Gravel. Gravel is fine to coarse, sub‐angular to rounded of quartzite. This
formation at certain locations was reported as gravelly Sand. The fact that the grading
envelope is quite wide contributes to the large scatter of Standard Penetration Test
(SPT) results. However this is a common feature for a coarse granular material. There
are some indications that River Terrace Gravel at isolated locations contains pockets
of loose material in the region of mudflats.
The current (CIRIA 574) classification of Chalk Formation was only possible from the
latest (2007) SI data as summarized in Prof. Mortimore’s report. This is because the
previous site investigations used percussive drilling techniques destroying the
structure of the chalk and making classification impossible. It should be noted that
the following assessment of the Chalk is representative of the formation below the
river bed and that weathering can be expected to be more pronounced, with a thicker
de‐structured starting sub‐layer over land. Based on the ELRC SI it can be expected
that the Chalk starts from ‐9.5mOD to ‐11mOD on the northern bank. This was
corroborated by the CPT tests carried out in 2007 SI (test ref nos: CPT364 to CPT370).
However the boreholes sunk at the proposed location of the northern pier suggest
that the top of chalk is somewhat lower around ‐16.0mOD. This could be due to the
normal erosion by the river flow.
Exploratory core logs from the ELRC SI and TGB SI are more consistent at the south
side and near the south bank of the river than on the north. Here the top horizon of
the chalk is between ‐10.0mOD and ‐15.0mOD.
At the location of the northern pier of the former TGB scheme, the de‐structured
(Class Dc/Dm) chalk is approximately 6m to 7m thick. The de‐structured chalk is
directly followed by class A (A1 to A4) intact material. The location of southern pier
shows more gradual transition from destructured chalk at the top horizon, which
varies in thickness from 1.5m to 6.0m. De‐structured chalk is followed by relatively
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thin layers of class B and C. However it should be noted that 10m below the top
horizon of chalk class A is encountered.
The two tables below show a typical soil profile with basic characteristic values for
the north and south river banks respectively. The average values are presented,
sometimes as a range.
It should be noted that the main difference between the stratigraphy on the north and
the south riverbanks is the apparent absence of the Peat layer on the south. The Peat
was only observed some 500m further south from the river. It is also noted that the
Made Ground is not present on the intertidal mudflats in the river channel.
Layer Thickness
(m)
Moisture
Content
(%)
γ
(kN/m3)
SPT
‘N’
Su
(kPa) ϕʹ (◦)
Eu
(MPa)
E’
(MPa)
Made
Ground 4 – 5 no data 18.0 8 – 20 35(1) 26(1) 12.25 9.8
Alluvium 4 [6(2)] 40 – 70 16.5 ‐ 25 26 7 5.6
Peat 3 210 11.5 ‐ 30 ‐ 7 5.6
Terrace
Gravel 6 ‐ 20.0 30 ‐ 36 ‐ 50
Chalk
Dc/Dm 7 31 18.0 ‐ ‐ ‐ ‐ ‐
Chalk C
and better not proven 22 20.5 36 3.5(3) ‐ ‐ ‐
Table 3 North bank stratigraphy and basic parameters
(1) Strength values for Made Ground were derived with the view that the significant
quantity of this material was generated by reworking alluvial clay and mixing with
manmade material, not just directly from testing such as SPT.
(2) These thicknesses are relevant to what appear to be paleo‐channels or in‐filled
erosion features.
(3) Unconfined Compressive Strength (UCS) in mega‐pascals (MPa)
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Layer Thickness
(m)
Moisture
Content
(%)
γ
(kN/m3)
SPT
‘N’
Su
(kPa) ϕʹ (◦)
Eu
(MPa)
E’
(MPa)
Made
Ground 3 – 5 no data 18.5 9 35 30(1) 12.25 9.8
Alluvium 5 [10(2)] 45 18.0 ‐ 30
[10(3)] 29
10.5
[3.5]
8.4
[2.8]
Terrace
Gravel 4 ‐ 20.0 30 ‐ 35 ‐ 35
Chalk
Dc/Dm 1.5 – 6.0 30 18.0 ‐ ‐ ‐ ‐ ‐
Chalk C
and better not proven 24 19.8 30 4.0(4) ‐ ‐ ‐
Table 4 South bank stratigraphy and basic parameters
(1) Strength values for Made Ground were derived with the view that the significant
quantity of this material was generated by reworking alluvial clay and mixing with
manmade material, not just directly from testing such as SPT.
(2) These thicknesses are relevant to what appear to be paleo‐channels or in‐filled
erosion features.
(3) Parameters for alluvial clay on mudflats
(4) Unconfined Compressive Strength (UCS) in mega‐pascals (MPa)
4.3 General Overview of Conditions in the River
Chalk below the river bed was the focal point of the 2007 SI.
Boreholes and cone penetration tests carried out in the current river channel proved
that river deposits varied in thickness from 2.40m (CPT 2) to 7.60m (CPT 3) and
directly overlay Chalk.
The depth to the chalk, observed in the 2007 SI, was shallower than was originally
anticipated at the borehole locations and the thickness of the overlying river deposits
varied from 0.90m (BH305) to 1.90m (BH 301 and BH302). The top horizon of chalk
was discussed in the section above. Chalk was then encountered to the base of each
hole. Standard penetration testing in chalk, which measures the resistance of soil to
penetration and is an indicator of shear strength of soil, was relatively consistent
throughout different SI campaigns. SPT ‘N’ values on the southern side of the river
(BH302) appear to become consistently greater than 50 from ‐22m OD. On the
northern side, SPT ‘N’ values become generally greater than 50 from ‐16m OD.
This difference in the value of SPT ‘N’ between the south and north side of the river
was suspected before the 2007 SI and was thought to result from a possible
displacement of the chalk beds by a fault running between the bridge pier locations.
New SPT ‘N’ values recorded a difference of approximately 6m between the eastern
and western side of the river.
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To reduce the uncertainty in the chalk weathering profile the Chalk was logged by
Prof. Rory Mortimer. Prof Mortimer concluded that a gentle dip of strata to the south
is present and a fault is possible within the area of BH303 and between the two sets of
boreholes. This potential fault, however, appears not to be the main reason behind
the differing SPT ‘N’ values.
Despite the use of modern techniques and detailed logging, the depth of the
weathered chalk between the northern and the southern side of the river cannot be
fully explained but is believed to represent differences in the local weathering profile.
4.4 Advice and Comment on the Feasibility of Piling
Predictions of differential settlement and the ability of the foundations to deal with
the considerable imposed horizontal loads are critically dependent on the local
weathering profile, together with the associated strength and stiffness properties, of
the Chalk stratum. The settlement aspects are particularly relevant to spread
foundations that rely primarily on bearing pressure to resist the vertical and
overturning loads; as a result, the founding level and hence constructability will
depend to a large extent on the weathering profile. For these reasons a piled solution
would be less sensitive to ground variation, and hence produce less risk to the
construction and the contract. Nevertheless, as stability of piled structures will be
derived from chalk the weathering profile at exact locations will be crucial for the
final design of the foundations.
One of the piling methods thought appropriate would be to install a permanent steel
casings into the top of the Chalk by a metre or so, where bored cast‐in‐situ reinforced
concrete piles would be constructed thorough the casing into better quality Chalk. If
constructed carefully cast‐in‐situ piles are more efficient in developing shaft
resistance in the Chalk than the alternative of driven steel tubular piles, since driven
piles produce a lot of fracturing which significantly reduces the structural strength of
good intact chalk. Also the precedent empirical data on which design of bored piles is
based is far more robust; hence the design can probably be less conservative.
Nevertheless, comparisons of cost and construction programme should be
undertaken before final selection of pile type.
In addition to the advantage over caisson type foundations that rely heavily on the
quality of chalk at the top horizon of the formation, which would be weathered and
variable, piled foundation construction would pose less disruption to the river traffic.
4.5 Advice and Comment on the Feasibility of Solid Slipway Structures
Alluvial clay present on the north and the south river bank is normally consolidated
and highly compressible. It also contains a considerable amount of organic matter
and sub‐layers of peat, on the northern bank. Peat has an extremely high water
content and compressibility potential. Because of this the slipways for a chain ferry
cannot be founded directly on the Alluvium.
Possible solutions are:
Piled deck on a grid, toeing into the Chalk – Prefabricated, either tubular steel
or reinforced concrete piles, could be used to minimize generation of spoil
and a need for disposal off site;
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Remove and Replace – Alluvial clay would need to be removed in
cofferdams and replaced with relatively coarse granular step graded and self
compacting material where it has to be placed under water. How easy the
installation of cofferdams will be will depend on water depth and thickness
of soft alluvial deposits and the level of top of Chalk. The spoil resulting from
excavation of Alluvium could be contaminated, which would require
specialist treatment and disposal;
Ground Improvement by Accelerated Consolidation – Depending on the
project programme and imposed loads and/or settlement tolerances of the
slipway structures it would be possible to pre‐load the compressible soil and
accelerate settlement by installing vertical drains. This option would not be
suitable where significant thickness of organic material/peat is present. Peat
is susceptible to significant prolonged deformation which is not associated
with drainage of pore water and it is very difficult to predict; or
Ground Improvement by Soil Mixing – There are different soil mixing
techniques available these days. This method increases the shear strength of
soft fine grained soil by admixing with stabilizing agents such as cement,
PFA, lime, etc. This technique can be expensive if large quantities of soil need
to be mixed and if high strength (say above 70kPa) of finished product is
required. The advantages of both ground improvement techniques are that
they are relatively low tech solutions requiring relatively simple plant as well
as that they do not require fabrication and erection of structural elements.
Also spoil generation is reduced to a minimum. However, there may be
issues with potential contamination of the river water.
Each of the techniques involving replacement or treatment of the Alluvial clay would
make construction of a solid slipway potentially costly and difficult option. It is
recommended that a piled slipway is investigated.
4.6 Advice and Comment on the Feasibility of Cofferdams
It is believed that cofferdams offer a viable construction technique and certainly can
be used at the proposed river crossing at the Gallions Reach. However their stability
(hence their cost) would primarily depend on the thickness and the state of the
weathered chalk as overlying granular river deposits have been proven to be thin and
possibly absent in some locations. A detailed investigation at exact locations is highly
recommended due to the soluble nature of the chalk material where variations over
short distances can be significant.
It is believed that the standard large section steel sheet piling is feasible. Heavy
percussive driving plant and relatively large steel sections would be required to reach
required penetration into structured chalk in order to achieve stability.
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5 Preliminary Infrastructure Design for Propeller Driven Ferry The first option considered for a ferry at Gallions Reach is that of propeller driven
vessels berthing at a pontoon on each side of the river, which is connected to the
shore by a hinged linkspan. The pontoon remains at a constant level in the water and
tidal movements are accommodated by articulation of the linkspan without the need
for any powered mechanical systems.
Design of the ferry vessels themselves is outside the scope of this task and TfL has
provided parameters for their size and capacity, which will be progressed to detailed
design by others.
5.1 Design Parameters
TfL has specified the following parameters to be used in the design of the
infrastructure for a propeller driven ferry:
Ferry ‐ 2 no. vessels (with passive provision for a third vessel);
‐ 90 Passenger Car Unit (PCU) capacity;
‐ 6 traffic lanes (2 x 2.7m wide outer lanes for cars, 4 x 3.0m wide
inner lanes for HGVs);
‐ PCU length of 5.0m, including longitudinal gap between vehicles;
‐ 80m maximum overall length, 22.5m beam, 3.0m draft; and
‐ Passenger lounge on one side of vessel.
Holding area ‐ Liaison with highways designer to ensure sufficient land side area
for waiting vehicles.
Lane options ‐ Investigate 2, 4 and 6 lanes connecting shore to ship.
5.2 Standards Used
The following standards have been used in the preliminary design of infrastructure
for the propeller driven ferry option:
BS 6349: pt 4 (1994) Maritime structures. Code of practice for design of
fendering and mooring systems.
Linkspan design to BS 6349: pt 8 (2007) Maritime structures. Code of practice
for the design of Ro‐Ro ramps, linkspans and walkways.
Other standards referred to within BS 6349 (BS 5400 for vehicular structures,
Lloyds rules for marine structures)
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5.3 Design Considerations and Assumptions
5.3.1 Vertical Geometry
The vertical geometry of the transition from shore to ship is established by
consideration of a number of factors including:
Tidal variation, normal and extreme;
Vessel threshold height;
Recommended gradients;
Transitions between elements; and
On‐shore tie‐in levels.
For preliminary design purposes the following assumptions are made:
The threshold height of the ferry vessels is assumed to be approximately 2
metres;
The on‐shore tie in level is assumed to be at the level of the flood defences
(+10.6m CD);
Normal operating tide levels are assumed to be from MLWS to MHWS
(+0.42m CD to +7.08m CD); and
Extreme tide levels are assumed to be from LRT to HRT (‐0.69m CD to
+8.53m CD).
The level of the roadway at the linkspan adjustment should be set as low as possible,
but high enough to avoid inundation and wave overtopping under normal
circumstances. The preliminary design sets the roadway level at the abutment at
+8.7m CD. This is one metre above HAT, providing a reasonable margin for wave
activity. This roadway level is also around 0.2 metres above HRT, which would avoid
complete inundation under extreme tidal levels.
The roadway should descend from the on‐shore tie‐in level at a normal highway
gradient of 5% or less. This level change requires a length of roadway of 38 metres,
which is considerably less than the length of roadway required from other
considerations.
BS 6349: pt 8 recommends that the gradient of the linkspan element between the
abutment and the pontoon should be a maximum of 10% at normal operating levels
and 12.5% at extremes. In this particular case the governing gradient is 10% at MLWS.
It is advantageous to minimise the length of linkspan required by setting the roadway
level as high as is practicable above the water level at the point where the linkspan
joins the pontoon. This can be achieved by providing a slight slope on the top profile
of the pontoon between the landing area for the vessel’s ramp and the linkspan
connection. For the preliminary design the level of the linkspan roadway is set at 2.7
metres above water level.
For the governing gradient case at MLWS the linkspan descends from +8.7m CD to
+3.1m CD. At a gradient of 10% the minimum length of linkspan required is 56.3
metres, which is rounded to 57 metres. The gradient at LRT is 11.8%, less than the
maximum recommended value of 12.5% for the extreme condition.
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5.3.2 Horizontal Geometry
The location of the ferry at its berth is obtained by positioning the ferry vessel in a
depth of water at low tide, sufficient to accommodate its draft with an allowance for
under‐keel clearance. The preliminary design positions the ferry close to the 4m CD
contour as shown on Port of London Authority (PLA) Chart 325, dated September
2011. This provides 1 metre under‐keel clearance at Chart Datum, which covers all
normal tides. It should be noted that at extreme tides the under‐keel clearance would
reduce, for example at the lowest recorded tide level it would reduce to around 0.3 m
with a consequent risk of grounding.
Roadway widths (2 lanes) are taken as 7.4 metres between kerbs as recommended by
BS 6348: pt 8.
An access walkway of 2 metres clear width is provided for pedestrians, again as
recommended by BS 6349: pt 8. It is assumed that cyclists would dismount and access
the ferry vessel using the same walkway.
A separate service walkway is provided with a clear width of 1 metre for use by staff.
The position of the northern connection to the highway network is in close proximity
to an outlet of the Northern Outfall Sewer. This may be an issue which could result in
some adjustment of the final position of the northern terminal.
5.3.3 Pontoons
The pontoon design should provide a stable platform, capable of supporting the
weight of the linkspan and being permanently ballasted to float horizontally.
It is assumed that the pontoon is essentially a passive platform serving one design of
ferry, thus requiring no sophisticated ballasting system to respond rapidly to vessels
of different threshold height.
As vehicles, particularly HGVs, traverse the linkspan and pontoon the pontoon
experiences freeboard and trim changes that can adversely affect the vertical
transition angles between the linkspan and pontoon and between the pontoon and
the ferry vessel, causing vehicles to ground. Similarly vehicles moving on the ferry
vessel’s deck also affect its ramp transition angles. This should be studied in detail
when the vessel design is available.
The preliminary design of pontoons in the feasibility study assumed that vehicles
would turn by up to 90 degrees (at the South terminal) from the end of the linkspan
to board the ferry and vice versa for alighting from the ferry. Halcrow has carried out
Autotrack swept path analyses to determine the minimum size of pontoon that could
accommodate such manoeuvres.
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Figure 2 Swept path for articulated HGV boarding vessel
Figure 3 Swept path for articulated HGV leaving vessel
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Figure 4 Swept path for rigid HGV boarding vessel
Figure 5 Swept path for rigid HGV leaving vessel
As can be seen in Figure 2, Figure 3, Figure 4 and Figure 5 above, a pontoon of
approximately 40m x 40m in plan would be necessary to accommodate the
movements of HGVs turning through 90 degrees. This size of pontoon is significantly
larger than that assumed at the feasibility stage, for which buoyancy to carry the
necessary loading would have been the primary sizing factor. A pontoon of this size
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would incur a much greater cost for construction, transportation to site and
maintenance as well as presenting a greater risk to navigational for other vessels on
the river.
This matter was discussed with TfL as part of this task and a decision has been taken
following a suggestion from TfL to assume the necessary turning movements are
carried out via a curved approach structure (similar to the current Woolwich Ferry
arrangement) such that vehicles would travel over the pontoon in as close to a
straight line as possible. This enables a reduction in the size of the pontoon from that
required above.
Figure 6 Example of curved approach structure at Woolwich (Google Maps, 2013)
For preliminary design a pontoon size is chosen and checked for trim and freeboard
changes under vehicle loading. For the chosen size of 30m x 30m a convoy of 40 tonne
HGVs on the linkspan causes the pontoon to rise by around 0.2 metres at the vessel
ramp landing area. Two HGVs traversing the vessel’s ramp causes the pontoon to fall
by around 0.2 metres at the landing area. The ability of the ship’s ramp to
accommodate such movements is not known at this stage, however the magnitude of
the movements is considered to be reasonable.
5.3.4 Linkspans
The length of the linkspan and the various width allowances are as discussed above.
The range of movement of the linkspan element is accommodated by the provision of
appropriate bearings that permit large rotations at the abutment end and large
rotations coupled with translation at the pontoon end. This caters for the rise and fall
of the pontoon with the tide and allows for pitching rotation.
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Rolling rotation, about the axis of the pontoon in line with the linkspan, is more
problematic, requiring the linkspan to twist. The previous feasibility study envisaged
through truss linkspan structures, which are stiff under this action and intolerant of
such rotations.
For preliminary design purposes a plate girder U‐frame structure is assumed. Whilst
this provides greater flexibility to accommodate twisting than a through truss it
should be stressed that the response of the pontoon/linkspan system should be
assessed in detail before any detailed design is undertaken. Such motions would be
induced by, for example, wave activity or the effect of passing ships.
Vehicular loading on the linkspan is taken as HRo loading in accordance with
BS6349: pt 8, which covers the effects of all permitted normal vehicles licensed under
the Road Vehicles (Construction and Use) Regulations. It is assumed that abnormal
weight vehicles would not be permitted to use the facility, alternative routes across
the river being available elsewhere.
5.3.5 Approach Structures
The approach structures are designed as multi‐span viaduct structures leading from
the shore to the linkspan abutment, supported on piles in the river bed.
The structures envisaged would make extensive use of standard pre‐cast concrete
bridge components for the roadway slab to minimise the need for temporary works
for formwork construction over the river.
5.3.6 Berthing Dolphins
For the layout and preliminary design of berthing dolphins berthing mode b) as set
out in BS 6349: pt 4 has been assumed, using the maximum recommended dolphin
spacing of 25% of the length of the vessel. This berthing mode is based on berthing
the vessel against the dolphins and then making a slow approach towards the
linkspan or pontoon.
Berthing energy is derived from the displacement mass of the berthing vessel and its
transverse approach velocity. For preliminary design purposes the mass of the ferry
vessel is estimated by its block dimensions (Length x Breadth x Draft) to which a
block coefficient of 0.7 is applied, being a typical value for ferries. The transverse
berthing velocity is assessed from Figure 1 of BS 6349: pt 4, assuming berthing
category b) (difficult berthing, sheltered) giving a normal berthing velocity of 0.25
m/s.
Berthing forces are derived from the berthing energy and the load/deflection
characteristics of the chosen fenders.
Typically ferry vessels are constructed with a belting, which protrudes from the hull
at the level of the main deck for the purpose of berthing. To avoid contact with other
areas of the hull it is important to consider the way fenders deflect. For preliminary
design parallel motion fenders are considered, which incorporate a mechanism that
ensures the fender face remains vertical as the fender deflects.
5.3.7 Pontoon Restraint Dolphins
The pontoon restraint dolphins are required to resist the horizontal forces applied to
the pontoons, which arise from vehicular traffic, wind, wave, current and berthing.
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The wave height at the site is assumed to be 0.5 metres for preliminary design
purposes. The actual wave climate at the site should be evaluated before detailed
design is undertaken.
Discussions with PLA during the previous feasibility study identified a maximum
current velocity in the River Thames of 6 knots. General published information for
the Thames warns of currents of up to 4 knots. For preliminary design a normal and
extreme current velocities of 4 knots and 6 knots respectively are assumed.
For berthing it is assumed that fenders are provided on the pontoon for a berthing
velocity appropriate to the berthing mode discussed above. For the berthing mode
considered, in the absence of factual data, BS 6349: pt 4 suggests a berthing velocity of
0.15 m/s, which is assumed for preliminary design.
5.3.8 Number of Lanes
TfL has requested consideration of 2, 4 and 6 traffic lanes connecting shore to ship.
This will have an effect on boarding and alighting times as well as cost.
Halcrow has investigated options and concluded that a linkspan structure with more
than two lanes is not a viable solution. The pontoon can be subject to differential
vertical movements at each side, particularly when acted upon by wash from passing
vessels. This results in a landing area for the lower end of the linkspan which is not
always level. The linkspan must accommodate this by having sufficient torsional
flexibility and a very wide linkspan with sufficient flexibility is likely to be
structurally unstable.
A solution would be to use multiple linkspans of two lanes each. The approach
structures would also have to be widened to accommodate more traffic lanes. The
existing Woolwich Ferry service has approach structures with four traffic lanes; two
in each direction. A similar arrangement would be possible at Gallions Reach though
it should be noted that this will result in additional piling in the river to support such
a structure. However, an additional benefit can be realised in the flexibility to deal
with vehicle movements around obstructions such as breakdowns in the queue whilst
they are awaiting recovery.
An important consideration when investigating multiple traffic lanes is that six lanes
of traffic alighting from the ferry will need to be clear of the pontoon before boarding
traffic can be allowed to enter this area. Queuing traffic would not be permitted on
the linkspans so it is feasible to use linkspans in a bi‐directional arrangement (ie. the
same lanes are used by both alighting and boarding vehicles in consecutive
operations). Given that queuing traffic could occupy half the total number of lanes on
the approach structures it is sensible to provide linkspans with half the number of
lanes as the approach structures.
If four traffic lanes are provided via two separate linkspans, it would be possible to
accommodate them within the same width of pontoon required for a two lane
solution as this width is determined by the width of the ferry vessel. However, the
effect of an additional linkspan on pontoon restraint structures, potential fouls with
piling or the performance of the pontoon under traffic loading has not yet been
considered.
Any introduction of multiple traffic lanes will still need to be linked to the existing
highway network eventually. Any more than two lanes of alighting traffic would
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create a “bottleneck” at the connection with the highway network, though it is
expected that the access roads from the ferry terminals to the highway network have
sufficient length and the movement of alighting vehicles can be sufficiently controlled
to allow all vehicles to be clear of the linkspans without causing delay to boarding
vehicles.
Six lanes of traffic would require a larger pontoon to accommodate the width of
linkspans landing upon it. In addition to the cost of more linkspans, this would
introduce a significant additional capital cost for the pontoons alone and present a
greater hazard to river navigation. With a six lane solution, the problem of
integrating multiple lanes of alighting traffic into the highway is exacerbated even
further. For these reasons, a maximum of four linkspan lanes has been considered.
In summary, the most viable solution based on a high‐level cost/benefit consideration
is a four lane approach structure with a single two‐lane linkspan to the pontoon.
Boarding vehicles will queue at the top of the linkspan and both lanes of the linkspan
will be used in each direction for consecutive alighting and boarding operations. This
decision is also informed by estimates of alighting and boarding times discussed in
section 7.
5.3.9 Existing Flood Defences
It is known from previous studies and discussions that the Environment Agency, as
manager of the flood defence walls, would prefer an option which requires little or no
modification to the existing provisions at Gallions Reach. A solution which does not
raise major objections from the Environment Agency is considered much more likely
to progress to construction.
In the course of developing preliminary designs, Halcrow has determined that it is
possible to achieve the required geometrical parameters with a solution which passes
over the existing flood defences, eliminating the need for costly specialist flood gates.
Indeed, the shorter approach lengths that could be achieved by starting from a lower
level and penetrating the walls would not result in a pontoon being positioned any
closer to the river bank due to depth constraints.
For these reasons, only the option of starting from the flood defence level of 10.6m
CD has been considered for the preliminary design.
5.3.10 Ancillary Infrastructure
The remote and open nature of the Gallions Reach site presents a need to provide
shelter for non‐motorised users whilst waiting for the ferry to arrive. A proprietary
shelter as used for bus stops may not be able to accommodate the number of non‐
motorised users if cyclists are included. However, a similar lightweight shelter with a
larger capacity can be positioned along the footpath at the top of the linkspans to
afford protection from the elements. It is not proposed to provide shelter along the
length of the approach structures but this could quite easily be accommodated if
necessary. A lightweight windshield which may incorporate a cantilevered roof could
be mounted to the edge beams and/or parapets of the approach structures, though
the effect of wind loading on the resulting increase in cross‐sectional area would need
to be checked at detailed design stage.
It is known that a key consideration for TfL is to develop a solution which requires a
minimal level of staffing, particularly in comparison with the existing Woolwich
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Ferry service. Further details of staffing levels are provided in the section of this
report which deals with operational procedures but it has been assumed that only a
relatively small cabin would need to be provided for staff welfare. A standard sized
“Portacabin” type building provided just inland from each terminal is considered
adequate to contain toilet, hand washing and rest facilities for operatives. There is
also expected to be sufficient room in the same building for a small administration
office if required.
Tolling is assumed to be via a cashless freeflow system using Automatic Number
Plate Recognition (ANPR), and not expected to be controlled from the ferry terminals.
Facilities for maintenance will consist of a secure and enclosed storage area roughly
6m x 6m. This will contain consumables and spares for keeping the terminals and
limited parts of the vessels in proper working order.
Other infrastructure requirements will include navigation lighting on the pontoon
and streetlighting for vehicles using the approach structures, linkspan and pontoon.
An electrical supply will also be necessary to provide power to pumps in the
pontoons. Firefighting equipment can consist of a saltwater pump using the river as a
supply. This removes the need for a water supply to the terminals and the associated
difficulties of providing and maintaining a supply pipe through the articulated
linkspan section. The terminal structures have been designed with gradients which
will aid drainage through gravity. Discrete penetrations in the roadway channels can
be provided to discharge run‐off directly into the river, subject to obtaining any
necessary consents.
5.3.11 Passive Provision for Third Vessel
The scope of this task requires consideration of passive provision for a third vessel.
The nature of the terminals for the propeller driven ferry would allow three vessels to
operate in rotation at peak times with no change to the infrastructure. The total
crossing time is a combination of berthing, alighting, boarding and sailing times. It is
expected that the sailing time would be relatively short in comparison to the berthing,
unloading and loading time. This could lead to a third vessel waiting for a terminal to
be available, delaying the crossing time and causing an obstruction to other river
users. In this circumstance, the need for a third vessel is questionable.
A non‐passive solution which would allow the use of three vessels would be to
construct additional infrastructure consisting of an extra linkspan and pontoon in the
opposite orientation to those in the preliminary design (ie. pointing in the upstream
direction), connected to the same approach structure. This would be a significant and
costly modification but it could be achieved at a later date with minimal disruption to
the existing terminals. The application of such a solution to service an additional
vessel is unlikely to provide sufficient justification for the additional cost of
infrastructure. It would be more appropriate to provide a total of four vessels in this
instance, which would effectively cost the same again as the preliminary design for
two vessels.
Given the factors above, it is considered unlikely that provision of a third vessel
would be practicable on the grounds of operability and/or cost.
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5.4 Construction Considerations
The preliminary design of the proposed pontoon and linkspan terminal solution has
considered a likely method of construction to optimise efficiency in cost and
programme. A detailed construction methodology will need to be developed as the
design progresses, preferably in consultation with an experienced marine
construction contractor.
5.4.1 Constructability
The preliminary design of infrastructure for a propeller driven ferry uses
prefabricated elements and precast sections wherever possible for ease of
construction. Major elements such as the pontoons and linkspans are likely to be
constructed away from the site by specialist fabricators and delivered as single
elements for installation. In the case of pontoons, these can be floated up the river
with tugs. The linkspans can also be delivered using a barge on the river to minimise
disruption on the local highway network.
The approach structures will consist of precast concrete beams supported on precast
concrete crossheads at the top of each set of piles/columns, connected with an insitu
concrete stitch. These can be installed quickly and provide a temporary working
platform for access to complete the deck with insitu concrete from a mobile pump.
Piling for the approach structures and dolphins will require the use of specialist river‐
based marine piling equipment. During construction, this equipment will present an
additional hazard to navigation in the river and will need to be suitably marked and
lit to warn vessels of its presence.
5.4.2 Closures/Diversions
The proposed site for both north and south terminals is within (or very close to) the
safeguarded corridor for the Thames Gateway Bridge. In the vicinity of the
infrastructure itself, there are no existing highways that would require closure or
diversion in the construction or operation phases.
On the south bank of the river, the scheme will need to take account of the existing
Thames Path. It is anticipated that pedestrians crossing the main access route to the
ferry can be accommodated by an at‐grade crossing where vehicles boarding or
alighting the ferry would have priority to eliminate delays to the ferry schedule.
5.4.3 Utilities
Based on information available for the area, there are no known utilities within the
footprints of either the northern or southern terminals.
Connections will need to be made to the electricity network for provision of power to
tolling equipment, operational facilities and navigational lighting. Existing power
networks are available in the vicinity of each terminal to which these connections are
assumed to be possible.
In the case of navigational marking equipment, an uninterruptable power supply will
need to be provided. This is anticipated to consist of a back‐up generator in the
vicinity of the operator facilities at each terminal.
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Telecommunications lines will also be necessary for the use of the operator and to
convey tolling information to a control centre which is assumed to be remote from the
ferry location.
5.4.4 Programme
The likely planning and procurement programme for provision of a ferry service at
Gallions Reach was considered by Halcrow in the 2009/10 Woolwich Ferry
Replacement and Gallions Reach Ferry Feasibility Study. Whilst this programme is
outside the scope of this task, Halcrow considers it to still be appropriate and has
refreshed it for the current start dates. The start date for construction of a propeller
driven ferry is based upon the date of completion of this planning and procurement
programme. This programme is included in Appendix H.
An outline programme for construction of the propeller driven ferry infrastructure is
included in Appendix H. This programme deals with construction works alone as
defined in the TfL brief for this task. Where appropriate, works are carried out
simultaneously on each side of the river. However, mobilization of multiple marine
piling rigs is not considered cost effective and would present a greater navigational
obstacle. Piling on one side of the river at a time will introduce a sequenced
construction for the approach structures and dolphins.
The overall construction duration from mobilisation to commencement of operation
is estimated to be two years and three months. This duration is based upon an
assumption that design and construction of pontoons and linkspans is let by TfL to a
specialist contractor up to 18 months in advance of the terminal construction contract.
5.5 Proposed Operational Procedures
The propeller driven ferry infrastructure has been designed assuming a minimal level
of staffing. The use of pontoons provides a self‐adjusting system to accommodate
tidal levels and ensure that it will always be at the same level relative to the ferry
vessel. This eliminates the need for an operative to adjust the linkspan angle at each
berthing.
Whilst consideration of the number of crew on the ferry vessel is outside the scope of
this task, it is recognized that navigation and berthing for a propeller driven ferry will
require more crew than for a chain ferry. It is assumed that the ferry crew will also be
able to deal with boarding and alighting traffic at the lower end of the linkspan,
providing direction to users as necessary.
Landside operations are expected to be carried out with a minimum of four
operatives on each side of the river (for traffic marshalling, mooring hands and
supervisors).
Vehicles would not be permitted to queue on linkspans or on the pontoon. This is
primarily a consideration of avoiding congestion between traffic queuing to board the
ferry and those vehicles which are alighting. Depending upon the number of traffic
lanes chosen, waiting vehicles would queue either behind the line of the flood
defences or at the top of the linkspan(s).
Ferry crew would communicate with an operative at the head of queue to advise
when vehicles are clear of the pontoon and the identity of the final vehicle. Once this
final vehicle has cleared the top of the linkspan, the landside operative would release
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the queuing vehicles, keeping a tally of PCUs. If more than a full ferry load of
vehicles is queuing, a number of vehicles corresponding to slightly lower than the
capacity of the vessels would be released by the landside operative. This is in order to
avoid congestion and/or the need to send vehicles back to the waiting area (which
would be extremely difficult in the case of HGVs).
Waiting pedestrians and cyclists could queue at the top of the linkspan, with suitable
provision of shelter as discussed in this report under ancillary structures. The
gradients of the approach structures, linkspans, pontoons and ferry ramp will enable
easy access for mobility impaired users. Non‐motorised users could be released at the
same time as vehicles and can safely board the ferry due to segregation provided
along the entire approach.
Alighting would follow the same procedure as boarding but in reverse. There is
considered to be no benefit in simultaneous alighting and boarding operations. The
number of available traffic lanes means that only half as many lanes could be used in
each direction, with no resulting net gain in time. Simultaneous movement of
alighting and boarding vehicles is also likely to increase the risk of disruption due to
queuing and/or clashes with space constraints. For these reasons, a simultaneous
alighting and boarding approach has therefore been discounted.
It is assumed that pedestrians and cyclists would use the ferry service free of charge.
Whilst it would be relatively simple to keep a tally of the number of non‐motorised
users as they board the ferry, this is not considered to be necessary for a crossing at
Gallions Reach. The Merchant Shipping (Counting and Registration of Persons on
Board Passenger Ships) Regulations 1999 require a record of the number of persons
on board a vessel but the relatively short river crossing at Gallions Reach satisfies
clauses 13(i) and 13(ii) for exemption. This is thought to be the case for the existing
Woolwich Ferry, where the number of non‐motorised users is recorded but the
number of occupants in vehicles is not recorded. It should be noted that an
application for exemption from these regulations needs to be made to the local
Maritime and Coastguard Agency Marine Office.
When the ferry is not in service (ie. outside operating hours), it is anticipated that one
vessel would be moored at each of the terminals.
5.5.1 Maintenance
Maintenance of the ferry vessels is assumed to be carried out at a dry dock facility
away from the terminal location. Until the ferry design is finalised such facilities
cannot be investigated, but this aspect is outside the scope of the infrastructure
preliminary design task. It is, however, anticipated that the size and draft of the
vessels would rule out a similar arrangement to that at Woolwich where vessels are
positioned on a maintenance grid at high tide.
The remaining maintenance tasks will consist of greasing linkspan bearings/joints,
cleaning and replacing worn parts from pumps and eventual reapplication of
protective coatings to the metal surfaces of linkspans and pontoons.
The propeller driven ferry infrastructure has been designed on the basis that
dredging will not be required for construction or throughout the service life of the
ferry.
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6 Preliminary Infrastructure Design for Chain Ferry The second option considered for a ferry at Gallions Reach is a chain ferry service
utilising slipways on each side of the river. The ferries pull themselves along chains,
which run along each side of the vessel and are anchored and tensioned on the shore.
Design of the ferry vessels themselves is outside the scope of this task and TfL has
provided parameters for their size and capacity, which will be progressed to detailed
design by others.
6.1 TfL Design Parameters
Ferry ‐ 2 no. vessels (with passive provision for a third vessel);
‐ 8.0m separation between vessels on the same slipway;
‐ 90 Passenger Car Unit (PCU) capacity;
‐ 6 traffic lanes (2 x 2.7m wide outer lanes for cars, 4 x 3.0m wide
inner lanes for HGVs);
‐ PCU length of 5.0m, including longitudinal gap between vehicles;
‐ 80m maximum overall length, 25.8m beam, 2.5m draft; and
‐ Passenger lounge on one side of vessel.
Holding area ‐ Liaison with highways designer to ensure sufficient land side area
for waiting vehicles.
Lane options ‐ Investigate 2, 4 and 6 lanes on each slipway.
6.2 Standards Used
Whilst no formal design standards have been adopted at this stage for the
preliminary design of infrastructure for the chain ferry option, the geometrical
requirements described in the following sections are based upon industry best
practice.
6.3 Design Considerations and Assumptions
6.3.1 Vertical Geometry
The top of the slipway is set at the flood defence level of 10.6m CD to avoid the need
to breach the flood defences. The lower end of the slipway is set at ‐0.5m CD.
Photographs of the Torpoint Ferry operation indicate that the vessel grounds the
inner portion of its two‐part ramp on stools. The stools contact the slipway at
approximately the water level on the slipway. At Lowest Astronomical Tide (LAT),
the water level is 0.00m CD, therefore the lowest point of contact, excluding extreme
low water levels, is at 0.00m CD. An allowance of 0.5m below this level has been
included to allow for tolerance or extreme events. The overall height of the slipway is
therefore 11.1m.
The gradient of the slipway is a compromise between a shallow gradient for the safe
use by both pedestrians and vehicles and a steeper gradient which would be
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beneficial to the vessel. There appears to be no standard that provides guidance on
recommended gradients for such installations so best practice has been adopted. A
gradient of 1 in 8 (or 12.5%) has been set for the slipway. This gradient is commonly
used for beaching type ferries both conventionally powered and chain driven. A 1 in
8 gradient gives an overall length of slipway of 88.8m from its lower end up to the
flood defence level.
6.3.2 Horizontal Geometry
The setting out point for the outer end of the slipway is the ‐3m CD contour. The
draft of the vessels is 2.5m and an underkeel clearance of 0.5m has been allowed.
This gives a level of 3.0m below the lowest operating level of 0.0m CD (LAT).The
lower end of the slipway is 20m inside the ‐3.0m CD contour (This is a 2.5m rise at a
gradient of 1 in 8). From this point, the slipway rises at 1 in 8 to the flood defence
level of +10.6m CD, a total length of 88.8m. As can be seen in the drawings in
Appendix C, the plan length of the slipway arrives at the +10.6m CD level just
riverward of the flood defence lines on both sides of the river.
The slipway on the north bank has been relocated some 100m north of the original
proposed position to avoid clashing with the two outfalls on the north bank.
The width of the slipway is 80m, made up of 2 x 25.8m wide ferries with an 8m
central clearance and 10.2m clearance allowance on either side. The side clearance
should be reconsidered when designs are more developed to take account of the
down‐current drift of the ferry in operation.
The Gallions Barge Road mooring is directly in front of the south bank slipway and
will require to be lifted and relocated remote from the slipway.
The position of the north bank slipway overlays some of the remaining piles from a
previous jetty. These piles will have to be removed or cut down over the extent of the
slipway.
6.3.3 Design of Slipways
The construction of the slipway is affected by tidal water which must be considered
in the design. The outer end of the slipway is permanently submerged and as the
slipway rises, the time available above water increases until above the high water
mark, the slipway is permanently above water.
The ground conditions at the slipway locations indicate that the existing bank/ river
bed comprises very soft alluvium up to 7m thick overlying chalk. The alluvium,
especially within the river area, is considered too weak to support a ground bearing
slab. The options are therefore to remove the alluvium and to replace it with a more
competent material or to support the slipway on piles. Due to uncertainties over the
extent of alluvium to be removed, together with uncertainties over its disposal and
potential contaminants, a ground bearing slab option for the slipway has been
discounted as an unviable solution.
The proposed slipway comprises a series of vertical piles supporting a composite
precast/insitu concrete deck over the river section of the slipways. At the top of the
slipways, the slipway is ground bearing within cut and fill as appropriate.
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The slipway has been designed for loading from the vessel and traffic loading. The
vessel is assumed to ground only its ramp at one end on stools. It has been assumed
that the stools effectively moor the vessel to the slipway and a preponderance of
300kN has been assumed for the loading from the stools. It is assumed that there are
four stools per ramp on each end of the vessel (ie. eight stools in total per vessel) and
that the preponderance load is shared evenly between the stools.
As discussed in more detail under the heading of boarding and alighting time
estimates, it is not possible to provide a physical segregation between
pedestrians/cyclists and vehicles on a chain ferry slipway.
6.3.4 Chains and Chain Tensioners
Simplified calculations, based on the drag and wind forces acting on the ferries have
been carried out to estimate the pull forces required within the chains. To determine
drag and wind forces on the ferry, the following assumptions have been made
The maximum speed of the ferry is 6Kn (3m/s); and
The maximum operational wind speed is 40 Kn (20m/s).
The proposed chain has a diameter of 42mm.
The length of each chain will be approximately 700m, therefore creep in the chain
plus wear on the links during use may lengthen the chain significantly. Regular
maintenance of the chain will involve a regime of checking for wear and extension
with removal of links as necessary to achieve a relatively consistent total length.
Following discussion with the operator of the Torpoint Ferry and without a detailed
specification for the ferry vessel, chain tensioners are considered necessary for this
location. Their function is primarily to take up slack on the chains in front of the ferry
as it approaches the slipway to berth. Without such a system, the momentum of the
approaching ferry may cause it to “overtake” its chains when the rate at which they
are pulled through the vessel slows. For this reason, it is proposed to provide chain
tensioning equipment at each side of the river.
A self‐adjusting chain tensioning system is employed at Torpoint (refer to Figure 7
below) and is considered to be a suitable example of a system that could also work at
Gallions Reach. This system has a relatively small footprint and relies on gravity
rather than powered equipment to maintain the required tension in the chains. It
should be noted that maintenance of this system will require training of operatives.
As the design of the ferry develops it may be possible to eliminate the need for chain
tensioners, replacing them with anchorages at each shore instead. These could consist
of piled foundations and are estimated to be up to approximately 40% of the cost of
the chain tensioners. In the development of cost estimates for the chain ferry, a
conservative allowance for the more expensive tensioners has been included. Relative
to the cost of the overall infrastructure proposal, the additional cost is considered to
be minor.
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Figure 7 Chain tensioning gantry at Torpoint Ferry (Tamar Crossings 2002)
6.3.5 Number of Lanes
TfL has requested consideration of 2, 4 and 6 traffic lanes on each slipway. As the size
of the slipway is determined by the width of the ferries, which accommodate six
traffic lanes each, this will have an effect on boarding and alighting times. It is
expected that the operational regime of the chain ferry will require all alighting
vehicles to be clear of the slipway before boarding vehicles are allowed to enter the
area. Therefore, the use of multiple lanes for alighting and boarding will be the fastest
procedure.
Any introduction of multiple traffic lanes will still need to be linked to the existing
highway network eventually. Any more than two lanes of alighting traffic would
create a “bottleneck” at the connection with the highway network, though it is
expected that the access roads from the ferry to the highway network have sufficient
length and the movement of alighting vehicles can be sufficiently controlled to allow
all vehicles to be clear of the slipway without causing delay to boarding vehicles.
An increasing number of traffic lanes will result in additional cost in the estimates for
highway configurations (outside the scope of this task). However, an additional
benefit can be realised in the flexibility to deal with vehicle movements around
obstructions such as breakdowns in the queue whilst they are awaiting recovery.
For the chain ferry option, the infrastructure arrangement does not impose any
restriction on the number of traffic lanes. For this reason it is possible to utilise any
number of lanes, subject to the availability of land to accommodate the required
width of highway approach. However, the estimation of alighting and boarding
times in section 7 would suggest that there is a balance to be achieved between the
number of lanes (and associated cost of construction) and the benefit in time savings
that can be realised.
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A highway approach using four lanes is considered to be the best compromise. This
would also allow a greater level of control than six lanes for marshalling staff, who it
is expected would follow a particular method of loading the ferry (eg. loading edge
lanes first and keeping HGVs in the centre lanes only).
6.3.6 Existing Flood Defences
The required vertical geometry can be achieved by starting from the level of the
existing flood defences. There is little or no benefit in penetrating the flood defences
to reduce the length of slipways as this would bring the lower end of the slipways too
close to the river bank to accommodate the required draft of the specified vessels
without expensive and ongoing dredging.
6.3.7 Ancillary Infrastructure
The waiting area for non‐motorised users of the chain ferry is assumed to be inland of
the flood defence walls. This would be less exposed than the waiting area for a
propeller driven ferry but it is considered appropriate to provide a shelter
nonetheless. As described for the propeller driven ferry, a large capacity lightweight
shelter can be positioned at the top of the slipways to afford protection from the
elements.
It is known that a key consideration for TfL is to develop a solution which requires a
minimal level of staffing, particularly in comparison with the existing Woolwich
Ferry service. Further details of staffing levels are provided in the section of this
report which deals with operational procedures but it has been assumed that only a
relatively small cabin would need to be provided for staff welfare. A standard sized
“Portacabin” type building provided just inland from each slipway is considered
adequate to contain toilet, hand washing and rest facilities for operatives. There is
also expected to be sufficient room in the same building for a small administration
office if required.
Tolling is assumed to be via a cashless freeflow system using ANPR, and not
expected to be controlled from the ferry terminals.
Facilities for maintenance will consist of a secure and enclosed storage area roughly
6m x 6m. This will contain consumables and spares for keeping the slipway, chains
and limited parts of the vessels in proper working order. A further area needs to be
reserved for slipway cleaning equipment and temporary storage of arising from the
cleaning operations.
Navigation lighting at the lower end of the slipway and streetlighting for vehicles
will require an electrical supply. The most appropriate method for firefighting at the
chain ferry terminals is considered to be through dedicated hydrants, which will
require a new mains water supply to be provided. The gradient of the slipways will
result in any run‐off discharging directly into the river. This is likely to require land
drainage consents.
6.3.8 Passive Provision for Third Vessel
The scope of this task requires consideration of passive provision for a third vessel.
The layout of the chain ferry slipway means that in theory any number of vessels can
be accommodated, provided a slipway of sufficient width is constructed. A chain
ferry follows a pre‐determined course and berths in the same lateral position on the
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slipway, subject to currents, every time. Widening the slipway is not a passive
solution however and would require greater land take in the river, with associated
hydrodynamic and environmental impacts.
A wider slipway to accommodate a third vessel would require further consideration
of the highway connection to it. It may not be practicable to provide sufficient
capacity and flexibility in the highway to allow users to board and alight any of three
possible vessels. Again, this would not be a passive provision.
In summary, it is not considered possible to have passive provision for a third chain
ferry. The level of intervention required would result in further design effort and
significant capital investment. However, should an additional vessel be required, it is
considered possible to construct an extension to the slipways with minimal
disruption to operations.
6.4 Construction Considerations
The preliminary design of the proposed slipway terminal solution has considered a
likely method of construction to optimise efficiency in cost and programme. A
detailed construction methodology will need to be developed as the design
progresses, preferably in consultation with an experienced marine construction
contractor.
6.4.1 Constructability
As discussed in previous sections, a solid slipway is not considered an appropriate
solution for the ground conditions. Piling for the slipways will require the use of
specialist river‐based marine piling equipment. During construction, this equipment
will present an additional hazard to navigation in the river and will need to be
suitably marked and lit to warn vessels of its presence.
For a piled slipway, the deck structure will consist of precast concrete beams
supported on insitu crossheads at the top of each set of piles/columns. These can be
installed quickly and provide a temporary working platform for access to complete
the deck with insitu concrete from a mobile pump.
The upper end of the slipway, down to about mid tide level could be built in the dry
with the works scheduled around the tides. The lower section of the slipway is only
exposed for a short period, therefore there are three options for construction.
Firstly, the construction could be undertaken in the short periods when the slipway is
above water. This would lead to both very slow construction and potential quality
issues with the works being submerged after only a short period of exposure so is not
recommended.
Secondly, the construction could be undertaken in the wet, using divers for the
periods when the slipway is submerged. However, visibility in the river is poor and
currents are relatively fast, therefore this would increase the difficulty of the already
difficult construction. Again, this option is not recommended.
Thirdly, the works could be constructed within a cofferdam. The cofferdam would
allow the works to be carried out in dry conditions without disruption due to tidal
waters, therefore both programme and quality can be maintained. The main
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disadvantage of a cofferdam is the cost of its provision, maintenance and removal but
it is the most suitable solution in terms of constructability.
The main benefit of constructing the lower end of the slipway within a cofferdam is
that the cost, programme and quality of the works can be more closely controlled.
The potential risks of working either in the wet or the dry on a tidal window are such
that they are considered unacceptable. Therefore the preliminary design of the
slipway has been undertaken assuming that the lower half of the slipway is
constructed within a cofferdam. The upper half of the slipway is above water level for
more than 50% of the time and works could be undertaken around the tides using
land‐based access and equipment.
At the lower end of the slipway, the depth of water excluded by the cofferdam could
be up to 10m deep to allow for works below the finished level of the slipway. In
order to minimise the internal strutting within the cofferdam, it is proposed to
construct the lower 40m of slipway in two sections 80m wide by 20m long, each
within cofferdams immediately adjacent to each other. It would be possible to
minimise costs by installing the two cofferdams one after the other, re‐using the
common wall of sheet piling between the two positions.
6.4.2 Closures/Diversions
The proposed site for both north and south slipways is within (or very close to) the
safeguarded corridor for the Thames Gateway Bridge. In the vicinity of the
infrastructure itself, there are no existing highways that would require closure or
diversion in the construction or operation phases.
On the south bank of the river, the scheme will need to take account of the existing
Thames Path. It is anticipated that pedestrians crossing the main access route to the
ferry can be accommodated by an at‐grade crossing where vehicles boarding or
alighting the ferry would have priority to eliminate delays to the ferry schedule.
6.4.3 Utilities
Based on information available for the area, there are no known utilities within the
footprints of either the northern or southern slipways.
Connections will need to be made to the electricity network for provision of power to
tolling equipment, operational facilities and navigational lighting. Existing power
networks are available in the vicinity of each slipway to which these connections are
assumed to be possible.
In the case of navigational marking equipment, an uninterruptable power supply will
need to be provided. This is anticipated to consist of a back‐up generator in the
vicinity of the operator facilities at each slipway.
Telecommunications lines will also be necessary for the use of the operator and to
convey tolling information to a control centre which is assumed to be remote from the
ferry location (ie. an addition to the existing London congestion charging scheme).
A mains water supply will need to be extended from the existing network to the
terminal locations for the provision of fire hydrants.
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6.4.4 Programme
As for the propeller driven ferry option, the likely planning and procurement
programme for a chain ferry will retain the same logic as presented by Halcrow in the
2009/10 Woolwich Ferry Replacement and Gallions Reach Ferry Feasibility Study.
The start date for construction of a chain ferry is based upon the date of completion of
this planning and procurement programme.
An outline programme for construction of the chain ferry infrastructure is included in
Appendix H. This programme deals with construction works alone as defined in the
TfL brief for this task. Where appropriate, it is assumed that works are carried out
simultaneously on each side of the river. However, mobilization of multiple marine
piling rigs is not considered cost effective and would present a greater navigational
obstacle. Piling on one side of the river at a time will introduce a sequenced
construction for the slipways.
The overall construction duration from mobilisation to commencement of operation
is estimated to be two years and nine months. This is some six months longer than the
construction duration for propeller driven ferry infrastructure and reflects the use of
largely prefabricated elements in the other option.
6.5 Proposed Operational Procedures
The chain ferry infrastructure has been designed assuming a minimal level of
staffing. Whilst consideration of the number of crew on the ferry vessel is outside the
scope of this task, it is recognized that navigation and berthing for a chain ferry will
require only a few crew members. The crew can have a relatively lower level of skill
in comparison to propeller driven ferry crew, as the course of the vessel is
predetermined by the route of the chains. It is assumed that the ferry crew will also
be able to deal with the positioning of boarding traffic and this is likely to be the
major factor in determining the number of crew.
Landside operations could feasibly be carried out with as little as two operatives on
each side of the river. This eliminates the hazards associated with lone working in the
relatively remote location whilst providing flexibility to allow continual operation
whilst one operative deals with user issues or takes a break.
Waiting vehicles would queue at the top of the slipways behind the line of the flood
defences. Given the relatively short straight length of the slipways, an operative at the
head of queue would be able to judge when to release the queuing vehicles, keeping a
tally of PCUs. If more than a full ferry load of vehicles is queuing, a number of
vehicles corresponding to slightly lower than the capacity of the vessels would be
released by the landside operative thought this is less critical than for the longer
approach to a propeller driven ferry and final additions to the number of vehicles
could be made relatively quickly.
Waiting pedestrians and cyclists could queue at the top of the slipway, with suitable
provision of shelter as discussed in this report under ancillary structures. The use of a
slipway and ferry ramp will enable access for mobility impaired users, however the
gradients are relatively steep. The only practicable solution would be for ferry staff to
assist passengers when required.
As physical segregation from vehicles is not possible with a chain ferry, non‐
motorised users would have to be carefully controlled to ensure segregation from
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vehicles. Segregation in time (ie. pedestrians and cyclists are released either before
vehicles are allowed to board or after all vehicles have boarded) is the safest
procedure, but this would increase alighting and boarding times and subsequently
affect crossing frequency. Taking an example from the Torpoint Chain Ferry, signage
and staff announcements could be employed to ensure the safe passage of non‐
motorised users at the same time as vehicles.
Alighting would need to be controlled by the ferry crew to ensure lines of vehicles on
the vessel are released in such a way that a bottleneck as they approach the fewer
number of lanes on the highway network is avoided.
It is assumed that pedestrians and cyclists would use the ferry service free of charge.
Whilst it would be relatively simple to keep a tally of the number of non‐motorised
users as they board the ferry, this is not considered to be necessary for a crossing at
Gallions Reach. As for the propeller driven ferry, this service is considered to be
exempt from the Merchant Shipping (Counting and Registration of Persons on Board
Passenger Ships) Regulations 1999. It should be noted that an application for
exemption from these regulations needs to be made to the local Maritime and
Coastguard Agency Marine Office.
When the ferry is not in service (ie. outside operating hours), it is anticipated that one
vessel would be moored at each of the slipways. However, the variation in tidal range
would require each vessel to be moored just short of the slipway. If the vessel were to
be moored closer to the shore at high tide, it could be beached until the next high tide,
which may not coincide with the scheduled resumption of service. Dedicated access
to and from the vessel will need to be provided for crew at the beginning and end of
each day. Whilst a bespoke gangplank arrangement could be designed, it is
envisaged that a simple and effective solution would be to provide a small craft for
crew access as part of the vessel specification.
It should be noted that overnight mooring of the vessels off the lower end of the
slipways would not cause them to encroach into the navigation channel in the river.
6.5.1 Maintenance
The removal of the ferry vessels and transportation to a suitable maintenance facility
is a more complicated operation for a chain ferry than for a propeller driven ferry.
Once removed from the chains, the vessels are assumed to be tugged to a remote dry
dock facility for maintenance. Until the ferry design is finalised such facilities cannot
be investigated, but this aspect is outside the scope of the infrastructure preliminary
design task. It is however considered that maintenance activities themselves would
be relatively simple and many tasks could be carried out without the need to take the
vessel away.
The remaining maintenance tasks will primarily consist of cleaning the slipways of
river deposits which would make them slippery and dangerous to users. An example
form the Torpoint Ferry is the most likely solution. A tractor at each slipway is used
with a purpose built cleaning tool on the front. This brushes and collects arisings
from the slipway which can then be deposited in a designated storage location for
collection and removal by a specialist contractor at regular intervals.
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Figure 8 Slipway cleaning equipment used at Torpoint Ferry (Merlo 2007)
The chain ferry infrastructure has been designed on the basis that dredging will not
be required for construction or throughout the service life of the ferry.
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7 Estimates of Alighting and Boarding Times Initial estimates of alighting and boarding times have been developed assuming a
system with 2 traffic lanes. For modelling the unloading and loading of the ferry, a
microsimulation model called VISSIM (developed by Planung Transport Verkehr
AG) was used. This is a car‐following model, which models the speed and gap
acceptance of drivers. It does this stochastically; different results will be produced
each time the model is run, as long as the random seed number is changed.
A fairly simple VISSIM model was created to model the vehicles loading on and off
the various ferry and highway configurations. This was primarily to observe the
occurrence of a “shockwave” or “concertina” effect, along the route from the waiting
area to the ferry. This is due to vehicles having to drop their speed when they go from
the linkspan to the pontoon (in the case of a propeller driven ferry) or from the
slipway to the ferry ramp (in the case of a chain ferry). This causes the vehicles
behind them to slow down, in turn impacting the vehicles behind these, creating a
wave effect which heads back up the line of vehicles, away from the linkspan or ferry
ramp where it started.
7.1 Propeller Driven Ferry
For the propeller driven ferry, additional VISSIM models have also been run for
terminal arrangements with four and six traffic lanes. The four‐lane model consists of
four lanes for marshalling vehicles on the approach structure and two lanes for
disembarking traffic. The advantage over the previous two‐lane model is that the
travel distance between the marshalling area and the ferry is reduced. The six‐lane
model consists of four marshalling vehicles on the approach structure and two lanes
for disembarking traffic with the same reduction in travel distance.
7.1.1 Two lanes – Assumptions for Alighting Model
In development of the VISSIM model for ferry alighting, the following assumptions
have been used:
This has the same dimensions as the loading model, but all the directions are
reversed;
It is assumed that only two of the 6 lanes of traffic in the ferry are allowed out
at any one time, to prevent a bottleneck between the pontoon and the
linkspan;
At the connection from the pontoon to linkspan, conflict areas are introduced,
to prevent the vehicles from the six different pontoon lanes running into each
other as they merge into the 2 lanes of the linkspan; and
There are no stop signs on this version of the model; the assumption is that the
vehicles can drive off the ferry.
7.1.2 Two lanes – Results of Alighting Model
The VISSIM model for alighting of the ferry using the above assumptions produces
the following results:
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The shockwave effect does not occur as vehicles start off at less than 5mph,
and then increase their speeds to 10mph, rather than the other way round;
The model was run ten times. Each time, after 440 seconds (7 minutes and 20
seconds) all vehicles have disappeared from the system;
The first vehicle disappears from the system typically at 110 seconds (1
minutes and 50 seconds) in; and
The last vehicle has left the ferry typically around 342 seconds (5 minutes and
42 seconds) in.
The following figures show screenshots from the VISSIM model where the different
coloured “vehicles” represent the different lanes of traffic.
Figure 9 Screenshot of VISSIM 2-lane alighting simulation after 70 seconds
Figure 10 Screenshot of VISSIM 2-lane alighting simulation after 110 seconds
Figure 11 Screenshot of VISSIM 2-lane alighting simulation after 210 seconds
7.1.3 Two lanes – Assumptions for Boarding Model
In development of the VISSIM model for ferry boarding, the following assumptions
have been used:
No vehicle in the model travels faster than 10mph;
The linkspan and approach structure combined are represented as a 280m two
lane highway, with no lane change allowed;
Ferry
Linkspan
Pontoon
Approach structure
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The linkspan is represented as a reduced speed area on the last 60m of this
section, with a maximum speed allowed of 5 mph;
The pontoon is represented as 6 connectors (length 28m), which connect the
two lanes of the linkspan and approach structure to the 6 lanes of the ferry.
These also are a reduced speed area, with a maximum speed allowed of 5mph;
The ferry is represented as a 6 lane section. It is a reduced speed area, with a
maximum speed allowed of 5mph;
It will take at least 5 seconds for vehicles to park once on the ferry. This is
represented in the model with a stop sign, at which the vehicles are delayed
for 5 seconds. After reaching the end of the ferry, vehicles wait for 5 seconds
then disappear from the model;
The distance of the ferry section which vehicles must drive across, is reduced
for vehicles entering the ferry later. As a compromise the section representing
the ferry is half the length of the actual ferry; and
The simulation starts with the first car leaving the marshalling area on the
land side of the river wall.
7.1.4 Two lanes – Results of Boarding Model
The VISSIM model for boarding of the ferry using the above assumptions produces
the following results:
90 vehicles are uploaded into the system, with 15 set to go at each of the 6
possible routes available at the pontoon;
The model was run ten times. Each time, after 460 seconds (7 minutes and 40
seconds) all vehicles have disappeared from the system. Note that this
disappearance occurs after vehicles have reached the section representing the
ferry;
It is about 240 seconds (4 minutes) until the last vehicle has entered the system
(ie. the last car has left the marshalling area);
It is about 130 seconds (2 minutes 10 seconds) until the first vehicle disappears
from the system (ie. the first car is parked.) This is a more conservative
estimate than was previously used;
It seems thus safe to assume that the previous estimate of 8 minutes for
loading is safe; and
The shockwave effect is observed slowing vehicles down.
The following figures show screenshots from the VISSIM model where the different
coloured “vehicles” represent the different lanes of traffic.
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Figure 12 Screenshot of VISSIM 2-lane boarding simulation after 60 seconds
Figure 13 Screenshot of VISSIM 2-lane boarding simulation after 130 seconds
Figure 14 Screenshot of VISSIM 2-lane boarding simulation after 250 seconds
Figure 15 Screenshot of VISSIM 2-lane boarding simulation after 340 seconds
7.1.5 Four lanes – Assumptions for Alighting Model
In development of the VISSIM model for ferry alighting, the following assumptions
have been used:
For this version of the model, the combined linkspan and approach was
represented as a 90m section, with two lanes and no lane changing allowed;
From this six connectors represent the six lanes on the pontoon; these connect
the two lanes of the linkspan to the six lanes on the ferry. They all have a
horizontal length of 30m;
Vehicles in the model can go a maximum speed of 10mph, however a 5mph
reduced speed area is present on the linkspan, the pontoon and the ferry;
As with the previous alighting models, it is assumed that only two of the six
lanes of traffic on the ferry are allowed out at any one time, to prevent a
bottleneck between the pontoon and the linkspan; and
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There are no stop signs on this version of the model; the assumption is that the
vehicles can drive straight off the ferry.
7.1.6 Four lanes – Results of Alighting Model
The VISSIM model for alighting of the ferry using the above assumptions produces
the following results:
The model was run ten times. Each time, after 398 seconds (6 minutes and 38
seconds) all vehicles have disappeared from the system. The median time
taken for all vehicles to disappear was 391 seconds (6 minutes 31 seconds);
The first vehicle disappears from the system typically at 71 seconds in; and
The last vehicle has left the ferry typically around 342 seconds (5 minutes and
22 seconds) in.
Figure 16 Screenshot of VISSIM 4-lane alighting simulation after 238 seconds
7.1.7 Four lanes – Assumptions for Boarding Model
In development of the VISSIM model for ferry boarding, the following assumptions
have been used:
This was broadly the same as the four‐lane alighting model, but with the
directions reversed;
Vehicles in the model can go a maximum speed of 10mph, however a 5mph
reduced speed area is present on the linkspan, the pontoon and the ferry; and
As with the previous boarding models, stop signs at the end of the ferry link
delay the vehicles for 5 seconds before they disappear from the model.
7.1.8 Four lanes – Results of Boarding Model
The VISSIM model for boarding of the ferry using the above assumptions produces
the following results:
The model was run ten times. Each time, after 400 seconds (6 minutes and 40
seconds) all vehicles have disappeared from the system. Note that this
disappearance occurs after vehicles have reached the section representing the
ferry. The median time taken for all vehicles to disappear was 385 seconds (6
minutes 25 seconds);
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It is about 281 seconds (4 minutes and 41 seconds) until the last vehicle has
entered the system (ie. the last car has reached the end of the marshalling
lanes on the approach structure); and
It is about 87 seconds until the first vehicle disappears from the system (ie. the
first car is parked on the ferry).
Figure 17 Screenshot of VISSIM 4-lane boarding simulation after 81 seconds
7.1.9 Six lanes – Assumptions for Alighting Model
In the six lane version of the model, there are still only two lanes available for
alighting, so this is considered to have the same alighting assumptions as the
four lane alighting model.
7.1.10 Six lanes – Results of Alighting Model
In the six lane version of the model, there are still only two lanes available for
alighting, so this is considered to have the same alighting results as the four
lane alighting model.
7.1.11 Six lanes – Assumptions for Boarding Model
In development of the VISSIM model for ferry boarding, the following assumptions
have been used:
For the six lane loading model, the approach structure and linkspan are now
represented as two 90m two‐lane sections, with no lane changing allowed;
As with the previous loading models, stop signs at the end of the ferry section
delay the vehicles for 5 seconds before they disappear from the model;
The pontoon is now represented as six sections, with a horizontal length of
30m. These connect to the four lanes of the two sections as is shown in the
screenshot below:
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Figure 18 Key to VISSIM 6-lane boarding regime
The traffic is loaded into the system as shown in Table 5 below:
Route Linkspan/Approach
section Pontoon section Number of PCUs
1 Linkspan 2, lane 2 1 15
2 Linkspan 2, lane 1 3 15
3 Linkspan 1, lane 2 4 15
4 Linkspan 1, lane 1 6 15
5 Linkspan 2, lane 2 2 8
6 Linkspan 2, lane 1 2 7
7 Linkspan 1, lane 1 5 7
8 Linkspan 1, lane 2 5 8
Table 5 Boarding regime with six-lane arrangement for propeller driven ferry
Vehicles in the model can travel at a maximum speed of 10mph, however a
5mph reduced speed area is present on the linkspan, the pontoon and the
ferry.
7.1.12 Six lanes – Results of Boarding Model
The VISSIM model for boarding of the ferry using the above assumptions produces
the following results:
The model was run ten times. Each time, after 330 seconds (5 minutes and 30
seconds) all vehicles have disappeared from the system. Note that this
disappearance occurs after vehicles have reached the section representing the
ferry. The median time taken for all vehicles to disappear was 318 seconds (5
minutes 18 seconds);
Linkspan 2
Lane 1 Linkspan 1
Pontoon section
1
Lane 1
Lane 2
Lane 2 Ferry2
3
4
5
6
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It is about 164 seconds (2 minutes and 44 seconds) until the last vehicle has
entered the system (ie. the last car has reached the end of the marshalling
lanes on the approach structure); and
It takes similar periods of time (ie. around 87 seconds) for the first vehicle to
leave the system, as it does for the four lane loading model. The additional
lanes do not speed the first vehicle out; they do however reduce delay for
vehicles queuing behind.
Figure 19 Screenshot of VISSIM 6-lane boarding simulation after 182 seconds
7.1.13 Summary of Overall Alighting and Boarding Time
The brief from TfL for estimating alighting and boarding times requires consideration
of the time taken from the ferry arriving at the terminal to the ferry departing. No
account is therefore taken of crossing or berthing time.
Combining the estimates of alighting and boarding times from the VISSIM model as
described in the above sections, the total anticipated times for alighting and boarding
with each arrangement of traffic lanes is given in Table 6 below:
Distance travelled in each
direction to/from ferry
Number of queuing
lanes
Total alighting &
boarding time
2 lanes 308m 2 (on land) 15 mins
4 lanes 88m 2 (top of linkspan) 13 mins
6 lanes 88m 4 (top of linkspan) 12 mins
Table 6 Comparison of alighting and boarding times for propeller driven ferry
7.2 Chain ferry
Additional VISSIM models are not considered necessary for the chain ferry with
different configurations of traffic lanes. In this instance, alighting and boarding times
have been estimated using a two‐lane VISSIM model only. The approach to the chain
ferry slipway is a straight section of road from the marshalling area, the length of
which does not vary between the different arrangements of traffic lanes, and there is
no physical restriction on the slipway to the number of traffic lanes that can be
accommodated. For this reason, the times for multiple lane arrangements are based
upon a pro‐rata of the two‐lane model results.
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7.2.1 Assumptions for Alighting Model
In development of the VISSIM model for ferry alighting, the following assumptions
have been used:
This has the same dimensions as the loading model, but all the directions are
reversed;
It is assumed that only two of the 6 lanes of traffic in the ferry are allowed out
at any one time, to prevent a bottleneck on the slipway;
At the connection on the slipway, conflict areas are introduced, to prevent the
vehicles from the six different lanes running into each other as they merge
into the 2 lanes of the landside highway; and
There are no stop signs on this version of the model; the assumption is that
the vehicles can drive straight off the ferry.
7.2.2 Results of Alighting Model
The VISSIM model for alighting of the ferry using the above assumptions produces
the following results:
The shockwave effect does not occur as vehicles start off at less than 5mph,
and then increase their speeds to 10mph, rather than the other way round;
The model was run ten times. Each time, after 370 seconds (6 minutes and 10
seconds) all vehicles have disappeared from the system;
The first vehicle disappears from the system typically at 54 seconds in; and
The last vehicle has left the ferry typically around 340 seconds (5 minutes 40
seconds) in.
The following figures show screenshots from the VISSIM model where the different
coloured “vehicles” represent the different lanes of traffic.
Figure 20 Screenshot of VISSIM 2-lane alighting simulation after 70 seconds
Figure 21 Screenshot of VISSIM 2-lane alighting simulation after 120 seconds
Ferry
Slipway
Approach highway
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Figure 22 Screenshot of VISSIM 2-lane alighting simulation after 250 seconds
7.2.3 Assumptions for Boarding Model
In development of the VISSIM model for ferry boarding, the following assumptions
have been used:
No vehicle in the model travels faster than 10mph;
The access to the top of the slipway is represented as a 60m two lane road,
with no lane change allowed;
The slipway is represented as 6 connectors (length 60m), which connect the
two lanes of the access to the 6 lanes of the ferry;
The ferry is represented as a 6 lane 50m section. It is a reduced speed area,
with a maximum speed allowed of 5 mph;
It will take at least 5 seconds for vehicles to park once on the ferry. This is
represented in the model with a stop sign, at which the vehicles are delayed
for 5 seconds. After reaching the end of the ferry, vehicles wait for 5 seconds
then disappear from the model;
The distance of the ferry link which vehicles must drive across, is reduced for
vehicles entering the ferry later. As a compromise the section representing
the ferry is half the length of the actual ferry. For the chain ferry version, the
ferry section is thus 50m long; and
The simulation starts with the first car reaching the access to the top of the
slipway.
7.2.4 Results of Boarding Model
The VISSIM model for boarding of the ferry using the above assumptions produces
the following results:
90 vehicles are uploaded into the system, with 15 set to go at each of the 6
possible routes available at the slipway;
The model was run ten times. Each time, after 295 seconds (4 minutes and 55
seconds) all vehicles have disappeared from the system. Note that this
disappearance occurs after vehicles have reached the section representing the
ferry. The median time taken for all vehicles to disappear was 270 seconds (4
minutes 30 seconds);
It is about 165 seconds (2 minutes and 45 seconds) until the last vehicle has
entered the system (ie. the last car has reached the access to the top of the
slipway);
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It is about 60 seconds (1 minute) until the first vehicle disappears from the
system (ie. the first car is parked.); and
The shockwave effect is observed slowing vehicles down a little, but not
much for this version of the ferry, as the slowing down occurs at one of the 6
entries to the ferry, rather than one of only two entries to the linkspan on the
propeller driven option. This means vehicles can avoid other vehicles by
taking a different access at the slipway, rather than being slowed down by
them.
The following figures show screenshots from the VISSIM model where the different
coloured “vehicles” represent the different lanes of traffic.
Figure 23 Screenshot of VISSIM 2-lane boarding simulation after 30 seconds
Figure 24 Screenshot of VISSIM 2-lane boarding simulation after 60 seconds
Figure 25 Screenshot of VISSIM 2-lane boarding simulation after 165 seconds
Figure 26 Screenshot of VISSIM 2-lane boarding simulation after 250 seconds
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7.2.5 Summary of Overall Alighting and Boarding Time
The brief from TfL for estimating alighting and boarding times requires consideration
of the time taken from the ferry arriving at the terminal to the ferry departing. No
account is therefore taken of crossing or berthing time.
Combining the estimates of alighting and boarding times from the VISSIM model as
described in the above sections, a total time of 665 seconds or 11 minutes and 5
seconds is anticipated. However, this is based on a boarding time of around 5
minutes and an alighting time of around 6 minutes which results from each vehicle in
the model having a pre‐determined lane on the ferry and vehicles being able to fan
out into more than two lanes on the slipway approach. In reality, the boarding time
can be expected to be slightly longer as each driver receives and reacts to directions.
Another anomaly arises from the fact that the position of a chain ferry on the slipway
can vary in two dimensions according to tides and currents. This makes it impossible
to provide a physical separation between pedestrians and vehicles. The only
longitudinal physical barrier on the slipways would be the chains for the ferry but
pedestrians cannot be expected to step over these chains and the area of slipway
beyond them may not be as easy to keep clean of slippery deposits as the central
section.
Separation of pedestrians and vehicles could be managed at each berthing by the
erection of temporary barriers, signage or staff announcements. This could allow
simultaneous movement of pedestrians and vehicles but would be a very labour‐
intensive approach. Separation in time is the most appropriate solution but this will
result in a further increase in the boarding and alighting times. The operational
regime for deal with safe segregation of users will need to be developed by the ferry
operator.
7.2.6 Additional Traffic Lanes
The VISSIM microsimulation used to estimate alighting and boarding times was
developed on the assumption that there are two lanes of queuing traffic waiting at the
top of the slipways. Unlike the propeller driven ferry terminals, there is greater
flexibility on the slipways to increase the number of traffic lanes.
Widening of the approaching highways to allow four or six lanes of queuing traffic
would clearly speed up boarding times, provided all lanes can be boarded
simultaneously. There would be an additional benefit in using six lanes for queuing
traffic as each lane would then directly correlate to a position on the ferry vessel and
remove the need for directing vehicles. This would be different from other examples
of chain ferries (eg. Torpoint ferry), where vehicles may only alight and board in
single file. Alighting vehicles would have to join the existing highway network at
some point and reducing from six or four lanes to one is expected to cause a
significant “bottleneck” which could tail back far enough to interfere with loading
operations. For this reason, the same number of alighting lanes has been assumed
throughout; hence alighting times are unchanged.
Table 7 below shows a comparison of the estimated alighting and boarding times for
each configuration of traffic lanes:
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Distance travelled in each
direction to/from ferry
Number of queuing
lanes
Total alighting &
boarding time*
2 lanes 120m 2 11 mins
4 lanes 120m 4 8.5 mins**
6 lanes 120m 6 7.5 mins**
Table 7 Comparison of alighting and boarding times for chain ferry
* minimum time assuming simultaneous boarding and alighting of non‐motorised
users without single file boarding and alighting of vehicles
** pro‐rata estimation of boarding times (validated from VISSIM model results for
multiple lanes on propeller driven ferry)
7.3 Validation of Alighting and Boarding Time Estimates
Based upon information in the previous Halcrow feasibility study into ferry crossings
of the River Thames, it is understood that the existing Woolwich Ferry, which uses a
linkspan arrangement with a four‐lane approach structure, has a capacity of 35 PCUs
and requires a total of 5 minutes for alighting and boarding. In consideration of the
similar four‐lane propeller driven ferry option with a capacity of 90 PCUs, a pro‐rata
increase in alighting and boarding times would match the 13 minute estimate
presented in Table 6 above.
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8 Discussion of Alternatives
8.1 Re-use of Existing Woolwich Ferry Vessels
An idea postulated by TfL’s expert advisor Bill Moses is to use the existing Woolwich
ferry vessels (with modifications) as pontoons in the new propeller driven ferry
terminals at Gallions Reach. Previous studies and inspections (most recently by
Lloyds Register in June 2010) of the vessels themselves have concluded that they still
have sound hull integrity. This suggests that, with ongoing maintenance, they could
remain afloat for many years to come.
Figure 27 Existing Woolwich Ferry vessel (Halcrow, 2009)
Whilst this idea could be technically feasible, it is believed that the necessary
modifications to the existing vessels would be prohibitively costly in comparison to
the provision of new purpose‐built pontoons. Likely modifications to the vessels
would include widening of the vehicle deck, sealing and ballasting to ensure the
vessels sits at the correct height in the water for the new ferry and removal of the
headroom obstruction posed by the current wheelhouse structure and associated
strengthening works to accommodate the possible loss of structural integrity such
modifications may cause.
Any new ferry service at Gallions Reach will have to be constructed whilst the
existing Woolwich Free Ferry service continues to operate. The Woolwich service
currently has three vessels; the Ernest Bevin, the John Burns and the James Newman.
Two vessels are normally in operation at any one time to provide a frequency of
approximately six crossings per hour in each direction. If two vessels were used as
pontoons for the new ferry terminals, only one vessel would remain in operation at
Woolwich, thus halving the frequency of crossings and introducing the risk of a
complete lack of service should the last remaining vessel break down.
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In summary, whilst there is merit on the grounds of sustainability in re‐using the
existing Woolwich vessels, cost and impracticalities are judged to far outweigh the
benefits that such a proposal could realise.
8.2 Alternative Linkspan Arrangement for Propeller Ferry
In the process of developing a preliminary design for the ferry infrastructure options,
Halcrow has considered an alternative solution which may realise improved cost
effectiveness and operational regimes. As discussed in the basis of the preliminary
design Autotrack swept path analysis of HGV manoeuvres on the pontoon led to the
decision by TfL to adopt a curved approach structure to reduce or eliminate the need
to turn large vehicles on the pontoon itself. This principle then establishes the
possibility of removing the pontoon from the system altogether. A solution without a
pontoon also eliminates the sensitivity of such a large floating structure to wave and
wash action in the river.
The suggested arrangement for this alternative system is to have a lifting mechanism
at the end of each linkspan which follows the level of the tide through mechanical
control. Figure 28 and Figure 29 show similar arrangements designed by Halcrow for
Dublin Port in 2000. This is a similar principle to the current Woolwich arrangement
but, unlike at Woolwich where linkspans are raised and lowered fully at each
berthing operation, the relative levels of the linkspans and the water would remain
constant. Fine adjustment of the linkspan level could be controlled remotely from the
ferry as it approaches to berth.
Figure 28 Single deck mechanical linkspan at Dublin Port (Halcrow, 2000)
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Figure 29 Double deck mechanical linkspan at Dublin Port (Halcrow, 2003)
It is envisaged that the operational regime for this type of terminal would include
lifting the linkspans to their uppermost position at the end of each day and locking
them in place to remove any load from the lifting mechanism.
TfL’s experience with the Woolwich Ferry suggests that a mechanical linkspan lifting
system would be subject to regular maintenance. Advances in technology and the
lesser strain on lifting equipment anticipated from less usage would be expected to
demonstrate the viability of this alternative. Halcrow has not carried out detailed cost
estimation as part of this task, but a cost saving in comparison to the proposed
solution utilising pontoons is confidently predicted.
Halcrow recommends that TfL investigates this option further as a separate study.
8.3 Self-Beaching Propeller Ferry
Section 6.3.1 refers to conventionally powered beaching type ferries. These were not
part of the original scope for this task, but have been considered at the request of TfL.
A self‐beaching propeller driven ferry utilises a slipway and ramp access in a similar
fashion to a chain ferry. There are numerous examples of self‐beaching ferries in the
UK, particularly in Scotland.
It is possible that a self‐beaching ferry can operate with a narrower slipway than the
chain ferry options explored in this task. This could have the advantage of more cost
effective infrastructure but would require a considerable level of skill in the crew for
navigation and berthing. Berthing with a ramp from the ferry onto the slipway is
usually sufficient to hold the vessel in position, however the River Thames is subject
to a particular regime of tides and currents that it is considered would render this
berthing method impossible. The vessel would have to be held in position with
berthing dolphins and, given that currents can act in both upstream and downstream
directions, such dolphins would need to be provided to both sides of the intended
berthing lane on the slipway.
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Provision of berthing dolphins is expected to require a widened slipway to
accommodate some manoeuvring of the vessel. As a result, the slipway dimensions
are likely to be similar to that for a chain ferry.
The self‐beaching vessel itself would require a similar level of maintenance to the
conventional propeller driven ferry in terms of complexity and number of
interventions.
Although a self‐beaching propeller driven ferry option has several similarities to a
chain ferry, it is discounted as an alternative on the grounds that it is less
advantageous on the grounds that it requires additional berthing dolphins when
placed in the River Thames, a higher level of crew skill and is likely to have a more
costly maintenance regime.
Figure 30 Typical self-beaching propeller ferry (MV Loch Dunvegan – Caledonian MacBrayne)
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9 Hydrodynamic Impact Assessment This assessment is based on design documents and drawings currently available for
each option. The current revision of documents, that are to provide the basis of
further design work currently being undertaken, are being used as the basis of the
hydrodynamic impact assessment. It is considered that the majority of further design
work currently being undertaken will have little effect on the hydrodynamic impacts
since features such as bridge piers or slipways are not likely to be modified
significantly.
Within the scope of this study, it is not possible to develop a detailed quantitative
analysis of each of the options. The study provides a comparative qualitative analysis
of each of the options supported by simple calculations where appropriate.
9.1 Hydrodynamic Features
The principal effect of each option is to cause a local change in the flow area of the
river channel in the vicinity of the structure. The hydrodynamic impact of the
structure depends, primarily, on the blockage ratio at the structure, defined in this
case, as the loss of cross‐sectional area as a percentage of the total flow area, without a
design option in place. It is calculated by comparing the cross sections of the river at
the appropriate location at both high and low spring tide with those of the river with
a design option added. Any features of the design that reduce the cross‐sectional area
are subtracted from the total area to yield the effective cross‐sectional area of each
design.
The addition of features along a parallel plane to the cross‐section considered may
cause localised upstream or downstream effects but this cannot be quantified without
a full analysis based upon a detailed hydrodynamic model. For the purposes of
option comparison, the use of blockage ratios is considered to be a suitable
calculation methodology.
In order to calculate the blockage ratios, the provided design drawings have been
used to develop cross sectional areas at the crossing location, using the chainage and
bed elevation values. These are then compared to the altered cross sections associated
with each option to evaluate changes in area.
9.1.1 Flow rates
The increase in water level (Afflux) associated with the design has been calculated
over a range of flows. The flows used cover a range representing a spring tide event.
These would be the highest flows normally expected in the tidal reaches of the
Thames and as such would represent the highest values of Afflux. The Afflux values
calculated therefore represent a worst case scenario.
9.2 Ferry
Blockage ratios throughout this report have been determined in the same manner as
in the existing feasibility study; Woolwich Ferry Replacement and Gallions Ferry
Feasibility Study undertaken by Halcrow in 2010.
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Option
MHWS (3.8mOD) MLWS (‐2.8mOD) MWL (0.5mOD)
CSA
(m2)
HSA
(m2)
BR
(%)
CSA
(m2)
HSA
(m2)
BR
(%)
CSA
(m2)
HSA
(m2)
BR
(%)
2 Propeller
Driven
Ferries
3126 3031 3.0 7145 6951 2.7 4927 4779 3.0
2 Chain
Ferries (solid
slipways)
3126 3009 3.7 7145 6503 9.0 4927 4607 6.5
Table 8: Ferry Option Blockage Ratios
Where:
CSA: Cross ‐ sectional Area
HSA: hydro ‐ structure Area (CSA minus area of slipway, piles, pontoons etc)
BR: Blockage Ratio = 100 x (HSA/CSA‐1)
The chain ferry (with a solid slipway) has a greater Blockage Ratio than that of the
propeller driven ferry option, particularly at low tide, due in large to the need for
fixed concrete slipways on both the north and south banks of the Thames. Minimal
blockage ratio occurs through the propeller driven ferry option as the majority of the
access structures are hinged and are able to float meaning that they do not obstruct
the flow area.
9.2.1 Effect on Water Level
The HDS1‐hydraulics of bridge waterways method has been used to estimate the
backwater associated with the constriction of flow area associated with construction
of slipways and other structures incorporated in the design for a range of flows,
covering the expected maximum flow for a spring tide, at mean water level of
0.5mOD. The analysis is based on the equation shown below, where the k* and αtermsarebasedonblockagesandtheassociatedchange invelocityused todeterminetheAfflux.
∗ ∗ ∝2
∝2
The results are tabulated in Table 10 and Table 9 below.
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Flow rate (m3/s) MWL (mOD)Average
velocity (m/s)Afflux (m) Afflux (mm)
1000 0.5 0.209 1.110x10‐4 0.1
2000 0.5 0.418 4.470x10‐4 0.4
3000 0.5 0.628 1.010x10‐3 1.0
4000 0.5 0.837 1.787x10‐3 1.8
Table 9: Back water Effect of Propeller Driven Ferry Option, calculated using the method described in HDS1- Hydraulics of Bridge Waterways.
Flow rate (m3/s) MWL (mOD)Average
velocity (m/s)Afflux (m) Afflux (mm)
1000 0.5 0.217 2.403x10‐4 0.2
2000 0.5 0.434 9.615x10‐4 1.0
3000 0.5 0.651 2.163x10‐3 2.2
4000 0.5 0.868 3.846x10‐3 3.8
Table 10: Back water Effect of Chain Ferry Option (solid slipway), calculated using the method described in HDS1- Hydraulics of Bridge Waterways.
9.2.2 Effects on Tidal Propagation
It is not anticipated that either of the ferry options will cause, other than locally,
significant changes to the propagation of tidal water levels in the Thames.
9.2.3 Effects on Flow Distribution
At lower tides, when the floating pontoons and jetties for the propeller driven ferry
are nearer to the channel bed, the flow velocity beneath them will increase, likely
increasing scour of the bed.
For the chain ferry option (with solid slipways), the majority of the redistributed flow
will be directed into the middle of the channel by the slipways which will increase
current speed and disrupt flow paths, making both velocity and direction of flow in
the area more varied.
Flows in the shallower waters towards the river margins will become more variable
in both speed and direction where flow velocities are increased and scour would
likely occur, whilst in areas of slower moving flow, accretion is likely.
Changes to the local suspended solids regime will be experienced while the riverbed
and inter‐tidal areas adjust to any changes during and following construction.
9.2.4 Effects on Sediment Transportation
The chain ferry option (with solid slipways) will introduce obstructions to the flow
within the channel potentially causing areas of more turbulent flow. There is also
potential for areas to have reduced energy, such as at the base of the toe, giving rise
to opportunities for both scour and accretion to occur.
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Local variations in velocity and flow around piles and spillways will have an impact
on the sedimentation processes that occur in the river. It is not possible to accurately
state what these effects will be. It is likely that some areas within the crossing will
experience scouring, whilst others may experience depositions of sediment
depending on the variances within the flow. It is thought that the downstream side of
the piles would experience some scouring whilst the upstream side of slipways might
experience depositions if the velocities in the water held behind the slipway became
too low.
If dredging is employed to obtain a foundation level for the construction of the
slipways, this could result in potential impacts on sediment transport and the
environment.
The movement of the chain, as a result of ferry crossing would likely impact on bed
sediment as it rises and drops again along its length as the ferry crosses. It is not
possible to determine the extent of this impact; however it is only likely to be a local
impact, resulting in small amounts of additional sediment potentially in the water
column.
9.2.5 Effects on Environment
The construction of slipways for the chain ferry option would likely impact on
migration of aquatic species in the river. Smaller species tend to stay in the shallower
water at the fringes of the river, and would potentially be affected by the slipways,
especially at lower tides, when the slipways represent a larger blockage over the
depth.
9.2.6 Effects on Navigation
Both of the ferry options will have a navigational impact. However the propeller
driven ferry option will have the lowest blockage factor and the smallest impact on
the flow regime within the navigation channel. The chain ferry option, with a
blockage factor of around 9% during low water would have a greater impact than the
propeller driven option.
The impact that the flow would have on navigation is only related to the velocity of
the flow in the navigational channel. For the chain ferry, the average velocity in the
channel would likely increase by 6.5% at mean water level, with a value of
approximately 3% for the propeller driven option.
Both options would result in regular ferry crossing which would pose a hazard to
navigation in the channel and the chain required for the chain ferry could pose a
continual issue for navigation, although when not in use it would lie on the river bed
to any other vessels in the channel. When crossing, the chain would be more elevated
in the channel and would pose a more substantial hazard to navigation.
9.3 Revised Chain Ferry (Piled Slipway)
Following geotechnical advice that a solid slipway for the chain ferry option would
be impractical, the hydrodynamic impact of a piled slipway has also been considered.
This updated version of the ferry crossing design, with cross sections as shown in
drawing 472413‐011, is likely to be comparable to the existing chain ferry design, with
hydrodynamic impacts assessed for a concrete slipway arrangement. The revised
design proposal incorporates a number of concrete deck sections, supported by
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beams linking the pile supports along the width of the slipway. This creates a number
of small openings along the length of the slipways, through which water may pass.
Due to the small opening size, it is likely that the flow through these areas will be
restricted significantly.
Option
MHWS (3.8mOD) MLWS (‐2.8mOD) MWL (0.5mOD)
CSA
(m2)
HSA
(m2)
BR
(%)
CSA
(m2)
HSA
(m2)
BR
(%)
CSA
(m2)
HSA
(m2)
BR
(%)
2 Chain
Ferries
(piled
slipways)
3126 3009 3.7 7145 6503 9.0 4927 4607 6.5
Table 11: Revised Ferry Option Blockage Ratios
Table 11 shows the blockage ratios associated with the design at 3 water levels. It can
be seen that the blockage ratios are less than the other designs.
The blockage ratio represents the restricted flow area associated with a structure in
the flow. This can be used to estimate changes in velocity, flow and afflux. In this
case, the flow areas under the slipway make up a large part of the total area of flow.
Due to the size of the openings, and the associated head losses, this type of analysis
would not be appropriate.
It could therefore be reasoned that the slipways would have similar impacts on the
hydrodynamics, although slightly reduced, to those associated with the concrete
slipway option.
9.3.1 Effect on water level
It is likely that the design would have some impact on the upstream water level, as
with the other proposed options, this impact would probably be only a few
millimetres. Due to the nature of the design, the method previously used to
determine the extent of the effect would not be appropriate.
9.3.2 Effects on flow distribution
It is thought that some of the flow under the slipways will be directed into the main
channel, especially at high water when losses under the slipway would be more
significant. This would result in changes to velocity in the channel and with flow
directions being altered locally.
9.3.3 Effects on sediment transportation
The revised chain ferry option will alter the flow paths within the channel, causing
local variations in velocity and flow direction, with increased turbulence around the
pile supports. This could increase sediment uplift in the area, increasing scour around
the piles.
The movement of the chain, as a result of ferry crossing would likely impact on bed
sediment as it rises and drops again along its length as the ferry crosses. It is not
possible to determine the extent of this impact; however it is only likely to be a local
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impact, resulting in small amounts of additional sediment potentially in the water
column.
9.3.4 Effects on Environment
The construction of slipways for the chain ferry option would likely impact on
migration of aquatic species in the river. Smaller species tend to stay in the shallower
water at the fringes of the river, and would potentially be affected by the slipways,
especially at lower tides, when the slipways represent a larger blockage over the
depth.
9.3.5 Effects on Navigation
The impact that the flow would have on navigation is only related to the velocity of
the flow in the navigational channel. For the new chain ferry design, the average
velocity in the channel would likely increase by between 6.5% and 3%.
The option would result in regular ferry crossing which would pose a hazard to
navigation in the channel and the chain required for the ferry could pose a continual
issue for navigation, although when not in use it would lie on the river bed to any
other vessels in the channel. When crossing, the chain would be more elevated in the
channel and would pose a more substantial hazard to navigation.
9.3.6 Construction phase
The design proposes the use of cofferdams during construction; these would impact
on migratory marine species during the construction phase, and would also have an
impact on sediment transport. The size of the cofferdams, as shown on drawing
472413‐011 would suggest that the blockage associated with them would be large,
even compared to the size of the slipway blockage. During the construction phase,
the impacts discussed above, could therefore be more significant.
9.4 Bridge (Concrete Box Girder)
Blockage ratios have been calculated for the bridge option at a number of water levels
as summarised in Table 12 below. It can be seen that the blockage ratios associated
with the bridge design are higher than those of the Ferry options.
Option
MHWS (3.8mOD) MLWS (‐2.8mOD) MWL (0.5mOD)
CSA
(m2)
HSA
(m2)
BR
(%)
CSA
(m2)
HSA
(m2)
BR
(%)
CSA
(m2)
HSA
(m2)
BR
(%)
Box Girder
Bridge
Crossing
3086 2716 12.08 6966 6108 12.32 4927 4352 11.67
Table 12: Concrete Bridge Blockage Ratios
9.4.1 Effects on Water Level
The HDS1‐hydraulics of bridge waterways method has been used to estimate the
backwater associated with the constriction of flow area associated with bridge
abutments and piers for a range of flows at mean water level of 0.5mOD. This is the
same method used to determine the Afflux associated with the ferry options.
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The results are tabulated in Table 13 below.
Flow rate (m3/s) MWL (mOD)Average
velocity (m/s)Afflux (m) Afflux (mm)
1000 0.5 0.203 4.834x10‐4 0.5
2000 0.5 0.406 1.934x10‐3 1.9
3000 0.5 0.609 4.354x10‐3 4.4
4000 0.5 0.812 7.734x10‐3 7.7
Table 13: Back water Effect of Concrete Bridge Option, calculated using the method described in HDS1- Hydraulics of Bridge Waterways.
With only relatively minor blockages from the piers of the bridge, the increase in
upstream water level has been found to be in the order of a few mm, with levels
ranging from 0.5mm to 8.0mm.
9.4.2 Effects on Flow Distribution
It is expected that local variations in velocity around the bridge piers will occur
resulting in fluctuations in flow around the piers. It is thought that these effects will
be most significant at the pier on the outside of the river bend as velocity will be
higher in this area of the river due to the irregular horizontal velocity profile
associated with the river bend.
9.4.3 Effects on Sediment Transportation
It is likely that changes to the flow paths in the river due to the piers will result in
areas of high velocity at the downstream end of the piers. It is thought that this could
result in high levels of scour downstream of the piers. At the abutment on the
northern bank of the crossing, the flow would probably be similarly affected. It is
thought that in this area, where flow could be restricted at high tides, deposition of
sediments could occur.
9.4.4 Effects on Environment
The use of cofferdams during construction would potentially have an impact on fish
populations within the river. The abutment arrangement on the northern bank may
affect migration of fish species.
9.4.5 Effects on Navigation
The bridge design has been developed in line with the navigation clearance and
navigation channel width proposed for the TGB scheme, therefore there should be
limited impact, however the piers would represent an additional collision hazard.
9.4.6 Construction Phase
A number of temporary berthing and access jetties would be required during the
construction phase. It is likely that these jetties would significantly reduce the cross
sectional area of flow through the stretch of river, affecting flow, velocity and water
level locally. This could further impact on environmental factors and sedimentation
processes occurring in the river.
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9.5 Bridge (Steel Arch)
Comparing the blockage ratios of the steel and concrete bridge options, it can be seen
that the blockages associated with the steel bridge (see Table 14 below) are slightly
lower.
Option
MHWS (3.8mOD) MLWS (‐2.8mOD) MWL (0.5mOD)
CSA
(m2)
HSA
(m2)
BR
(%)
CSA
(m2)
HSA
(m2)
BR
(%)
CSA
(m2)
HSA
(m2)
BR
(%)
Steel Arch
Bridge
Crossing
3086 2716 12.08 6966 6108 12.32 4927 4352 11.67
Table 14: Steel Bridge Blockage Ratios
9.5.1 Effects on Water Level
The HDS1‐hydraulics of bridge waterways method has been used to estimate the
backwater associated with the constriction of flow area associated with bridge
abutments and piers for a range of flows at mean water level of 0.5mOD. This is the
same method used to determine the Afflux associated with the ferry options.
The results are tabulated in Table 13 below.
Flow rate (m3/s) MWL (mOD)Average
velocity (m/s)Afflux (m) Afflux (mm)
1000 0.5 0.203 4.200x10‐4 0.4
2000 0.5 0.406 1.680x10‐3 1.7
3000 0.5 0.609 3.780x10‐3 3.8
4000 0.5 0.812 6.726x10‐3 6.7
Table 15: Back water Effect of Steel Bridge Option, calculated using the method described in HDS1- Hydraulics of Bridge Waterways.
The afflux associated with the steel bridge option, is, as for the blockage ratios,
slightly lower than the afflux associated with the concrete bridge. The afflux levels
range from 0.4mm to 6.7mm.
9.5.2 Effects on Flow Distribution
Although the blockage ratio associated with the steel bridge option is lower than that
of the concrete design, it would be possible for the design to have a greater impact on
the flow distribution as there are a higher number of bridge piers, each of which is
likely to affect the flow paths of water in the channel. If the new alignment was used,
the bridge would be closer to the river bend, and the flow would be less uniformly
distributed along its width, giving greater flow, and velocity in the deeper channel on
the outside of the bend. It is likely that any effects associated with the bridge piers
would be more significant in this area.
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9.5.3 Effects on Sediment Transportation
There is potential for scour to occur on the downstream side of the bridge piers as
with the concrete design. This again could be more prevalent on the outside of the
bend if the new alignment was used. As all of the bridge piers are free standing, it is
unlikely that large dead spots of flow would occur in the channel, and therefore large
depositions of sediment would be unlikely.
9.5.4 Effects on Environment
The use of cofferdams during construction would potentially have an impact on fish
populations within the river. The abutment arrangement on the northern bank may
affect migration of fish species.
9.5.5 Effects on Navigation
The bridge design has been developed in accordance with PLA specifications for
navigation clearance and navigation channel width, therefore there should be limited
impact, however the piers would represent an additional collision hazard.
9.5.6 Construction Phase
A number of temporary berthing and access jetties would be required during the
construction phase. It is likely that these jetties would significantly reduce the cross
sectional area of flow through the stretch of river, affecting flow, velocity and water
level locally. This could further impact on environmental factors and sedimentation
processes occurring in the river.
9.6 Immersed Tunnel
Option
MHWS (3.8mOD) MLWS (‐2.8mOD) MWL (0.5mOD)
CSA
(m2)
HSA
(m2)
BR
(%)
CSA
(m2)
HSA
(m2)
BR
(%)
CSA
(m2)
HSA
(m2)
BR
(%)
Immersed
Tunnel
Crossing
3086 4645 ‐50.53 6966 9089 ‐30.48 4927 6845 ‐38.94
Table 16: Immersed Tunnel Blockage Ratios
Negative blockage ratios, as shown above in Table 16, denote an increase in cross
sectional area. In this case the dredging of the crossing area is to a depth such that,
when the submerged tunnel is placed in situ and locking and cover back fill is added,
the depth of the river to the top of the protective cover layer of the tunnel is
significantly greater than the original depth of the river.
9.6.1 Effects on Water Level
Due to the reduction in bed level that would result from the implementation of the
submerged tunnel option, there would be a local increase in the cross sectional area of
flow. Depending on the full extent of the dredged area around the tunnel, this would
likely have an impact on the water level locally; unlike other options, however the
water level would likely drop marginally.
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9.6.2 Effects on Flow Distribution
Local variations in flow distribution may occur within the channel, especially during
construction where features are not uniform over the width of the river creating the
potential for transverse flow paths and vortices.
9.6.3 Effects on Sediment Transportation
It is thought that lower velocities through the dredged area will likely result in
deposition over time as the channel bed reforms. Sedimentation is likely to occur on
rock protection layer over the tunnel. This effect would likely occur over a long
period of time, however if during the construction phase, a surge tide or large fluvial
flow occurred, it would be possible for sedimentation, significant enough to partially
fill in the dredged tunnel channel to occur.
9.6.4 Effects on Environment
It is possible that the dredging required for the immersed tunnel option would have
an impact on the migration and populations of fish and other aquatic species within
the river.
9.6.5 Effects on Navigation
A number of short term closures of the river, required when the tunnel sections are
floated into place, will have an impact on navigation in the river. It is possible that the
dredging phase of construction, in which the tunnel channel across the river is
dredged out to the required level could impact on navigation. Once the construction
phase has been completed, there are no foreseeable impacts on navigation associated
with the design, as the net effect of the design will be the formation of a small section
of deeper channel within the crossing.
9.6.6 Construction Phase
In order to construct the immersed tunnel, the individual tunnel sections would have
to be manoeuvred into place on jetties or on floating barges. If jetties were used, they
would likely have a larger impact on water level as they would represent a larger
blockage ratio.
9.7 Bored Tunnel
It is not expected that the construction of a bored tunnel will have any significant
impact on the hydrodynamic feature of the Thames at Gallions Reach. The only issue
would arise from potential bed deformation as a result of the tunnelling, possibly
resulting from unforeseen geological features beneath the channel.
9.8 Conclusions
It is expected that all of the options, except the bored tunnel option would have an
impact on the hydrodynamics of the river locally at the crossing, the extent of which
would vary depending on tide and water level at the crossing.
Both of the ferry options and the bridge options would have an impact on the flow
distribution in the channel. A reduction in flow area results from each of these
options, and it is likely that this would result in changes in velocity in the channel as
well as an increased upstream water level. The changes in velocity could impact on
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the sediment transport occurring in the river with the possibility of increased scour or
deposition occurring. There are likely to be impacts on navigation and environmental
factors such as fish migration during the construction phase of both the ferry and
bridge options due to the necessity of cofferdams during construction and the use of
additional access jetties during the bridge construction.
No issues have been identified for the bored tunnel option. The immersed tunnel
option is likely to have significant navigational and environmental impacts during
the construction phase due to large scale dredging and the positioning of the tunnel
sections. Initially, the immersed tunnel option would result in an increased flow area
over the dredged site and in the vicinity of the tunnel, it is possible however, that
over time, sediment depositions would accumulate in this area, re‐establishing the
bed topography to similar to the existing bed profile.
Table 17 below shows a comparison of the effects of each option in the long‐term
permanent case. The table shows a comparison in the likelihood and severity of the
effects on a scale, with 6 being the most likely or severe impact and 1 being the least
likely or the least severe.
Options
Effect Chain
Ferry*
Propeller
Ferry
Concrete
Bridge
Steel
Bridge
Immersed
Tunnel
Bored
Tunnel
Blockage Ratio 2 1 4 3 N/A N/A
Afflux
(low flow) 2 1 4 3 N/A N/A
Afflux
(high flow) 2 1 4 3 N/A N/A
Flow
distribution 4 3 5 6 2** 1
Sediment
transportation 4 3 6 5 2** 1
Environment 6 3 4 5 2** 1
Key
Lowest hydrodynamic impact
Highest hydrodynamic impact
Table 17: Option impact comparison
* The hydrodynamic impact of the alternative chain ferry utilising a piled slipway is
assessed as being similar to that for a solid slipway.
** Impacts during construction phase and short term are likely to be more significant.
The long term impacts, as classified above, depend on the time required to re‐
establish the existing bed profile.
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10 Environmental Issues A high level appraisal in terms of the key environmental issues and risks associated
with each option was carried out by Halcrow for the Woolwich Ferry Replacement
and Gallions Reach Ferry Feasibility study in 2009/10. The environmental constraints
within the immediate study area, and significant features outside the immediate area,
were identified.
Data sources used by Halcrow for the initial appraisal included existing data from
Natural England, Multi‐Agency Geographic Information for the Countryside
(MAGIC), the Environment Agency (EA), English Heritage as well as baseline
information from environmental statements in the area (such as the Thames Gateway
Bridge Draft Updated Environmental Statement 2008).
The topics previously assessed have been revisited and updated where appropriate
for the principles of the preliminary design as it has developed. These key issues
remain subject to ongoing review as the project continues into more detailed stages.
The comparison of design options takes environmental issues and risks into
consideration. It is anticipated that detailed design of TfL’s preferred crossing option
would include a more in‐depth environmental appraisal.
A summary of environmental issues considered is included in Appendix D. The
following sections highlight particular issues of note for each type of ferry
infrastructure.
10.1 Comparison of Ferry Types
In addition to the summary of environmental issues in Appendix D, the same key
topic headings have been considered in the comparison of propeller driven and chain
driven ferry options. The results of this comparison are presented in Table 18 below:
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Topic Propeller Driven Ferry Chain Ferry
Energy use and
material use
It is generally considered that a propeller driven ferry will use
more energy as it work against currents and makes berthing
manoeuvres. However, less frequent crossings are anticipated
which will offset this to some extent.
The structural components for the terminals (particularly
linkspans and pontoons) are likely to embody a significant
amount of energy in their production.
It is generally considered that a chain ferry will use less energy.
However, more frequent crossings are anticipated which will offset
this to some extent.
Depending upon the type of slipway used (ie. solid or supported
on piles), there could be significant quantities of concrete used for
this option.
General land use of
immediate area
There is no differentiation between the two options in this aspect as both options are in the same location.
Links with
transportation
Whilst very similar new highway links will be required to
service both options of ferry type, the propeller driven ferry is
expected to provide less of an improvement to accessibility
across the river as it would make fewer crossings per hour. This
is due to the effect on alighting and boarding times that the
length of the vehicular approach will have.
Whilst very similar new highway links will be required to service
both options of ferry type, the chain ferry is expected to provide a
greater improvement to accessibility across the river through more
frequent crossings. This is due to the more direct route for alighting
and boarding of vehicles.
Land take
requirements
Whilst very similar highway links will service both options of
ferry type, the propeller driven ferry will take less land in the
immediate area of the flood defence wall.
Whilst very similar highway links will service both options of ferry
type, the chain ferry is expected to take significantly more land in
the immediate area of the flood defence wall to accommodate a
slipway wide enough for two vessels.
Community and
pedestrian links
Whilst both options of ferry type will serve the same
community (including provision for pedestrians), the propeller
driven ferry is expected to make fewer crossings per hour due
to the effect on boarding and alighting times the length of the
vehicular approach will have.
Whilst both options of ferry type will serve the same community
(including provision for pedestrians), the chain ferry is expected to
make more crossings per hour due to the more direct route for
boarding and alighting of vehicles.
Biodiversity
There is little or no differentiation between the two options in
terms of the effect on landside biodiversity.
It is anticipated that disturbance to habitats in the river will be
There is little or no differentiation between the two options in
terms of the effect on landside biodiversity.
The slipways necessary for a chain ferry are anticipated to have a
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Topic Propeller Driven Ferry Chain Ferry
restricted by the use of a limited number of piles at each
terminal location.
significantly greater impact on biodiversity in the intertidal zone of
the river. This may be mitigated to a large extent by selection of a
“bridge” type slipway supported on piles.
Floodrisk There is no differentiation between the two options in this aspect as both options are in the same location.
Hydrodynamics
and sediment
transport
The propeller driven ferry is anticipated to have a
comparatively lesser effect upon hydrodynamics and sediment
transport (refer to Hydrodynamic Impact Assessment section of
this report).
The chain ferry is anticipated to have a comparatively greater effect
upon hydrodynamics and sediment transport (refer to
Hydrodynamic Impact Assessment section of this report).
Archaeology
(including UXO)
and heritage
features
There is little or no differentiation between the two options in
terms of the effect on local archaeology or heritage features.
The smaller footprint of terminals for a propeller driven ferry
lessens the risk of discovering unexploded ordnance resulting
from extensive bombardment during the Second World War.
There is little or no differentiation between the two options in
terms of the effect on local archaeology or heritage features.
The larger footprint of a chain ferry slipway increases the risk of
discovering unexploded ordnance resulting from extensive
bombardment during the Second World War.
Residential
properties,
receptors of air and
noise impacts
No air pollution impact is anticipated from the terminal
infrastructure. Modern propulsion systems are not anticipated
to present an air pollution issue. Given the existing use of the
river by other propeller driven vessels, noise at receptors is not
anticipated to increase with the introduction of the ferry service.
No air pollution impact is anticipated from the terminal
infrastructure. Modern propulsion systems are not anticipated to
present an air pollution issue. Whilst it is recognised that the noise
of chain ferry may be noticeable due to the difference from other
river traffic, modern chain ferries are not considered to be
particularly noisy.
Visual and
landscape impact
The infrastructure for a propeller driven ferry will comprise of
large pontoon and linkspan structures which will have a
significant visual impact for some distance along the river.
However, there are other large manmade structures in the
vicinity (eg. Barking flood barrier to the north and Tripcock Hill
to the south) which would remain dominant features.
Although terminals for a chain ferry will occupy a larger reach of
the river bank, their low‐level nature is expected to have a lesser
visual impact.
Table 18: Environmental comparison of ferry types
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11 Risk Assessment Halcrow developed an initial risk register for the Woolwich Ferry Replacement and
Gallions Reach Ferry Feasibility Study in 2009/2010 through workshops with TfL.
This risk register is intended to be a live document which is to be developed further
under TfL’s ownership throughout the life of the scheme as options are progressed.
In order to continue the principles of risk management established in the previous
Halcrow study, the risk register presented in Appendix E has been revisited and
refreshed as appropriate for the scope of this preliminary design package. Each
existing risk item has been examined for its validity and ratings adjusted if necessary.
The issues highlighted in the risk register have been considered in the development
of preliminary designs. Any new risks that have emerged as the design process has
progressed have also been added to the risk register and given appropriate ratings.
11.1 Significant Risks
The most significant risks for a proposed ferry crossing at Gallions Reach are
summarised below:
Policy change following General, Local or Mayoral elections leads to
cancellation of scheme;
Existing safeguarding direction for crossing at Gallions Reach may be for a
bridge only, resulting in increased cost and delays associated with obtaining
necessary powers for a ferry crossing. Could possibly jeopardise the viability
of the scheme;
(Chain ferry only) Tidal river deposits on slipway causes slippery surface
which would be a danger to users;
(primarily chain ferry) EA will not give necessary consents due to
environmental or hydrodynamic impacts of the chosen design;
TWA Orders refused by Secretary of State, resulting in increased cost and
delays associated with obtaining necessary powers;
Higher cost of materials than anticipated;
Higher than anticipated tender prices from construction contractors; and
The following risks have been assessed as significant in the risk register but have
been mitigated in the preliminary design as described:
(Chain ferry only) Depth of unsuitable material to be removed for
construction of solid slipway is too large to be practicable/cost effective.
Mitigation: review geotechnical information and if necessary, choose a piled
slipway solution instead;
(Primarily propeller ferry) Further investigation of preliminary design options
results in infrastructure encroaching into the navigational envelope previously
considered in MARICO risk assessment.
Mitigation: design to consider repositioning of terminals as necessary to avoid
encroachment into navigational envelope, but navigational risk assessment
can be revisited if necessary;
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Dredging may be necessary to accommodate larger vessels than originally
envisaged, which would damage habitats, increase construction costs and
present an ongoing maintenance liability.
Mitigation: design to consider repositioning of terminals as necessary to
eliminate the need for dredging as far as reasonably practicable;
Non‐motorised users endangered by vehicular movements and exposure to
elements.
Mitigation: design to include segregation of non‐motorised users from traffic
where possible with provision of adequate shelter; and
Welfare of operations staff.
Mitigation: design to include staff welfare facilities at each terminal.
11.2 Retired Risks from Previous Study
The previous version of the risk register was developed from a study which
considered a possible replacement of the existing Woolwich Ferry as well as a ferry
service at Gallions Reach. Several of the risks have been retired under the scope of the
Gallions Reach Marine Aspects task as they are applicable to the Woolwich operation
only.
A number of other risks have been retired as the brief for the Gallions Reach Marine
Aspects task addresses their causes. In the case of interface with construction works
for Crossrail, Thames Tideway Tunnel and the 2012 Olympic and Paralympic Games,
it is considered that ferry infrastructure construction will no longer overlap with the
demands on the local logistical network from these schemes.
The risk register in Appendix E continues to show all items, but those risks that have
been retired are annotated as such.
11.3 Construction (Design and Management) Regulations 2007
Through the development of preliminary design solutions in this task, Halcrow has
assumed the role of Designer as defined in Regulation 2 of the Construction (Design
and Management) Regulations 2007. Regulations 11 and 18 set out the duties of the
Designer which include the elimination of hazards and reduction of risks during the
design process as far as reasonably practicable. Any remaining health and safety risks
shall be advised for the benefit of the Client and future duty holders as the scheme
progresses.
In order to satisfy these requirements, a Designer’s Risk Assessment has been
prepared and is included in Appendix F.
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12 Cost Estimates Cost estimates for each of the preliminary design options developed by Halcrow and
discussed in this report have been prepared for comparison by TfL with each other
and with other river crossing options.
12.1 Assumptions
The cost estimates contain a number of assumptions as follows:
Linkspans for the propeller driven ferry option will be fabricated off site and
transported by river (cost of transportation included in estimate);
Pontoons for the propeller driven ferry option will be fabricated off site and
floated up the river into position (cost of transportation included in estimate);
Marine piles will be of tubular steel construction, infilled with concrete;
The cost estimate for the chain ferry infrastructure includes the cost of chains
for the avoidance of doubt over their inclusion as part of the infrastructure or
part of the vessels;
The cost of any highway infrastructure is not included in these estimates as
this work is outside the scope of this task;
The four‐lane option for a propeller driven ferry incurs a pro‐rata cost increase
on approach structures from the two‐lane option. The pontoon widths
between two and four lane options can remain the same;
The six‐lane option for a propeller driven ferry incurs a pro‐rata cost increase
on approach structures, linkspans and pontoons from the two‐lane option;
The number of traffic lanes will not have an effect on the size of the slipway
for a chain ferry;
No allowance has been made for dredging, as it is assumed that this activity is
not permitted by PLA;
Staff accommodation cost estimates include for boundary fencing and
provision of slipway cleaning equipment in the case of the chain ferry option;
Maintenance of ferry vessels is assumed to be carried out in dry‐dock remote
from Gallions Reach and is not included in these cost estimates; and
Whilst it is assumed that the ferry service will be tolled, the cost of tolling
equipment cannot be quantified at this stage (and is outside the scope of this
task).
12.2 Risk and Optimism Bias
According to instruction from TfL, risk and contingency is excluded from the cost
estimate. However, it is recommended that a project risk contingency of 25% is
applied to the cost estimates presented in this report. This value has been derived
from the value of 30% in the previous feasibility study, with an appropriate reduction
to allow for the retirement of some risks from the risk register and further
development of the infrastructure solutions.
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Specific issues which should be considered by TfL when determining an appropriate
level of Optimism Bias to apply to the cost estimates presented in this report are as
follows:
The scheme is considered to be “non‐standard” in terms of a highway link;
The scheme is at a point in its development between conception and preferred
route decision; and
A qualitative risk assessment has been carried out, though outline quantities
could be determined from the assessed cost impacts of each risk item.
12.3 Summary of Ferry Options
Table 19 presents a summary of the cost estimates for each option. A full build‐up of
costs for each option is provided in Appendix G:
Propeller Ferry Chain Ferry
2 traffic lanes £16,677,673 £13,926,290
On‐costs £7,254,788 £6,057,936
Total for 2 lanes £23,932,461 £19,984,226
4 traffic lanes £19,807,820 £13,926,290
On‐costs £7,507,164 £6,057,936
Total for 4 lanes £27,314,984 £19,984,226
6 traffic lanes £29,891,823 £13,926,290
On‐costs £8,354,764 £6,057,936
Total for 6 lanes £38,246,587 £19,984,226
Table 19 Summary of Cost Estimates
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13 Conclusions and Recommendations
13.1 Summary of Infrastructure Options
Table 20 below provides a comparative summary of the two ferry infrastructure
options investigated at the preliminary design stage:
Propeller Ferry Chain Ferry
Cost Infrastructure is more
expensive.
Ferry vessel is expected to be
more expensive (outside scope
of this task).
Number and skill level of staff
will be higher.
Infrastructure is less expensive.
Ferry vessel is expected to be
less expensive (outside scope of
this task).
Number and skill level of staff
will be lower.
Programme Minimal piling and insitu
construction works are
expected to result in a shorter
construction period than for a
chain ferry.
Procurement of vessels (outside
scope of this task) may take
longer.
More temporary works and
significantly larger plan area of
insitu concrete works are
expected to take longer to
construct.
Procurement of vessels (outside
scope of this task) may be
quicker.
Constructability Can be constructed largely
using “modular” components.
Hazard to river navigation
presented by piling equipment
for approach structures and
dolphins.
Cofferdams would be needed
for construction of lower
sections of slipways.
Hazard to river navigation
presented by piling equipment
for suspended slipways.
Operation Self‐levelling terminal system
requires no operative
intervention but longer
approaches will require more
staff for co‐ordination of traffic.
Vessels will require highly
skilled key staff to navigate the
river and berth efficiently at
every crossing.
Pedestrians can be segregated
from vehicles easily.
Multiple vehicle lanes produce
Simple operation using staff
with a comparatively lower
level of navigational skill.
Safe segregation of pedestrians
and vehicles is not feasible
leading to longer boarding and
alighting times.
Multiple vehicles lanes for
boarding and alighting can be
accommodated on slipways.
Slipways will need to be kept
clean of river deposits from
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Propeller Ferry Chain Ferry
faster turnaround times but are
more difficult to provide.
tidal washing.
Environmental
impact
The terminal infrastructure is
largely suspended above the
river, meaning less disruption
to the inter‐tidal zone of the
river and associated effects on
biodiversity.
Noise from a propeller ferry is
unlikely to be distinguished
from other river traffic by local
receptors.
Lower energy demand is
anticipated from a chain ferry.
A more frequent service is
possible through shorter berth,
alighting and boarding times.
The low‐level slipway terminals
will have a lower visual impact.
Hydrodynamic
impact
There is considered to generally
be lesser impact from a
propeller ferry due to the lower
blockage ratio presented by the
infrastructure.
A slipway would present a
significant blockage ratio which
is likely to have a greater effect
upon hydrodynamic processes.
Other risk The terminals for a propeller
driven ferry will present a
greater hazard to navigation in
the river.
Regular washing of the slipway
by the tide would present a
slippery surface requiring
regular cleaning.
Table 20 Comparative summary of ferry infrastructure options
13.2 Recommendations
It must be appreciated that a ferry crossing at Gallions Reach will not be able to
provide the same capacity as a fixed tunnel or bridge crossing. Bearing this in mind, if
TfL wishes to pursue a ferry crossing, the recommended option is that of a chain ferry
using a piled slipway.
Whilst a chain ferry would be more difficult to construct initially, with a longer
construction duration, it has more benefits than the propeller driven ferry in terms of
construction cost, number of operatives and vessel operation.
The slipway arrangement allows for flexibility in the number of highway lanes
servicing the ferry. An arrangement using four lanes is considered to be the best
compromise in terms of land take and highway construction cost, with turnaround
times of approximately 8.5 minutes per sailing.
Unfortunately, environmental and hydrodynamic impacts remain significant, despite
the elimination of a solid slipway in favour of a piles solution for geotechnical
reasons. This is a major disadvantage that remains for such an option.
A well considered operational regime will be essential to ensure the safety of users is
given paramount importance. Procedures for regularly cleaning the slipways of
slippery deposits and dealing with the interface between pedestrians and vehicles
would be amongst the highest priorities.
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Appendix A
List of Figures, Tables and Graphs
Gallions Reach River Crossings – (Task 102) Marine Aspects
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Appendix A: List of Figures and Tables
Figures Page
Figure 1 Location of Gallions Reach (Google Maps, 2013) 9
Figure 2 Swept path for articulated HGV boarding vessel 23
Figure 3 Swept path for articulated HGV leaving vessel 23
Figure 4 Swept path for rigid HGV boarding vessel 24
Figure 5 Swept path for rigid HGV leaving vessel 24
Figure 6 Example of curved approach structure at Woolwich 25
Figure 7 Chain tensioning gantry at Torpoint Ferry (Tamar Crossings
2002)
36
Figure 8 Slipway cleaning equipment used at Torpoint Ferry (Merlo
2007)
42
Figure 9 Screenshot of VISSIM 2‐lane alighting simulation after 70
seconds
44
Figure 10 Screenshot of VISSIM 2‐lane alighting simulation after 110
seconds
44
Figure 11 Screenshot of VISSIM 2‐lane alighting simulation after 210
seconds
44
Figure 12 Screenshot of VISSIM 2‐lane boarding simulation after 60
seconds
46
Figure 13 Screenshot of VISSIM 2‐lane boarding simulation after 130
seconds
46
Figure 14 Screenshot of VISSIM 2‐lane boarding simulation after 250
seconds
46
Figure 15 Screenshot of VISSIM 2‐lane boarding simulation after 340
seconds
46
Figure 16 Screenshot of VISSIM 4‐lane alighting simulation after 238
seconds
47
Figure 17 Screenshot of VISSIM 4‐lane boarding simulation after 81
seconds
48
Figure 18 Key to VISSIM 6‐lane boarding regime 49
Figure 19 Screenshot of VISSIM 6‐lane boarding simulation after 182
seconds
50
Figure 20 Screenshot of VISSIM 2‐lane alighting simulation after 70
seconds
51
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Figure 21 Screenshot of VISSIM 2‐lane alighting simulation after 120
seconds
51
Figure 22 Screenshot of VISSIM 2‐lane alighting simulation after 250
seconds
52
Figure 23 Screenshot of VISSIM 2‐lane boarding simulation after 30
seconds
53
Figure 24 Screenshot of VISSIM 2‐lane boarding simulation after 60
seconds
53
Figure 25 Screenshot of VISSIM 2‐lane boarding simulation after 165
seconds
53
Figure 26 Screenshot of VISSIM 2‐lane boarding simulation after 250
seconds
53
Figure 27 Existing Woolwich Ferry vessel (Halcrow, 2009) 56
Figure 28 Single deck mechanical linkspan at Dublin Port (Halcrow, 2000) 57
Figure 29 Double deck mechanical linkspan at Dublin Port (Halcrow,
2003)
58
Figure 30 Typical self‐beaching propeller ferry (MV Loch Dunvegan –
Caledonian MacBrayne)
59
Tables
Table 1 Documentation received from TfL 12
Table 2 Other sources of information used in this task 13
Table 3 North bank stratigraphy and basic parameters 16
Table 4 South bank stratigraphy and basic parameters 17
Table 5 Boarding regime with six‐lane arrangement for propeller driven
ferry
49
Table 6 Comparison of alighting and boarding times for propeller
driven ferry
50
Table 7 Comparison of alighting and boarding times for chain ferry 55
Table 8 Ferry Option Blockage Ratios 61
Table 9 Back water Effect of Propeller Driven Ferry Option, calculated
using the method described in HDS1‐ Hydraulics of Bridge
Waterways.
62
Table 10 Back water Effect of Chain Ferry Option (solid slipway),
calculated using the method described in HDS1‐ Hydraulics of
Bridge Waterways.
62
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Table 11 Revised Ferry Option Blockage Ratios 64
Table 12 Concrete Bridge Blockage Ratios 65
Table 13 Back water Effect of Concrete Bridge Option, calculated using
the method described in HDS1‐ Hydraulics of Bridge
Waterways.
66
Table 14 Steel Bridge Blockage Ratios 67
Table 15 Back water Effect of Steel Bridge Option, calculated using the
method described in HDS1‐ Hydraulics of Bridge Waterways.
67
Table 16 Immersed Tunnel Blockage Ratios 68
Table 17 Option impact comparison 70
Table 18 Environmental comparison of ferry types 73
Table 19 Summary of Cost Estimates 77
Table 20 Comparative summary of ferry infrastructure options 79
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
Appendix B
Glossary of Abbreviations
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
Appendix B: Glossary of Abbreviations
ANPR Automatic Number Plate Recognition
BR Blockage Ratio
BS British Standard
CD Chart Datum
CIRIA Construction Industry Research and Information Association
CPT Cone Penetration Tests
CSA Cross ‐ sectional Area
EA Environment Agency
ELRC East London River Crossing
HAT Highest Astronomical Tide
HGV Heavy Goods Vehicle
HRT Highest Recorded Tide
HSA Hydro ‐ structure Area
LAT Lowest Astronomical Tide
LRT Lowest Recorded Tide
MAGIC Multi‐Agency Geographical Information for the Countryside
MHWN Mean High Water Neaps
MHWS Mean High Water Springs
MLWN Mean Low Water Neaps
MLWS Mean Low Water Springs
MWL Mean Water Level
OD Ordnance Datum
PCU Passenger Car Unit
PLA Port of London Authority
PTV Planung Transport Verkehr AG
SI Site Investigation
SPT Standard Penetration Test
TDE Traffic Design Engineering
TfL Transport for London
TGB Thames Gateway Bridge
TWA Transport and Works Act 1992
UCS Unconfined Compressive Strength
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
Appendix C
Preliminary Design Drawings
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
Appendix C: Preliminary Design Drawings
Propeller Driven Ferry:
472413‐001 Layout Plan – 2 Lane Option
472413‐002 Layout Plan – 4 Lane Option
472413‐003 Layout Plan – 6 Lane Option
472413‐004 Typical Longitudinal Section
472413‐005 Plan on Ferry Berth – 2 Lane & 4 Lane Options
472413‐006 Plan on Ferry Berth – 6 Lane Option
472413‐007 Details Sheet 1 of 3
472413‐008 Details Sheet 2 of 3
472413‐009 Details Sheet 3 of 3
Chain Ferry:
472413‐010 Layout Plan
472413‐011 Longitudinal & Cross Sections
Highway Alignments (in consultation with Task 95 team) northern shore only:
472413‐201 Propeller Driven Ferry Layout Plan – 2 Lane Option
472413‐202 Propeller Driven Ferry Layout Plan – 4 Lane Option
472413‐203 Propeller Driven Ferry Layout Plan – 6 Lane Option
472413‐204 Chain Ferry Layout Plan – 2 Lane Option
472413‐205 Chain Ferry Layout Plan – 4 Lane Option
472413‐206 Chain Ferry Layout Plan – 6 Lane Option
100 20 90604030 50 70 80 100
SCALE 1:1000 (A1)
SCALE 1:2000 (A3)
METRES
LAYOUT PLAN
PROPELLER DRIVEN FERRY
2 LANE OPTION
Halcrow Group Limited
www.halcrow.com
A CH2M Hill Company
GALLIONS REACH RIVER CROSSING
( TASK 95 & TASK 102 )
NOTES:
1. LEVELS ARE TO ORDINANCE DATUM
2. ALL DIMENSIONS ARE IN METRES UNLESS NOTED
OTHERWISE.
100 20 90604030 50 70 80 100
SCALE 1:1000 (A1)
SCALE 1:2000 (A3)
METRES
LAYOUT PLAN
PROPELLER DRIVEN FERRY
4 LANE OPTION
Halcrow Group Limited
www.halcrow.com
A CH2M Hill Company
GALLIONS REACH RIVER CROSSING
( TASK 95 & TASK 102 )
NOTES:
1. LEVELS ARE TO ORDINANCE DATUM
2. ALL DIMENSIONS ARE IN METRES UNLESS NOTED
OTHERWISE.
100 20 90604030 50 70 80 100
SCALE 1:1000 (A1)
SCALE 1:2000 (A3)
METRES
Halcrow Group Limited
www.halcrow.com
A CH2M Hill Company
GALLIONS REACH RIVER CROSSING
( TASK 95 & TASK 102 )
NOTES:
1. LEVELS ARE TO ORDINANCE DATUM
2. ALL DIMENSIONS ARE IN METRES UNLESS NOTED
OTHERWISE.
LAYOUT PLAN
PROPELLER DRIVEN FERRY
6 LANE OPTION
100 20 90604030 50 70 80 100
SCALE 1:1000 (A1)
SCALE 1:2000 (A3)
METRES
Halcrow Group Limited
www.halcrow.com
A CH2M Hill Company
GALLIONS REACH RIVER CROSSING
( TASK 95 & TASK 102 )
NOTES:
1. LEVELS ARE TO ORDINANCE DATUM
2. ALL DIMENSIONS ARE IN METRES UNLESS NOTED
OTHERWISE.
CHAIN FERRY
LAYOUT PLAN
2 LANE OPTION
100 20 90604030 50 70 80 100
SCALE 1:1000 (A1)
SCALE 1:2000 (A3)
METRES
Halcrow Group Limited
www.halcrow.com
A CH2M Hill Company
GALLIONS REACH RIVER CROSSING
( TASK 95 & TASK 102 )
NOTES:
1. LEVELS ARE TO ORDINANCE DATUM
2. ALL DIMENSIONS ARE IN METRES UNLESS NOTED
OTHERWISE.
CHAIN FERRY
LAYOUT PLAN
4 LANE OPTION
100 20 90604030 50 70 80 100
SCALE 1:1000 (A1)
SCALE 1:2000 (A3)
METRES
Halcrow Group Limited
www.halcrow.com
A CH2M Hill Company
GALLIONS REACH RIVER CROSSING
( TASK 95 & TASK 102 )
NOTES:
1. LEVELS ARE TO ORDINANCE DATUM
2. ALL DIMENSIONS ARE IN METRES UNLESS NOTED
OTHERWISE.
CHAIN FERRY
LAYOUT PLAN
6 LANE OPTION
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
Appendix D
Environmental Summary Table
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
Environmental Issue Commentary
Energy use and material use Provision of a new ferry service at Gallions Reach would be linked to a cessation of services at Woolwich and may also
result in the removal of the redundant infrastructure, which should be disposed of in a sustainable matter.
New infrastructure at Gallions Reach will allow new technology to be used. The new technology is highly likely to
have a lower energy use than the existing Woolwich infrastructure. The energy demands of the proposed
infrastructure options will be considered at the detailed stage of the project.
The sustainability of materials used in the preferred option design will be assessed at the detailed stage of the project.
Ferry infrastructure which does not require electricity but relies on tidal power is preferable in terms of energy use.
General land use of immediate area There are relatively few residential areas to the north and south of the Gallions Reach area, particularly in comparison
to the Woolwich Ferry area.
A disused area of former industrial land and mixed land use area of the Royal Albert Basin are located on the north
river bank. This includes a commercial area, a residential area and the Docklands Campus of the University of East
London.
The residential area of Beckton and Gallions Reach Primary School, the London Industrial Park and Gallions Reach
Shopping Park are located north of the river.
Tripcock Park, Tilfen Landfill site, the residential areas of Broadwater and Gallions Reach and Discovery Primary
School are located on the south bank. South of these areas are Belmarsh Prison, the residential area of Thamesmead
and Abbey Wood and an industrial area.
The historical and current industrial land uses in the wider area should be taken into consideration at the detailed
stage of the project, due to the potential for contaminated land and water.
Links with transportation There is no existing road infrastructure leading to the river bank at the Gallions Reach location and therefore new road
infrastructure would be required to both the north and south of the river.
Demands for a ferry service at this location and the impact of removal of a ferry service from Woolwich on the road
network should be considered. Proposed public transport schemes that can be linked with the ferry service will have
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
Environmental Issue Commentary
to be considered at the detailed stage.
Land take requirements Land take would be required for the new road infrastructure and associated queuing/waiting provisions to the north
and south of the river.
South of the river approximately 1.1km of new highway would be required to connect the new ferry to the existing
highway network. provide a junction with Western Way approximately 250m west of the roundabout. It has been
confirmed from discussions with the highway preliminary designer that a signalised T‐Junction with Western Way
will be provided. There may also need to be a signalised junction where the new highway crosses Barnham Drive and
a bridge over the Gallions Canal.
North of Barnham Drive the highway would permanently occupy land within Tripcock Park. It is understood that
developer Tilfen submitted a planning application to London Borough of Greenwich in November 2009 for
landscaping of this area as part of the ‘Thamesis’ park development. Part of this park area encroaches into the corridor
being considered for any ferry option at Gallions Reach. Permanent highway access to a ferry terminal will require
reconfiguration of the current Tilfen plan.
All the land that would be required for the highway connection south of the river is in the ownership of Tilfen Land
Limited. Construction of the link would have to interface with Tilfen’s haul route to their licensed tip which connects
to Western Way at the point that the new junction would be provided. Previously it was suggested that tip traffic
could share the new highway to the north of the Gallions Canal.
North of the river the connection to the principal highway network would be via a combination of new and improved
highways to Gallions Roundabout. Atlantis Avenue which runs east from Gallions Roundabout could be dualled on
its south side and the existing signalised junction with Armada Way and Gallions Road could be modified. Atlantis
Avenue currently terminates at a signalised T‐Junction with Magellan Boulevard and it is proposed that this junction
would be modified to a cross roads with a new connection to the ferry continuing straight on from Atlantis Avenue.
The new connection to the ferry would follow an ‘S’ curve and the eastbound (towards ferry) carriageway would be
widened to provide stacking/waiting capacity as there would not be enough land available to provide an off‐line
waiting/parking area.
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
Environmental Issue Commentary
The land north of the river is generally in the ownership of the London Development Agency (LDA) although PLA
and Thames Water also have interests in land close to the river. Discussions would be required with LDA as to the
acceptability of taking land to dual Atlantis Avenue as this land is currently designated for development. The land
between Magellan Boulevard and the river is designated in the Royal Albert Basin masterplan to become a park and
there is an aspiration to extend the riverside footpath right through this area which may not be compatible with an
access road to a ferry.
Community and pedestrian links The Thames Path is located along the south bank of the river at Gallions Reach, however there are currently no river
crossing provisions for pedestrians.
Pedestrians from the residential areas north and south of the river wishing to cross at this location have to use the
Woolwich foot tunnel to the west. Vehicle users from the residential areas north and south have to use Woolwich
Ferry or divert further west to Blackwall Tunnel.
As there are no provisions for pedestrians currently, the demand for a pedestrian crossing is not known. Pedestrians
currently using the Woolwich Ferry to cross the river will need to use the Woolwich foot tunnel or walk to the
proposed Gallions Reach ferry. A survey of pedestrian demand at this location and at Woolwich Ferry and foot tunnel
should be carried out. In addition, the existing land use and planning applications for future land use, as well as
existing and proposed public transport links would have to be considered at the detailed stage in order to assess the
catchment area for a pedestrian crossing facility at this location.
Biodiversity A new ferry service at Gallions Reach would result in a change to the existing situation, as there would be construction
works in the river itself, on the river bed and on the mudflats of the river in an area of the river where there is
currently no development. There would also be changes arising from decommissioning the Woolwich Ferry, which is
expected to occur with the introduction of a new service at Gallions Reach.
There are no statutory designated sites within the immediate study area. The closest statutory designated sites are
Abbey Wood SSSI and Gilbert’s Pit’ a geological SSSI both located more than 2km south of the proposed ferry location.
There are a number of non statutory sites and locally designated sites within the immediate study area.
The Thames Estuary is a Site of Metropolitan Importance. The area of the Thames Estuary and Marshes that falls in the
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
Environmental Issue Commentary
immediate area is an Important Bird Area, an international initiative that aims to identify and protect a network of
sites for birds. The mudflats of the Thames fall under the Biodiversity Action Plan Priority Habitat as a rare or
threatened semi‐natural habitat.
The Thamesmead Historic Area and Wetlands is a site of Borough Importance on the south of the river.
The non statutory sites and locally designated sites within the immediate and wider area would have to be taken into
consideration at the more detailed stage of the project through further ecological surveys and assessments. In
particular impacts on the inter‐tidal zone will have to be considered.
The surveys may include aquatic ecology and ornithology surveys as well as terrestrial ecology surveys.
Floodrisk The last major tidal flooding of the Thames Estuary occurred in 1953 when hundreds of lives were lost: the Thames
Barrier and associated flood defences were constructed as a result of this event and were designed to protect against a
1 in 1000 year flood event in 2030. They are set at a height of +7.2m OD and are located approximately 1.6 km west of
the existing Woolwich ferry service.
The Environment Agency flood map shows that the Gallions Reach area is within Flood Zone 3, an area that could be
affected by flooding either from rivers or the sea. Some smaller parts of the area could be affected by an extreme flood
and are located in Flood Zone 2.
Taking the current flood risk assessment into consideration, the detailed stage of the project design is required to
include a PPS 25 Flood Risk Assessment.
Hydrodynamics and sediment transport A ferry service at Gallions Reach would introduce new structures at a location where there were previously no
structures.
Hydrodynamics and sediment transport are key issues that would need to be assessed further using detailed
modelling and analysis at the detailed stage of the project, once the preferred option has been selected and designed,
in order to mitigate any potential impacts such as build up of sediment, changes in hydrodynamics, dredging
requirements on other upstream or downstream sites.
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
Environmental Issue Commentary
As shown in the initial hydrodynamic comparisons in this report, the type of ferry infrastructure and its size, shape
and location would influence hydrodynamics and sediment transport.
Archaeology (including UXO) and heritage
features
There are fewer archaeological and heritage features within the immediate area. There are no listed buildings in the
immediate study area. The Royal Arsenal Conservation Area is not in the immediate area but may need to be taken
into consideration in terms of impacts from changes in traffic volumes at the detailed stage of the project. Newham
Archaeological Priority Area is located on the north bank and Greenwich Area of High Archaeological Interest is
located on the south bank of the river.
The heritage features in the immediate area include evidence of a prehistoric landscape in North Woolwich and
Thamesmead and historical ordnance testing ground area, where foundry cannon balls have been found at Gallions
Reach Urban Village.
An unexploded ordnance survey has been carried out and would need to be taken into account prior to any
construction works in the River Thames as the area was subject to bombardment in World War II.
Residential properties, receptors of air and
noise impacts
This option introduces new impacts for residents in Thamesmead and Beckton. It will lead to a change in the number
of residential properties and to the residential areas affected by traffic impacts associated with the ferry crossing.
The Gallions Reach area contains fewer residential properties on the north bank and south bank of the river in
comparison to the area of the existing Woolwich Ferry.
However, there may be impacts on other residential areas in the wider area around Gallions Reach. This change in
residents impacted by road traffic impacts such as air, noise and congestion will be assessed and determined at the
detailed stage of the project, taking the traffic study into consideration.
Visual and landscape impact The site is located within the Greater Thames Estuary National Character Area .This option will introduce a new visual
feature to the Gallions Reach area. Potential receptors of any visual and landscape impacts include residents in the
Albert Dock development, residents in Thamesmead as well as users of Tripcock Park and the Thames Path. The
detailed stage of the assessment will include the visual and landscape impacts, taking into consideration the landscape
character and maritime heritage of the River Thames.
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
Appendix E
Risk Register
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
(This page is blank for double‐sided printing)
Gallions Reach CrossingsMarine Aspects
Project Risk Register
Management Arrangements
This register records all currently identified threats and opportunities identified by the feasibility project team
Version No Date Prepared By Checked By Approved By Authorised Comments
Issue 1 22-Jan-10 Halcrow Group JPH MFG TfL Register prepared for Initial Ferry Feasibility Study
Issue 2 19-Apr-13 Halcrow Group MFG MFG TfL Register updated for Marine Aspects Outline Design
Risk Ranking Values
From To From To From To
1% 10% 1 0 10k 0 1wk 1
11% 25% 2 10k 50k 1wk 1mth 2
26% 50% 3 50k 250k 1mth 6mth 3
51% 75% 4 250k 500k 6mth 1yr 4
76% 100% 5 500k 1yr 5
-25 -20 -15 -10 -5 5 10 15 20 25
-20 -16 -12 -8 -4 4 8 12 16 20
-15 -12 -9 -6 -3 3 6 9 12 15
-10 -8 -6 -4 -2 2 4 6 8 10
-5 -4 -3 -2 -1 1 2 3 4 5
Insignificant
Marginal
ScoreScoreDescription Description
Improbable
Remote
Probability Impact (£) Impact (time)
Occasional
Probable
Significant
Substantial
Extreme
ThreatOpportunity
Frequent
Risk Register Gallions Reach Marine Aspects Transport for London
Risk Figures & Statistics Risk Mitigation Information
Category Sub-Category Risk/Opp Title Description Cause Effect Date By Status Last Updated Min (£k) Likely (£k) Max (£k) Opt (wks) Most (wks) Pess (wks)
1.01Planning &
Outline Design
Transport & Works Act
approval issues Risk LegislationTransport & Works Act orders
refusedNot considered to be an acceptable route by SoS
New legislative procedures required (CPO, PLA, MFA, TfL
Bill) 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 0 5 TfL
Early communication with DfT Transport & Works Act unit to establish whether acceptable or not 10
1.02Planning &
Outline Design
Transport & Works Act
approval issues Risk LegislationTransport & Works Act orders
delayedLate application / unclear or
unacceptable solution Delay / cost of redesign 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 2 3 TfLLiaison during solution development 6
1.03Planning &
Outline Design
Transport & Works Act
approval issues Risk PLA approvals
Delay to or lack of approval/consent to TfL
applications (eg. temporary works licence, PLA opinion on
chains)Late application / unclear or
unacceptable solution Delay / cost of redesign 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 2 2 TfLOngoing liaison with PLA 2
1.04Planning &
Outline Design
Transport & Works Act
approval issues RiskPLA navigation
aidsUnknown extent of PLA
requirements
Further design work required (for chain or self-propelled -
don't yet know) Delay/additional cost 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 1 0 TfLEarly and ongoing discussions with PLA 1
1.05Planning &
Outline Design
Transport & Works Act
approval issues Risk Navigation aids
Replacement PLA radar or other navigation aids not procured in time for construction of terminal
infrastructure to commenceDifficulty in agreeing
requirements with PLA Delay / loss of revenue 13/01/2010 Tfl/Halcrow Retired 19/04/2013 1 0 2 TfL
Retired:Outside scope of Gallions Reach Marine Aspects outline design 2
Time scoreProb. Score
Total Risk Score
Owner Strategy
Risk Register IdentificationRisk No. Cost score
1.05 Outline Design approval issues Risk Navigation aids infrastructure to commence requirements with PLA Delay / loss of revenue 13/01/2010 Tfl/Halcrow Retired 19/04/2013 1 0 2 TfL Aspects outline design 2
1.06Planning &
Outline Design
Transport & Works Act
approval issues RiskConsultation on
proposed solution Acceptability of solutionObjections by key stakeholders
and/or users Re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 4 2 2 TfLEarly liaison with stakeholder groups 8
1.07Planning &
Outline Design
Transport & Works Act
approval issues Risk Legislation
Existing order for crossing at Gallions Reach may be for a
bridge onlyFerry crossing may require new
orders to be drawn up Delay/increased cost or
cancellation 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 0 0 TfL
TfL to take legal advice on whether existing bridge orders can be used for a ferry
potential cancellation
2.01Planning &
Outline DesignConsents & approvals Risk EA consents
Delay of EA approval for necessary consents (also applicable to MFA & PLA)
Late application / unclear or unacceptable solution Delay 13/01/2010 Tfl/Halcrow Open 19/04/2013 3 2 3 TfL
Agree objective criteria with stakeholders and meet regularly.Proposals being developed further 9
2.02Planning &
Outline DesignConsents & approvals Risk
Works outside Transport & Works Act
Planning process for highway improvements remote from ferry
terminals
Highway improvements may still require conventional planning
process Delay 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 1 1 TfL
Establish whether Transport & Works Act will cover these works early. If not, start planning process ASAP 1
Establish whether Transport & Works Act will cover tolling early If
2.03Planning &
Outline DesignConsents & approvals Risk
Tolling system & enforcement Tolling system approval delays
Tolling regime may still require conventional approval process Delay 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 2 2 TfL
will cover tolling early. If not, start approval process ASAP 4
2.04Planning &
Outline DesignConsents & approvals Risk
Tolling system & enforcement
Tolling system seen as additional costs to locals in comparison to
existing free service at Woolwich Adverse local reaction to tolls Reputation 13/01/2010 Tfl/Halcrow Open 19/04/2013 3 2 1 TfL
TfL to publicise benefits of new service (ie. greater capacity) 6
2.05Planning &
Outline DesignConsents & approvals Opp
Tolling system & enforcement
Tolling system brings in additional revenue Toll revenue stream Cost reduction 13/01/2010 Tfl/Halcrow Open 19/04/2013 3 -3 0 TfL -9
2.06Planning &
Outline DesignConsents & approvals Risk
London City Airport Interference with navigation aids
LCY may impose restrictions on scheme (particularly temporary
works) Cost and delay from re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 1 1 TfL Early liaison with LCY 1
2.07Planning &
Outline DesignConsents & approvals Risk Ecology
Requirements to protect fish paths
Proposed solution may not be acceptable to EA (eg. Slipway
across shallow bank area) Cost and delay from re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 1 1 TfL Early liaison with EA 1
2.08Planning &
Outline DesignConsents & approvals Risk
Apron on southern foreshore
Interruption of mud reach flow by chain
Objections by PLA, MFA & EA about effect of works on river Cost and delay from re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 5 3 TfL
Early liaison with EA/PLA/MFA in conjunction with hydrodynamic impact assessment 5
Retired:Outside scope of Gallions Reach Marine Aspects outline design -
3.01Planning &
Outline DesignLocal Authority
Obligations RiskPlanning
conditions TrafficRestrictions on traffic levels or
further mitigation requiredAdditional data and modelling
required (micro-simulation) 13/01/2010 Tfl/Halcrow Retired 19/04/2013 1 1 1 TfL
p gassumed to be carried out by others 1
3.02Planning &
Outline DesignLocal Authority
Obligations RiskPlanning
conditions AestheticsProposed solution does not meet aesthetic requirements Cost and delay from re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 1 1 TfL
Establish and agree planning conditions with local authority early 1
3.03Planning &
Outline DesignLocal Authority
Obligations RiskPlanning
conditions Noise
Noise from chain ferry (residual noise after mitigation through
vessel design) Cost and delay from re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 3 1 1 TfL
Establish and agree planning conditions with local authority early 1
4.01Planning &
Outline DesignAgreements with
landowners RiskAgreements with
landowners
Failure to reach agreement resulting in objections to Transport & Works Act
Delays in procurement & construction processes mean
deadlines are missed Delay/re-negotiation 13/01/2010 Tfl/Halcrow Retired 19/04/2013 1 1 1 TfL
Retired:Outside scope of Gallions Reach Marine Aspects outline design - assumed to be carried out by others 1
Project Risk Register 1 of 5
Risk Register Gallions Reach Marine Aspects Transport for London
Risk Figures & Statistics Risk Mitigation Information
Category Sub-Category Risk/Opp Title Description Cause Effect Date By Status Last Updated Min (£k) Likely (£k) Max (£k) Opt (wks) Most (wks) Pess (wks)
Time scoreProb. Score
Total Risk Score
Owner Strategy
Risk Register IdentificationRisk No. Cost score
5.01Planning &
Outline DesignWorkforce
Issues RiskChange
managementWillingness of WFF workforce to accept the staffing levels solution
Unionised workforce may not accept proposed solution
Protest action by workforce unless demands are met 13/01/2010 Tfl/Halcrow Retired 19/04/2013 2 2 1 TfL
Retired:Outside scope of Gallions Reach Marine Aspects outline design 4
6.02Planning &
Outline DesignInterfacing
infrastructure RiskThames Tideway
Tunnel
Tunnel may be affected by the proposed solution (eg. piles in
river)
Failure to understand interaction between tunnel and terminal
foundationsDelay/cost from re-design.
Possible cost of compensation 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 3 3 TfL
Early liaison with Thames Water and Thames Tideway Tunnel project team 3
6.03Planning &
Outline DesignInterfacing
infrastructure RiskThames flood
defencesEffect of proposed solution on
defence wallsProposed solution may not be
acceptable to EA Cost and delay from re-design 13/01/2010 Tfl/Halcrow Retired 19/04/2013 1 1 1 TfL
Retired:Outline design to take account of flood defences 1
7.02Planning &
Outline DesignDesign
parameters RiskLarge capacity infrastructure
Design brief requires consideration of
loading/unloading up to 6 lanes of traffic simultaneously
Difficult to achieve without uneconomically/impractically
large infrastructure. Associated problems with connection to
lower capacity highway network
Increased construction cost, land take and navigational
obstacle in river 19/04/2013 Tfl/Halcrow Open 19/04/2013 1 5 3 TfL
Proposed to discount this suggestion at outline design stage due to impracticalities 5
Design to avoid encroachment into
7.03Planning &
Outline DesignDesign
parameters RiskSize of
infrastructure
Larger than anticipated terminals encroach into navigational
envelope considered in previous risk assessment
Further investigation of required geometry and increased
capacity parameters Delay/cost from re-design 19/04/2013 Tfl/Halcrow Open 5 1 2 TfL
encroachment into navigation envelope where possible. Navigational risk assessment to be revisited if necessary 10
8.01Planning &
Outline Design Political Issues Risk Political changesGeneral, local & mayoral elections & tolling regime
Change of scope or cancellation of scheme
Delay/increased cost or cancellation 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 0 0 TfL
Cancellation becoming less likely as workable options are developed
potential cancellation
9.00 NOT USED 19/04/2013
10.01 ProcurementUnanticipated
charges Risk Costs
Increase in scheme costs affecting viability of business
caseHigher cost of materials than
anticipated Possible cancellation 13/01/2010 Tfl/Halcrow Open
Note cancellation scenario not reflected in
risk values 2 5 0 TfLAllow contingency in cost estimate 10
10.02 ProcurementUnanticipated
charges Risk Costs
Increase in scheme costs affecting viability of business
caseDisposal of more waste than
anticipated Possible cancellation 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 4 0 TfLAllow contingency in cost estimate 8
10.03 ProcurementUnanticipated
charges Risk Costs
Increase in scheme costs affecting viability of business
case Lead-in times Possible cancellation 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 0 4 TfL
Investigate procurement of long-lead items 8
10.04 ProcurementUnanticipated
charges Risk Costs
Increase in scheme costs affecting viability of business
caseTender prices higher than
anticipated Possible cancellation 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 5 0 TfLCarry out market testing 10
11.01 ProcurementProgramme alterations Risk
Co-ordinated procurement
Costs of civils works unknown at time of ordering vessels (two
different contracts for civils and vessels)
Costs increase to fit civils design (eg. Affected by ground conditions) to vessels already
ordered. Scheme may be cancelled due to increased
costs
Increased costs, possible delays. Unwanted vessels
delivered 13/01/2010 Tfl/Halcrow Retired 19/04/2013 TfL
Retired:Outside scope of Gallions Reach Marine Aspects outline design. Parameters for ferry provided by TfL following consultation with renowned expert
12.01 Detailed Design Design
Solutions RiskProposed solutions
Design solutions not acceptable to TfL
Unclear brief / requirements of Transport & Works Act cannot
be met within budget Cost and delay from re-design 13/01/2010 Tfl/Halcrow Retired 19/04/2013 1 4 4 TfL
Retired:Brief defined by TfL from consultation following feasibility studies 4
13.01 Detailed DesignEnvironmental
issues Risk Water qualityWater quality affected by
proposed solution
Possible polution/turbidity from proposed solution causes
objections from EA Cost and delay from re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 3 4 TfL Mitigate through design 8
14.01 Detailed DesignDesign
Assumptions RiskDesign
parameters Change to parameters required Initial assumptions not valid Cost and delay from re-design 13/01/2010 Tfl/Halcrow Retired 19/04/2013 1 4 4 TfL
Retired:Brief defined by TfL from consultation following feasibility studies 4Retired:Brief defined by TfL from consultation
14.02 Detailed DesignDesign
Assumptions RiskDesign
parameters Traffic capacity requirements Initial assumptions not valid Cost and delay from re-design 13/01/2010 Tfl/Halcrow Retired 19/04/2013 2 4 4 TfLfollowing feasibility studies 8
14.03 Detailed DesignDesign
Assumptions Risk Geotechnical Unknown ground conditionsAssumptions in design found to
be inadequate
Cost of additional ground investigation. Cost and delay
from re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 3 3 TfLAvailable data being reviewed 3
14.04 Detailed DesignDesign
Assumptions RiskTolling system
(M&E) Design of M&E components
Significant design effort required if electronic "free-flowing" tolling
system usedCost and delay from design and
negotiation with operators 13/01/2010 Tfl/Halcrow Open 19/04/2013 3 2 2 TfL
Early discussion of requirements between designer, client and operator 6
15.01 Detailed DesignDesign
Requirements Opp/RiskChanging
requirementsConsideration of hazardous
goods provisionSavings through reduced specification for vessels Cost increase/savings 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 -2 / 3 -1 / 1 TfL
Explore opportunity with designer, client and operator
-2
3
15.02 Detailed DesignDesign
Requirements OppChanging
requirements
Increase hazardous goods provision or size/weight of
vehiclesOpportunity to provide better
provision for hazardous goods Better service, higher usage 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 -1 -1 TfL
Explore opportunity with designer, client and operator -2
3
Project Risk Register 2 of 5
Risk Register Gallions Reach Marine Aspects Transport for London
Risk Figures & Statistics Risk Mitigation Information
Category Sub-Category Risk/Opp Title Description Cause Effect Date By Status Last Updated Min (£k) Likely (£k) Max (£k) Opt (wks) Most (wks) Pess (wks)
Time scoreProb. Score
Total Risk Score
Owner Strategy
Risk Register IdentificationRisk No. Cost score
15.03 Detailed DesignDesign
Requirements RiskChanging
requirements
Requirements for ferry operations change during design life (for example - larger vehicles, bendy buses, hazardous goods)
Ferry unable to comply with new requirements
Reduced effectiveness of service (conscious decision to
be made at design stage) 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 2 1 TfL
Ferry capacity increased in brief for outline design 2
15.04(was 2.09) Detailed Design
Consents & approvals Risk Sedimentation
Effect on sedimentation patterns -will affect adjacent riparian
facilities
Proposed solution may not be acceptable to EA/PLA/key
stakeholdersCost and delay from re-design (full hydraulic model required) 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 2 2 TfL
Early liaison with EA/PLA/key stakeholders and full hydrodynamic analysis during detailed design stage 2
15.05(was 2.10) Detailed Design
Consents & approvals Risk
Coastal processes
Disruption to coastal processes caused by proposed solution
Proposed solution may not be acceptable to EA/PLA Cost and delay from re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 2 2 TfL
Early liaison with EA/PLA and full hydrodynamic analysis during detailed design stage 2
15.06(was 2.11) Detailed Design
Consents & approvals Risk Archaeology
Effect on known archaeology from proposed solution Objections by English Heritage Cost and delay from re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 1 3 TfL
Review of available data on known archaeology and watching brief for developments 3( ) g pp gy p p j y g g y g p p
15.07(was 6.01) Detailed Design
Interfacing infrastructure Risk Utilities
Change to utilities outside TfL control (eg. Unknown services)
Disruption to services or delay/cost from wayleaves or
diversions. Delay/cost 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 2 1 TfL
Ongoing review of available data and services searches 2
16.01 Enabling WksNavigation
Issues RiskPLA navigation
aidsUnknown extent of PLA
requirements Further design work required Delay/additional cost 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 4 4 TfL
Early and ongoing discussions with PLA assumed to be advancing with progress of design 4
17.01 Enabling WksEnvironmental
Issues RiskNoise & air quality
mitigationUnknown extent of EA & PLA
requirements Further design work required Delay/additional cost 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 3 2 TfL
Early and ongoing discussions with PLA assumed to be advancing with progress of design 3
17.02 Enabling WksEnvironmental
issues Risk Dredging
Dredging of river may be required to achieve necsesary
draft under vessels and/or pontoons
Position of ferry terminals in previous study may not be
compatible with larger vessels in outline design specification
Damage to habitats, additional construction cost and ongoing maintenance requirement (see
29.04) 19/04/2013 Halcrow Open 2 5 2 TfL
Outline design to consider re-positioning terminals as necessary to avoid dredging as far as possible - certainly aim to avoid ongoing maintenance dredging during life of scheme (see 29.04) 10Review all available d t t i i i
18.01 Construction Archaeology Risk ArchaeologyDiscovery of uncharted
archaeology during construction Work halted Delay/additional cost 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 2 2 TfL
data to minimise likelihood of unknown finds 4
19.01 ConstructionEnvironmental
Issues Risk PollutionAccidental pollution of river
during construction Water quality affected
Delay and associated cost. Cost of remediation. Possible cost of
compensation 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 3 1 TfL
Method statements for construction to include procedures to avoid pollution 3
20.01 Construction WW2 Ordnance RiskUnexploded
ordnance
Discovery of unexploded ordnance during construction - no previous construction works
in area Work halted Delay/additional cost 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 1 2 TfL
Review all available data to minimise likelihood of unknown finds 2
21.01 Construction Ecology Risk FishDisturbance to fish during
construction Ecology affected
Delay and associated cost. Cost of remediation. Possible cost of
compensation 13/01/2010 Tfl/Halcrow Open 19/04/2013 3 2 2 TfL
Temporary works designed to avoid disturbance 6
22.01 Construction Site boundaries RiskExisting Woolwich
serviceMaintaining continuous service at
Woolwich during works
Issues with availability of land for construction (developer of
adjacent land demands payment/compensation for delay
to their own project)
Land taken from existing facility resulting in reduced service.
Possible delay from negotiation with adjacent landowners to
take temporary possession of their land 13/01/2010 Tfl/Halcrow Retired 19/04/2013 2 4 4 TfL
Retired:Outside scope of Gallions Reach Marine Aspects outline design 8
23.01 Construction Political Issues RiskExisting Woolwich
servicePolitical implications of stopping
Woolwich serviceCessation of service not
permittedConstruction cannot proceed as
planned 13/01/2010 Tfl/Halcrow Retired 19/04/2013 3 4 4 TfL
Retired:Outside scope of Gallions Reach Marine Aspects outline design 1223.01 Construction Political Issues Risk service Woolwich service permitted planned 13/01/2010 Tfl/Halcrow Retired 19/04/2013 3 4 4 TfL Aspects outline design 12
24.01 ConstructionOther project
interfaces Risk
Interface with other major
projects in the area
Crossrail, Thames Tideway Tunnel & Olympics, may result in conflicts during construction or
reduced ferry service not possible (during Olympics)
Construction may be interrupted/postponed Delay/additional cost 13/01/2010 Tfl/Halcrow Retired 19/04/2013 1 4 4 TfL
Retired:Others schemes no longer likely to impact upon construction programme 4
25.01 ConstructionGround
conditions RiskContaminated spoil removal
High likelihood of contaminated ground requiring specialist
disposal
More contaminated spoil than anticipated needing to be disposed of at high cost Additional cost 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 2 2 TfL
Review all available data to minimise likelihood of unexpected contamination 4
25.02 ConstructionGround
conditions Risk
Removal of unsuitable material
Impractical to remove alluvium deposits (which may be
contaminated)
Alluvial deposits will need to be removed to form suitable
foundation for solid chain ferry slipways
Additional cost - may make solution unviable 19/04/2013 Tfl/Halcrow Open 3 4 2 TfL
Review geotechnical data. If significant removal required, consider alternative option of piled slipway 12
Project Risk Register 3 of 5
Risk Register Gallions Reach Marine Aspects Transport for London
Risk Figures & Statistics Risk Mitigation Information
Category Sub-Category Risk/Opp Title Description Cause Effect Date By Status Last Updated Min (£k) Likely (£k) Max (£k) Opt (wks) Most (wks) Pess (wks)
Time scoreProb. Score
Total Risk Score
Owner Strategy
Risk Register IdentificationRisk No. Cost score
26.01 ConstructionInterfacing
infrastructure RiskExisting
structures
Accidental damage to existing structures caused by construction methods
For example - flood defences, Northern Outfall Sewer, etc
Delay and associated cost. Cost of remediation. Possible cost of
compensation 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 3 2 TfL
Design takes account of existing structures.Method statements for construction to include procedures to avoid damage to existing structures 3
27.01 ConstructionInterfacing operations Risk
Construction in river
Impact on navigation during construction
Disruption to river services or collision with river users. Construction method not
accepted by PLACost and delay from revisiting
construction methods 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 3 3 TfL
Early and continuous liaison with PLA and river users in conjunction with navigational risk assessment 6
27.02(was 3.04) Construction
Local Authority Obligations Risk
Agreements with local authorities
Compliance with agreements not carried out in specified time
Delays in procurement & construction processes mean
deadlines are missed Delay / re-negotiation 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 1 1 TfL
Strategy to be developed and managed to ensure compliance during construction in time with set deadlines 1
28.01 ConstructionProgramme
Management Risk
Delivery of pontoons /
vesselsTowing from remote location and
negotiating river traffic Late delivery Delay 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 2 3 TfL
Allow enough time during procurement phase for elements to be fabricated and delivered. Method statements to be prepared (discussed with PLA for operations in Thames) 3
28.02 ConstructionProgramme
Management Risk LogisticsDelivery & installation of terminal
infrastructure Late delivery Delay 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 2 2 TfL
Allow enough time for procurement of elements. Method statements for delivery to be prepared 4
30.01Testing and
commissioning Risk Test failureSite testing of systems is not
passedInadequate design brief or poor
manufactureDelay (possible re-design),
reputational damage 19/04/2013 Tfl/Halcrow Open 2 3 3 TfL
Full design speficiation required plus Factory Approval Tests before installation on site 6
30.02Testing and
commissioning Risk Incompatibility
Ferry and terminal systems/infrastructure do not
work together adequatelyDifferent designers for each
element Cost and delay from re-design 19/04/2013 Tfl/Halcrow Open 2 3 3 TfL
Close liaison between each design organisation at detailed design stage 6g p y g q y y g p g g
30.03Testing and
commissioning Risk Component failureFailure of components during
commissioningInadequate design/specification or poor manfacturing practices
Cost and delay from repair / re-design 19/04/2013 Tfl/Halcrow Open 1 3 3 TfL
Detailed design to specify required materials and approvals. Trial erection off-site recommended 3
30.04Testing and
commissioning Risk Inability to toll
Tolling systems are not operational in time for service
commencementProcurement / design / manufacturing delay Loss of revenue 19/04/2013 Tfl/Halcrow Open 2 2 1 TfL
Necessary approvals to be obtained in a timely manner and procurement timed to meet operational date 2
29.01 Operation Risk
Damage during operation
(responsibility of operator)
Accidental damage to infrastructure / vessel during
operation (eg. berthing collisions, beaching) Service failure
Suspension of service. Cost of repairs and possible
compensation to affected parties 13/01/2010 Tfl/Halcrow Open
Note operational risks to be passed onto operator -
contratual risk of unsuitable handover see
7.01(now 29.10) TfL
Operating procedures to be developed to minimise the likelihood of accidental damage
29.02 Operation Risk
Potential conflict with other river
traffic
Promotion of greater river taxi use could cause
demand/operational issues (also consider wash from clipper vessels causing damage)
Changes in usage from that anticipated during design
development Costs outweigh revenue 13/01/2010 Tfl/Halcrow Open 19/04/2013 TfL
Discussion of strategy between designer, client and operator during design phase
29.03 Operation Opp River taxi
Opportunity to design for combined ferry and river taxi use
of infrastructureGreater flexibility in infrastructure usage
"Future-proofed" terminal design 13/01/2010 Tfl/Halcrow Retired 19/04/2013 TfL
Retired:Brief defined by TfL from consultation following feasibility studies
29.04 Operation Risk Sedimentation
Interference with operations, adjacent riparian facilities and
habitats Dredging required
Cost of dredging. Possible compensation to affected river
users 13/01/2010 Tfl/Halcrow Open 19/04/2013 TfL
Carry out full hydro-dynamic study during detailed design phase
29.05 Operation Risk Traffic levelsIncrease in road/river traffic
beyond expectations
Ferry unable to deal with new traffic levels - despite
allowances for extra capacity made at design stage
Reduced effectiveness of service 13/01/2010 Tfl/Halcrow Open 19/04/2013 TfL
If tolled, could control demand by setting price levels accordingly
29.06 Operation Risk Pollution Pollution of river during operation Water quality affectedCost of remediation. Possible
cost of compensation 13/01/2010 Tfl/Halcrow Open 19/04/2013 TfLDesign ferry to avoid pollution
Project Risk Register 4 of 5
Risk Register Gallions Reach Marine Aspects Transport for London
Risk Figures & Statistics Risk Mitigation Information
Category Sub-Category Risk/Opp Title Description Cause Effect Date By Status Last Updated Min (£k) Likely (£k) Max (£k) Opt (wks) Most (wks) Pess (wks)
Time scoreProb. Score
Total Risk Score
Owner Strategy
Risk Register IdentificationRisk No. Cost score
29.07 Operation Risk MaintenanceMaintenance costs higher than
anticipated
More maintenance required than expected. Higher cost of
labour/materials than expected. Reduced service in operation if maintenance cannot be carried out due to budgetary constraints
Additional cost. Delay caused by disruption to service 13/01/2010 Tfl/Halcrow Open 19/04/2013 TfL
Maintenance procedures to be developed during design phase in discussion with current Woolwich operator (and other operators) to minimise the likelihood of unexpected cost increases
29.08 Operation Risk Tolling Revenue less than anticipated
Reduced service in operation if costs cannot be covered by tolling revenues (resulting in
reduced ability to recoup costs) Costs outweigh revenue 13/01/2010 Tfl/Halcrow Open 19/04/2013 TfL
Discussion of strategy between designer, client and operator during detailed design phase
Retired:Outside scope of
29.09 Operation Risk
Possible bridge crossing at
Gallions Reach
Operation of ferry service not possible during construction of a
bridgeOperations ceased for up to 4
years
Loss of revenue. Possible cancellation of scheme at
planning stage 13/01/2010 Tfl/Halcrow Retired 19/04/2013 TfL
Outside scope of Gallions Reach Marine Aspects outline design - bridge option not being considered in this task
29.10(was 7.01) Operation Risk
Operational contractual
arrangementsOperational risk not sufficiently
managedLack of detailed thought in
developing operational contracts Operational costs increase 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 3 3 TfL
Early discussion and negotiation during planning phases, but deemed to be operational risk 3
29.11 Operation RiskNon-motorised
usersSafety of foot passengers and
cyclistsInterface with traffic and exposure to elements Injury/illness 19/04/2013 Tfl/Halcrow Open 3 3 1 TfL
Design to include for non-motorised users to be segregated from traffic with adequate shelter provided 9
29.12 Operation Risk Staff welfare Facilities for ferry operations staffInsufficient welfare facilities /
shelter Injury/illness 19/04/2013 Tfl/Halcrow Open 3 3 1 TfL
Sufficient facilities to be included in design from the outset 9
Boarding and alighting to be controlled on the basis of slightly lower th it "b t h "
29.13 Operation RiskFrequency of
serviceDesired capacity is not achieved due to low frequncy of crossings
Frequency dictated largely by boarding/alighting times (linked
to size of vessel)Queuing or uneconomical
service 19/04/2013 Tfl/Halcrow Open 1 3 2 TfL
than capacity "batches" of traffic to eliminate delay caused by sending vehicles back to queuing area 3
29.14 Operation Risk Safety of slipways Slippery sloping surfaceAccumulation of
silt/algae/riverdeposits with tide Injury/accident 19/04/2013 Tfl/Halcrow Open 4 3 1 TfL
Maintenance procedures to be developed during design phase in discussion with other chain ferry operators to minimise the likelihood of silt/algae accumulation 12
Project Risk Register 5 of 5
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
Appendix F
Designer’s Risk Assessment
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
(This page is blank for double‐sided printing)
Stage: Preliminary Design
Likelihood Consequence Index Likelihood Consequence Index
1 Construction: Working near and over water Risk of drowning, particular hazard presented by large tidal range 3 5 15 Designer Prior to constructionRiver works minimised through use of land access and prefabricated elements as far as reasonably practicable
1 5 5Contractor to develop safe method of working and issue operatives with necessary safety equipment (including provision of a safety boat)
Disruption or damage to local residences and businesses. Few local recptors in area. It is suggested that contractor informs
No. HAZARD Risk Owner
Project: Gallions Reach Crossings - Marine Aspects River Thames, London
Next Formal Risk Review Date
Designer's Health and Safety risk assessment
Location:
ANTICIPATED MEASURE THAT COULD BE APPLIED BY THE CONTRACTOR (OR OTHERS)
CONSEQUENCE OF HAZARD (RISK)
RISK LEVEL BEFORE MITIGATION MITIGATION MEASURE TO BE TAKEN BY DESIGNER
RISK LEVEL AFTER MITIGATION
A CH2M HILL COMPANYThis is a Mandatory Form
2 Construction: Noise and vibration from piling operations Possible minor loss of structural integrity which could result in injury to building occupants from falling or broken materials
3 3 9 TfL Prior to construction None 3 3 9 affected residents and busineses in advance and restricts piling operations to normal working hours
3 Construction: Lifting operations Death/injury to operatives and/or damage to structures 2 5 10 Designer Prior to constructionDesign includes consideration of size, weight and shape of prefabricated elements to allow for relatively simple lifting operations
1 5 5 Contractor to develop a suitable lifting plan
4 Construction: Interface with existing structuresRisk of damage to existing flood defence walls, Northern Outfall Sewer and Tideway Tunnel (from piling)
3 4 12 Designer Prior to constructionInfrastructure has been designed to be sufficiently remote from known existing structures
1 4 4Contractor to carry out survey prior to works to ensure construction plant will not encraoch too clsoe to existing structures
5 Construction: Interference with other river usersRisk of collision between river vessels and marine construction plant resulting in death or injury
3 5 15 Designer Prior to constructionDesigned for a large proportion of works to be carried out from land access
1 5 5Contractor to establish navigational channels and provide suitable risk control measures in consultation with Port of London Authority as necessary
6 Construction: Contaminated landInjury/illness to operatives and local flora/fauna due to excavation in contaminated land, and subsequent disposal
3 4 12 Designer Prior to construction Excavation works minimised 1 4 4Contractor to establish suitable methodology for excavation, treatment and/or disposal of contaminated materials
7 Construction: Pollution of riverDamage/injury to river flora/fauna and/or significant penalties from Environment Agency due to hazardous construction materials entering watercourse
3 3 9 Designer Prior to constructionUse of hazardous materials (eg. protective coatings) on site miniimised by use of prefabricated elements
1 3 3Contractor to develop suitable method of working to avoid pollution during construction and deal with pollution incidents if they occur
8 Construction: Buried servicesDeath/injury to operatives from contact with unknown buried services, particularly gas and electricity
3 5 15 Designer Prior to constructionNo services charted in the vicinty of either terminal. Design only requires minimal excavation
1 5 5Contractor to conduct appropriate surveys to check before any excvavtion works
9 Construction: Unexploded ordnanceDeath/injury to operatives and/or damage to nearby property from discovery and accidental detonation of unexploded ordnance
2 5 10 TfL Prior to construction None 2 5 10Area is known to have been heavily bombarded during World War II. Contractor to conduct appropriate surveys and keep a watching brief during construction
10 Construction: Use of the river for deliveriesInjury of operatives or damage to equipment caused by large elements being transported upriver to site colliding with fixed obstacles or other river users
3 4 12 Designer Prior to constructionDesign includes consideration of size, weight and shape of prefabricated elements to allow for transport by river
1 4 4Contractor to develop a suitable methodology for transport of large elements by river
11 Operation: Working in river environmentRisk of drowning for operatives and/or public, primarily during ferry sailing activity
2 5 10 Operator Prior to operation Design includes barriers to prevent access to river at terminals 1 5 5Operator to provide safety equipment on board vessel and PPE (eg. life jackets) for operatives in combination with emergency plans
Injury to operatives or damage to property if local objectorsTfL i i i i k f h h d di i i
12 Operation: Locals object to tollingInjury to operatives or damage to property if local objectors become violent or abusive about paying for a ferry service which previously (at Woolwich) was free of charge
3 3 9 TfL Prior to construction None 3 3 9TfL to minimise risk of protests through targeted media campaign prior to commencement of operation
13Operation: Management of vehicles and non-motorised users
Death or injury to operatives and/or public (particularly non-motorised users) in clue proximity to live traffic
4 5 20 Operator Prior to operationDesign includes physical seggregation of non-motorised users from vehicles wherever possible
2 5 10
Operator to develop procedures for safe interaction between non-motorised users and vehicles where physical barriers are not possible (eg. on chain ferry slipway). Procedures to be developed for dealing with broken down vehicles on infrastructure.
14 Operation: Slippery sloping surfacesInjury to operatives and/or public due to slippery surfaces on proposed ferry access ramps. Possible damage caused by errant vehicles
4 3 12 Operator Prior to operationAnti-skid surfacing specified to sloping surfaces, particaulrly on linkspan and pontoon for propeller driven ferry
2 3 6Operator to ensure surface is kept clean for anti-skid surfacing to be effective, particualrly on chain ferry slipway which is regularly washed by tidal water
15 Operation: Pollution of riverDamage/injury to river flora/fauna and/or significant penalties from Environment Agency due to hazardous materials (eg. fuel oil from vessel or vehicles on board) entering watercourse
2 3 6 Operator Prior to operation None 2 3 6Operator to develop suitable procedures for quickly dealing with pollution incidents if they occur
16 Operation: Transport of hazardous goodsDeath/injury to operatives and/or public due to leakage of hazardous goods whilst being carried on the ferry, or waiting to board
2 5 10 TfL/Operator Prior to operation None 2 5 10TfL to determine whether hazardous goods are permissible on the ferry, and if so operator to develop emergency plans to deal with any incident
17 Operation: Interference with other river usersDeath/injury to operatives and/or public and damage to equipment caused by collision between ferry and other river users
3 5 15 TfL/Operator Prior to operationTerminals designed to be remote from navigation channels in the river meaning risk of collision is most likely during sailing of the ferry
2 5 10Operator to develop methodology in consultation with Port of London Authority for safe traversing of river. TfL to specify vessel design which incorporates all necessary marine safety systems
18 Operation: Accidental damage to infrastructureInjury/damage (and subsequent loss of service) caused by severe or misplaced berthing loads
4 4 16 Operator Prior to operationInfrastructure designed to accommodate a certain level of impact from berthing
2 4 8Operator to utilise highly competent crew (particularly for the propeller driven ferry option) and arrange for training if ncessary
19 Operation: Welfare of staffInjury/illness to operatives caused by working in exposed and remote location.
4 3 12 TfL Prior to operationDesign includes provision of welfare facilities for staff. No lone working to be permitted, allowing staff to take breaks and deal with the public as necessary
1 3 3Operator to develop suitable roster of shifts in consideration of staff welfare
Index:
16-25
Likelihood x Consequence (See also CIRIA SP125).Likelihood:
1 Improbable Extremely unlikely to occur in relevant period
Consequence:
5 Catastrophic Death or major loss; total systems failure Very High Risk - Unacceptable Re-examine activities to provide lower risk16-25
9-15
6-8
1-5
Mike Green 15 May 2013
Paul Bowerman 16 May 2013
Mike Green 16-May-13
Rev 2 - 07/2012 PRISM - DESIGNERS RISK ASSESSMENT
Approved by: Title: Project Manager / Asst CDM co-ordinator Date:
Reviewed by: Title: CDM co-ordinator Date:
1 - Improbable - Extremely unlikely to occur in relevant period2 - Remote - Unlikely to occur in relevant period3 - Occasional - Likely to occur in relevant period4 - Probable - Likely to occur several times in relevant period5 - Frequent - Likely regular occurrence in relevant period
5 - Catastrophic - Death or major loss; total systems failure4 - Critical - Major injury, major damage to property/infrastructure, or major environmental effect.3 - Serious - Lost time injury or illness; minor damage to property/infrastructure or significant environmental effect.2 - Marginal - Minor first aid incident, or requiring routine maintenance repair. 1 - Insignificant - Unlikely to have impact on works.
Low Risk - Broadly acceptable if all reasonably practicable control measures in place.
Medium Risk - Tolerable only if further mitigation is not reasonably practical and there is need to continue activity with identified controls.
Very High Risk Unacceptable. Re examine activities to provide lower risk.
Prepared by: Title: Project Manager / Asst CDM co-ordinator Date:
High Risk - Apply further mitigation measures and/or alter method of work to reduce risk further. Seek Project Manager approval if risk cannot be reduced.
Rev 0 (04/2012) Page 1 of 1 PRISM - DESIGNERS RISK ASSESSMENT
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
Appendix G
Cost Estimates
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
(This page is blank for double‐sided printing)
ESTIMATE SUMMARY SHEET
00001 Revision 2 GRIP 3
14-May-13 Anticipated Start Date TBA TBA
TOTAL
Section Code of Account Headings VALUE%age of
Sub-total D VALUE
Level 2 £ % £A Roadworks General N/A
Main carriageways
Interchanges
Signage & Communication
Landscaping
B Piling 4,040,400
Substructure - End Supports 2,067,441
Substructure - Main & Approach Spans 3,975,000
Superstructure 4,203,800
Finishings 992,283
C Main Construction N/A
Finishings
DStructures - Tunnels
Special prelims N/A
Cut & Cover - Main Construction
Bored - Main Construction
Immersed Tube - Main Construction
E Other Works (Inc Utilities) General 1,398,750
16,677,673 0.00% - Other Costs - e.g: % SAY
F 25% 4,169,418
G 5% 833,884
H 2% 333,553
J (incl in Design)
K 3% 500,330
L 1% 166,777
M 7.5% 1,250,826
Sub - Total B 7,254,788 0.00% -
Structures - Retaining Walls, Culverst, Subways,etc
Base Construction Cost : Sub-Total A
Spares
Other - Contractor's O/H & profit
Preliminaries & General Items
Design
Testing & Commissioning
Consultancy Charges
Training
Project Title / Location
Gallions Reach Ferry - Propeller Driven (2 lanes)
1
Structures - Bridges, Viaducts, etc
Estimate No. Level
Estimate Date Anticipated Finish Date
Project /Contract No. Gallions Reach Crossings - Marine Aspects
Cost Estimate - Propeller Ferry - 2 lanesMain Summary Job Nr:
Date:
Total Construction Cost C 23,932,461 0.00% - OTHER Client Costs % SAY
N (by TfL)
P Possession / Isolation Management (by TfL)
R Compensation charges (by TfL)
S TWA Charges (by TfL)
T Land / Property Costs (by TfL)
U Escalation (by TfL)
V Other ( State ) N/A
Network Rail Costs - 0.00% -
Sub - Total D 23,932,461 0.00% -
X01 Mean cost from QRA
PROJECT BUDGET 23,932,461 -
X02 Plus contingency @ - -
FIXED PRICE (If Applicable)
X03 QRA @ P80
AUTHORITY VALUE 23,932,461 -
01/05/2002
SCHEDULE 4 CHARGES
Name :-
Company :-
Position :-
Signed :-
Date :- 14/05/2013 14/05/2013
Halcrow Group Ltd Halcrow Group Ltd
Team Leader Project Manager
APPROVAL & ENDORSEMENT
Estimate Produced By :- Estimate Endorsed by :-
Tom Aikman Mike Green
Project Management
Cost Estimate - Propeller Ferry - 2 lanesMain Summary Job Nr:
Date:
Gallions Reach River Crossings ‐ Marine Aspects
Infrastructure Implementation Cost Estimate (Propeller Driven Ferry)
Ref Description Qty Unit Rate Price
GENERAL ITEMS
Method Related Charges
Plant ‐ Establish and remove
A Pile driving 1 sum 1,500,000.00 1,500,000£
B Ground investigation 1 sum 300,000.00 300,000£
IN SITU CONCRETE
Provision of concrete, standard mix
A Grade C50 5399 m3 100.00 539,900£
Placing of reinforced concrete
B Bank seat and approach structure 4392 m3 50.00 219,600£
C Pile cap, dolphins 787 m3 50.00 39,350£
D Pontoon ballast 220 m3 50.00 11,000£
CONCRETE ANCILLARIES
Formwork, fair finish
Plane horizontal
A Width exceeding 1.22 m 4988 m2 60.00 299,292£
Plane vertical
B Width exceeding 1.22 m 2636 m2 45.00 118,599£
Reinforcement
Deformed high yield steel bars to BS 4449
C Bar reinforcement to bankseat @ 180 kg/m3 77 t 900.00 69,300£
D Bar reinforcement to approach structure @ 180 kg/m3 714 t 900.00 642,600£
E Bar reinforcement to dolphin type A @ 180 kg/m3 62 t 900.00 55,800£
F Bar reinforcement to dolphin type B @ 180 kg/m3 54 t 900.00 48,600£
G Bar reinforcement to dolphin type C @ 180 kg/m3 26 t 900.00 23,400£
Concrete accessories
H Finishing of top surfaces 4455 m2 2.50 11,138£
STRUCTURAL METALWORK
Fabrication of main members for linkspans
A Link span of approximate length 58 m (2 No.) 826 t 3,500.00 2,891,000£
B Link span flaps 72 t 3,500.00 252,000£
Fabrication of other members
C Steel floating pontoon 30 m x 30 m (2 No.) 1300 t 2,500.00 3,250,000£
D Walkways to dolphins 25 t 2,500.00 62,500£
Gallions Reach River Crossings ‐ Marine Aspects
Infrastructure Implementation Cost Estimate (Propeller Driven Ferry)
Ref Description Qty Unit Rate Price
Erection of members for linkspans
E Transportation and installation of link spans 826 t 800.00 660,800£
Erection of other members
F Transportation and installation of floating pontoons 1300 t 500.00 650,000£
G Transportation and installation of walkways to dolphins 25 t 500.00 12,500£
Miscellaneous metalwork
H Linkspan bearings 8 No. 50,000.00 400,000£
Off Site surface treatment
I Anti skid surfacing to floating pontoons 1350 m2 50.00 67,500£
J Paint protection system to link span bridges 2 No. 380,400.00 760,800£
K Protective coating to marine piling on approach structures 2100 m2 35.00 73,500£
(assume average 10 m length)
L Protective coating to dolphin type A (15 m length) 872 m2 35.00 30,520£
M Protective coating to dolphin type B (12 m length) 1046 m2 35.00 36,610£
N Protective coating to dolphin type C (12 m length) 349 m2 35.00 12,215£
PILES
Isolated steel piles
Mass 250 ‐ 500 kg/m
610 mm diameter 16 mm wall thickness
A Depth driven ‐ vertical piles on approach structures 2068 m 150.00 310,200£
(assume average bed level = 0 m CD)
B Depth driven ‐ raking piles on dolphins & bankseats 1512 m 200.00 302,400£
(assume average bed level = ‐4 m CD)
Approach structure
C Number of piles 32 m long (average length taken across 1:38 slope) 44 No. 8,500.00 374,000£
D Number of piles 31 m long 44 No. 8,000.00 352,000£
Bank seat
E Number of piles 28 m long 16 No. 7,500.00 120,000£
Dolphin type A
F Number of piles 34 m long 24 No. 9,000.00 216,000£
Dolphin type B
G Number of piles 31 m long 36 No. 8,000.00 288,000£
Gallions Reach River Crossings ‐ Marine Aspects
Infrastructure Implementation Cost Estimate (Propeller Driven Ferry)
Ref Description Qty Unit Rate Price
Dolphin type C
H Number of piles 31 m long 12 No. 8,000.00 96,000£
965 mm diameter 19.1 mm wall thickness
I Depth driven ‐ vertical piles on dolphins 216 m 175.00 37,800£
(assume average bed level = ‐4 m CD)
Dolphin type A
J Number of piles 35 m long 4 No. 17,000.00 68,000£
Dolphin type B
K Number of piles 32 m long 6 No. 15,500.00 93,000£
Dolphin type C
L Number of piles 32 m long 2 No. 15,500.00 31,000£
Ground anchors
M Ground anchors for all raking piles 84 No. 3,000.00 252,000£
MISCELLANEOUS WORK
Vehicle barrier
A Galvanised steel vehicle barrier 675 m 150.00 101,250£
Pedestrian barrier
B Galvanised steel pedestrian barrier 675 m 100.00 67,500£
Berthing fenders
C Provision and installation of marine fenders suitable for designated 8 No. 30,000.00 240,000£
ferry
Electrical services
D Provision and installation of electrical services for pontoon and link 2 No. 20,000.00 40,000£
span structure
Lighting
E Provision and installation of lighting for pontoon and link span 2 No. 50,000.00 100,000£
structure
Navigation markers
Including ducted services and power supply
F Navigation beacons and markings to pontoon and linkspan structure 2 No. 75,000.00 150,000£
SIMPLE BUILDING WORKS INCIDENTAL TO CIVIL ENGINEERING WORKS
Staff accommodation building
Including provision of all services and security measures
A Staff accommodation and maintenance building 2 No. 200,000.00 400,000£
Propeller Driven Ferry Infrastructure Total 16,677,673£
ESTIMATE SUMMARY SHEET
00002 Revision 2 GRIP 3
14-May-13 Anticipated Start Date TBA TBA
TOTAL
Section Code of Account Headings VALUE%age of
Sub-total D VALUE
Level 2 £ % £A Roadworks General N/A
Main carriageways
Interchanges
Signage & Communication
Landscaping
B Piling 5,196,600
Substructure - End Supports 3,956,750
Substructure - Main & Approach Spans 3,975,000
Superstructure 4,203,800
Finishings 1,076,920
C Main Construction N/A
Finishings
DStructures - Tunnels
Special prelims N/A
Cut & Cover - Main Construction
Bored - Main Construction
Immersed Tube - Main Construction
E Other Works (Inc Utilities) General 1,398,750
19,807,820 0.00% - Other Costs - e.g: % SAY
F 21.1% 4,179,450
G 4.2% 835,890
H 1.7% 336,733
J (incl in Design)
K 2.5% 501,138
L 0.9% 168,366
M 7.5% 1,485,587
Sub - Total B 7,507,164 0.00% -
Estimate No. Level
Estimate Date Anticipated Finish Date
Project /Contract No. Gallions Reach Crossings - Marine Aspects
Project Title / Location
Gallions Reach Ferry - Propeller Driven (4 lanes)
1
Structures - Bridges, Viaducts, etc
Structures - Retaining Walls, Culverst, Subways,etc
Base Construction Cost : Sub-Total A
Spares
Other - Contractor's O/H & profit
Preliminaries & General Items
Design
Testing & Commissioning
Consultancy Charges
Training
Cost Estimate - Propeller Ferry - 4 lanesMain Summary Job Nr:
Date:
Total Construction Cost C 27,314,984 0.00% - OTHER Client Costs % SAY
N (by TfL)
P Possession / Isolation Management (by TfL)
R Compensation charges (by TfL)
S TWA Charges (by TfL)
T Land / Property Costs (by TfL)
U Escalation (by TfL)
V Other ( State ) N/A
Network Rail Costs - 0.00% -
Sub - Total D 27,314,984 0.00% -
X01 Mean cost from QRA
PROJECT BUDGET 27,314,984 -
X02 Plus contingency @ - -
FIXED PRICE (If Applicable)
X03 QRA @ P80
AUTHORITY VALUE 27,314,984 -
01/05/2002
SCHEDULE 4 CHARGES
Name :-
Company :-
Position :-
Signed :-
Date :-
Project Management
APPROVAL & ENDORSEMENT
Estimate Produced By :- Estimate Endorsed by :-
Tom Aikman Mike Green
14/05/2013 14/05/2013
Halcrow Group Ltd Halcrow Group Ltd
Team Leader Project Manager
Cost Estimate - Propeller Ferry - 4 lanesMain Summary Job Nr:
Date:
Gallions Reach River Crossings ‐ Marine Aspects
Infrastructure Implementation Cost Estimate (Propeller Driven Ferry)
Ref Description Qty Unit Rate Price
GENERAL ITEMS
Method Related Charges
Plant ‐ Establish and remove
A Pile driving 1 sum 1,500,000.00 1,500,000£
B Ground investigation 1 sum 300,000.00 300,000£
IN SITU CONCRETE
Provision of concrete, standard mix
A Grade C50 10798 m3 100.00 1,079,800£
Placing of reinforced concrete
B Bank seat and approach structure 8784 m3 50.00 439,200£
C Pile cap, dolphins 787 m3 50.00 39,350£
D Pontoon ballast 220 m3 50.00 11,000£
CONCRETE ANCILLARIES
Formwork, fair finish
Plane horizontal
A Width exceeding 1.22 m 9976 m2 60.00 598,560£
Plane vertical
B Width exceeding 1.22 m 5272 m2 45.00 237,240£
Reinforcement
Deformed high yield steel bars to BS 4449
C Bar reinforcement to bankseat @ 180 kg/m3 154 t 900.00 138,600£
D Bar reinforcement to approach structure @ 180 kg/m3 1428 t 900.00 1,285,200£
E Bar reinforcement to dolphin type A @ 180 kg/m3 62 t 900.00 55,800£
F Bar reinforcement to dolphin type B @ 180 kg/m3 54 t 900.00 48,600£
G Bar reinforcement to dolphin type C @ 180 kg/m3 26 t 900.00 23,400£
Concrete accessories
H Finishing of top surfaces 8910 m2 2.50 22,275£
STRUCTURAL METALWORK
Fabrication of main members for linkspans
A Link span of approximate length 58 m (2 No.) 826 t 3,500.00 2,891,000£
B Link span flaps 72 t 3,500.00 252,000£
Fabrication of other members
C Steel floating pontoon 30 m x 30 m (2 No.) 1300 t 2,500.00 3,250,000£
D Walkways to dolphins 25 t 2,500.00 62,500£
Gallions Reach River Crossings ‐ Marine Aspects
Infrastructure Implementation Cost Estimate (Propeller Driven Ferry)
Ref Description Qty Unit Rate Price
Erection of members for linkspans
E Transportation and installation of link spans 826 t 800.00 660,800£
Erection of other members
F Transportation and installation of floating pontoons 1300 t 500.00 650,000£
G Transportation and installation of walkways to dolphins 25 t 500.00 12,500£
Miscellaneous metalwork
H Linkspan bearings 8 No. 50,000.00 400,000£
Off Site surface treatment
I Anti skid surfacing to floating pontoons 1350 m2 50.00 67,500£
J Paint protection system to link span bridges 2 No. 380,400.00 760,800£
K Protective coating to marine piling on approach structures 4200 m2 35.00 147,000£
(assume average 10 m length)
L Protective coating to dolphin type A (15 m length) 872 m2 35.00 30,520£
M Protective coating to dolphin type B (12 m length) 1046 m2 35.00 36,610£
N Protective coating to dolphin type C (12 m length) 349 m2 35.00 12,215£
PILES
Isolated steel piles
Mass 250 ‐ 500 kg/m
610 mm diameter 16 mm wall thickness
A Depth driven ‐ vertical piles on approach structures 4136 m 150.00 620,400£
(assume average bed level = 0 m CD)
B Depth driven ‐ raking piles on dolphins & bankseats 1512 m 200.00 302,400£
(assume average bed level = ‐4 m CD)
Approach structure
C Number of piles 32 m long (average length taken across 1:38 slope) 88 No. 8,500.00 748,000£
D Number of piles 31 m long 88 No. 8,000.00 704,000£
Bank seat
E Number of piles 28 m long 32 No. 7,500.00 240,000£
Dolphin type A
F Number of piles 34 m long 24 No. 9,000.00 216,000£
Dolphin type B
G Number of piles 31 m long 36 No. 8,000.00 288,000£
Gallions Reach River Crossings ‐ Marine Aspects
Infrastructure Implementation Cost Estimate (Propeller Driven Ferry)
Ref Description Qty Unit Rate Price
Dolphin type C
H Number of piles 31 m long 12 No. 8,000.00 96,000£
965 mm diameter 19.1 mm wall thickness
I Depth driven ‐ vertical piles on dolphins 216 m 175.00 37,800£
(assume average bed level = ‐4 m CD)
Dolphin type A
J Number of piles 35 m long 4 No. 17,000.00 68,000£
Dolphin type B
K Number of piles 32 m long 6 No. 15,500.00 93,000£
Dolphin type C
L Number of piles 32 m long 2 No. 15,500.00 31,000£
Ground anchors
M Ground anchors for all raking piles 84 No. 3,000.00 252,000£
MISCELLANEOUS WORK
Vehicle barrier
A Galvanised steel vehicle barrier 675 m 150.00 101,250£
Pedestrian barrier
B Galvanised steel pedestrian barrier 675 m 100.00 67,500£
Berthing fenders
C Provision and installation of marine fenders suitable for designated 8 No. 30,000.00 240,000£
ferry
Electrical services
D Provision and installation of electrical services for pontoon and link 2 No. 20,000.00 40,000£
span structure
Lighting
E Provision and installation of lighting for pontoon and link span 2 No. 50,000.00 100,000£
structure
Navigation markers
Including ducted services and power supply
F Navigation beacons and markings to pontoon and linkspan structure 2 No. 75,000.00 150,000£
SIMPLE BUILDING WORKS INCIDENTAL TO CIVIL ENGINEERING WORKS
Staff accommodation building
Including provision of all services and security measures
A Staff accommodation and maintenance building 2 No. 200,000.00 400,000£
Propeller Driven Ferry Infrastructure Total 19,807,820£
ESTIMATE SUMMARY SHEET
00003 Revision 2 GRIP 3
14-May-13 Anticipated Start Date TBA TBA
TOTAL
Section Code of Account Headings VALUE%age of
Sub-total D VALUE
Level 2 £ % £A Roadworks General N/A
Main carriageways
Interchanges
Signage & Communication
Landscaping
B Piling 6,352,800
Substructure - End Supports 5,851,565
Substructure - Main & Approach Spans 5,925,000
Superstructure 8,407,600
Finishings 1,956,108
C Main Construction N/A
Finishings
DStructures - Tunnels
Special prelims N/A
Cut & Cover - Main Construction
Bored - Main Construction
Immersed Tube - Main Construction
E Other Works (Inc Utilities) General 1,398,750
29,891,823 0.00% - Other Costs - e.g: % SAY
F 14.0% 4,184,855
G 2.8% 836,971
H 1.2% 358,702
J (incl in Design)
K 1.7% 508,161
L 0.8% 224,189
M 7.5% 2,241,887
Sub - Total B 8,354,764 0.00% -
Structures - Retaining Walls, Culverst, Subways,etc
Base Construction Cost : Sub-Total A
Spares
Other - Contractor's O/H & profit
Preliminaries & General Items
Design
Testing & Commissioning
Consultancy Charges
Training
Project Title / Location
Gallions Reach Ferry - Propeller Driven (6 lanes)
1
Structures - Bridges, Viaducts, etc
Estimate No. Level
Estimate Date Anticipated Finish Date
Project /Contract No. Gallions Reach Crossings - Marine Aspects
Cost Estimate - Propeller Ferry - 6 lanesMain Summary Job Nr:
Date:
Total Construction Cost C 38,246,587 0.00% - OTHER Client Costs % SAY
N (by TfL)
P Possession / Isolation Management (by TfL)
R Compensation charges (by TfL)
S TWA Charges (by TfL)
T Land / Property Costs (by TfL)
U Escalation (by TfL)
V Other ( State ) N/A
Network Rail Costs - 0.00% -
Sub - Total D 38,246,587 0.00% -
X01 Mean cost from QRA
PROJECT BUDGET 38,246,587 -
X02 Plus contingency @ - -
FIXED PRICE (If Applicable)
X03 QRA @ P80
AUTHORITY VALUE 38,246,587 -
01/05/2002
SCHEDULE 4 CHARGES
Name :-
Company :-
Position :-
Signed :-
Date :- 14/05/2013 14/05/2013
Halcrow Group Ltd Halcrow Group Ltd
Team Leader Project Manager
APPROVAL & ENDORSEMENT
Estimate Produced By :- Estimate Endorsed by :-
Tom Aikman Mike Green
Project Management
Cost Estimate - Propeller Ferry - 6 lanesMain Summary Job Nr:
Date:
Gallions Reach River Crossings ‐ Marine Aspects
Infrastructure Implementation Cost Estimate (Propeller Driven Ferry)
Ref Description Qty Unit Rate Price
GENERAL ITEMS
Method Related Charges
Plant ‐ Establish and remove
A Pile driving 1 sum 1,500,000.00 1,500,000£
B Ground investigation 1 sum 300,000.00 300,000£
IN SITU CONCRETE
Provision of concrete, standard mix
A Grade C50 16197 m3 100.00 1,619,700£
Placing of reinforced concrete
B Bank seat and approach structure 13176 m3 50.00 658,800£
C Pile cap, dolphins 787 m3 50.00 39,350£
D Pontoon ballast 330 m3 50.00 16,500£
CONCRETE ANCILLARIES
Formwork, fair finish
Plane horizontal
A Width exceeding 1.22 m 14965 m2 60.00 897,900£
Plane vertical
B Width exceeding 1.22 m 7907 m2 45.00 355,815£
Reinforcement
Deformed high yield steel bars to BS 4449
C Bar reinforcement to bankseat @ 180 kg/m3 231 t 900.00 207,900£
D Bar reinforcement to approach structure @ 180 kg/m3 2142 t 900.00 1,927,800£
E Bar reinforcement to dolphin type A @ 180 kg/m3 62 t 900.00 55,800£
F Bar reinforcement to dolphin type B @ 180 kg/m3 54 t 900.00 48,600£
G Bar reinforcement to dolphin type C @ 180 kg/m3 26 t 900.00 23,400£
Concrete accessories
H Finishing of top surfaces 13365 m2 2.50 33,413£
STRUCTURAL METALWORK
Fabrication of main members for linkspans
A Link span of approximate length 58 m (4 No.) 1652 t 3,500.00 5,782,000£
B Link span flaps 144 t 3,500.00 504,000£
Fabrication of other members
C Steel floating pontoon 30 m x 30 m (2 No.) 1950 t 2,500.00 4,875,000£
D Walkways to dolphins 25 t 2,500.00 62,500£
Gallions Reach River Crossings ‐ Marine Aspects
Infrastructure Implementation Cost Estimate (Propeller Driven Ferry)
Ref Description Qty Unit Rate Price
Erection of members for linkspans
E Transportation and installation of link spans 1652 t 800.00 1,321,600£
Erection of other members
F Transportation and installation of floating pontoons 1950 t 500.00 975,000£
G Transportation and installation of walkways to dolphins 25 t 500.00 12,500£
Miscellaneous metalwork
H Linkspan bearings 16 No. 50,000.00 800,000£
Off Site surface treatment
I Anti skid surfacing to floating pontoons 2025 m2 50.00 101,250£
J Paint protection system to link span bridges 4 No. 380,400.00 1,521,600£
K Protective coating to marine piling on approach structures 6300 m2 35.00 220,500£
(assume average 10 m length)
L Protective coating to dolphin type A (15 m length) 872 m2 35.00 30,520£
M Protective coating to dolphin type B (12 m length) 1046 m2 35.00 36,610£
N Protective coating to dolphin type C (12 m length) 349 m2 35.00 12,215£
PILES
Isolated steel piles
Mass 250 ‐ 500 kg/m
610 mm diameter 16 mm wall thickness
A Depth driven ‐ vertical piles on approach structures 6204 m 150.00 930,600£
(assume average bed level = 0 m CD)
B Depth driven ‐ raking piles on dolphins & bankseats 1512 m 200.00 302,400£
(assume average bed level = ‐4 m CD)
Approach structure
C Number of piles 32 m long (average length taken across 1:38 slope) 132 No. 8,500.00 1,122,000£
D Number of piles 31 m long 132 No. 8,000.00 1,056,000£
Bank seat
E Number of piles 28 m long 48 No. 7,500.00 360,000£
Dolphin type A
F Number of piles 34 m long 24 No. 9,000.00 216,000£
Dolphin type B
G Number of piles 31 m long 36 No. 8,000.00 288,000£
Gallions Reach River Crossings ‐ Marine Aspects
Infrastructure Implementation Cost Estimate (Propeller Driven Ferry)
Ref Description Qty Unit Rate Price
Dolphin type C
H Number of piles 31 m long 12 No. 8,000.00 96,000£
965 mm diameter 19.1 mm wall thickness
I Depth driven ‐ vertical piles on dolphins 216 m 175.00 37,800£
(assume average bed level = ‐4 m CD)
Dolphin type A
J Number of piles 35 m long 4 No. 17,000.00 68,000£
Dolphin type B
K Number of piles 32 m long 6 No. 15,500.00 93,000£
Dolphin type C
L Number of piles 32 m long 2 No. 15,500.00 31,000£
Ground anchors
M Ground anchors for all raking piles 84 No. 3,000.00 252,000£
MISCELLANEOUS WORK
Vehicle barrier
A Galvanised steel vehicle barrier 675 m 150.00 101,250£
Pedestrian barrier
B Galvanised steel pedestrian barrier 675 m 100.00 67,500£
Berthing fenders
C Provision and installation of marine fenders suitable for designated 8 No. 30,000.00 240,000£
ferry
Electrical services
D Provision and installation of electrical services for pontoon and link 2 No. 20,000.00 40,000£
span structure
Lighting
E Provision and installation of lighting for pontoon and link span 2 No. 50,000.00 100,000£
structure
Navigation markers
Including ducted services and power supply
F Navigation beacons and markings to pontoon and linkspan structure 2 No. 75,000.00 150,000£
SIMPLE BUILDING WORKS INCIDENTAL TO CIVIL ENGINEERING WORKS
Staff accommodation building
Including provision of all services and security measures
A Staff accommodation and maintenance building 2 No. 200,000.00 400,000£
Propeller Driven Ferry Infrastructure Total 29,891,823£
ESTIMATE SUMMARY SHEET
00004 Revision 2 GRIP 3
14-May-13 Anticipated Start Date TBA TBA
TOTAL
Section Code of Account Headings VALUE%age of
Sub-total D VALUE
Level 2 £ % £A Roadworks General N/A
Main carriageways
Interchanges
Signage & Communication
Landscaping
B Piling 3,197,250
Substructure - End Supports
Substructure - Main & Approach Spans 3,817,920
Superstructure
Finishings 35,200
C Main Construction N/A
Finishings
DStructures - Tunnels
Special prelims N/A
Cut & Cover - Main Construction
Bored - Main Construction
Immersed Tube - Main Construction
E Other Works (Inc Utilities) General 6,875,920
13,926,290 0.00% - Other Costs - e.g: % SAY
F 25% 3,481,573
G 5% 696,315
H 2% 278,526
J (incl in Design)
K 3% 417,789
L 1% 139,263
M 7.5% 1,044,472
Sub - Total B 6,057,936 0.00% -
Structures - Retaining Walls, Culverst, Subways,etc
Base Construction Cost : Sub-Total A
Spares
Other - Contractor's O/H & profit
Preliminaries & General Items
Design
Testing & Commissioning
Consultancy Charges
Training
Project Title / Location
Gallions Reach Ferry - Chain Ferry
1
Structures - Bridges, Viaducts, etc
Estimate No. Level
Estimate Date Anticipated Finish Date
Project /Contract No. Gallions Reach Crossings - Marine Aspects
Cost Estimate - Chain FerryMain Summary Job Nr:
Date:
Total Construction Cost C 19,984,226 0.00% - OTHER Client Costs % SAY
N (by TfL)
P Possession / Isolation Management (by TfL)
R Compensation charges (by TfL)
S TWA Charges (by TfL)
T Land / Property Costs (by TfL)
U Escalation (by TfL)
V Other ( State ) N/A
Network Rail Costs - 0.00% -
Sub - Total D 19,984,226 0.00% -
X01 Mean cost from QRA
PROJECT BUDGET 19,984,226 -
X02 Plus contingency @ - -
FIXED PRICE (If Applicable)
X03 QRA @ P80
AUTHORITY VALUE 19,984,226 -
01/05/2002
SCHEDULE 4 CHARGES
Name :-
Company :-
Position :-
Signed :-
Date :- 14/05/2013 14/05/2013
Halcrow Group Ltd Halcrow Group Ltd
Slipway Designer Project Manager
APPROVAL & ENDORSEMENT
Estimate Produced By :- Estimate Endorsed by :-
John McLaren Mike Green
Project Management
Cost Estimate - Chain FerryMain Summary Job Nr:
Date:
Gallions Reach River Crossings ‐ Marine Aspects
Infrastructure Implementation Cost Estimate (Chain Ferry)
Ref Description Qty Unit Rate Price
GENERAL ITEMS
Method Related Charges
Plant ‐ Establish and remove
A Pile driving 1 sum 1,500,000.00 1,500,000£
B Ground investigation 1 sum 300,000.00 300,000£
Temporary Works ‐ Establish and remove
C Cofferdams 4 sum 1,000,000.00 4,000,000£
D Pumping 4 sum 100,000.00 400,000£
IN SITU CONCRETE
Provision of concrete, standard mix
A Grade C50 11680 m3 100.00 1,168,000£
Placing of reinforced concrete
B Slipways (inc crossheads) 10170 m3 50.00 508,500£
C Concrete bearing slab (inc retaining walls) 1510 m3 50.00 75,500£
CONCRETE ANCILLARIES
Formwork, fair finish
Plane horizontal
A Width exceeding 1.22 m 10520 m2 60.00 631,200£
Plane vertical
B Width exceeding 1.22 m 3856 m2 45.00 173,520£
Reinforcement
Deformed high yield steel bars to BS 4449
C Bar reinforcement @ 180 kg/m3 2102 t 600.00 1,261,200£
Concrete accessories
D Finishing of top surfaces 14080 m2 2.50 35,200£
Earthworks
E Earthworks 1 sum 200,000.00 200,000£
F Sub‐base for on‐shore slabs 3688 m2 15.00 55,320£
STRUCTURAL METALWORK
Off Site surface treatment
A Protective coatng to marine piling (assume average 5m length) 1640 m2 35.00 57,400£
Gallions Reach River Crossings ‐ Marine Aspects
Infrastructure Implementation Cost Estimate (Chain Ferry)
Ref Description Qty Unit Rate Price
PILES
Isolated steel piles
Mass 250 ‐ 500 kg/m
610 mm diameter 16 mm wall thickness
A Depth driven ‐ vertical piles (assume average bed level = 0.3m CD) 3905 m 150.00 585,750£
B Number of piles 25m long (average length taken across 1:8 slope) 171 No. 6,500.00 1,111,500£
MISCELLANEOUS WORK
Fences
A Galvanised steel two rail safety handrail 320 m 75.00 24,000£
Lighting
B Provision and installation of lighting for slipway approach 2 No. 50,000.00 100,000£
Navigation markers
Including ducted services and power supply
C Navigation beacons and markings to slipways 2 No. 35,000.00 70,000£
Water supply
D Provision and installation of water and fire hydrant supply for slipways 2 No. 50,000.00 100,000£
Chains and tensioners
E Troughs for chains 264 m 300.00 79,200£
F Chains 4 sum 100,000.00 400,000£
G Chain anchorages / tensioners 4 sum 60,000.00 240,000£
Stabilisation works
H Stabilisation of northern flood defence wall (provisional) 1 sum 250,000.00 250,000£
SIMPLE BUILDING WORKS INCIDENTAL TO CIVIL ENGINEERING WORKS
Staff accommodation building
Including provision of all services and security measures
A Staff accommodation and maintenance building 2 No. 300,000.00 600,000£
Chain Ferry Infrastructure Total 13,926,290£
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
Appendix H
Outline Construction Programmes
Gallions Reach River Crossings – (Task 102) Marine Aspects
Preliminary Design Report
(This page is blank for double‐sided printing)
ID Task Name Duration Start Finish
1 TfL Strategic Review of Crossing Options 8 wks Mon 29/04/13 Fri 21/06/13
2 TfL receipt of preliminary design reports 0 wks Mon 29/04/13 Mon 29/04/13
3 TfL review of all Thames crossing options 8 wks Mon 29/04/13 Fri 21/06/13
4 TfL selects a ferry crossing at Gallions Reach 0 wks Fri 21/06/13 Fri 21/06/13
5 Planning and Orders 182 wks Mon 29/04/13 Fri 21/10/16
6 Resolution of current legal position 52 wks Mon 29/04/13 Fri 25/04/14
7 Preparation of illustrative design 52 wks Mon 29/04/13 Fri 25/04/14
8 Prepare information for SoS to consider TWA Order 26 wks Mon 28/10/13 Fri 25/04/14
9 SoS decides to pursue TWA Order 0 wks Fri 25/04/14 Fri 25/04/14
10 TWA Order drawn up 26 wks Mon 28/04/14 Fri 24/10/14
11 TWA Order in Force (planning permission 'granted') 0 wks Fri 24/10/14 Fri 24/10/14
12 Enactments amended / repealed under TWA Order 104 wks Mon 27/10/14 Fri 21/10/16
13 CPO & Land Acquisition 84 wks Mon 24/06/13 Fri 30/01/15
14 CPO approved 0 wks Fri 24/10/14 Fri 24/10/14
15 Identify landowners 52 wks Mon 24/06/13 Fri 20/06/14
16 Notice of Intention published 0 wks Fri 24/10/14 Fri 24/10/14
17 General Vesting Declaration executed 0 wks Fri 23/01/15 Fri 23/01/15
18 Title transferred 0 wks Fri 23/01/15 Fri 23/01/15
19 Take possession of land 1 wk Mon 26/01/15 Fri 30/01/15
20 Procurement 191 wks Mon 24/06/13 Fri 17/02/17
21 Prepare Business Case 52 wks Mon 24/06/13 Fri 20/06/14
22 Business Case review by GoL/DfT 6 wks Mon 23/06/14 Fri 01/08/14
23 Business Case Review by Treasury 6 wks Mon 04/08/14 Fri 12/09/14
24 Initial Business Case approved 0 wks Fri 12/09/14 Fri 12/09/14
25 Business Case revised 8 wks Mon 25/07/16 Fri 16/09/16
26 2nd review of Business Case 8 wks Mon 19/09/16 Fri 11/11/16
27 Final Approval of Business Case 0 wks Fri 11/11/16 Fri 11/11/16
28 Preparation of procurement strategy 52 wks Mon 29/07/13 Fri 25/07/14
29 TfL approval of procurement strategy 0 wks Fri 25/07/14 Fri 25/07/14
30 Market testing 13 wks Mon 28/07/14 Fri 24/10/14
31 OJEU Notice and Prequalification 29 wks Mon 04/08/14 Fri 20/02/15
32 Preparation of OJEU Notice and PQQ 12 wks Mon 04/08/14 Fri 24/10/14
33 Issue OJEU Notice and PQQ 0 wks Fri 24/10/14 Fri 24/10/14
34 OJEU Notice Period 9 wks Mon 27/10/14 Fri 26/12/14
35 Evaluation of Prequalification submissions 8 wks Mon 29/12/14 Fri 20/02/15
36 TfL confirmation of selected candidate list 0 wks Fri 20/02/15 Fri 20/02/15
37 Tender 116 wks Mon 24/02/14 Fri 13/05/16
38 Preparation of ITT documents 52 wks Mon 24/02/14 Fri 20/02/15
39 Issue ITT to selected bidders 0 wks Fri 20/02/15 Fri 20/02/15
40 Tender period (incl. preliminary design) 52 wks Mon 23/02/15 Fri 19/02/16
41 Tenders returned 0 wks Fri 19/02/16 Fri 19/02/16
42 Tender evaluation 12 wks Mon 22/02/16 Fri 13/05/16
43 Announce shortlist 0 wks Fri 13/05/16 Fri 13/05/16
44 BAFO 26 wks Fri 13/05/16 Fri 11/11/16
45 Issue BAFO 0 wks Fri 13/05/16 Fri 13/05/16
46 BAFO preparation 10 wks Mon 16/05/16 Fri 22/07/16
47 BAFO returned 0 wks Fri 22/07/16 Fri 22/07/16
48 BAFO evaluation 4 wks Mon 25/07/16 Fri 19/08/16
49 BAFO negotiations 4 wks Mon 22/08/16 Fri 16/09/16
50 Confirm Preferred Bidder 0 wks Fri 11/11/16 Fri 11/11/16
51 Preferred Bidder 14 wks Mon 14/11/16 Fri 17/02/17
52 Final negotiations with preferred bidder 12 wks Mon 14/11/16 Fri 03/02/17
53 TfL Board Approval 2 wks Mon 06/02/17 Fri 17/02/17
54 Concession Award 0 wks Fri 17/02/17 Fri 17/02/17
55 Financial Close 0 wks Fri 17/02/17 Fri 17/02/17
29/04
21/06
25/04
24/10
24/10
24/10
23/01
23/01
12/09
11/11
25/07
24/10
20/02
20/02
19/02
13/05
13/05
22/07
11/11
17/02
17/02
Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Se2014 2015 2016 2017 2018
Gallions Reach Ferry - Outline Programme for 'TWA Order' PFI Procurement Route
Page 1 of 1 Appendix G1
ID Task Name Duration Start Finish
1 Implementation 149 wks Mon 23/02/15 Fri 29/12/17
2 Design and Approvals 26 wks Mon 20/02/17 Fri 18/08/17
3 Finalise permits, consents and approvals (outside TWA) 26 wks Mon 20/02/17 Fri 18/08/17
4 Detailed design and drawing production 25 wks Mon 20/02/17 Fri 11/08/17
5 Advance works 129 wks Mon 23/02/15 Fri 11/08/17
6 Environmental baseline monitoring 104 wks Mon 17/08/15 Fri 11/08/17
7 Procurement and construction of PLA RCMs 104 wks Mon 23/02/15 Fri 17/02/17
8 PLA Risk Control Measures operational 0 wks Fri 17/02/17 Fri 17/02/17
9 Construction 45 wks Mon 20/02/17 Fri 29/12/17
10 Mobilisation and site clearance 8 wks Mon 19/06/17 Fri 11/08/17
11 Surveys and investigations 4 wks Mon 20/02/17 Fri 17/03/17
12 Topographical survey 4 wks Mon 20/02/17 Fri 17/03/17
13 Site investigation 4 wks Mon 20/02/17 Fri 17/03/17
14 Environmental & archaeological monitoring 28 wks Mon 19/06/17 Fri 29/12/17
15 Construction on land 20 wks Mon 14/08/17 Fri 29/12/17
16 Road diversions / traffic management 20 wks Mon 14/08/17 Fri 29/12/17
17 Utility diversions 4 wks Mon 14/08/17 Fri 08/09/17
18 Earthworks 4 wks Mon 11/09/17 Fri 06/10/17
19 Drainage 4 wks Mon 09/10/17 Fri 03/11/17
20 Roadworks 8 wks Mon 06/11/17 Fri 29/12/17
21 Construction in river 2 wks Mon 11/09/17 Fri 22/09/17
22 Temporary access 2 wks Mon 11/09/17 Fri 22/09/17
17/02
Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan F2016 2017 2018
Gallions Reach Ferry - Outline Programme for Common Implementation Tasks
Page 1 of 1 Appendix G2
ID Task Name Duration Start Finish
1 Implementation of Propeller Driven Ferry 198 wks Mon 17/08/15 Fri 31/05/19
2 Environmental & archaeological monitoring 74 wks Mon 01/01/18 Fri 31/05/19
3 Construction 88 wks Mon 25/09/17 Fri 31/05/19
4 Mobilisation for river works 9 wks Mon 25/09/17 Fri 24/11/17
5 Install piles for dolphins 22 wks Mon 27/11/17 Fri 27/04/18
6 Construct dolphins 39 wks Mon 30/04/18 Fri 25/01/19
7 Float pontoons into position 2 wks Mon 28/01/19 Fri 08/02/19
8 Connect linkspans 2 wks Mon 11/02/19 Fri 22/02/19
9 Construction of land-based concrete deck 52 wks Mon 29/01/18 Fri 25/01/19
10 Miscellaneous and finishing works 4 wks Mon 25/02/19 Fri 22/03/19
11 Landscaping 4 wks Mon 25/02/19 Fri 22/03/19
12 Road markings 1 wk Mon 25/02/19 Fri 01/03/19
13 Commissioning of infrastructure 6 wks Mon 25/03/19 Fri 03/05/19
14 Snagging and remedials 8 wks Mon 11/03/19 Fri 03/05/19
15 Demobilisation and cleanup 4 wks Mon 06/05/19 Fri 31/05/19
16 Ferry Procurement 198 wks Mon 17/08/15 Fri 31/05/19
17 Tendering process (traditional route by TfL) 26 wks Mon 17/08/15 Fri 12/02/16
18 Design of pontoons and linkspans 27 wks Mon 15/02/16 Fri 19/08/16
19 Construction of pontoons and linkspans 104 wks Mon 22/08/16 Fri 17/08/18
20 Design of propeller driven ferry 26 wks Mon 22/08/16 Fri 17/02/17
21 Construction of propeller driven ferries 52 wks Mon 20/02/17 Fri 16/02/18
22 Commissioning of propeller driven ferries 10 wks Mon 25/03/19 Fri 31/05/19
23 Commence operations 0 wks Fri 31/05/19 Fri 31/05/19 31/05
Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun2016 2017 2018 2019
Gallions Reach Ferry - Outline Programme for Construction of Propeller Driven Ferry (2 Lane Approach)
Page 1 of 1 Appendix G3a
ID Task Name Duration Start Finish
1 Implementation of Chain Ferry 147 wks Mon 20/02/17 Fri 13/12/19
2 Environmental & archaeological monitoring 96 wks Mon 01/01/18 Fri 01/11/19
3 Construction 116 wks Mon 25/09/17 Fri 13/12/19
4 Mobilisation for river works 9 wks Mon 25/09/17 Fri 24/11/17
5 Install cofferdam for slipway (1st phase) 9 wks Mon 27/11/17 Fri 26/01/18
6 Install cofferdam for slipway (2nd phase) 9 wks Mon 23/04/18 Fri 22/06/18
7 Install cofferdam for slipway (3rd phase) 9 wks Mon 24/09/18 Fri 23/11/18
8 Install cofferdam for slipway (4th phase) 9 wks Mon 25/02/19 Fri 26/04/19
9 Remove cofferdams for slipways 4 wks Mon 29/07/19 Fri 23/08/19
10 Install piles for suspended slipways (1st phase) 4 wks Mon 29/01/18 Fri 23/02/18
11 Install piles for suspended slipways (2nd phase) 4 wks Mon 25/06/18 Fri 20/07/18
12 Install piles for suspended slipways (3rd phase) 4 wks Mon 26/11/18 Fri 21/12/18
13 Install piles for suspended slipways (4th phase) 4 wks Mon 29/04/19 Fri 24/05/19
14 Construction of suspended slipway decks (1st phase) 8 wks Mon 26/02/18 Fri 20/04/18
15 Construction of suspended slipway decks (2nd phase) 9 wks Mon 23/07/18 Fri 21/09/18
16 Construction of suspended slipway decks (3rd phase) 9 wks Mon 24/12/18 Fri 22/02/19
17 Construction of suspended slipway decks (4th phase) 9 wks Mon 27/05/19 Fri 26/07/19
18 Install piles for land-based slabs (1st phase) 4 wks Mon 26/03/18 Fri 20/04/18
19 Install piles for land-based slabs (2nd phase) 5 wks Mon 21/01/19 Fri 22/02/19
20 Construction of land-based concrete deck (1st phase) 17 wks Mon 23/04/18 Fri 17/08/18
21 Construction of land-based concrete deck (2nd phase) 17 wks Mon 25/02/19 Fri 21/06/19
22 Construction of ground slab (1st phase) 9 wks Mon 23/07/18 Fri 21/09/18
23 Construction of ground slab (2nd phase) 9 wks Mon 27/05/19 Fri 26/07/19
24 Miscellaneous and finishing works 2 wks Mon 26/08/19 Fri 06/09/19
25 Landscaping 4 wks Mon 26/08/19 Fri 20/09/19
26 Road markings 1 wk Mon 26/08/19 Fri 30/08/19
27 Commissioning of infrastructure 4 wks Mon 23/09/19 Fri 18/10/19
28 Snagging and remedials 4 wks Mon 23/09/19 Fri 18/10/19
29 Demobilisation and cleanup 8 wks Mon 21/10/19 Fri 13/12/19
30 Ferry Procurement 140 wks Mon 20/02/17 Fri 25/10/19
31 Tendering process (traditional route by Contractor) 8 wks Mon 20/02/17 Fri 14/04/17
32 Design of chain ferry 16 wks Mon 17/04/17 Fri 04/08/17
33 Construction of chain ferries 40 wks Mon 07/08/17 Fri 11/05/18
34 Commissioning of chain ferries 5 wks Mon 23/09/19 Fri 25/10/19
35 Commence operations 0 wks Fri 13/12/19 Fri 13/12/19 13/12
Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan2018 2019 2020
Gallions Reach Ferry - Outline Programme for Construction of Chain Ferry
Page 1 of 1 Appendix G3b
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