penang bridge widening booklet

8/12/2019 Penang Bridge Widening booklet

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chairman, hssi

This book is specially dedicated to our late chairman Dato Ir. Haji Abu Bakar

Bin Haji Mohd Amin and late Dato Ir C. Sivasubramaniam in GratefulAppreciation for their years of outstanding service and devotion.

They set the foundation f or what we have become today

They fortif ied the pillars to help us weather the storm

They taught us to bri dge over insur mountable odds

Th ey showed us the hi ghway to a better tomorr ow.

Though sorely missed, be assured that their legacy lives on through all of usat the HSS Group.

Dato Ir. Haji Abu Bakar Bin Haji Mohd Amin

1941 - 2009

Dato Ir. C. Sivasubramaniam

1925 - 2009


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contents1.0

2.0

3.0

4.0

5.0

6.0

7.0

introduction

design concept and key considerations

design development

award of contract

scope of widening works

construction challenges and innovations

conclusion

references

appendices


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key milestonedates

15 10 2006

Completion of

toll plaza

03 02 2006

Starting of firstsoil investigation

boreholes

18 08 2006

Driving of first

bore piles

06 11 2007

First beam

launched

27 05 2009

Completion ofstitching Prai side

26 04 2009

Completion of

stitching Penangside

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introduction1.0

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The Penang Bridge is a 13.5 km crossing that

connects Gelugor on the Penang Island to Seberang

Perai on the mainland of Peninsular Malaysia. It

comprises a 2.2 km length of cable-stayed bridge and

high level approach viaducts (dual 3 lane) and 5.76km of low level approach viaducts (dual two-lane).

Construction of this bridge started in 1982 and was

officially opened to traffic in 1985. By 2002, the traffic

demand on the bridge had increased to 98,000

vehicles, reaching capacity during peak hours.

Under the terms of the Concession Agreement, PBSB

as the Concession Company was required to widen

the existing dual two-lane low-level approach viaducts

at an appropriate time in the Concession Period to

enable traffic capacity and toll revenue to bemaximized.

The Penang Bridge1.1

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The Consultants

Penang Bridge Sdn Bhd engaged Consultants HSSI

to provide the following professional engineering

services for the Project, as the lead consultant:

Preliminary engineering study Traffic studies

Preliminary environmental impact screening

study

Detailed engineering design

Tender documentation

Pre-qualification of tenderers

Construction and supervision works

In engaging HSSI, Penang Bridge Sdn Bhd sought

the following standards of services:

Formulation and implementation of a cost-

effective method of widening the bridge Minimization of construction impacts on traffic

flows

Project delivery on-time and to budget

Rigorous application of QA standards

Regular reporting to Penang Bridge Sdn Bhd

HSSI was engaged in September 2003 and provided

services through to August 2009. At the peak, HSSI

had 70 professional staffs working on the project.

This booklet records the design and construction

work and, in the process, summarizes the main

challenges faced by the consultant and contractor

involved in widening the Penang Bridge.

This Booklet1.2 1.3

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design concept2.0

Design Concept And Key Considerations 5


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Layout

T h e l o c a t io n o f t h e l o w - l e v el a p p r o a c h v i a d u c t s i n

r el at io n t o t h e o v er al l c r o ss i n g , i n c l u di n g t h e

m ai n c ab le -s tay ed b ri dg e an d t he h ig h -l ev el

approach spans, is shown in Fig 2.1.1.

The eastern low-level viaduct, with a total length of

3.96 km and referred to as the Prai Shore Approach,

extends from the east abutment to pier 24E. It

comprises nineteen five-span units, each 40 m in

length. At the eastern end, there is one three-span

unit, each 40 m in length, and one 38 m long single-

span. The western low-level viaduct, with a total

length of 1.8 km and referred to as the Middle Bank

Bridge, extends from pier 24W to pier 69W. It

comprises nine five-span units, each 40 m in length.

Penang bridge general layout

Fig 2.1.1

2.1

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2.2

The Penang Bridge carries a significant volume of

motorcycles and scooters. At the feasibility study

stage, Consultants HSSI examined options for adding

a dedicated motorcycle lane to each side of the

existing dual two-lane low level approach viaducts, onthe basis that this could significantly improve traffic

capacity and in turn avoid widening works involving

new foundations. However, it was concluded that a

lower cost option of this form would only provide an

interim solution and would not maximize the traffic

capacity provided by the existing dual three-lane

cable stayed bridge and high-level approach spans.

It was therefore recommended that the low-level

approach viaducts and Penang Island Interchange

ramp bridges should be widened to dual three-lane

standard in order to provide the same capacity as that

available on the existing dual three-lane sections ofthe Penang Bridge.

This recommendation was approved by LLM

(Lembaga Lebuhraya Malaysia) on 11 November

2003. Fig 2.2.1 shows the carriageway layout on the

existing low-level viaducts and the final layout

required with the widening.

375 375 375 375

35 355 35 355 2

Existing cross-section

New cross-section

48 Widening48 Widening

9 25 9 25

3925 3925

Bridge Cross-section

Fig 2.2.1

Cross-Section of widened carriageway

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2.3

The present dual two lane arrangement of the low-level approach is to be widened to dual three lane. This will

form the major component of the construction works.

Several widening options were considered including symmetric widening, asymmetric widening and a new

parallel, separate structure. Both asymmetric and parallel widening posed the problem of having to overcomemore difficult transition zones and for this reason they were not adopted. Symmetric widening was recommended

on the basis that it would facilitate easier integration with the cable-stayed bridge, the high level approach spans

and the existing interchanges, as well as minimizing the impacts on users during construction.

Widening Options

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2.4

The design concept for the low-level viaduct widening

works envisaged that the widening would be achieved

as follows:

Extending the sub-structure on either side ateach pier location and providing two additional

longitudinal beams with a composite deck slab

on each side of the deck

Adding two reinforced concrete bored piles, an

extension to the pile cap, a new column and an

extension of the crosshead on each side at each

pier location, designed to support the extended

deck

Providing structural connections between the

existing and new works at pile cap and deck

level

The basic design concept for widening of the low-level viaducts is shown in Fig 2.4.1

The typical cross-section of the widened viaducts that

was finally adopted is shown in Fig 2.4.2. In order to

provide a harmonious solution for the widening, the

new works incorporate structural elements of similar

size and form to those of the existing structure

F i g 2 .4 .2 Typical Cross-Section of Completed

Viaduct Widening (symmetrical about existing viaduct

centerline)

Fig 2.4.1

Design Concept for the Widening

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At layby locations, the design of the widening works

follow a similar approach with two additional precast

beams are placed to the outside of the existing layby

in order to form a new layby at the same location. The

design also provides for the controlled breaking-out of

the existing deck in the vicinity of the existing

longitudinal joints and the casting of concrete stitching

in order to ensure that the deck is fully integral.

So as to avoid any disruption to traffic, the design

approach established by Consultants HSSI allowed

all of the construction works related to widening of the

bridge to be completed independently to the existing

structure and outside of the existing parapets.

Controlled traffic management was only required for

the demolition of the existing parapets and the

stitching of the new deck slab to the existing deck

slab.

By using precast concrete pile cap shells as

permanent formwork to the in-situ structural concrete

pile cap, a dry working environment was provided for

the in-situ works once the shell was placed and

positively located against the existing pile cap face.

Fig 2.4.2

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The following options were considered for the

additional beams required:

Prestressed concrete I -beams (ie similar to the

existing beams): Not recommended because it

would detract from the visual appearance of the

deck edge (refer Section 2.5)

Prestressed concrete U -beams (therecommended arrangement refer Section 2.5):

Results in a shorter edge overhang and also

provides more elegant appearance to the edge

of the superstructure (note that the addition of

two precast U-beams on each was not adopted

because it could not provide a standardized

solution for all spans)

Steel box girders: Offers the same advantages

as the prestressed U-beam and is significantly

lighter, thus reducing the magnitude of the

additional load transferred to the existing

foundations

Steel I-beams: Offers the advantage of being

light, but requires a long deck cantilever and

would be more flexible than the existing precast

concrete beams - in order to limit differential

deflection effects between the new steel and

existing concrete beams, it would be necessary

to use a comparatively uneconomic section,

working at low stresses, so as to provide

adequate stiffness.

Various options were considered for the new pile

foundations, including:

Driven precast concrete spun piles: Not

recommended due to the risk of damage and/or

differential settlement occurring to the existing

spun pile foundations and viaduct structures

during driving of such high-displacement piles. Driven open-ended tubular steel piles: Whilst

this option provided a lower-displacement pile

solution compared to drive spun piles, it was

also not recommended on the grounds of risk of

damage / differential settlement risk resulting

either from vibration effects or from the

densification of the soil during pile driving

Bored / cast-in-situ reinforced concrete piles

with permanent casings (recommended)

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2.5

Aesthetics was given due importance in selecting the

beam type. The Consultant recommended that post-

tensioned precast U -beams should be used for the

edge girders on the widening, rather than thestandard precast I-beams used in the original

structure.

This offered the following advantages:

Improved visual appearance to the deck edge in

elevation Higher flexural stiffness, which eliminated the

need to provide intermediate in-span

diaphragms between the new beams and the

existing beams for the purposes of matching

deflections across the deck width

I - Beam U - Beam

Aesthetics

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designdevelopment

3.0

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Design and LoadingStandards for

Widening Scheme

The design criteria adopted for the new widening

works are presented in Appendix A. The structural

design of the components of the widened portion is inaccordance to the British Standard; BS 5400 and the

loadings are according to BD37/01.

3.2

The construction sequence needed to account for the

transfer of load between the new construction and the

existing structure, along with the need to minimize

disruption to traffic. This led to the sequence for the

construction of the new works as indicated in Figs

3.2.1 to 3.2.5.

The staging of the construction was programmed in

five stages, as follows:

Stage 1: Construct new piles adjacent to the

existing pier supports

Stage 2: Construct the new column on top of the

new pile cap extension

Stage 3: Place the new precast beams and

construct the in-situ concrete deck diaphragms

Stage 4: Construct the new deck slab wideningand new parapet, and install street lighting on

the new parapet

Stage 5: Cast the in-situ concrete stitch between

the existing and new pile caps

Fig 3.2.1

Fig 3.2.5

Fig 3.2.4

Fig 3.2.3

Fig 3.2.2

3.1

Construction

sequence

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3.3

For the reasons given in Section 2.4, the use of driven prestressed spun concrete piles or low-displacement

driven steel tabular pile were not recommended. Bored/cast-in-situ reinforced concrete piles would minimize the

risk of differential settlement and the risk of damage to the existing spun concrete raked pile foundations during

construction of any new piles. Correspondingly, this low-displacement pile solution was adopted for the design.

Finalization of the pile location, size and number of new piles was constrained by the spacing, rake angle and

rake direction of the existing piles. Further, the size of pile cap in the longitudinal direction was constrained by the

fact that there was to be no additional obstruction to the tidal flow because this could result in excessive local

scour at the pile group. It would also have made the pile caps more visually obtrusive than the existing simple

rectangular plan shape.

In addition, any new piles had to be located sufficiently far from the outer face of the existing bridge parapets to

allow a piling rig and other piling equipment to work safely at all times, without disruption to traffic on the existing

bridge.

Figs 3.3.1 and3.3.2 show the typical layout of piles in the existing foundations - these illustrate the dimensional

constraints applying to design and construction in adding new piles to extend the foundations.

Fig 3.3.1

Fig 3.3.2

Constraints Imposed by the Existing Pile Foundations

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3.4

The subsoil conditions at the Penang Bridge site are

highly variable, but are generally characterized by a

deep layer of soft marine clay (typically 15 m to 20m

deep, but reaching depths of between 40m and 60 m

at certain sections on the eastern side), overlyingmedium dense silty sands and silty clays. In some

locations, the silty sands overlay residual soils formed

from the weathering of the granite bedrock. The depth

to the bedrock horizon varies considerably across the

site and is deepest on the eastern side of the crossing

where it occurs at depths of over of 100 m.

On the western side of the crossing, the bedrock is

found at shallower depths of between 50 m to 80 m.

The silty sand layers are also denser on the western

side of the crossing. The soil profile (as shown in

Appendix B) indicates the variability of along length ofthe bridge.

A total of 70 boreholes, to depths between 35 m and

80 m, were drilled to establish the soil characteristics

across the site.

Sub-Soil Conditions

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Durability Considerations

A design life of 120 years was specified for all

elements of the bridge widening works. Durability of

the piles, pile caps, piers and superstructure was

ensured in the design by a combination of the

following measures: Limiting the flexural crack width in reinforced

concrete members

Limiting the tensile stress in prestressed

concrete

Specifying appropriate values of minimum cover

to the embedded steel reinforcement

For concrete mixes, specifying maximum

water/cement ratios and minimum proportions of

pulverised fuel ash (pfa) or ground granulated

blast furnace slag (ggbs) cement replacement

For the bored piles and concrete structures exposed

to aggressive marine conditions, dense and durable

concrete was recommended. In order to ensure

adequate durability, a minimum proportion of 60% of

ggbs or 25% of pfa was specified to be mixed withOrdinary Portland Cement (OPC).

For the deck stitch, silica fume and polypropylene

fibres were specified in the mix design in order to

provide early-age strength and resistance to early -

age cracking.

The steel casing to the bored piles was considered to

be sacrificial in the original design of the bored piles

constructed with short casings under bentonite.

Structural

Element

Grade Cement

Replacement

Maximum

Water:

CementRatio

Location Nominal

Cover

(mm)

Design

Crack

Width(5)

(mm)

In -situ

concretebored piles

(cased)

40 60% ggbs 0.35 Faces

adjacentto casing

75 N/A

Pile capprecast

shell(offshore)

50 60% ggbs 0.40 Exposedfaces

Internalfaces

5045

0.10n/a

Pile cap in -situ pour(offshores)

40 60% ggbs 0.45 Exposedfaces 65 0.13

Piers (in -

situ)

40 60% ggbs 0.45 Exposed

facesBearing

plinths

65

65

0.13

0.13

Deckbeams

(precast)

60 60% ggbs 0.35 Exposedfaces

Internalfaces

45 (1)

45 (1)0 (2)

0 (2)

Deck slab

(in - situ)

50 60% ggbs 0.45 Top

surface

Soffit

40 (3)

35 (4)0.25

0.15

Parapetplinths (in -

situ)

40 60% ggbs 0.45 All faces 55 0.17

The deck slab concrete uses cement with 5 8% silica fume and 25% pfa or 50% ggbs. Elsewhere, the cement

includes either 60% ggbs or 25% pfa.

3.5

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4.0 award of contract

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4.0

Tenders for the construction of the proposed Penang

Bridge widening works were invited in October 2005.

In April 2006 the contract was awarded to UEM

Construction Sdn Bhd in three packages, namely:

Toll plaza Main approaches and ramps for Bridge Nos 3, 7

& 8

Two ramps over the North-South Highways

Award Of Contract

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5.0 scope of widening

works

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5.1

In total, 620 1 m diameter bored piles were

constructed for the main viaduct widening, with a

further 92 1 m diameter bored piles constructed forthe Bridges 3, 7 and 8 widening works. The majority

of these piles were constructed over water within full-

depth permanent steel casings using barge-mounted

Reverse Circulation Drill (RCD) rigs for pile

excavation. Between Piers 114E and 123E (eastern

abutment) on the Prai Shore approach viaduct, where

the viaduct runs over land, piling was undertaken

using land-based RCD machines, again using full-

depth casings.

Twenty land-based piles for the Bridges 3, 7 and 8

widening works were constructed under bentonite,using a conventional rotary percussion drilling rig. A

further 45 marine piles on the western low level

viaduct (where full length casings could not be

installed fully to the target geotechnical design depth

due to ground conditions) were completed by RCD,

using bentonite to stabilize the open bore below the

partial-depth casing toe.

In-situ reinforced concrete structural infill to the

precast pile cap shells was then completed, followed

by in-situ concrete construction of the new circularcolumns and new extensions to the existing

crossheads.

At the land area at the eastern end of the Prai Shore

approach viaduct, wholly in-situ pile cap extensions

were provided at nine of the pier supports.

At the stitching gap between the existing and new pile

caps, dowels were provided at regular intervals

across the interface in order to prevent differential

vertical displacement once the new pile cap extension

was finally stitched to the existing structure. Holes forthe dowels were drilled into the existing pile cap side

face, and galvanized dowel bars placed into the holes

and secured using a proprietary chemical anchoring

system. The dowel bars were then cast into the stitch

concrete.

Similar construction techniques were adopted for the

widening of the sub-structure to Bridges 3, 7 and 8. A

total of 24 precast concrete permanent formwork

shells were placed at marine piers. Where two

supports to Bridge 3 and seven supports at Bridge 7

were located on land, wholly in-situ pile cap

extensions were possible.

5.1.1

A total of 288 precast reinforced concrete pile capshells were cast for the low-level viaduct widening

works. The shells, each weighing approximately 40 t,

were precast on specially constructed casting beds at

two separate precasting yards close to the Prai side

of the bridge. At the marine piers the shells were

installed using cranes mounted on barges. The shells,

incorporating soffit holes at pile locations, were lifted

over the pile tops and supported on steel brackets

welded to the permanent steel pile casings.

Temporary horizontal prestressing was then applied

to locate the precast shells firmly to the existing pile

cap, following by the installation of a steel bracketdesigned to allow relative vertical movement (but not

relative horizontal movement) between the new shell

and the existing pile cap.

Sub-structure

Longitudinal Precast Post-tensioned Beams

The precast post-tensioned beams were cast at a

precasting yard established adjacent to the bridge site

on the Prai shore. The precasting yard included four

casting beds for the I-beams and eight casting beds

for the U-beams, along with stressing beds and a

beam storage area. Each I-beam weighedapproximately 80 t, whilst each U-beam weighed

approximately 130 t.

For the beams required for the widening of Bridges 3,

7 and 8, a separate precasting yard was set up on the

Penang Island shore.

5.1.3

Bridge Structural Works

Pile Foundations

5.1.2

Superstructure

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A total of 576 precast post tensioned beams were

cast and stressed on site for the main bridge viaduct

widening, along with 70 beams for the widening to

Bridges 3, 7 and 8.

For Bridges 3 and 7, the single-sided widening

generally comprised an additional I-beam and U-

beam. With the Bridge 7 widening width being

tapered into the existing carriageway, the use of

either single U-beam or single I-beam widening was

adopted.

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constructionchallenges &innovations

6.0

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Changes to Bored Pile Construction Method

Following contract award, the Contractor submitted to

the Employer an alternative proposal to the designapproach which involved under bentonite with short

casings installed through the alluvial cohesive soils,

This new proposal was to construct the piles using

full-depth permanent steel casings (refer Fig 6.1.1.1).

This proposal was accepted by the Employer on the

basis of the Contractors advice that it would eliminate

the risk of collapse of the pile shaft. This acceptance

was given despite the reservations held by the

Engineer that it would radically increase the length of

the piles and would be likely to cause settlement and

risk damage to the welded joints of the existing spun

piles.

6.1.1

On the eastern side, many casings were prematurely

stuck at dense residual soil at various depths before

reaching required geotechnical length. Arising fromthis, extensive and rigorous monitoring of piers and

existing sub-structure were implemented, comprising

visual inspections, leveling of settlement monitoring

pins and vibration meter recordings. These measures

were essential in ensuring that any signs of damage

or distress to the existing structure were detected

before they became excessive.

6.1.2 Casing Installation

6.1

Full Depth PermanentSteel Casings

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At locations where the casing could not be installed to the

full geotechnical depth, a series of innovative solutions were

adopted to overcome critical delays. These included the

following:

Additional soil investigations to further study the nature

of dense layers and to revise the casing installationmethod accordingly

Redesign of the new pile foundations to adopt a three-

pile group, with shorter pile depths to achieve the

equivalent design load capacity

Changing from the original vibro-hammer installation

method to drop hammer methods with controlled drop

height and re-driving of stuck casings

Partial boring and removal of soil within the stuck

casing

Use of additional inner casings

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For all marine piles, the pile shaft excavation was completed using RCD rigs. Initially, excavation of the pile shaft

was completed using muddy seawater as a stabilizing fluid. This was done whilst maintaining a 3 m head above

mean sea level, leaving a 3m to 5 m plug of soil undisturbed at the casing toe.

In some cases, this construction method resulted in the plug blowing in before the concrete could be placed. Thisrisk of blow-in was avoided by raising the pile and toe level to leave a longer soil plug in the casing. However, this

method was not satisfactory where the casings could not be installed to the target toe level for the pile and instead

bentonite was used.

6.1.2 Pile shaft excavation

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Installation of Reinforcement Cages for Piles

The Grade 460 high yield reinforcement cages were

assembled on land in 12 m lengths and transported to

the pier location on barges, where they were lowered

by crane into the pile shaft and spliced by lap welding.

6.2

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Protecting the Existing Bridge against Damage

The control limits defining refusal, as set out below,were imposed during casing driving in instances

where dense/ hard layers were encountered. Casing

driving activity was stopped immediately if refusal

was encountered.

Controls on CasingInstallation

The following instrumentation and monitoring worksare carried out:

Precise leveling

Vibration monitoring

Tilt meter monitoring

Pier Monitoring andSettlement Mitigation

6.3

6.3.1 6.3.2

7 t Vibro

10 t Vibro

13 t and 14 t Vibro

20 t drop hammer

500 mm / 10 minutes

500 mm / 5 minutes

500 mm / 5 minutes

100 mm / 40 blows at 400 mm height drop

Hammer Weight Minimum Penetration Rates before Refusal

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Jacking sledge

Fixed Gantry mounted on

crosshead

Fixed leg resting on existing parapet

Beam Launching over Marine and Land

With approved traffic management procedures in place, the precast I-beams and U-beams for the spans over land

were transported to site by day, using multi-axle low loaders. The beams were erected on the same night as they

were delivered, using two 100 t cranes located on the land adjacent to the bridge. This approach was applied in

place of the initial proposals by the Contractor to deliver the beams for the land spans via the existing deck prior to

placement.

6.6.1

The challenges in erection of the precast beams for the marine s pans involved detailed traffic management

planning. These in turn included slow lane closures, contra flow and the delivery of beams every night for 12

months. The whole operation was restricted to a 6-hour time window from 12 midnight to 6 am each weekday

night, in accordance with restrictions imposed by LLM, in order not to disrupt traffic flow on the bridge.

The Contractor planned and obtained permission to deliver all beams via the existing deck using a tractor unit and

jinkers travelling in the cordoned-off slow lane for both the eastern and western viaducts.

Two methods for launching the beams were planned, as listed below, but only method II proved to be successful:

(i) Method I - Beam launching using Jacking Gantry System: For this method, the Contractor undertook full-scale

trials using a purpose-fabricated gantry supported on an extended crosshead. The launching gantry comprised a

fixed frame, a temporary moveable leg (prop), top beam, 60 t hydraulic jack and jacking sledge.

Figures 6.6.2.1a to 6.6.2.1d Principal Details of Gantry and the Trials

Beam erection on Marine Spans

Installation of Gantry from

Barge (Stage 1)

Diagram 1 : Installation of TopBeam 1, Jacking Sledge and

Fixed Leg

6.6

Beam erection on land spans

6.6.2

Fig 6.6.2.1a

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Moveable

Leg

Installation of Top Beam 2 &

Moveable Leg

Fig 6.6.2.1b

Installation of Gantry and movable

leg on bridge (Stage 2)

Diagram 2 : Installation of Top Beam 2, Moveable Leg

Folded Moveable Leg

6.6

Beam Launching From Deck

Diagram 3 : Move the jacking sledge to beam lowering positionFig 6.6.2.1d

Beam Launching over Marine and Land

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Stage 3 Delivery and Erection of Precast Beams

(ii) Method II - Beam Launching by Marine Crane Barge: Beams for marine spans were successfully launched

using two 350 t capacity crawler cranes mounted on a large modified barge. Each crane had a lifting capacity of

78 t at a working radius of 17m. For this exercise, the barge was maneuvered and controlled by a 1600 hp tug

boat and experienced crew to ensure safe mooring and launching of beams. In total, 544 out of 576 low-level

viaduct marine span beams were transported over the bridge slow lane and successfully launched over a 12-

month period from March 2008 to March 2009 in the 5-hour available time window each night. The maximumoutput achieved was six beams per night.

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Fig 6.6.3.1b

Fig 6.6.3.1c

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Innovative Method Used to Shift Layby Beams

The widening scheme included the removal and

reconstruction of nine laybys on extended pier

crossheads at locations on either side of the

carriageway along the low-level viaducts. The original

design involved demolition of part of the existing deckslab over water, breaking out the existing diaphragms

and removal of the existing I-beams below the

existing layby for temporary storage and re-use in the

widened layby span. This method imposed critical

time and cost constraints because the works involved

barging, heavy lifting and marine logistics to handle

and store the existing I -beams, and re-launching at

the outer edge of the new deck after deck widening.

An innovative alternative approach, proposed during

the construction period by Consultants HSSI, and

adopted after detail study by the Contractor, involved

the retention, unmodified, of each complete layby

deck unit. In this approach, the entire unit was shiftedsideways in order to allow the standard widening

works to be constructed in the resulting gap. This

process was facilitated by the structural

independence of the layby deck unit and the

existence of the longitudinal joint between the layby

deck and the main deck. The adoption of this

alternative approach resulted in the successful in-situ

jacking and lateral shifting of nine complete layby

span units with only minimal demolition to remove

existing dowel bars at the layby diaphragms.

6.7

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Each layby span unit weighed about 300 t and comprised two 40m long I-beams, complete with deck slab and

parapet. The procedure applied was as follows:

The whole layby unit was jacked up 300 mm above its existing position - the four lifting jacks and their

supports had a maximum jacking capacity of 800 t, with a 500 t horizontal pushing capacity

The unit was then moved horizontally into its new position on the extended crosshead, using a drag and

skidding system working from temporary towers erected on the existing and extended pile caps

The temporary works and jacking operations are shown below.

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Deck Stitching

The new widening deck slab was progressively

stitched to the existing deck once all additional dead

load from the widening works was carried on the new

piles, and after the extended pile caps were stitched

to the existing pile caps. In this way, load transferfrom the new works construction to the existing

structure was minimized.

Prior to the start of the stitch concreting works, a

vibration monitoring study was carried out by the

Institute of Noise and Vibration, Universiti Teknologi

Malaysia. For safety reasons, the monitoring was

performed at layby areas. The UTM report indicated

that PPV from vibrations due to ambient traffic are

high (up to 22 mm/s maximum PPV) during the

daytime, but with a marked reduction in both average

PPV and maximum PPV values recorded during the

hours from 12 midnight to 5 am.

Further monitoring on newly extended sections was

also carried out to confirm the initial monitoring and to

ensure that vibration during and immediately after

stitch concreting was maintained within the permitted

limit of 5mm/s PPV.

Vibration mitigation measures included traffic lane

constriction, speed reduction measures, traffic

management plans and providing a high early

strength grade for the stitch concrete.

6.8

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Challenges in relation to the deck stitching included

the following:

Vibration effects from traffic on the existing slow

lane had the potential to impair the development

of early bond strength of concrete if not

mitigated

Two lanes had to be kept opened through thedaytime on both carriageways at all times. Slow

lane closures for stitching were only permitted

between the hours of 11 pm to 6 am, although a

slow lane closure would have been preferred for

longer to keep traffic -induced vibration away

from the concrete stitch area

Vibration peak value is directly related to axle

wheel load, vehicular speed and volume of

traffic using the bridge

Penang Bridge is heavily congested and traffic

volume only reduces to low levels between 12

midnight and 5 am each night. Heavy traffic

volume at night was affected by the earlier

partial closure of the slow lane to allow concrete

delivery. This had impact on the Contractors

planned stitching, since it was proposed to

deliver the concrete via the deck. Therefore allstitching works were confined between 10 pm

and 6 am

It was observed that slow moving traffic during

congested hours does not materially induce

vibration in the deck. However, fast moving and

heavy vehicles such as lorries and trailers cause

deck vibrations that are of concern

Demanding traffic management solutions were

required to be implemented when stitch pours

were carried out on both carriageways

concurrently with transportation of beams forlaunching and other simultaneous deck slab

works.

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The approach to vibration mitigation and solutions for stitch concreting can be summarized as follows:

Slow lane constriction and control of vehicular speed limit approaching the particular section of deck stitch

concrete pour were implemented. Controls were introduced to keep vehicular speed to below 40 kph. The

imposition of speed humps as a means of slowing down traffic was also considered but not invoked

Traffic vibration studies were carried out to understand the nature of traffic volume, speed and effect of axle

loads causing vibration on the deck - this also assisted with planning timing of the night-time deck pours Deck vibrations were controlled to below 5mm/sec PPV, although occasional peaks exceeding 15mm/sec

PPV were experienced from speeding vehicles over bridge deck joints

Lane constriction assisted in keeping wheel loads away from the freshly poured deck stitch concrete,

thuereby reducing the impact of transmitted vibration

Comprehensive concrete setting time studies were carried out on the Grade 50 concrete for the stitching

works. Initial and final set consistency and workability of design mixes had to be fine tuned to achieve the

following:

Initial set that could allow sufficient time for concrete delivery, compaction and placing without loss of

workability - this was found to vary from 2 to 3 hours

Final set that was consistent and guaranteed to be achieved before opening partial lane closures to heavy

traffic - this was found to vary from 3 to 5 hours

The use of polypropylene fibres in the deck stitch concrete mix was specified to protect concrete fromstresses at early age, given that this can cause cracking - 900 g/m3 of microfibre was used with a super-

plasticizer to achieve high early strength and the required workability with a reduced water / cement ratio

Silicafume at 27 kg/m3 (6% by weight of cement) was added to improve early age strength gain of the stitch

concrete

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7.0 conclusions

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7.0

Due to the increase of the traffic volume and to

ensure the smooth traffic flow, the widening of the

existing Penang Bridge was necessary. The approach

adopted by the Consultants HSSI and the contractor

embodied the following principles:

Whilst the scheme for widening the low-level

viaducts was simple in concept, both the detail

engineering design and construction presented

many challenges

For the successful completion of the works, it

was necessary to avoid compromising the

structural integrity or appearance of the existing

structure and with minimum disruption to traffic

Innovative mitigation measures were developed

and applied to overcome the constraints, whilst

at the same time recognizing the need to avoid

excessive construction risks and other thanminor traffic disruption

This booklet summarizes the main challenges

involved in widening the Penang Bridge. In doing so it

not only records the work that was carried out but is

also intended to provide useful information to others

involved in the design and construction of bridge-

widening projects.

Conclusions

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references

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References

UK Ministry of Transport Memorandum No.771,

Standard Highway Loadings

UK Ministry of Transport Memorandum No.785,

Concrete Bridges and Structures

UK Department of Transport Standard BE2/73,

Prestressed Concrete for Highway Structures

British Standard Code of Practice CP110, Structural

Use of Concrete

UK Department of Transport Standard BE5, TheDesign of Highway Bridge Parapets

British Standard Code of Practice CP2004,

Foundations

Jabatan Kerja Raya Loading / Design Standards, JKR

Specification for Bridge Live Loads

UK Highways Agency Standard BD 37/01, Loads for

Highway Bridges

The Penang Bridge - Planning, Design andConstruction, Tan Sri Datuk Professor Ir Chin Fung

Kee, Malaysian Highway Authority, 1988

Report on Soil Investigation for Subsurface

Exploration for Proposed Jambatan Pulau Pinang

(Parts I and II), Malaysian Soil Investigation Sdn Bhd,

Dec 1978

Pile Design & Construction Practice, MJ Tomlinson,

4th Edition E & FNSPON

Terzaghi and Peck, Soil Mechanics in Engineering

Practices, 1967

Chang & Broms, Design of Bored Piles in Residual

Soils based on Field Performance Data, Canadian

Geotechnical Journal, Vol. 28, pp. 200 209, 1991

A Brief Guide to the Design of Bored Piles under Axial

Compression A Malaysian Approach, Ir Dr Gue

See Sew, Tan Y.C and Liew S.S, Seminar on

Bridges: Kuala Lumpur, Malaysia, 2003

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Appendix A

The structural design of the Penang Bridge viaduct was carried o ut in accordance with the applicable British

Standard, augmented as necessary by other internationally and locally recognized guidelines to suit site

conditions. From this, the main design criteria can be summarized as follows:

Both the mainline viaduct and the ramps were to be designed for live loads type HA and HB (both 45 units

and 30 units, as appropriate) loading, as specified in the British Department Standard (DB 37/01)

Collision loads on bridge supports in the proximity to highways were as per BD60/94

The design temperature range was 13C to 37C, along with consideration of differential temperature as per

BD37/01

The design mean hourly wind speed is 27m/s

No allowance for differential settlement was made in the design of the deck slab instead, the extended pile

cap was rigidly connected to the existing structure (ie thereby eliminating any possibility of differential

settlement between the new and existing deck slabs)

Design Criteria for New Widening Works

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acknowledgement

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Acknowledgement

HSS Integrated Sdn. Bhd. would like to thank the following for providing the necessary information,kind assistance and support in the implementation of this Project:

Lembaga Lebuhraya Malaysia

Lembaga Lebuhraya Malaysia

Penang Bridge Sdn. Bhd.

Penang Bridge Sdn. Bhd.

OPUS Management Sdn. Bhd.

OPUS Management Sdn. Bhd.

Majlis Perbandaran Pulau Pinang

Majlis Perbandaran Seberang Perai

PLUS (Butterworth Kulim Expressway)Jabatan Alam Sekitar Pulau Pinang

Tenaga Nasional Berhad, Pulau Pinang

TNB Transmission Sdn. Bhd

Jabatan Kerja Raya Pulau Pinang

Jabatan Kerja Raya Bukit MertajamJabatan Laut Malaysia, Pulau Pinang

Jabatan Pengairan dan Saliran, Pulau Pinang

Jabatan Bekalan Air, Pulau Pinang

Telekom Malaysia, Pulau Pinang

GAS Malaysia Sdn Bhd

Ketua Polis Daerah, IPD Seberang Perai

Halcrow

Halcrow

Environment Asia Sdn. Bhd.

Perunding Trafik Klasik Sdn. Bhd.

TRARS Konsult Sdn. Bhd.

CT Toh Consultant

Jurukur Perunding Services

Arkitek Shilpa

Dato Ir.Hj. Ismail B. Md. Salleh

Ir. Mohd. Shuhaimi B. Hassan

Pn. Hjh Suhaina Bt. Baharudin

Tn. Hj. Ir. Abd. Rahman Hassan

Mr. Muhinder Singh

Ir. Wan Meow Kwan

Pn. Hajah Rosnani Bt. Mahmud

En. Ku Jamil B. Zakaria

Ir. Abdul Aziz B. Jaafar

Ir. Hj. Husaini Hussin

En. Nik Azhar B. Abd. Samad

En. Izmal B. Ibrahim

Tn. Hj. Mohd. Abu Bakar B. Othman

En. Jamil B. Mohd. Nor

En. Sukardi B. Sukarno

Unit Trafik

Mr. Roger Buckby

Mr. Paul W Corbett

Mr. Edward Wong

Dr. Tai Tuck Leong

Ir. Amran B. Alias

Dr. Toh Cheng Teik

Mr. Wong Kam Fai

Mr. Lim Take Bane 48


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Dato Ir. Haji Abu Bakar Haji Mohd Amin Datuk Ir. S Santhakumar /

Datuk Ir. Kuna Sittampalam

Co-Project Director

Ir. Chan Kin Pooi

Chief Executive Officer

Ir. B Nitchiananthan

Chief Operating Officer

Ir. Chen Wai Peng

Project Manager

Ir. Kho Poh Teck

Design Engineer

Ir. Tan Wee Kong

Design Engineer

Mr. B Ramesh BalakrishnanQuantity Surveyor

Mr. Anand Sharvanandan

Project Coordinator

Ir. Nor Afizza Bt. JuniProject Coordinator

Ir. Mathew PhilipHighway

Mr. RabindranathHighway

Mr. Tan Joon Lye

Highway

Ir. Lee Yew Seng

Drainage / Utilities

Ir. Azman Abd RahmanMechanical & Electrical

Ir. Kun Goon HongMechanical & Electrical

Ir. Tan Seng Guan

Mechanical & Electrical

Ir. Khairul Anuar B. Mohd. Said

Geotechnical

Design and Supervision Team

Ir. Wee Eng Leong

Chief Resident Engineer

Ir. Charles Low Boo Tean

Resident Engineer

Mr. Liew Sin KhoonDeputy Resident Engineer

(Geotechnical)

Mr. Teng Jit Poh

Deputy Resident Engineer

En. Shamsuri Salleh


Mr. M Marimuthu


En. Al-Rifae

ARE Piling 1

En. Rahim RejabARE Piling 1

En. Ku Adenan Ku Ismail

ARE Piling 2

Mr. Law Peng Swee

ARE Piling 2

En. Hussin MuhammadARE Casting Yard

En. Azmi MohamadARE Bridge 1

En. Md. Fadzil Abd Rahman

ARE Bridge 1

Mr. P KumaranARE Bridge 2

En. Zulkifli HusseinARE Measurement 2

Mr. Woo Wooi Lim

ARE M&E

Cik. Norhabina Mohd ArisEnvironmental Officer

Mr. Donny RamasamyInstrumentation Officer 49


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Mr. Ashokumar RamasamySafety Officer

Mr. Sivabalan Arumugam

Safety Officer

Mr. Mah Kim TongSurvey Technician 1

Mr. Tee Yoke ChuanSurvey Technician 2

En. Sabri Sharif

Survey Technician 3

Mr. K VijayanMaterial Technician 1

En. Mohd. Salam NgajimanMaterial Technician 2

Mr. Sophee Khoo B. Abdullah

IOW Traffic 1

Mr. S Seenivasan

IOW Bridge 1

Mr. Sunny Tan

IOW Bridge 2

Mr. Ramamurthy Letchumanan

IOW Bridge 3/Piling

Mr. Tan Teong Hin

IOW Bridge/Piling 4

En. Afraizal Abdul Aziz

IOW Bridge 5

Muaizam Abdul AzizIOW Bridge 6

Robert King Amros

IOW Bridge 7

Mr. Tan Tong Siew

IOW Piling 1

Mr. Revindran Ramakrishnan

IOW Piling 2

En. Alzahari SaadIOW M&E 1


Mr. Yeoh Hun Poh

IOW Casting Yard 1

Mr. Silverster Douglas

Draughtman

Mr. S Kanathasan

Draughtman

Cik Nor Azlina Mohd. Saad

Draughtwoman

En. Fairuz Zamri IsmailDraughtman

Mr. Jagjit SinghAdministrative Manager

Ms. Nirmala Devi

Administrative Manager

Pn. Mazni Abdul WahabSecretary

Ms. Mary Janet PasqualSecretary

Pn. Badariah Rahmad

Clerk

Cik Khadijah Abdul Majid

Clerk

Pn. Emilia AzudinClerk

Ms. Nanda Devi

Clerk

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penang bridge widening booklet

Documents