central laboratories report 12-5c1617.93 callum murton · callum murton peter cenek russell kean...

Basin Bridge Project, Technical Report 8: Assessment of Ground Vibration Effects from Construction and Operation

Central Laboratories Report 12-5C1617.93

Callum Murton Peter Cenek Russell Kean


Basin Bridge Project, Technical Report 8: Assessment of Ground Vibration Effects from Construction and Operation

Callum Murton Peter Cenek Russell Kean

Prepared By:

Opus International Consultants Limited

Central Laboratories 138 Hutt Park Road, Gracefield PO Box 30 845, Lower Hutt 5040,

Callum Murton New Zealand Instrumentation Engineer

Reviewed By:

Telephone: +64 4 587 0600 Facsimile: +64 4 587 0604

Peter Cenek Date: May 2013 Research Manager Reference: Issue 1 Physical & Engineering Sciences Status: Final

This document and its contents are the property of Opus International Consultants Limited. Any unauthorised employment or reproduction, in full or part is forbidden. The document has been prepared solely for the benefit of the NZ Transport Agency. No liability is accepted by Opus International Consultants or any employee or subconsultant of this company with respect to its use by any other person. This disclaimer shall apply notwithstanding that the document may be made available to other persons for an application for permission or approval or to fulfil a legal requirement. © Opus International Consultants Limited 2013


Basin Bridge Project: Technical Report 8 Assessment of ground vibration effects

May 2013 8-i

Executive Summary

This report presents an assessment of ground-borne vibrations resulting from the construction of the Basin Reserve Transportation Improvements project and from traffic once it becomes operational. The assessment has been predicated on the results of ground vibration measurements made at various sites around the Basin Reserve on the 26th and 30th of April 2012 and application of predictive models contained in various standards and technical references.

The measured and estimated vibrations were assessed from the perspectives of human comfort, cosmetic building damage and reduced serviceability of underground services using guidelines given in British Standard BS 5228 2:2009, Code of practice for noise and vibration control on construction and open sites – Part 2: Vibration and German Standard DIN 4150-3:1999, Structural vibration – Part 3: Effects of vibration on structures.

The primary conclusions arising from this assessment of ground vibrations generated by the construction and operation of transportation improvements around the Basin Reserve are as follows:

1. There may be some short term disturbance to occupants of nearby buildings resulting from construction activity. However, these disturbances are likely to be acceptable if proven vibration management methods are applied, such as selection of appropriate equipment and construction methodology and keeping affected parties informed as to when vibration generating activity is to take place and its duration.

2. The existing environment around the Basin Reserve is exposed to low level traffic-induced vibrations from State highway 1. These vibrations are considered to be acceptable as they are within recognised guidelines for human comfort applied internationally. The Project, once operational, will not result in any worsening of existing traffic-induced vibration levels.

3. Buried services are expected to be exposed to maximum vibration levels of between 4 mm/s and 16 mm/s peak particle velocity (PPV) during construction and about 6 mm/s PPV once the Project is operational. By comparison, the maximum level of intermittent and transient vibrations that underground services should be subjected to is 30 mm/s PPV if in good condition or 15 mm/s PPV if old or dilapidated according to British Standard BS 5228-2:2009. Therefore, ground vibrations generated by construction activities can be easily tolerated if the buried pipework is not old or in a dilapidated condition. Because of the historic nature of the brickwork Waitangi Stream culvert, it would be prudent to perform condition surveys pre and post construction of the Project to ensure no change to its structural integrity takes place. In addition, vibrations should be monitored, as detailed in the Construction Noise and Vibration Plan (CNVMP), whenever piling activity occurs in close proximity to the culvert to ensure vibrations measured on the culvert are below levels that could cause structural damage or settlement of the ground surrounding the culvert. Once the Basin Bridge becomes operational, all the buried services will be exposed to traffic induced vibrations that will be of the same magnitude as a present.

4. Foundations for the two proposed new buildings, one to be erected within the Basin Reserve immediately adjacent to the RA Vance Stand (northern gateway building) and the other to be erected at the intersection of Ellice Street with Kent Terrace immediately adjacent to the Grandstand Apartments (building under the bridge), will most likely need to be piled. Therefore, care will have to be taken in selecting a method



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of piling that creates minimum soil disturbance to prevent any vibration-induced building damage occurring. An international literature search and New Zealand experience suggests that both steel screw-in piling and bored piling using oscillators are two techniques that are able to generate vibration levels that comply with guidance thresholds in standards for avoiding damage to nearby structures.

5. For the Basin Bridge project, the bored piling operations associated with bridge piers have the potential to generate problematic vibrations, the driving of steel casings in particular. Therefore, there is a need to select the most appropriate casing driving technology for the soil conditions expected to be encountered to ensure any disturbance of the soil surrounding the pile borehole is minimised. Experience under Wellington conditions indicates that steel casings driven by a hydraulic casing oscillator generates vibrations whose magnitude is about a third of those when driven by a vibratory hammer highlighting the effect equipment selection can have.

6. A draft Construction Noise and Vibration Management Plan has been prepared (refer Volume 4), which provides a methodology for managing ground vibrations resulting from construction activities associated with the Project. The objective of this plan is to minimise damage due to construction vibration by all reasonable and feasible means possible. Therefore, there is specific consideration of the two activities identified as having the potential for adverse effects: (i) piling associated with the bridge piers and foundations of the two proposed buildings and (ii) vibratory compaction. The plan also considers how the construction vibrations will be monitored to ensure compliance with the established vibration thresholds for minimising structural damage. Central to this plan is the need for the contractor to demonstrate that vibration levels assumed in making the assessments presented in this report will not be exceeded by the equipment that will be used on the Project.

7. Overall, the operation of the Project will not generate any adverse vibration effects, provided current road maintenance management practices are maintained. Similarly, no adverse vibration effects are expected to result during the temporary construction period on account of the Construction Noise and Vibration Management Plan being in place to ensure compliance with the established vibration thresholds.

Also included in the report are predictor curves for estimating the magnitude of ground vibrations from impact related construction activity derived from on-site measurements on the main soil types found in the area of the project. These predictor curves will assist with the selection of appropriate methods and equipment for construction activities that have the potential for the greatest adverse effects, these being driven pile casings for bridgework and vibratory compaction.



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Contents Executive Summary ................................. ...................................................................................... i

1 Introduction ...................................... ...................................................................................... 1

2 Project Description ............................... ................................................................................. 3

2.1 Transport Improvements ................................................................................................... 3

2.2 Urban Design and Landscape ........................................................................................... 6

2.3 Related Projects ................................................................................................................ 9

2.4 Key considerations of the Project from a vibrations perspective ........................................ 9

3 Methodology ....................................... .................................................................................. 12

3.1 Test methods .................................................................................................................. 12

3.2 Test sites ......................................................................................................................... 14

4 Assessment criteria ............................... .............................................................................. 15

4.1 Human comfort ................................................................................................................ 15

4.2 Building damage ............................................................................................................. 16

4.3 Underground services ..................................................................................................... 17

4.4 Vibration levels generated by everyday activities ............................................................ 18

5 Measured vibrations ............................... ............................................................................. 19

5.1 Peak particle velocities due to traffic-induced vibrations .................................................. 19

5.2 Vibration magnitude attenuation ...................................................................................... 22

6 Discussion of results ............................. .............................................................................. 25

6.1 Baseline conditions ......................................................................................................... 25

6.2 Construction-related issues ............................................................................................. 25

6.3 Traffic-induced vibrations once operational ..................................................................... 29

6.4 Vibration from bridge traffic ............................................................................................. 29

6.5 Underground Services ..................................................................................................... 30

6.6 The Basin Reserve northern gateway building ................................................................ 31

6.7 Relocated CS Dempster Gate ......................................................................................... 34

6.8 Seismic rating of Grandstand Apartments ....................................................................... 34

6.9 Suggested mitigation measures ...................................................................................... 34

7 Confirmation of Critical Vibration Levels ......... .................................................................. 37

7.1 Monitoring of Piling Activity at One Market Lane, Wellington ........................................... 37

7.2 Vibratory Roller ............................................................................................................... 39

7.3 Concluding Remarks ....................................................................................................... 39

8 Conclusions ....................................... .................................................................................. 40

9 References......................................... ................................................................................... 42

Appendix 8.A: Vibration measurement locations ................... .................................................. 44

Appendix 8.B: Impact related predictor curves ................... ..................................................... 48

Appendix 8.C: Drop-weight comparison ............................ ....................................................... 51

Appendix 8.D: Accelerometer calibration data .................... ..................................................... 53



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List of figures Figure 8.1: Project Area showing the proposed roading layout and land to be designated .............. 3

Figure 8.2: Proposed traffic directions for the Project ...................................................................... 4

Figure 8.3: Urban and landscape zones for proposed works outside of the traffic lanes ................. 7

Figure 8.4: Histogram of peak particle velocities (mm/s), due to traffic-induced vibrations, within each 10-second period at testing Site S4 on the southern side of Paterson Street........................ 19

Figure 8.5: Annoyance due to vibrations in dwellings plotted against calculated statistical maximum values for weighted velocity, vw,95 (NS 8176.E:2005) ..................................................................... 21

Figure 8.6: Location of historic Waitangi Stream Culvert relative to Basin Reserve northern gateway building ........................................................................................................................... 32

Figure 8.7: One Market Lane construction site .............................................................................. 37

List of tables Table 8.1: Test sites and test types ............................................................................................... 14

Table 8.2: Guidance on effects of vibration levels (from British Standard BS 5228-2:2009, Annex B) ..................................................................................................................................................... 15

Table 8.3: Guideline values for vibration velocity to be used when evaluating the effects of short-term vibration on structures (from German Standard DIN 4150-3 1999) ....................................... 16

Table 8.4: Guideline values for vibration velocity to be used when evaluating the effects of long-term vibrations on structures (from German Standard DIN 4150-3 1999) ...................................... 17

Table 8.5: Guideline values for evaluating the effects of construction-related vibration on buried services (from British Standard BS 5228-2:2009).......................................................................... 17

Table 8.6: Guideline values for vibration velocity to be used when evaluating the effects of short-term vibration on buried pipework (from German Standard DIN 4150-3:1999) .............................. 18

Table 8.7: Common ground vibration levels .................................................................................. 18

Table 8.8: Measured peak particle velocities (mm/s) due to traffic-induced vibrations ................... 20

Table 8.9: Estimated site specific attenuation coefficients ............................................................. 22

Table 8.10: Measured vibration magnitude attenuation parameters due to vibrations caused by sandbag drops .............................................................................................................................. 24

Table 8.11: Estimated vibration levels at properties most effected by bore piling operations ......... 27

Table 8.12: Estimated vibration levels at properties most affected by vibratory roller activity ........ 28

Table 8.13: Estimated vibration levels at properties most affected by bored pile activity associated with the northern gateway building ................................................................................................ 33

Table 8.14: Highest vibration levels measured during vibratory and oscillatory piling activity at One Market Lane site ........................................................................................................................... 37

Table 8.15: Estimated vibration levels at properties most effected by bore piling operations if vibration levels measured at One Market Lane could be replicated for the Project ........................ 38



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Client NZ Transport Agency (Wellington Office)

Level 9, PSIS House 20 Ballance Street PO Box 5084, Lambton Quay Wellington 6145

Contact Greg Lee (Principal Transport Planner)

1 Introduction

This report presents an assessment of ground-borne vibrations resulting from the construction of the Basin Bridge project (hereafter referred to as the Project) and from traffic once it becomes operational. In carrying out this assessment, no consideration of either construction or operational induced vibrations at 28 Ellice Street has been made based on the assumption that the existing residential building at this site will be removed to maintain the car park space at St Joseph’s Church at present levels. This is discussed in greater detail in section 2.3 of this report.

The assessment has been predicated on the results of ground vibration measurements made at various sites around the Basin Reserve on the 26th and 30th of April 2012. The measurements were undertaken to:

• quantify the current vibration magnitudes induced by traffic;

• establish how quickly the traffic vibrations decay with distance for the main soil types found around the Basin Reserve; and

• derive site specific predictor curves for estimating the magnitude of ground vibrations from impact related construction activity.

The principal objectives of measurements were to provide an indication of existing traffic-induced vibration levels (the baseline case) and the expected vibration magnitudes that will arise as a result of the construction of and traffic flow over the proposed bridge to be constructed as a part of the Project.

The measurement of the traffic-induced ground-borne vibrations and their attenuation were carried out using either an array of four accelerometers evenly spaced along a line perpendicular to the road, or a single accelerometer at a point of interest that could not accommodate the full array. The traffic-induced ground-borne vibrations were recorded at each site investigated for a period of 15 minutes.

The array of four accelerometers was also used to derive the predictor curves. In this case, vibrations were induced by dropping a 25 kg sandbag from a height of 1 m at a location in-line with the accelerometer array, and at a specified distance from the end of the array. Three drops were recorded at each end of the array, resulting in six measurements in total for each location investigated.

The measurement of the ground vibrations conformed to the following International Organisation for Standardisation (ISO) standards:

• International Standard ISO 8041:2005, Human response to vibration - Measuring instrumentation, and



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• International Standard ISO 4866:2010, Mechanical vibration and shock – Vibration of fixed structures – Guidelines for the measurement of vibrations and evaluation of their effects on structures.

The measured vibrations were assessed using guidelines given in British Standard BS 5228-2:2009, Code of practice for noise and vibration control on construction and open sites – Part 2: Vibration and German Standard DIN 4150-3:1999, Structural vibration – Part 3: Effects of vibration on structures.

The report has been structured as follows:

• Section 2 presents an overview of the Project. Key aspects of the Project from a vibration perspective are also highlighted.

• Section 3 describes the vibration measurement methods utilised.

• Section 4 details the criteria by which the measured vibrations were evaluated from the perspectives of human comfort and cosmetic building damage.

• Section 5 summarises the key results from the measurement programme.

• Section 6 discusses baseline conditions and identifies possible issues related to construction and operational traffic vibrations generated from the Project along with suggested remedial actions.

• Section 7 lists the main conclusions resulting from the assessment.

• Appendix A shows aerial views of each vibration monitoring site and were the accelerometers were placed.

• Appendix B gives all the predictor curves derived from the sandbag drop tests.

• Appendix C investigates the effect of different drop-weight characteristics on drop test results.



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2 Project Description

The Project proposes to construct, operate and maintain new transport infrastructure for State Highway 1 at the Basin Reserve. A key component of the proposal is a multi-modal bridge that connects Paterson Street with Buckle Street. The bridge will provide a two lane one-way carriageway for SH1 westbound road users and includes a shared walking and cycling path on its northern side.

Proposed at-grade road improvements include changes to Dufferin Street and sections of Paterson Street, Rugby Street (including the intersection with Adelaide Road), Sussex Street, Buckle Street (SH1), Taranaki Street, Vivian Street (SH1), Pirie Street, Cambridge Terrace, Kent Terrace (SH1), Ellice Street and Hania Street. The overall road layout is shown diagrammatically on Figure 8.1 below.

Figure 8. 1: Project Area showing the proposed roading layout and land to be designated

The Project also provides urban design and landscape treatments. These include new landscaped open space areas, a new building under the bridge, a new entrance and Northern Gateway Building to the Basin Reserve, an improved streetscape entrance to Government House and adjacent schools, a revised car park for St Joseph’s Church, dedicated bus lanes and bus stops around the Basin Reserve, as well as new walking and cycling paths.

Proposed landscaping and urban design treatments include low level plantings, raingardens, trees, terracing, architectural bridge design including sculptured piers, furniture and paving. These measures aim to contribute to the overall integration of the proposed bridge structure into the surrounding urban environment.

2.1 Transport Improvements

The Project proposes a grade-separated route (the bridge element) for SH1 westbound traffic on the northern side of the Basin Reserve. As a result, SH1 traffic will be removed from the local road network around the eastern, southern and western sides of the Basin Reserve.



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The bridge soffit will be up to 7.3m above the ground surface and the top of the guard rail will up to 10.5m high above the ground. The bridge is approximately 263m long or 320m long if abutments are included. It will be supported by six sets of piers (2 are double piers) and six smaller diameter piers to support the western end of the shared pedestrian and cycleway. The bridge has a minimum width of approximately 11.3m and a maximum width of approximately 16.7m. There are 2 bridge joins, one at each end.

The Project proposes changes to the SH1 westbound route, the SH1 eastbound route, and other roads on the network where they connect with SH1, including clearways on the eastern part of SH1 Vivian Street (from Tory Street to Cambridge Terrace). These propose to improve the efficient and safe movement of traffic (including buses), pedestrians and cyclists through intersections and provide entry and exit points for SH1. Supplementary works on the existing local road network are also proposed to be undertaken to take advantage of the additional capacity created by the SH1 improvements.

The Project proposes new pedestrian and cycling routes throughout the Project area as well as improvements to existing infrastructure. The majority of the works to improve the walking and cycling routes are located on the north side of the Basin Reserve and connect with Mount Victoria, Mount Victoria Tunnel and schools on Dufferin Street. These improvements will also connect with the National War Memorial Park which is currently under construction and also with potential future duplication of Mount Victoria Tunnel.

A reduction in state highway traffic on the roads around the Basin Reserve allows for more efficient northbound and southbound movements from Kent and Cambridge Terrace to Adelaide Road. Accordingly, new dedicated bus lanes are proposed to provide for better public transport movements around the Basin Reserve.

The key traffic flows around the Basin Reserve following the implementation of the proposed Project are shown in Figure 8.2 below and described thereafter.

Figure 8. 2: Proposed traffic directions for the Project

The package of transportation improvements proposed by the Project are summarised below and followed by a brief description of the works:



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SH1 westbound (from Mount Victoria Tunnel to Buckle Street)

• The Bridge - new direct link from Paterson Street to Buckle Street via a bridge;

• Buckle Street three laning - provision of third lane along Buckle Street between Sussex Street (including minor modifications to Sussex Street) and Taranaki Street to improve capacity and accommodate the two lanes from the Bridge; and

• Taranaki Street improvements – modifications to the layout of Taranaki Street and Buckle Street intersection to accommodate the three laning of Buckle Street and to increase capacity.

SH1 eastbound (from Vivian Street – Kent Terrace - Mount Victoria Tunnel)

• SH1 Eastbound re-alignment - realignment of SH1 eastbound between Hania Street and Brougham Street; and

• Vivian Street and Pirie Street Improvements – as part of the modifications to the intersection of Pirie Street and Kent / Cambridge Terrace and Vivian Street, clearways on Vivian Street are proposed. The combination of improvements increases the capacity of the intersection for all traffic movements including public transport.

Improvements to roads around the Basin Reserve

• Paterson Street / Dufferin Street intersection – modifications to the layout of Paterson Street/Dufferin Street and change in priority at the signals to provide a significant increase in priority to Dufferin Street (south bound traffic from Kent Terrace/ Ellice Street);

• Adelaide Road / Rugby Street intersection – reducing through lanes along Rugby Street from 3 lanes to 1 and allowing Adelaide Road traffic and Rugby Street traffic to flow at the same time. Pedestrian and cycling crossings will be via on-demand signals. Two lanes for access into Adelaide Road would remain with one operating as a bus lane;

• Ellice Street link – new road link from Ellice Street to Dufferin Street/Paterson Street intersection (a similar vehicular movement can currently be made between Ellice Street and Dufferin Street). A new shared pathway for pedestrians and cyclists would be provided adjacent to this link to facilitate movements between the Mount Victoria suburb, the schools on Dufferin Street, and further south toward Adelaide Road;

• Dufferin Street improvements – works to modify the layout of the road space and bus drop off zones on Dufferin Street and Rugby Street on the south east corner of the Basin Reserve and to improve vehicular access to Government House; and

• Basin Reserve Gateway – treatment to Buckle Street where it meets Kent/Cambridge Terraces, and retains an entry point to the re-aligned SH1 eastbound.

Walking, Cycling, Public Transport (throughout the Project Area)

• Walking and cycling path on bridge – new walking and cycling path on the bridge between Paterson Street and Buckle Street / NWM Park;

• Existing pedestrian and cycle routes – existing at-grade pathways are retained or enhanced and additional and alternative routes are provided. Additional and improved pedestrian and cycling access would be provided in the landscaped area on the corner of Cambridge Terrace and Buckle Street and between Brougham Street and Kent Terrace. These routes link to the proposed pedestrian and cyclist facilities proposed through NWM Park;



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• Public Transport - new dedicated bus lanes are proposed on Ellice Street, Dufferin Street and Buckle Street, and the southbound bus stop is proposed to be relocated from Adelaide Road onto Rugby Street; and

• Public Transport - existing priority for buses from Kent Terrace onto Ellice Street is retained.

For further detail on the proposed transport improvements refer to Volume 3: Technical Report 4: Assessment of Transportation Effects of these documents. Details of the road design layouts are shown in Volume 5: Plan and Drawing Set.

2.2 Urban Design and Landscape

Proposed urban design and landscape treatments to areas outside of the road carriageway form part of the Project works. The development of the proposed Project design has been iterative, responsive and collaborative. As such, it has been developed through an Urban Landscape and Design Framework (refer to Volume 3: Technical Report 2) to address the specific urban design principles for the Project. The Project proposes treatments to areas adjacent to the road network that would assist with the integration of the proposed bridge into the surrounding urban context.

Six zones and elements for the Project area have been identified within which character and zone specific principles for those areas have been developed to define the design intent and to provide a framework for post RMA consenting detailed design development. The zones are shown on Figure 8.3 below.



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Figure 8. 3: Urban and landscape zones for proposed works outside of the t raffic lanes

These are briefly described for the urban and landscape zones below:

• Zone 1 Cambridge/Buckle Bridge Interface Zone - proposed landscape treatments to land between Cambridge Terrace and the NWM Park, which includes rain gardens and wetland plantings for stormwater treatment. This landscape area has been designed as a continuation of NWM Park. The terracing in the NWM Park starts from Kent and Cambridge Terraces and are reflective of the cultural heritage of the area, as cultivation terraces. Wetland planting reflects the former Waitangi Lagoon which is now the Basin. The landscaping also provides an interface with the curtilage of the newly relocated Home of Compassion Crèche (former)1.

• Zone 2 Kent/Cambridge Basin Gateway: proposed landscaping between Kent/Cambridge Terrace responds to tangata whenua values in relation to the proposed historical wetland ecology and provides a safe and enlarged public access and gathering area relative to the Basin Reserve entrance. The proposed landscape aims to facilitate gathering and includes reconfigured pedestrian crossings, bus stops and Basin Reserve entrance.

• Element 2.1 Entrance to the Basin Reserve – proposes a combination of planting (pohutakawa trees) and a new Northern Gateway Building on the northern boundary within

1 The Home of Compassion Crèche (former) is being relocated as part of the National War Memorial Park project.



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the Basin Reserve. The combination of new Northern Gateway Building and pohutakawa trees screen the bridge from general views from within the Basin Reserve. The new Northern Gateway Building is designed to specifically remove potential views of traffic on the bridge from the views of batsmen (facing bowlers from the north). The new Northern Gateway Building) would provide space for player facilities and includes a wider entrance for visitors to the Basin Reserve that is aligned with the new entrance plaza located between Kent and Cambridge Terrace.

The new structure will occupy the space between the RA Vance Stand and the existing toilet block at the edge of the northern embankment. The new structure will be up to 65m long and up to 11.2m high and includes a screen that covers the gap between the new building and the RA Vance Stand. This option is preferred by the Basin Reserve Trust. Alternative mitigation proposals entailing a 45m long structure and a 55m long structure and consequent increases in proposed tree planting have also been considered and are assessed within this report.

• Zone 3 Kent/Ellice Integrated building zone – proposes a new building under the proposed bridge at the corner of Kent Terrace and Ellice Street which would be made available for commercial use. It is intended to re-establish the historical built / street edge in this location and the building helps incorporate the bridge into the built urban environment. A green screen is proposed to be located above the new building to provide a level of screening for the adjacent apartment building and assist to visually integrate the bridge with the buildings at this corner.

• Zone 4 Paterson/ Ellice/Dufferin Interface zone – proposes to continue ground landscape linking from across Kent/Cambridge Terraces and additional tree planting around the Basin Reserve’s outer square.

The Project proposes works within St Joseph’s Church property using land that is currently used for car parking. Thus, the Project proposes to remove the existing building at 28 Ellice Street and to adjust the existing carpark and provide landscape improvements for the Church within the remaining space. All of these works are located on land owned by the Church.

• Zone 5 Dufferin/Rugby Streets, Schools/Church/Government House Interface zone which serves as a vehicular and pedestrian access area serving key adjacent land uses of the schools and Government House. Proposed works include the re-allocation of space in the roading corridor, layout modification and urban design and landscape treatments.

• Zone 6 The Bridge Element – the horizontal alignment of the Bridge has retained a close reference to the historic street pattern (the Te Aro Grid) to strengthen and define the Basin square. The vertical alignment has utilised underlying landform to achieve grade separation between north-south and east west routes. The width of the bridge has been kept to a minimum that meets safe traffic design standards for a 50km/h road. Abutments are integrated and grounded in the form and material of the landscaping. Lighting on the bridge seeks to minimise glare and spill onto surrounding areas and integrates with the bridge form and with the adjacent NWM Park. Architectural lighting is provided underneath the bridge and across the landscape, highlighting forms, surfaces and textures of the superstructure, undercroft, piers, abutments and landscape. The combination of treatments and design promote the perception of the bridge being an elevated street rather than motorway flyover.



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The Project will result in a number of transport benefits for the State highway network and the local road network (including public transport and walking and cycling) as well as new buildings, structures and landscape treatments for the Basin Reserve area.

Construction of these transportation improvements is currently scheduled to start in 2014/15.

2.3 Related Projects

The Project forms part of the Tunnel to Tunnel package of works that in combination would improve traffic and transportation between the Terrace Tunnel and Mount Victoria Tunnel. The Tunnel to Tunnel package also comprises of:

• The Buckle Street Underpass as part of the National War Memorial Park project by the Ministry of Culture and Heritage. This project is currently under construction and expected to be completed by the end of 2014.

Other NZTA studies of SH1 sections that are also being considered or are being progressed concurrently within Wellington:

• Duplication of Mount Victoria Tunnel (construction planned for 2017/18).

• Duplication of the Terrace Tunnel (subject to feasibility investigation in 2013/14).

• Roading improvements along Cobham Drive and Ruahine Streets (construction planned for 2017/18).

While there are linkages between these projects, each one is complex and entails significant use of resource. As a consequence each is being progressed separately while maintaining the appropriate design standards and specifications in order to achieve the NZTAs strategic objectives for the RoNS.

2.4 Key considerations of the Project from a vibrat ions perspective

2.4.1 General background

With reference to Hunaidi (2000), vibration amplitudes and the predominant frequencies are influenced significantly by the soil type and stratification. The lower the stiffness and damping of the soil, the higher the vibration. For impact loads, ground vibrations are highest at the natural frequencies of the site. At these frequencies, the soil, like any structural system, offers the least resistance and therefore the greatest response to loads. For soils, the natural frequencies depend on stiffness and stratification.

Vibration amplitudes decrease with distance from the vibration source. The decay is faster in softer soils than stiffer soils. Also vibrations of a higher frequency decay faster than those of lower frequency. However, because of the complex nature of soil characteristics, attenuation relationships are site-specific.

Road traffic tends to produce vibrations with frequencies predominantly in the range from 5 to 25 Hz (oscillations per second). The amplitude of the vibrations ranges between 0.05 and 25 mm/s measured as velocity. The predominant frequencies and amplitude of the vibration depend on many factors including the condition of the road; vehicle weight, speed and suspension system; soil type and stratification; season of the year; distance from the road; and type of building The effects of these factors are interdependent and it is difficult to specify simple relationships between them. The effect of vehicle speed, for instance, depends on the roughness of the road. Generally,



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the rougher the road, the more speed affects the vibration amplitude. The effect of the suspension system type also depends on vehicle speed and road roughness. For low speed and smooth road conditions, the effect of the type of suspension system is not significant. However, for high speeds and rough roads, the type of suspension system becomes important.

2.4.2 Soil considerations

There are five main soil types that the Project will encounter (refer Volume 5, Sheet GE.2.01). These are:

1. Alluvium

2. Alluvium, Silt, Peat, Loess

3. Alternating Sandstone and Agrillite/Limestone

4. Marginal Marine Sediments

5. Reclamation Landfill.

The first three soil types are found in the vicinity of Mount Cook to the west of the Basin Reserve and Mount Victoria to the east of Basin Reserve and can be classified according to Dowding (2000) as competent soils (i.e. can dig with a shovel). The last two soil types are found in the vicinity of the Basin Reserve and Kent and Cambridge Terrace corridor and can be classified as weak or soft soils (i.e. a shovel penetrates easily). Therefore, with reference to Table 8.1, the Project areas having the greatest potential for large vibration amplitudes from construction activity and operational traffic are the Kent/Cambridge Basin Gateway (Area 3) and the Kent/Ellice Street Corner Zone (Area 4).

2.4.3 Operational traffic

The Project will have a 50 km/h posted speed and a structural asphalt pavement. Therefore, because of the slow speed and smooth road conditions, a deterioration of the existing traffic-induced vibration conditions can only occur if the Project brings traffic closer to neighbouring buildings. The key location in this regard is St Joseph’s Church, where the separation distance from the eastbound SH1 will be reduced to 4.18 m.

2.4.4 The bridge element

The bridge element has the potential to generate problematic vibrations. Firstly, during the construction of the bridge piers, as this will necessitate vibration inducing piling operations. Secondly from operational traffic if the transitions at the bridge abutments and expansion joints aren’t sufficiently smooth to limit impact wheel loading. This will have particular bearing on the preferred treatment of the space under the bridge between Kent Terrace and Hania Street, which is a building integrated with the bridge, as vibration levels within this building will have to be at an acceptable level for occupants.

2.4.5 The Crèche

Given the intrinsic value of this listed building, it is important to establish if ameliorating measures are required to limit the magnitude of vibrations arising from the construction and operation of the Project in the vicinity of the Crèche to a level that at most causes only cosmetic damage. Ameliorating measures available range from relocating the Crèche a greater distance from



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construction activity and traffic through to careful management of construction activities and traffic speed and road condition once the Project is operational.

2.4.6 New building within the Basin Reserve

The foundation of the new building proposed for the Basin Reserve, hereafter referred to as the Northern Gateway Building, will require a specific geotechnical solution, which is yet to be determined. This solution may involve piling to support the foundation slab. Given its close proximity to nearby structures and buildings, the RA Vance Stand in particular, there is a need to ensure ground vibration resulting from the construction of the foundation will not disturb the surrounding soil to a degree that may cause structural damage to nearby buildings. Ameliorating measures available include use of piling techniques that generate little vibration such as steel screwed-in piles.

2.4.7 Underground services

There is a concentration of underground services in the project area, which includes gas mains, water pipes, sewer lines and stormwater lines. Construction activities, such as pile driving and dynamic compaction, and traffic generate vibrations that are transmitted through the ground in the form of stress waves. When these waves encounter an underground structure such as a pipeline, part of the wave is reflected and part of it is transmitted into the structure. The cyclic nature of these vibrations will induce changes in the stress levels in the pipes. This in turn may lead to fatigue related damage, such as crack propagation. There is also the potential for failure from distortion due to the vibrations causing settlement of the ground surrounding the service pipes. Therefore, it is an important consideration that the level of surface vibrations generated by the Project during construction and once operational will be insufficient to cause damage to underground services.

2.4.8 Concluding remark

The above considerations guided where the monitoring of existing traffic induced vibrations and sandbag drop tests to generate impact related predictor curves detailed in this report were performed.



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3 Methodology

3.1 Test methods

With impact related ground vibrations, such as induced by traffic, radial motion dominates close-in and gives way to a vertical dominance at greater distance. To accurately define this motion, three orthogonal components should therefore be measured (transverse, longitudinal (radial) and vertical). Accordingly, all vibration measurements were made using high-sensitivity Colibrys Si-flex SF3000L tri-axial accelerometers and IOtech LogBook/360 data acquisition systems. This enabled acceleration-time histories to be obtained in the three orthogonal components i.e.

• vertical accelerations (in the z axis direction)

• horizontal accelerations in the x-y plane.

Recommended signal processing practices of oversampling, downsampling to a desired frequency of at least the Nyquist rate2 and digital filtering were employed to improve resolution, reduce signal noise and avoid aliasing3 (Schilling and Harris, 2011). Specifically, all recordings were made at a sampling frequency of 6 kHz, decimated to 300 Hz, and then bandpass filtered with Butterworth filters between 0.67 Hz and 100 Hz. As a result, output from the accelerometers were processed to include only vibration components over the frequency range 0.67 Hz to 100 Hz to allow application of international standards related to the assessment of ground borne vibration effects detailed in Section 4 of this report.

The measurements of vibration followed international best practice by conforming to ISO 8041:2005, Human response to vibration - Measuring instrumentation, and ISO 4866:2010, Mechanical vibration and shock – Vibration of fixed structures – Guidelines for the measurement of vibrations and evaluation of their effects on structures.

As such, the accelerometers used were calibrated against gravity at the start and end of the monitoring period to ensure output from each channel was consistent with the calibration data supplied by the manufacturer, which has been reproduced in Appendix 8.D. Also, particular care was taken in how the accelerometers were mounted to ensure the mounting was firm to prevent slippage. For hard surfaces, such as footpaths and driveways, the triaxial accelerometers were attached by means of a thin layer of plasticine. Where the triaxial accelerometers were mounted on ground, a 2mm thick steel plate with a 90mm long spike attached to its underside was used to provide a rigid coupling. The spike was pressed into the ground until the plate lay flat on the ground surface and the accelerometer fixed to the plate by means of industrial grade magnetic tape.

3.1.1 Measurements of traffic-induced vibrations

The traffic-induced vibration measurements were recorded for 15 minutes. The 15-minute data file was then separated into multiple data files of 10-second duration. For each 10-second data file, the resultant (vector sum) particle velocities were determined for each accelerometer. The largest peak particle velocities (in mm/s), within each 10-second data file, were then isolated for each accelerometer. The five largest peak particle velocities that can be attributed to traffic-induced vibrations for each site are listed in Table 8.8, in Section 5.1.

2 Nyquist rate is the lowest sampling rate that will permit accurate reconstruction of a sampled analog signal. 3 Aliasing is an effect that causes different signals to become indistinguishable from each other during sampling and is caused in analog to digital conversion by a too low rate of data sampling.



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When considering baseline traffic vibration levels, we are interested in determining the range of vibration levels presently being experienced by occupants of affected residences. Therefore, the 15 minute recording covered not only just traffic on SH1 but when there was also traffic movement on adjacent local roads.

For all the main soil types encountered by the project, measurements of traffic induced ground vibrations were able to be made at various distances from the source using the four accelerometer array. This allowed an assessment of traffic induced vibrations resulting from the Project to be inferred directly from measured rather than indirectly from predicted vibration levels derived from vibrations measured at a known distance from the kerb in combination with an attenuation model.

Both BS 5228-2:2009 and DIN 4150-3:1999 provide guidelines based on Peak Particle Velocity (PPV), which accounts only for vibration magnitude and not the exposure duration. As the magnitude of traffic induced vibrations are directly a function of vehicle weight and speed (Hunaidi, 2000), a 15 minute measuring time interval was considered to be sufficient to obtain an estimate of the likely upper limit vibration levels provided it coincided with free flow traffic conditions (i.e. when speeds were at a maximum) and significant heavy commercial vehicle activity.

For this project, all measurements of traffic induced vibrations were made between 10:00am and 3:30pm, therefore avoiding the morning and afternoon peak time congestions but coinciding with pick-up and delivery operations of commercial businesses.

With reference to Figure 8.4: and Table 8.8, it was possible to record at each location at least 5 high vibration events caused by the drive-by of heavy commercial vehicles. This is a sufficient number to have confidence that a representative maximum has been captured.

3.1.2 Sandbag drop tests

The sandbag drop test has traditionally been used to investigate dynamic characteristics of floor systems, because of its better repeatability when compared to heel drop tests (Xu, 2005). It involves dropping a bag of sand of known weight from a specified height so that the amount of energy transferred to the floor can be calculated.

The use of energy based methods to identify vibration sensitive work zones has been reported by Jackson et al. (2008). Despite being site specific, this approach doesn’t require detailed knowledge of the site geology and therefore soil attenuation characteristics are automatically accounted for.

The main intent of the sandbag drop tests was to derive predictor curves for each soil type found in area of the Project so that reliable estimates of ground vibrations from impact related construction activity (such as pile driving and dynamic compaction) could be made rather than for estimating the effects of traffic.

The vibration attenuation measurements were induced by dropping a 25 kg sandbag from a height of 1 m at a location in-line with the accelerometer array and at a specified distance from the end of the array. The resultant (vector sum) peak particle velocities were then determined for each accelerometer for each sandbag drop.

Care was taken to ensure that:

• there was no traffic present when a sandbag drop test was being performed as this would have invalidated the recorded decay time histories;

• all accelerometers making up the array were placed on the same surface type; and

• the sandbag was dropped on the same surface as the accelerometer array was located on.



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The dropping of a sandbag was preferred to traffic for inducing ground vibrations used to determine soil attenuation because the very short duration of the drop test made it much easier to control for any traffic movements in the vicinity of the test site.

Rather than using a steel plate to replicate the falling weight deflectometer device used by Jackson et al. (2008), a sandbag was utilised for the drop tests as it better represented the area source characteristics of a roller compactor and also it minimised the likelihood of the drop weight bouncing on impact and causing damage to footpaths and roads.

Furthermore, comparative testing involving drop tests using both a 25 kg sandbag and 25 kg metal rail performed at Opus Central Laboratories prior to the field measurements being carried out showed that the sandbag provided more reliable estimates of the power rate of attenuation.

Appendix 8C provides a summary of the results of the comparative drop tests performed by Opus to identify differences between using a sandbag and a steel plate as the drop-weight.

3.2 Test sites

Table 8.1 lists the test sites and the type of testing carried out.

Table 8.1: Test sites and test types

Site Location Date Test types Number of accelerometers

S1a Corner of Ellice St and Kent Tce 26 April 2012 Traffic and Attenuation 4

S1b Same as S1a (repeat measurement) 30 April 2012 Traffic and Attenuation 4

S2 Ellice St 26 April 2012 Attenuation 4

S3 Paterson St, northern side 30 April 2012 Traffic and Attenuation 4

S4 Paterson St, southern side 30 April 2012 Traffic 1

S5 Buckle St crèche 30 April 2012 Traffic 1

S6 Tory St 30 April 2012 Traffic and Attenuation 4

S7 Interislander Ferry terminal car park 30 April 2012 Traffic 1

With reference to Table 8.1, measurements were made at site S7 adjacent to a bridge pier of the Wellington Urban Motorway’s 1335m long Thorndon overbridge to determine the likely magnitude of traffic-induced vibrations at the foundation of the commercial building to be built at the corner of Kent Terrace and Ellice Street under the proposed bridge structure. Because of the close proximity of the vibration measurements to the source, the effect of any differences in soil characteristics between Thorndon and Basin Reserve will be insignificant. Therefore, so long as concrete bridge piers are utilised, the vibration levels measured at location S7 can be considered to be representative.

Aerial photographs showing the approximate locations of the accelerometers at each test site are included in Appendix 8A.

As previously mentioned in section 2.5, the locations of the accelerometer measurements were selected to cover the Project areas having the greatest potential for large vibration amplitudes from construction activity and operational traffic and also special interest areas, such as the Crèche (site S5).



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4 Assessment criteria

The only vibration related policies or rules contained in The Wellington City District Plan relate to controlled activities in residential and rural areas4. Furthermore, where vibration related criteria have been incorporated in district plans, these relate to either blasting activity or human comfort. In the case of human comfort, district plan criteria have been taken from the withdrawn New Zealand standard, NZS/ISO 2631 (1989): “Evaluation of Human Exposure to Whole Body Vibration, Part 2: Continuous and Shock Induced Vibration in Buildings (1 to 80 Hz).” This standard considered continuous, intermittent and transient vibrations as well as time of day. It also specified that vibrations from traffic passing by should be treated as intermittent vibration in terms of the standard.

In assessing the effects of vibration caused by the Project from the perspectives of human comfort and damage to buildings and underground services, vibration guidelines contained in current international standards were, therefore, used. These guidelines are discussed below.

4.1 Human comfort

The British Standard, BS 5228.2, 2009, “Code of practice for noise and vibration control on construction and open sites – Part 2: Vibration,” is a current standard that is commonly adopted in New Zealand to provide guidance on the response of humans to vibration levels. This is reproduced below as Table 8.2 for ready reference.

Table 8.2: Guidance on effects of vibration levels (from British Standard BS 5228-2:2009, Annex B) Vibration level Effect

0.14 mm/s Vibration might be just perceptible in the most sensitive situation for most vibration frequencies associated with construction. At lower frequencies, people are less sensitive to vibration.

0.3 mm/s Vibration might be just perceptible in residential environments.

1.0 mm/s It is likely that vibration of this level in residential environments will cause complaint, but can be tolerated if prior warning and explanation has been given to residents.

10 mm/s Vibration is likely to be intolerable for any more than a very brief exposure to this level.

The vibration levels in Table 8.2 are in terms of peak particle velocity (PPV), which is the vibration parameter routinely measured when assessing potential building damage.

Although BS 5228-2:2009 is concerned with construction related vibrations, it is valid to apply the guidance on effects of vibration levels given in this standard to traffic vibrations. This is because most vibration frequencies associated with construction and traffic are greater than 8 Hz eliminating any frequency dependency effects. As a result, there is complete agreement between NZS/ISO 2631 (1989) and BS 5228-2:2009 for vibration levels that are just perceptible in the most sensitive of situations (0.14 mm/s PPV) and just perceptible in residential environments (0.3 mm/s PPV).

4 Wellington City District Plan, Volume 1:Objectives, Policies & Rules

• Chapter 5, Residential Rules, clauses 5.2.2.1; 5.2.2.6; 5.4.1.2 • Chapter 6, Suburban Centres, clauses 6.2.2.1; 6.2.3.3A • Chapter 8, Institutional Precincts, clause 8.2.2.1 • Chapter 12, Central Area, clause 12.2.2.2 • Chapter 15, Rural Area, clause 15.4.1.2 • Chapter 24, Designations, Appendix V:Transmission Gully Motorway Designation, clause 7.10



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4.2 Building damage

The German Standard DIN 4150-3 (1999) “Structural vibration – Part 3: Effects of vibration on structures” provides guideline vibration levels which, “when complied with, will not result in damage that will have an adverse effect on the structure’s serviceability.” For residential buildings, the standard considers serviceability to have been reduced if:

• Cracks form in plastered surfaces of walls.

• Existing cracks in the building become enlarged.

• Partitions become detached from load bearing walls or floors.

These effects are deemed ‘minor damage’ in DIN 4150-3.

The DIN 4150-3 (1999) guideline values for evaluating short-term and long-term vibration on structures are given in Table 8.3 and Table 8.4, respectively, where short-term vibrations are defined as those that do not occur often enough to cause structural fatigue and do not produce resonance5 in the structure being evaluated and long-term vibrations are all the other types of vibration.

Table 8.3: Guideline values for vibration velocity to be used when evaluating the effects of short-term vibration on structures (from German Sta ndard DIN 4150-3 1999)

Line Type of structure

Guidelines values for velocity in mm/s

Vibration at the foundation at a frequency of Vibration at horizontal plane of highest floor at all frequencies

1 Hz to 10 Hz 10 Hz to

50 Hz 50 Hz to 100 Hz*

1

Buildings used for commercial purposes, industrial buildings, and buildings of similar design

20 20 to 40 40 to 50 40

2 Dwellings and buildings of similar design and/or occupancy

5 5 to 15 15 to 20 15

3

Structures that, because of their particular sensitivity to vibration, cannot be classified under lines 1 and 2 and are of great intrinsic value (e.g. listed buildings under preservation order)

3 3 to 8 8 to 10 8

* At frequencies above 100 Hz, the values given in this column may be used

5 Resonance is the condition occurring when a vibrating system is subjected to a periodic force that has the same frequency as the natural vibrational frequency of the system. At resonance, the amplitude of vibration is a maximum.



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Table 8.4: Guideline values for vibration velocity to be used when evaluating the effects of long-term vibrations on structures (from German Sta ndard DIN 4150-3 1999)

Line Type of structure Guideline values for velocity in mm/s of vibration in horizontal plane of highest floor, at all frequencies

1 Buildings used for commercial purposes, industrial buildings, and buildings of similar design

10

2 Dwellings and buildings of similar design and/or occupancy

5

3

Structures that, because of their particular sensitivity to vibration, cannot be classified under lines 1 and 2 and are of great intrinsic value (e.g. listed buildings under preservation order)

2.5

With reference to Tables 8.3 and 8.4, the German Standard DIN 4150-3 (1999) recognises commercial buildings can withstand higher vibration levels than residential and historic buildings. Also, the guideline values for short-term vibration increase as the vibration frequency increases.

4.3 Underground services

Discussions held with the utility providers during the design development of the Project did not identify vibrations of their underground services being of particular concern. Therefore, in the absence of the utility providers supplying specific criteria governing the maximum level of vibrations to which their underground services should be subjected to, guideline values for groundborne vibrations that could cause damage to underground services given in British Standard BS 5228-2:2009 and German Standard DIN 4150-3 (1999) were considered. These values are reproduced below in Table 8.5 and Table 8.6.

The limits recommended in Table 8.5 should be applied at the nearest point to the source or activity. In the event of encountering old and /or dilapidated underground pipes, culverts and sewers, BS 5228.2:2009 specifies that the guideline values in Table 8.5 should be reduced by between 20% and 50%. For this project, a reduction factor of 50% has been adopted to err on the conservative side when assessing vibration effects on old underground pipework.

Table 8.5: Guideline values for evaluating the effe cts of construction-related vibration on buried services (from British Standard BS 5228-2:20 09)

Vibration Classification Guideline values for maximum velocity measured on the pipe, in mm/s PPV

Continuous 15

Intermittent or Transient 30

Guideline values given in German Standard DIN 4150-3 (1999) for evaluating the effects of short-term vibration on buried pipework and tabulated in Table 8.6 assume that the pipes have been manufactured and laid using current technology. The standard also specifies that drain pipes should be evaluated using the values in line 3 of Table 8.6.

When evaluating the effects of long-term vibration, such as vibrations generated by passing traffic, German Standard DIN 4150-3 (1999) specifies that the guideline values given in Table 8.6 may be reduced by 50%.



May 2013 8-18

Table 8.6: Guideline values for vibration velocity to be used when evaluating the effects of short-term vibration on buried pipework (from Germa n Standard DIN 4150-3:1999)

Line Pipe Material Guideline values for velocity measured on the pipe, in mm/s PPV

1 Steel (including welded pipes) 100

2 Clay, concrete, reinforced concrete, pre-stressed concrete, metal (with or without flange)

80

3 Masonry, plastic 50

Both standards fail to state the basis on which the guideline values were obtained, or the frequencies at which these limits apply with regard to underground structures. However, recent work by Thusyanthan et al (2006), has found that different pipe materials absorb different amounts of energy in agreement with German Standard DIN 4150-3:1999.

With reference to Table 8.5 and Table 8.6, it will be noted that the guideline values specified in BS 5528-2:2009 for evaluating the effects of vibration on underground services are more stringent than those specified in German Standard DIN 4150-3:1999 and so have been employed in this assessment.

4.4 Vibration levels generated by everyday activiti es

To help provide context for the guideline vibration levels tabulated in Table 8.3 to Table 8.6, Table 8.7 lists typical vibration levels generated by everyday activities.

Table 8.7: Common ground vibration levels Vibration level (mm/s PPV) Description of Activity

1 – 2.51 Walking measured on a wooden floor

5 – 501 Foot stamp, measured on a wooden floor

1 Table 3.2 of “Environmental Management Guidelines in the Extractive Industry (Non-Scheduled Minerals)”, EPA, 2006



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5 Measured vibrations

The recorded data was processed to give the resultant (vector sum) peak particle velocities (in mm/s) for each triaxial accelerometer. This was done because no one component was consistently dominant.

The guideline threshold values given in the standards used to assess the measured vibration levels from the perspectives of human comfort and building damage (BS 5228-2:2009 and DIN 4150-3:1999), are generally based on the peak component (i.e. the worst case of the three axes monitored). Therefore, by applying peak true vector sum PPV’s to the guideline threshold values is not in accordance with the standards but results in the assessment of vibration effects being on the conservative side.

Measured peak true vector sum values hereafter are referred to as peak particle velocities for simplicity and to avoid possible confusion when applying the vibration criteria given in section 4.

5.1 Peak particle velocities due to traffic-induced vibrations

The peak particle velocities for the five 10-second recording periods containing the largest traffic-vibration events for each site are included in Table 8.8.

It should be noted that the largest peak vector sum values tabulated in Table 8.8 represent rare occurrences. As an example, Figure 8.4 shows a histogram of the peak particle velocities for all 10-second data files measured at Site S4 on the southern side of Paterson St.

Figure 8. 4: Histogram of peak particle velocities (mm/s), due t o traffic -induced vibrations , within each 10-second period at testing Site S4 on the southern side of Paterson Street



May 2013 8-20

Table 8.8: Measured peak particle velocities (mm/s) due to traffic-induced vibrations

Site Location Event Peak particle velocity (mm/s) Distance from road edge (m)

A1 A2 A3 A4 A1 A2 A3 A4

S1a Corner of Ellice St and Kent Tce

1 0.36 0.40 0.38 0.52 18 13 8 3

2 0.23 0.34 0.24 0.44 18 13 8 3

3 0.17 0.22 0.24 0.41 18 13 8 3

4 0.17 0.17 0.22 0.39 18 13 8 3

5 0.28 0.23 0.35 0.36 18 13 8 3

S1b Same as S1a (repeat measurement)

1 0.22 0.33 0.50 0.67 18 13 8 3

2 0.25 0.35 0.49 0.52 18 13 8 3

3 0.21 0.20 0.34 0.51 18 13 8 3

4 0.24 0.25 0.35 0.49 18 13 8 3

5 0.24 0.24 0.38 0.36 18 13 8 3

S3 Paterson St, northern side

1 0.16 0.17 0.15 0.24 20 15 10 5

2 0.15 0.17 0.21 0.23 20 15 10 5

3 0.15 0.12 0.16 0.23 20 15 10 5

4 0.18 0.20 0.16 0.23 20 15 10 5

5 0.17 0.16 0.15 0.22 20 15 10 5

S4 Paterson St, southern side

1 0.94 2

2 0.61 2

3 0.53 2

4 0.52 2

5 0.39 2

S5 Buckle St crèche

1 0.82 4.5

2 0.50 4.5

3 0.45 4.5

4 0.42 4.5

5 0.29 4.5

S6 Tory St 1 0.52 0.48 0.50 0.57 20 15 10 5

2 0.49 0.49 0.44 0.51 20 15 10 5

3 0.32 0.31 0.31 0.32 20 15 10 5

4 0.35 0.26 0.27 0.31 20 15 10 5

5 0.30 0.30 0.32 0.31 20 15 10 5

S7 Interislander Ferry terminal car park

1 0.74 N/A

2 0.66 N/A

3 0.59 N/A

4 0.45 N/A

5 0.41 N/A

Note: Columns A1, A2, A3, and A4 represent accelerometers 1, 2, 3, and 4 respectively. The accelerometer at site S7 was placed adjacent to a load bearing pier beneath the north-bound lane of the Wellington Urban Motorway (SH1) Thorndon overbridge.

With reference to Table 8.8, the largest peak particle velocities and their corresponding distances from the road edge for site S1a are 0.52 mm/s at 3 m, 0.38 mm/s at 8 m, 0.40 mm/s at 13 m, and 0.36 mm/s at 18 m. According to the guidelines provided by British Standard BS 5228-2:2009 for



May 2013 8-21

human comfort, all of these values fall above the threshold for perception (0.3 mm/s) but below the threshold that will likely cause complaint (1.0 mm/s) within a residential environment. The same was also true for all of the other locations tested.

The largest recorded peak particle velocity (0.94 mm/s) that was attributable to traffic-induced vibration occurred at Site S4 on the southern side of Paterson St.

According to the guidelines provided by German Standard DIN 4150-3 1999, none of the peak particle velocities that were attributable to traffic-induced vibration approached even the lowest magnitude that could cause damage to a structure (2.5 mm/s).

Figure 8.5 shows the percentage of people with four levels of annoyance due to traffic induced vibrations in dwellings, plotted against calculated statistical maximum values for weighted velocity as provided by the Norwegian Standard NS 8176.E:2005.

Figure 8.5: Annoyance due to vibrations in dwellings plotted against calc ulated statistical maximum values for weighted velocity, vw,95 (NS 8176.E:2005)

The value vw,95 is a statistical maximum calculated from the mean and standard deviation of the frequency weighted root-mean-square (r.m.s.) vibration velocities. The frequency weightings for r.m.s. velocities in the frequency range 10 Hz to 60 Hz is approximately 1. Outside of this range the frequency weightings reduce the effective magnitude of the peak particle velocities. For this investigation, the statistical maximum values for weighted velocities have not been calculated as the highest spectral content fell well within the 10 Hz to 60 Hz range.

The peak particle velocities listed in Table 8.8 are the sum of all vibrations within the range 1 Hz to 80 Hz. In order to apply them to Figure 8.5, they must be converted from peak to r.m.s values by dividing by √2. Furthermore, since they have not been weighted according to NS 8176.E:2005, applying them to Figure 8.5 to obtain the percentage of building occupants who may be annoyed by the vibration level, will result in a conservative estimate (i.e. higher percentage).



May 2013 8-22

Considering the highest recorded traffic-induced ground vibration level 0.94 mm/s PPV that occurred once on the south side of Paterson Street (site S4), this corresponds to a vw,95 value of about 0.7 mm/s. With reference to Figure 8.5, about 11% of people are likely to be highly annoyed by this level of vibration, whereas about 60% of people will perceive it.

5.2 Vibration magnitude attenuation

The site specific attenuation has been analysed in two individual ways. The analysis in Section 5.2.1 below determines the site specific attenuation coefficient, whereas the analysis in Section 5.2.2 determines the power rate of attenuation based on the potential energy of the vibration-inducing impact.

5.2.1 Site specific attenuation coefficient

Equation 8.1 (Dowding, 2000) provides a simplified means for estimating the site specific attenuation coefficient from two simultaneous peak particle velocity measurements and their corresponding distances from the source of vibration.

� � ��

��

��

Equation 8.1

where:

α is the site specific attenuation coefficient,

V1 is the peak particle velocity (mm/s) at distance R1 from the vibration source (m),

V2 is the peak particle velocity (mm/s) at distance R2 from the vibration source (m),

γ is the geometric attenuation coefficient (this is assumed to be 0.5 for Rayleigh waves, which provides the most conservative attenuation coefficient).

For each test site, individual attenuation coefficients were calculated using every combination of accelerometer pairs for each sandbag drop. The mean of all of the calculated attenuation coefficients was then determined to provide the best estimate of the true site specific attenuation coefficient. Table 8.9 shows the mean site specific attenuation coefficient for each of the test sites and also when normalised for a frequency of 5 Hz to allow comparison with expected values for the various soil classifications.

With reference to Table 8.9, the dominant soil frequency values range from 28 Hz to 56 Hz, with soils displaying low attenuation tending to have higher values of dominant frequency.

Table 8.9: Estimated site specific attenuation coef ficients

Site Location Attenuation Coefficient,

α (m-1)

Dominant Frequency (Hz)

Attenuation Coefficient

at 5 Hz

S1a Corner of Ellice St and Kent Tce 0.069 28 0.012

S1b Same as S1a (repeat measurement) 0.091 31 0.015

S2 Ellice St 0.071 38 0.009

S3 Paterson St, northern side 0.065 41 0.008

S6 Tory St 0.049 56 0.004



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It should be noted that the second measurement at Site 1 (S1b) was carried out after a period of rain that lasted multiple days. Due to the fact that the measurements at this site were made on soil, the value for α determined during the first test (S1a) should be used as it is more conservative.

It should also be noted that the attenuation measurements were only made on the northern side of Paterson Street for logistical reasons (i.e. there was no suitable location on the southern side to mount the 20 m long array of accelerometers at right angles to the direction of traffic). However, they are representative because the soil characteristics in this area are fairly consistent (refer the geology map, sheet GE.2.01, in Volume 5).

With reference to Cenek et al (2012), 5 Hz attenuation coefficient values range between 0.01 and 0.03 for weak or soft soils and between 0.003 and 0.01 for competent soils. Therefore, test site S1 is on a weak or soft soil and test sites S2, S3 and S6 are on competent soils. This is in agreement with the Project’s geology map (refer Volume 5, sheet GE.2.01, version R0 of NZTA 380PN drawing issue for specialist assessment, 2 July 2012).

Equation 8.1 can be rearranged to give Equation 8.2. The attenuation coefficients can then be inserted to calculate the estimated peak particle velocity at a specified distance from the vibration source (V2 and R2 respectively) given a known peak particle velocity at a known distance from the vibration source (V1 and R1 respectively).

��

��.�

�� Equation 8.2

5.2.2 Power rate of attenuation

The estimated peak particle velocity (PPV) relative to the distance from the vibration source and the energy of the impact causing the vibration is given by:

�� !"#. $. %�& � � !

√'�& Equation 8.3

where:

A is coefficient related to the nature of the impact,

d is the radial distance from the vibration source in metres,

m is the mass of the impacting body in kg (25 kg for the sandbag),

g is the gravitational constant (taken to be 9.81 m/s2),

h is the height that the impacting body is dropped from in metres (1 m for the sandbag),

E is the energy of the impact in joules,

n is the power rate of attenuation.

When plotting square-root attenuation relationships It is usual to omit the gravitational constant g in Equation 8.3 when square-root scaling the radial distance d. Therefore, the resulting independent variable PPV is plotted against has units m/(kg.m)0.5 and is referred to as scaled distance. This practice has been followed in this report and so the values A and n determined at each test site and tabulated in Table 8.10 pertain to scaled distance in units of m/(kg.m)0.5.

The plots used to derive the values for A and n for each testing site are included in Appendix 8B.

When using data in Table 8.10 to predict vibrations from impact related construction activities, care should be exercised as, with reference to Appendix 8C, the resulting levels are likely to be realistic but may not represent the upper bound.



May 2013 8-24

Table 8.10: Measured vibration magnitude attenuatio n parameters due to vibrations caused by sandbag drops

Site Location A n

S1a Corner of Ellice St and Kent Tce 0.50 -1.07

S1b Same as S1a but wet ground 0.55 -1.45

S2 Ellice St 0.17 -1.31

S3 Paterson St, northern side 0.26 -1.11

S6 Tory St 0.19 -1.05



May 2013 8-25

6 Discussion of results

6.1 Baseline conditions

Existing traffic-induced vibration levels in the vicinity of the Basin Reserve fall between the threshold for perception (0.3 mm/s PPV) and the threshold that will likely cause complaint (1 mm/s PPV) within a residential environment. Furthermore, the largest magnitude ground-borne vibrations are associated with a rare event i.e. an isolated heavy commercial vehicle striking an irregularity in the road surface due either to its axle configuration or load or speed of travel or a combination of all three. As expected, the largest magnitude vibrations were recorded where heavy commercial vehicles can travel at the legal speed limit (50 km/h) in close proximity to buildings e.g. Paterson Street near St Mark’s School and Buckle Street in the vicinity of the Crèche. Bus traffic in particular, was shown to generate large magnitude ground vibrations in proximity of the Crèche.

None of the vibrations attributable to passing traffic approached even the lowest level that could cause damage to a structure (i.e. 2.5 mm/s PPV).

These baseline conditions are unlikely to change as a result of the Buckle St tunnel being built as part of the Memorial Park project because the factors affecting vibration levels, i.e. road surface condition, speed limit and proximity of buildings to the road will not change in the vicinity of the Basin Reserve.

6.2 Construction-related issues

The attenuation measurements confirmed that there were weak or soft soils in the area of Kent and Cambridge Terraces and competent soils in the area of Paterson, Buckle and Tory Streets.

If we compare weak soils with competent soils, we would expect the weaker soil to have a greater displacement for the same amount of energy inputted into the soil. However, weak soils display greater attenuation than stiffer soils Dowding (2000). Therefore, even though vibrations attenuate quicker in weaker soils, the amplitude of the source vibration will be considerably greater than for a competent soil and so a longer separation distance may be required to satisfy a specified vibration threshold. Or in other words, greater impact loads can be accommodated by the competent soils than the weak or soft soils.

For example, on the basis of the sandbag drop measurements, the energy required to generate a ground vibration of 1 mm/s PPV at 10 m from the source is calculated to be 365 Joules for weak soil but 1133 Joules for competent soil.

For the Project, piling operations will cause some degree of ground vibration and so will require particular consideration. The preliminary geotechnical appraisal report (refer Volume 3, Technical Report 1: Design philosophy statement) has identified that bored and cased piles will be required to support the bridges and form the foundation for the building under the bridge and the Basin Reserve northern gateway building.

Bored piles are cast-in-place cylindrical concrete piles excavated using purpose designed drill tools including rotary equipment operated soil and rock augers, drilling buckets, core barrels and down hole hammer drills. Both the diameter of the pile and the depth of the pile are highly specific to the ground conditions, loading conditions and the nature of the project. The bored piles are installed through an overburden of soil strata down to firmer ground to achieve the design capacity by skin friction, base bearing or both.



May 2013 8-26

For the Project, the bored piles will require the use of a steel casing to provide support to the soil surrounding the borehole in order to prevent cave-in of the excavation and destabilising the surrounding soil formation. The steel casing is typically driven using a vibratory hammer or hydraulic casing oscillator to minimise noise and vibrations. On reaching the design depth, a reinforcing cage is introduced and concrete is poured in the borehole and brought up to the required level.

For the purposes of estimating the lower and upper bound vibration levels expected from bored piling operations, vibration levels measured by Opus personnel during piling operations in the Wellington region in similar soil conditions to that of the Project were utilised.

To estimate the lower-bound level, corresponding to a bored pile with oscillated steel casing, vibration measurements of hard piling operations undertaken along the Waiwhetu Stream in 2009 were used as in this case the steel casing was already in place to secure the borehole. These measurements covered the three stages of the piling operation: drilling; drill extraction; and drill relocation (McIver and Cenek, 2009). The maximum vibration level measured at a distance of 5 m from source was 4 mm/s PPV and the dominant frequency was around 70 Hz.

To estimate the upper-bound level, corresponding to a bored pile with vibrated steel casing, measurements of a steel pile casing being driven during the construction of the Dowse Interchange has been used (Sutherland and Cenek, 2007). In this case, a vibration level of 5 mm/s PPV with a dominant frequency of about 18 Hz was measured at a distance of 14.5 m from the source.

For the Project’s bridge element, it is critical that vibrations generated during the construction of the piers can be kept at levels that will not cause damage to the buildings that are closest to the piers. These buildings are tabulated in Table 8.11, along with the estimated distance to the closest pier and the estimated lower and upper-bound vibration level from the piling operation. Piers for the pedestrian/cycle ramp in the vicinity of Ellice Street have also been included. The distances have been scaled from drawings contained in Volume 4 and should be treated as indicative only as the bridge pier layout plan has yet to be confirmed.

With reference to the lower-bound vibration levels tabulated in Table 8.11, the largest vibration level is predicted to be 3.4 mm/s PPV and will occur at 15 Ellice Street (i.e. Regional Wines and Spirits) during piling operations associated with the construction of the pedestrian/cycle ramp. This level of vibration is significantly less than the German Standard DIN 4150-3:1999 threshold of 10 mm/s PPV for cosmetic damage to commercial buildings and is comparable to vibrations generated by walking on a lively wooden floor (EPA, 2006). Therefore, it is unlikely that this level of vibration will have an adverse effect on the operation of this business.

For the remaining buildings and structures of interest that are close to the Project’s bore piling activity, vibration levels are calculated to not exceed 1.1 mm/s PPV. The estimated vibration levels tabulated in Table 8.11 indicate that vibrations will reach perceptible levels at the RA Vance Stand and at residential and commercial buildings in the vicinity of the eastern abutment of the bridge and may cause annoyance to residents of the Grandstand Apartments (80-82 Kent Terrace) and 21 Ellice Street. However, there is no risk of structural or cosmetic damage.

Considering the upper-bound vibration levels tabulated in Table 8.11, the complaint threshold of 1 mm/s PPV will be exceeded at the Grandstand Apartments (80-82 Kent Terrace), Regional Wine and Spirits (15 Ellice Street) and 21 Ellice Street. In fact, complaints can be expected from occupants of buildings that are within 34 m of the piling activity if vibrated steel casings are employed for the bored piles. There is also a risk of structural or cosmetic damage. Specifically, the vibration level of 10 mm/s PPV, estimated at 15 Ellice Street is at the German Standard DIN 4150-3:1999 damage threshold for long-term vibration of commercial buildings whereas estimated



May 2013 8-27

vibration levels at all the other buildings and structures considered are below the 5 mm/s PPV DIN 4150-3:1999 damage threshold for long-term vibration of residential buildings.

Table 8.11: Estimated vibration levels at propertie s most effected by bore piling operations Location

Relative to Bridge

Abutments

Property Distance to Closest Pier (m)

Estimated Vibration Level (mm/s PPV)

Lower-bound Upper-bound

Western Abutment

The Crèche 50 0.1 0.3

Relocated CS Dempster Gate, Basin Reserve

192 <0.1 <0.1

RA Vance Stand, Basin Reserve

22 0.7 2.6

Grandstand Apartments (80-82 Kent Terrace)

16 1.1 4.5

Eastern Abutment St Joseph’s Church 54 <0.1 0.2

9 Dufferin Street 54 <0.1 0.2

Regional Wines & Spirits (15 Ellice Street) (i) Main bridge (ii) Pedestrian/Cycle Ramp

24 8.5

0.6 2.4

2.2 10.0

21 Ellice Street: (i) Main bridge (ii) Pedestrian/Cycle Ramp

28 18

0.4 1

1.6 3.7

Taken overall, this analysis highlights the need to carefully manage any piling activity associated with piers for the pedestrian/cycle ramp due to the close proximity of 15 and 21 Ellice Street and piers 2, 3 and 4 of the SH1 bridge due to their closeness to the Grandstand Apartments. This will require the selection of appropriate piling equipment and monitoring of the resultant vibrations as detailed in the Construction Noise and Vibration Management Plan (CNVMP) contained in Volume 4. It is also obvious from the above analysis that non-impact related piling operations such as steel screw-in piling6 and bored piling using oscillators are preferable to impact related piling operations such as drop mass impact hammer and vibratory hammer piling when piling is to take place in close proximity to buildings as the magnitude of the resulting vibrations will be considerably less.

Regarding typical road construction activity, such as breaking road surfaces, levelling ground and earth removal etc., vibratory compaction is likely to be the main source of construction vibration with the potential for adverse effects. With reference to BS 5228-2:2009, vibrations from vibratory compaction are a function of the number of vibrating drums the roller has as well as the width and amplitude of vibration of the drums. For example, vibrations measured at a distance of 5 m for a 10.5 tonne Sakai SV91T vibrating roller were about 8 mm/s PPV at low setting and 5 mm/s PPV at high setting. By comparison, vibrations measured at the same construction site and distance from source for a 7.5 tonne Hamm HD75 vibrating roller were 1 mm/s PPV at low setting and 2 mm/s PPV at high setting (McIver and Cenek, 2011). This serves to illustrate that operation of vibratory rollers at the high setting does not necessarily result in the magnitude of the induced ground

6 Screw piles are a type of deep foundation that can be installed quickly with minimal noise and vibration. Screw piles are wound into the ground, much like a screw is wound into wood. This is an efficient means of installation and coupled with their mechanism of dispersing load, provides effective in-ground performance in a range of soils, including earthquake zones with liquefaction potential.



May 2013 8-28

vibrations being greater than operation at the low setting. Therefore, equipment selection and settings are important considerations when trying to mitigate construction related vibrations.

It is estimated that a minimum separation distance of 10 m from buildings will be required to keep the resulting ground-borne vibrations below the complaint threshold of 1 mm/s PPV and to 4 m (separation distance) to keep the resulting ground-borne vibrations below the cosmetic damage threshold of 2.5 mm/s PPV. These separation distances are only indicative as they have been derived assuming the lowest measured soil attenuation factor of 0.049 (i.e. worst case) and a source vibration level of 2 mm/s PPV at a distance of 5 m, this being representative of excavators and rollers operating in residential environments.

The only buildings located at a distance closer than 5 m from vibratory roller activity are in Paterson Street and Dufferin Street. The specific buildings are listed in Table 8.12.

Table 8.12: Estimated vibration levels at propertie s most affected by vibratory roller activity

Building 1 Distance

from Source (m)

Estimated Vibration Level from Roller (mm PPV)

Vibratory Mode Static Mode

Representative Lowest Expected

St Marks (Paterson St frontage)

3.6 2.5 1.3 0.4

St Joseph’s Church (Paterson St frontage)

4.2 2.3 1.2 0.3

11 Dufferin St 4.6 2.1 1.1 0.3

St Marks Church Hall 4.6 2.1 1.1 0.3

With reference to Table 8.12, none of the buildings closest to vibratory roller activity will be at risk of structural or cosmetic damage. However, the potential for these effects will need to be managed through careful selection and operation of equipment as detailed in the CNVMP given in Volume 4. For example, by using the lowest expected source vibration level of 1 mm/s PPV at a distance of 5 m (i.e. a Hamm HD75 vibrating roller operating at the low setting), the complaint threshold of 1 mm/s PPV may still be marginally exceeded during vibratory roller activity. If there is a desire to maintain vibrations to below levels that may cause annoyance to building occupants (i.e. < 1 mm/s PPV), then the only mitigation option available will be to operate the rollers in static mode (i.e. the drum is not vibrated).

From McIver and Cenek (2011), the measured ground vibration at 5 m for rollers operated in static mode ranged between 0.2 and 0.3 mm/s PPV, irrespective of roller mass. The upper value of 0.3 mm/s PPV and soil attenuation factor of 0.049 have been used to derive the static roller induced vibration levels given in Table 8.12.

In considering the vibration levels tabulated in Table 8.12, it should be noted that these are representative of new (i.e. greenfield) road construction and so are likely to be on the conservative side when applied to realignment and resurfacing of existing roads, such as in the case of Dufferin and Paterson Streets, since the same degree of compaction may not be required.

As Downers are the contractors for both the Memorial Park project and the Basin Bridge project, It is recommended that the opportunity be taken to monitor vibration levels generated by vibratory roller activity on the Memorial Park project to ensure that the magnitude of ground vibrations generated by Downers preferred choice of vibratory roller are below the representative values tabulated in Table 8.12.



May 2013 8-29

We can conclude that whilst the Project is within a dense urban environment and, therefore, results in construction activity being very close to existing buildings, the only intrusive type of activity identified has been associated with bore piling for the pedestrian/cycle ramp and compaction using vibratory rollers in the vicinity of Paterson and Dufferin Streets. Fortunately, both construction activities are of short duration (days rather than weeks). Therefore, if equipment selected by Downers for these activities generate vibrations above the complaint threshold of 1 mm/s PPV in the vicinity of occupied buildings, the activities should be timed, where practicable, so as to not interfere with the occupants of the affected buildings. For example, the works could be undertaken at night (Regional Wine and Spirits and St Marks School) or during school holidays (St Marks School) or the residents provided with the option of staying somewhere else if they are given sufficient prior warning as to when the potentially disturbing construction activity is to take place (21 Ellice Street and 9 and 11 Dufferin Street).

In the case of vibratory roller activity in Paterson and Dufferin Streets, the vibratory roller could alternatively be operated in static mode in this Project area (areas 5 and 6 in Table 8.1), resulting in vibration levels that will be just perceptible but achieved at the expense of the construction of the road taking longer to complete.

The CNVMP contained in Volume 4 explains how construction methodologies will be chosen and how effects will be managed in accordance with the above.

6.3 Traffic-induced vibrations once operational

The shortest separation distance between buildings and the revised transport routes will be 4.18m. This occurs between State highway 1 and St Joseph’s Church. Based on measured ground vibrations caused by existing State highway 1 traffic in the vicinity of St Joseph’s Church, the magnitude of vibrations that will be experienced are unlikely to exceed 0.3 mm/s PPV, provided both the posted speed limit of 50 km/h, the enforcement of this speed limit and the management practices regarding the roughness of the road surface remain as at present. This value of 0.3 mm/s PPV was estimated from Equation 8.2 using the measured value of 0.23 mm/s PPV at 5 m for V1 and R1, the measured attenuation value (α) of 0.065 for Paterson Street, and setting R2 to 4.18m.

Ideally, to account for all the different soil types in the vicinity of the planned transport improvements around the Basin Reserve and likely degradation in roughness condition of the road surface as a result of trafficking, the minimum separation distance between the edge of the roadway and buildings should be maintained to at least 5 m to limit vibration levels to 0.5 mm/s PPV and ideally at least 9.5 m to limit vibration levels to 0.3 mm/s PPV. The percentage of people that are likely to be highly annoyed by these vibration levels are 8% and 5% respectively. Where a minimum separation distance of 5 m is not possible as a result of project constraints, effects will need to be managed via ensuring road surface roughness is maintained at a level that is appropriate for the speed environment and available separation distance.

6.4 Vibration from bridge traffic

Based on measurements of traffic induced vibrations made at the Inter-Islander Ferry terminal adjacent to a pier of the Wellington Urban Motorway’s Thorndon Overbridge, maximum ground vibrations near piers of the proposed bridge are expected to be between 0.4 and 0.8 mm/s PPV. This assumes that the type of pier proposed for the Basin Bridge is comparable to those of the Thorndon Overbridge. Such vibration levels are insufficient to cause any damage to a building located under the bridge. However, subject to the detailed design and consideration of the use of the building, some form of vibration treatment may be required to ensure that the majority of the



May 2013 8-30

building occupants will not become annoyed. For example, at 0.4 mm/s PPV, about 32% of building occupants will be highly, moderately and slightly annoyed by this vibration level, whereas at 0.8 mm/s PPV, this percentage increases to about 44%.

6.5 Underground Services

6.5.1 Assessment of effects from construction

Piling activity in weaker soils at Kent Terrace and Cambridge Terrace will take place in close proximity to where there is a concentration of buried pipework, including gas and water mains and stormwater and sewer lines. This pipework is typically at a depth of 0.6 m or more below the road surface. The closest radial distance from piling activity to a major buried pipeline is about 5 m. Therefore, the maximum vibration levels these service pipes are likely to be subjected to is somewhere between 4 mm/s PPV (lower-bound estimate) and 16 mm/s PPV (upper-bound estimate).

With reference to British Standard BS 5228-2:2009 , “Code of practice for noise and vibration control on construction and open sites – Part 2: Vibration,” the maximum level of intermittent or transient vibration to which underground services should be subjected to is 30 mm/s PPV if in good condition or 15 mm/s PPV if old or dilapidated. These guideline values are deemed to be applicable to most metal and reinforced concrete service pipes. Therefore, direct dynamic stresses in the service pipes caused by ground vibrations generated by the bore piling operations will be easily tolerated if they are not old or in dilapidated condition.

There is the potential for failure from distortion due to the vibrations causing settlement of the ground surrounding the service pipes. However, this is considered to be extremely unlikely for the following reasons.

1. In creating the borehole, the drilling method produces little vibration and so there is little disturbance of the surrounding soil provided the correct drilling technology is selected.

2. The steel casing will be driven into very weak soil strata, which is expected to extend to a depth of at least 10 m. Therefore, because not much energy will be required to drive the casing, vibration levels in the proximity of the underground services and at the ground surface should be comparatively low magnitude and so insufficient to cause settlement.

Nevertheless, British Standard BS 7385:Part2:1993, Annex C, alerts to the possibility of structural damage due to ground vibrations causing consolidation and densification in loose and water-saturated soils as found in the vicinity of the Basin Reserve. Such soils become vulnerable at PPV values of about 10 mm/s, so, in the absence of more specific information, it is recommended that vibrations around buried pipework be limited to 10 mm/s PPV. Therefore, in the case of underground services, acceptable vibrations will be set by considerations of differential settlement rather than damage brought about by dynamic stressing of the pipework.

6.5.2 Assessment of effects when the Project is ope rational

Based on the measured maximum traffic-induced vibration level of 0.94 mm/s PPV, the measured soil attenuation factor of 0.069 (m-1) in the vicinity of Kent Terrace and Ellice Street and a minimum buried depth of 0.6 m, the largest traffic-induced vibration level buried pipework is expected to be exposed to is calculated to be 6 mm/s PPV. Therefore, it can be concluded that the minimum guideline value for damage of 7.5 mm/s PPV given in British Standard BS 5228-2:2009,



May 2013 8-31

corresponding to continuous vibration of old or dilapidated buried pipework, is unlikely to be exceeded, even if the buried pipework is only a very small distance beneath the road surface.

6.6 The Basin Reserve northern gateway building

If piling to support the foundation slab of the northern gateway building is required, it will most likely involve bored and cased piles because of the soft nature of the soil and close proximity of the RA Vance Stand and the historic Waitangi Stream Culvert.

The lower and upper-bound estimates of groundborne vibrations from piling operations can be obtained using the following equations, which have been derived from measured data described in section 6.2:

��()*+,�-).&/ � 4 1 �53�

�.�1 ��.�4��5�� Equation 8.4

��.66+,�-).&/ � 5 1 �14.53 �

�.�1 ��.�4��5� 8.�� Equation 8.5

9%�:�: 3 � !<=>?�@� A:B# =BC:@� #�?=C:�! ?�B�$ $:BC�! =C:A?@� �#�

Table 8.13 tabulates expected vibration levels at structures closest to the bored pile activity associated with the northern gateway building calculated from equations 8.4 and 8.5.

Three different building lengths for the northern gateway building were considered: 45 m; 55 m; and 65 m. The effect of increasing building length with respect to ground vibrations is to reduce the separation distance to the nearest inhabited building, Grandstand Apartments, from 46 m to 41 m. As can be seen from table 8.13, this results in the upper bound vibration level increasing from 0.4 mm/s PPV for the 45 m scenario to 0.5 mm/s PPV for the 55 m and 65 m scenarios. This upper-bound value of 0.5 mm/s PPV is just above the perception threshold of 0.3 mm/s PPV but below the complaint threshold of 1 mm/s PPV.

The other structure affected by the length of the northern gateway building is the historic Waitangi Stream culvert, which is constructed from brick. Assuming that separation distances to the culvert are measured along the ground, the 45 m scenario has a separation distance of about 12 m, the 55 m scenario is very close at 1.5 m and the 65 m scenario straddles the culvert (refer Figure 8.6).

British Standard BS 5528-2:2009 suggests that the maximum vibration level old brickwork underground services should be subjected to is between 15 and 24 mm/s PPV. With reference to table 8.13, only the 45 m scenario will result in the upper-bound vibration levels being below this guidance value. Therefore, particular care will need to be taken with the foundations of the 55 m and 65 m scenarios with respect to the location of the piles and the piling technique used to ensure the historic Waitangi Stream culvert is subjected to vibration levels that will not result in adverse effects. For example, if bored piling is to be used, a minimum slope distance of 6 m will need to be achieved.



May 2013 8-32

Figure 8.6: Location of historic Waitangi Stream Culvert rela tive to Basin Reserve northern gateway building



May 2013 8-33

Table 8.13: Estimated vibration levels at propertie s most affected by bored pile activity associated with the northern gateway building

Location of Interest Building Scenario

Distance from Piling Activity (m)

Estimated Vibration Level (mm/s PPV)

Lower-bound

Upper-bound

RA Vance Stand 45 m, 55 m & 65 m 1 12 47

Grandstand Apartments 45 m 46 <0.1 0.4

55 m & 65 m 41 0.1 0.5

The Crèche 45 m, 55 m & 65 m 62 <0.1 0.1

Waitangi Stream Culvert 45 m 12 2 7

55 m 1.5 9 36

65 m 1 12 47

It is clear that it will be difficult to eliminate any risk of the structural integrity of the Waitangi Stream culvert being comprised by the 55 m and 65 m scenarios for the northern gateway building. For this reason it is recommended that if either of these scenarios proceeds, condition surveys should be performed pre and post construction. As an extra precaution, vibration levels at the culvert should be monitored during any piling activity associated with the foundation of the northern gateway building to ensure guidance thresholds for structural damage are not exceeded.

With reference to Table 8.13, the only other building that will be affected is the RA Vance Stand. The lower-bound vibration level at the RA Vance Stand is below the 20 mm/s PPV German Standard DIN 4150-3:1999 damage threshold for short-term vibration of commercial buildings (refer Table 8.3) but slightly above the 10 mm/s PPV German Standard DIN 4150-3:1999 damage threshold for long-term vibration of commercial buildings (refer Table 8.4).

At the upper-bound estimate of 47 mm/s PPV, the 10 mm/s PPV German Standard DIN 4150-3:1999 damage threshold for long-term vibration of commercial buildings is exceeded by a considerable margin. To satisfy the short-term vibration damage criteria, the frequency of the vibratory hammer used to drive the steel casing into the ground will have to be at least 85 Hz.

This analysis clearly indicates that if a vibratory hammer is used to drive the steel casing into the ground, great care will have to be taken to ensure the frequency of vibration is appropriate for the level of vibration measured at the foundation of the RA Vance Stand to prevent cosmetic damage from occurring.

Given the proximity of the piling operation to the RA Vance Stand, there is a very high likelihood of both the short and long term vibration damage criteria of German Standard DIN 4150-3:1999 being exceeded when measured at the foundation of the RA Vance Stand, particularly if vibratory piling is used and possibly if oscillatory piling is used. Therefore, it is recommended that a less invasive form of piling, such as steel screw piles, be also considered for the foundations of the northern gateway building.

This is also desirable from the perspective of ensuring ground vibrations in the vicinity of the RA Vance Stand don’t reach levels that can cause consolidation or densification of the surrounding soil. With reference to British Standard BS 7385:Part2:1993, soils can become vulnerable at PPV values of about 10 mm/s, which corresponds to the German Standard DIN 4150-3:1999 guideline value for evaluating effects of long-term vibration on commercial buildings.



May 2013 8-34

As a consequence, selection of the piling technique used in the construction of the northern gateway building’s foundation will be dictated by considerations of damage to the soil structure and the RA Vance stand.

6.7 Relocated CS Dempster Gate

The CS Dempster Gate will be relocated from the northern side of the Basin Reserve to the southern side, just west of the existing JR Reid Gate. This will place the CS Dempster Gate about 200 m away from construction activity associated with the Basin Bridge project. Because vibration levels decrease with distance as a result of “geometrical spreading” of the vibration energy and its dissipation by soil viscosity and/or friction (Hunaidi, 2000), the magnitude of construction related vibrations will be too small to cause any damage by the time they reach the CS Dempster Gate (refer Table 8.11).

Regarding traffic induced vibrations, in its existing location, the CS Dempster gate was about 8 m from the road edge and in its new location it will be 6 m. With reference to Table 8.8, traffic-induced vibrations measured at a distance of 5 m from the road edge ranged between 0.22 to 0.57 mm/s PPV. These vibration levels are well below the DIN 4150-3 (1999) damage threshold value of 2.5 mm/s PPV for structures of great intrinsic value.

6.8 Seismic rating of Grandstand Apartments

Residents of Grandstand Apartments have expressed concern that their building may be particularly susceptible to ground vibrations generated by the Project as the building has received a “yellow’ earthquake-prone notice from Wellington City Council. This building has been rated at 15% compliance with the building code. To put this in context, the peak ground acceleration (PGA) Wellington buildings are seismically designed to is 0.4g, which is equivalent to 3.92 m/s2. Therefore, the 15% rating of the Grandstand Apartments corresponds to a maximum allowable ground acceleration of 0.59 m/s2, which with reference to the United States Geographical Survey Instrumental Intensity Scale7 is equivalent to 55 mm/s PPV.

With reference to table 8.11, the maximum expected ground velocity at the Grandstand Apartments generated by the Project is 4.5 mm/s PPV. This represents only 8% of the building’s rated value of 55 mm/s PPV and so we can be confident that the Grandstand Apartments will be able to accommodate vibrations generated by the Project without its structural integrity being compromised.

6.9 Suggested mitigation measures

6.9.1 Construction related

A draft CNVMP has been prepared (refer Volume 4), which provides a methodology for managing ground vibrations resulting from construction activities associated with the Project. Central to this CNVMP is the need for the contractor to demonstrate that vibration levels assumed in making the assessments presented in this report will not be exceeded by the equipment that will be used on the Project.

7 http://earthquake.usgs.gov/earthquakes/shakemap/background.php



May 2013 8-35

6.9.2 Traffic related

Provided a speed limit of 50 km/h applies and the road surfaces are constructed and maintained to existing roughness standards, traffic induced vibrations are unlikely to be problematic. However, care will need to be taken to ensure smooth transitions at the bridge abutments so that vibration inducing impact wheel loading common in such situations is minimised. Furthermore, bus only lanes should be sited so that the separation distance to bordering buildings is a minimum of 5 m and ideally 10 m whenever the buses can readily travel at the 50 km/h speed limit.

6.9.3 Building under the bridge

Should design and usage considerations dictate vibration treatment will be required, rather than trying to reduce vibrations from bridge traffic, a better course of action would be to take into account traffic induced ground vibrations in the order of 0.8 mm/s PPV in the design of the building under the bridge to ensure the impact of these vibrations is minimal on the comfort of people residing in this building. This will require monitoring of vibrations in the vicinity of the bridge once the Project is operational to determine the amplitude and frequency of the vibrations to guide the design of the building under the bridge’s structural system to avoid the occurrence of resonance. Another possible option is to incorporate a base isolation system in the building under the bridge in an attempt to minimise the transmission of vibrations generated by bridge traffic.

6.9.4 Underground services

The upper-bound estimate of vibration levels that the underground services are expected to be exposed to is 16 mm/s PPV. According to British Standard BS 5228-2:2009, this is slightly above the 15 mm/s PPV maximum level of intermittent or transient vibrations to which old or dilapidated underground services should be subjected to. Also, it is above the 10 mm/s PPV at which water-saturated cohesionless soils become vulnerable to compaction (BS 7385:Part2:1993).

Therefore, it is important to identify whether there are any old underground services in the vicinity of the pile driving operations and to monitor vibrations at their nearest point to the source to ensure the magnitude of the measured vibrations is less than 10 mm/s PPV. Should the magnitude of these measured vibrations be greater than 10 mm/s PPV, then the only option will be to relocate the affected underground services further away from the piling operations since it is expected that advice from the piling contractor would have been sought when selecting the drilling technology for the bored piles and the method for driving the steel casings into the ground to ensure disturbance of the soil surrounding the underground services will be minimal.

6.9.5 Northern gateway building

In order to minimise damage to the RA Vance Stand and the historic Waitangi Stream Culvert, either through foundation settlement or structural damage, vibrations from the piling activity associated with the northern gateway building within the Basin Reserve will have to be limited to no more than 10 mm/s PPV when measured at the foundation of the RA Vance Stand or on the historic Waitangi Stream Culvert at the nearest point to the vibration source. The piling technologies that can satisfy this condition are either steel screw piles or steel reinforced concrete piles with the casings oscillated into the ground because their non-impact nature causes minimal noise and vibration.

In this case steel casings driven into the ground by impact means using drop weights or vibratory hammers are not recommended because of the close proximity of the RA Vance Stand and the



May 2013 8-36

historic Waitangi Stream Culvert for the 55 m and 65 m configurations of the northern gateway building.

Given that the northern gateway building will butt up against the RA Vance Stand, it is also advisable that a condition survey of the RA Vance Stand (including the player’s pavilion for the 65 m configuration of the northern gateway building) be carried out by a suitably qualified building inspector pre and post construction of the northern gateway building as an additional precautionary measure. Therefore, if any damage occurs from construction activity, whether it is piling or some other activity, it can be identified and rectified.



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7 Confirmation of Critical Vibration Levels

The two construction activities identified as having the potential for adverse effects are piling associated with bridge piers and foundations of the two proposed buildings and vibratory compaction. In order to confirm that the vibration levels used for assessing the impacts from these two construction activities in this report are realistic, two independent investigations were carried out and the findings summarised below.

7.1 Monitoring of Piling Activity at One Market Lan e, Wellington

The Memorial Park Alliance took the opportunity to monitor noise and vibrations generated when 1.2 m diameter piles were being driven by both vibratory and oscillatory means, in soil conditions similar to those in the vicinity of the Basin Reserve (Block, 2013). The monitoring was performed at the site of the Willis Bond & Co apartment development, One Market Lane, situated at the junction of Taranaki and Cable Streets in Wellington’s historic Taranaki Wharf Precinct. Figure 8.7 shows a view of the construction site.

Figure 8.7: One Market Lane construction site

The vibratory piling took place on 23rd February 2013 and the oscillatory piling took place on 1st March 2013. The vibrations were measured using a Nomis Seismograph, 10 metres away from where the piling was taking place in the three orthogonal directions. The highest vibration level of the measured three directions is summarised in Table 8.14.

Table 8.14: Highest vibration levels measured during vibratory and oscillatory piling activity at One Market Lane site

Activity Vibration Level at 10 m from Source

(PPV, mm/s)

Vibratory Piling 3

Oscillatory Piling 1

With reference to Table 8.14, it will be noted that the peak vibration level measured for the vibratory piling is a factor of 3 higher than for the oscillatory piling confirming the vibration reduction potential of oscillatory piling over the more commonly used vibratory piling.



May 2013 8-38

More importantly, the measured vibration level of 1 mm/s PPV at a distance of 10 m for oscillatory piling compares with the 2 mm/s PPV at a distance of 10 m assumed in making the assessment of oscillatory piling activities associated with the Project. Similarly, the measured vibration level of 3 mm/s PPV at a distance of 10m for vibratory piling compares with the 8 mm/s PPV at a distance of 10 m assumed in making the assessment of vibratory piling activities associated with the Project.

Table 8.15 shows lower and upper bound estimates of vibration levels at properties most affected by bore piling if vibration levels from vibratory and oscillatory piling operations at One Market Lane could be replicated for the Project.

Table 8.15: Estimated vibration levels at propertie s most effected by bore piling operations if vibration levels measured at One Market Lane cou ld be replicated for the Project

Location Relative to

Bridge Abutments

Property Distance to Closest Pier (m)

Revised Vibration Levels (mm/s PPV)

Lower-bound (Oscillatory

Piling)

Upper-bound (Vibratory

Piling)

Western Abutment

The Crèche 50 <0.1 0.1

Relocated CS Dempster Gate, Basin Reserve

192 <0.1 <0.1

RA Vance Stand, Basin Reserve

22 0.3 0.9

Grandstand Apartments (80-82 Kent Terrace)

16 0.5 1.6

Eastern Abutment St Joseph’s Church 54 <0.1 <0.1

9 Dufferin Street 54 <0.1 <0.1

Regional Wines & Spirits (15 Ellice Street) (i) Main bridge (ii) Pedestrian/Cycle Ramp

24 6

0.3 1.7

0.8 5.0

21 Ellice Street: (i) Main bridge (ii) Pedestrian/Cycle Ramp

28 18

0.2 0.5

0.6 1.3

With reference to Table 8.15, it will be noted that the lower bound values are now all well below the complaint threshold of 1 mm/s PPV apart from 15 Ellice Street, which is a commercial building (Regional Wine and Spirits). Therefore, if possible, piers associated with the pedestrian/cycle ramp should be repositioned so that they are at least 10 metres away from 15 Ellice Street to achieve a vibration level of just below 1 mm/s PPV at this location.



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7.2 Vibratory Roller

A source vibration level of 2 mm/s PPV at a distance of 5 m has been assumed to be representative of rollers operating in residential environments. To confirm that this is valid, measured vibration levels of mechanised construction equipment given in Table 4.1 of NZTA Research Report 485, which included roller activity at 13 different sites, were compared. This NZTA research report can be downloaded for ready reference from: http://www.nzta.govt.nz/resources/research/reports/485/

The vibration levels given in NZTA Research Report 485 are for a distance of 10 m from the source. Assuming the worst case soil attenuation factor of 0.049, a vibration level of 2 mm/s PPV at a distance of 5 m corresponds to a vibration level of 1.1 mm/s PPV at a distance of 10 m.

With reference to Table 4.1 of NZTA Research Report 485, 5 sites out of the 13, corresponding to 38%, had a measured vibration level of 1 .1 mm/s PPV our less at a distance of 10 m. As a different make or model roller was used on each of these 5 sites, this provides a degree of confidence that a vibratory roller capable of achieving the vibration levels used to assess roller activity from the project, can be readily replicated.

7.3 Concluding Remarks

The above analysis provides a degree of confidence that appropriate source levels of vibration have been employed in making the impact assessments presented in this report and that the construction vibration criteria contained in Table 4 of the CNVMP (refer Volume 4) can be met by equipment routinely being used by New Zealand contractors.



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8 Conclusions

The primary conclusions arising from this assessment of ground vibrations generated by the construction and operation of the Project are as follows:

1. There may be some short term disturbance to occupants of nearby buildings resulting from construction activity. However, these disturbances are likely to be acceptable if proven vibration management methods are applied, such as selection of appropriate equipment and construction methodology and keeping affected parties informed as to when vibration generating activity is to take place and its duration. These vibration management methods have been incorporated in the draft Construction Noise and Vibration Management Plan given in Volume 4.

2. The existing environment around the Basin Reserve is exposed to low level traffic-induced vibrations from State Highway 1. These vibrations are considered to be acceptable as they are within recognised guidelines for human comfort applied internationally. The proposed project, once operational, will not result in any worsening of existing traffic-induced vibration levels.

3. Buried services are expected to be exposed to maximum vibration levels of between 4 mm/s and 16 mm/s peak particle velocity (PPV) during construction and about 6 mm/s PPV once the Project is operational. By comparison, the maximum level of intermittent and transient vibrations that underground services should be subjected to is 30 mm/s PPV if in good condition or 15 mm/s PPV if old or dilapidated according to British Standard BS 5228-2:2009. Therefore, ground vibrations generated by construction activities can be easily tolerated if the buried pipework is not old or in a dilapidated condition. Because of the historic nature of the brickwork Waitangi Stream culvert, it would be prudent to perform condition surveys pre and post construction of the Project to ensure no change to its structural integrity takes place. In addition, vibrations should be monitored, as detailed in the Construction Noise and Vibration Plan (CNVMP), whenever piling activity occurs in close proximity to the culvert to ensure vibrations measured on the culvert are below levels that could cause structural damage or settlement of the ground surrounding the culvert. Once the Basin Bridge becomes operational, all the buried services will be exposed to traffic induced vibrations that will be of the same magnitude as a present.

4. Foundations for the two proposed new buildings, one to be erected within the Basin Reserve immediately adjacent to the RA Vance Stand (northern gateway building) and the other to be erected at the intersection of Ellice Street with Kent Terrace immediately adjacent to the Grandstand Apartments ( building under the bridge), will most likely need to be piled. Therefore, care will have to be taken in selecting a method of piling that creates minimum soil disturbance to prevent any vibration-induced building damage from occurring. An international literature search and New Zealand experience suggests that both steel screw-in piling and bored piling using oscillators are two techniques that are able to generate vibration levels that comply with guidance thresholds in standards for avoiding damage to nearby structures.

5. For the Basin Bridge project, the bored piling operations associated with bridge piers have the potential to generate problematic vibrations, the driving of steel casings in particular. Therefore, there is a need to select the most appropriate casing driving technology for the soil conditions expected to be encountered to ensure any disturbance of the soil surrounding the pile borehole is minimised. Experience under



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Wellington conditions indicates that steel casings driven by a hydraulic casing oscillator generates vibrations whose magnitude is about a third of those when driven by a vibratory hammer highlighting the effect equipment selection can have.

6. A draft Construction Noise and Vibration Management Plan has been prepared (refer Volume 4), which provides a methodology for managing ground vibrations resulting from construction activities associated with the Project. The objective of this plan is to minimise damage due to construction vibration by all reasonable and feasible means possible. Therefore, there is specific consideration of the two activities identified as having the potential for adverse effects: (i) piling associated with the bridge piers and foundations of the two proposed buildings and (ii) vibratory compaction. The plan also considers how the construction vibrations will be monitored to ensure compliance with the established vibration thresholds for minimising structural damage. Central to this plan is the need for the contractor to demonstrate that vibration levels assumed in making the assessments presented in this report will not be exceeded by the equipment that will be used on the Project.

7. Overall, the operation of the Project will not generate any adverse vibration effects, provided current road maintenance management practices are maintained. Similarly, no adverse vibration effects are expected to result during the temporary construction period on account of the Construction Noise and Vibration Management Plan being in place to ensure compliance with the established vibration thresholds.

The following secondary conclusions have been derived from the vibration measurements made on 26th and 30th April 2012.

1. According to British Standard BS 5228-2:2009, for human comfort the largest measured peak particle velocities due to traffic-induced vibration for all testing sites fall between the threshold for perception (0.3 mm/s PPV) and the threshold that will likely cause complaint (1.0 mm/s PPV) within a residential environment.

2. According to the guidelines provided by German Standard DIN 4150-3 1999, none of the peak particle velocities that were attributable to traffic-induced vibration approached even the lowest magnitude that could cause damage to a structure (2.5 mm/s PPV).

3. The largest peak particle velocities recorded generally represent rare events.

4. Greater care in managing construction and traffic-induced vibrations will be required in the areas of weak soils (i.e. marginal marine sediments and reclaimed landfill in the vicinity of Cambridge and Kent Terraces) than competent spoils (i.e. alluvium based soils in vicinity of Buckle, Sussex and Ellice Streets). This is because impact loads, for example from vibratory compaction, cannot be accommodated by weak soils as well as competent soils.

5. Vibrations induced by traffic once the Project is completed are unlikely to be any different from present provided that the same speed limits and maintenance practices with regard to road surface roughness are maintained and the separation distance between a building and the realigned road is at least 4 m (as shown on the drawings).



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9 References

Block, J. (2013) Market Lane piling noise and vibration, Memorial Park Alliance Memorandum dated 7 March 2013.

British Standard, BS 5228.2:2009. Code of practice for noise and vibration control on construction and open sites – Part 2: Vibration.

British Standard, BS 7385:Part 2:1993. Evaluation and measurement for vibration in buildings. Part 2. Guide to damage levels from groundborne vibration.

Cenek, P.D., Sutherland, A.J. and McIver, I.R.(2012) Ground Vibration from Road Construction, NZ Transport Agency Research Report 485, downloadable from: http://www.nzta.govt.nz/resources/research/reports/485/index.html

Dowding, C. H. (2000). Construction Vibrations (2nd ed.) Prentice Hall

EPA (2006). Environmental Management Guidelines: Environmental Management Guidelines in the Extractive Industry (Non-Scheduled Minerals), Environmental Protection Agency, Ireland, downloadable from: http://www.epa.ie/downloads/advice/general/epa_management_extractive_industry.pdf

German Standard, DIN 4150-3:1999. Structural Vibration – Part 3: Effects of vibration on structures.

Hunaidi, O. (2000). Traffic Vibrations in Buildings, Construction Technology Update No.39, Institute for Research in Construction, National Research Council of Canada, Ottawa.

International Standard, ISO 26321-2:1989. Evaluation of human response to whole-body vibration – Part2: Continuous and shock-induced vibration in buildings (1 to 80 Hz).

International Standard, ISO 4866:2010. Mechanical vibration and shock – Vibration of fixed structures – Guidelines for the measurement of vibrations and evaluation of their effects on structures.

International Standard, ISO 8041:2005. Human response to vibration - Measuring instrumentation.

Jackson, N.M., Choubane, B., Lee, H.S., Holzschuher, C., Hammons, M.I. and Walker, R. (2008). Recommended Practice for Identifying Vibration-Sensitive Work Zones based on Falling Weight Deflectometer Data, Transportation Research Record No 2081, pp.139-149.

McIver, I.R. and Cenek, P.D (2009). Vibration Assessment: Waiwhetu Stream Seaview, Opus Central Laboratories Report 09-29B38.00.

McIver, I.R. and Cenek, P.D. (2011). Bridge Street Retaining Wall: Assessment of Roller Induced Ground Vibrations, Opus Central Laboratories Report 11-6CM015.04.

Norwegian Standard NS 8176.E:2005 (2nd ed.). Vibration and Shock. Measurement of vibration in buildings from landbased transport and guidance to evaluation of its effects on human beings. Standards, Norway, 2005. English translation version, 2006.

Schilling, R.A. and Harris, S.L. (2011) Fundamentals of Digital Signal Processing Using Matlab Second Edition, Florence, KY: Cengage Learning, pp. 611-617

Sutherland, A.J. and Cenek, P.D. (2007). Vibration Assessment: Dowse Interchange, Opus Central Laboratories Report 07-522432.39.



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Thusyanthan, N.I., Chin, S.L.D. and Madabhushi, S.P.G. (2006). Effect of Ground Borne Vibrations on Underground Pipelines. Proceedings of the International Conference on Physical Modelling in Geotechnics 2006, Hong Kong, pp. 753-758.

Xu,L. (2005). Site Investigation of the Dynamic Behaviour of the ISPAN Floor System, University of Waterloo, Ontario, Canada, downloadable from: http://www.totaljoist.com/Assets/pdfs/TechDetails/SIDBR.pdf



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Appendix 8.A: Vibration measurement locations

Figures 8A1 to 8A7 below show the approximate locations of the accelerometers at each testing site.

Figure 8A1: Accelerometer locations at S1 – Corner of Ellice St and Kent Tce

Figure 8A2: Accelerometer locations at S2 – Ellice St



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Figure 8A3: Accelerometer locations at S3 – Paterso n St, northern side

Figure 8A4: Accelerometer location at S4 – Paterson St, southern side



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Figure 8A5: Accelerometer location at S5 – Buckle S t crèche

Figure 8A6: Accelerometer locations at S6 – Tory St



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Figure 8A7: Accelerometer location at S7 – Interisl ander Ferry terminal car park



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Appendix 8.B: Impact related predictor curves

Figures 8B1 to 8B5 below show the plots used to derive the values for A and n for each testing site.

It should be noted that scaling of distance is necessary to predict peak particle velocities when the energy released is a variable as in drop-weight impact and/or dynamic compaction (Dowding, 2000).

Figure 8B1: Peak particle velocity vs scaled distan ce – Site S1a – Corner of Ellice St and Kent Tce

Figure 8B2: Peak particle velocity vs scaled distan ce – Site S1b – Corner of Ellice St and Kent Tce

y = 0.4974x-1.073

0.01

0.1

1

10

100

0.1 1 10

Pe

ak

Pa

rtic

le V

elo

city

(m

m/s

)

Scaled Distance (m/(kg.m)0.5)

y = 0.5481x-1.45

0.01

0.1

1

10

100

0.1 1 10

Pe

ak

Pa

rtic

le V

elo

city

(m

m/s

)




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Figure 8B3: Peak particle velocity vs scaled distan ce – Site S2 – Ellice St

Figure 8B4: Peak particle velocity vs scaled distan ce – Site S3 – Paterson St, northern side

y = 0.1683x-1.308

0.01

0.1

1

10

100

0.1 1 10

Pe

ak

Pa

rtic

le V

elo

city

(m

m/s

)


y = 0.2583x-1.105

0.01

0.1

1

10

100

0.1 1 10

Pe

ak

Pa

rtic

le V

elo

city

(m

m/s

)




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Figure 8B5: Peak particle velocity vs scaled distan ce – Site S6 – Tory St

y = 0.1884x-1.053

0.01

0.1

1

10

100

0.1 1 10

Pe

ak

Pa

rtic

le V

elo

city

(m

m/s

)




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Appendix 8.C: Drop-weight comparison

A limited series of drop tests was carried out at Opus Central Laboratories on 24th of April 2012 to determine the effect of drop-weight characteristics on the resulting vibration predictor curves.

The drop-weights investigated were a 25 kg sandbag and a 25 kg metal rail. The metal rail was used in preference to a metal plate as it could be readily caught after impacting on the ground to prevent multiple impacts occurring due to bouncing.

The sandbag was dropped from a height of 1 m, resulting in impact energy of 245 J. In comparison, the metal rail, because of its length, was only able to be dropped from a height of 0.45 m, resulting in impact energy of 110 J.

The resulting ground acceleration levels were measured at a distance of 2, 7, 12 and 17 m from where the mass was dropped by an in-line array of 4 triaxial accelerometers. The resultant (vector sum) peak particle velocity (PPV) was then determined for each accelerometer for each drop.

Table 8C1 tabulates the PPV’s at each accelerometer location averaged over three drops. With reference to this table, it can be seen that at distances of 7 m or greater, the PPV values are very similar. However, at 2 m, the metal rail generates a ground acceleration that is about 20 times greater than for the sandbag. This is attributed to the impact from the metal rail consisting of higher frequency components than the impact from the sandbag.

Table 8C1: Measured vibrations for metal rail and sandbag drop-weights

Distance (m)

Impact Hammer

25 kg Metal Rail 25 kg Sandbag

Scaled Distance (m/(kg.m) 0.5)

PPV (mm/s)

Scaled Distance (m/(kg.m) 0.5)

PPV (mm/s)

2 0.60 33.03 0.40 1.63

7 2.09 0.35 1.40 0.31

12 3.58 0.17 0.72 0.14

17 5.07 0.11 3.40 0.11

The following model was fitted to the data summarised in Table 8C1:

�� !√#. %�& � A 1 Scaled Distance& Equation C1

where: A is coefficient related to the nature of the impact d is the radial distance from the vibration source in metres m is the mass of the impacting body in kg h is the height that the impacting body is dropped from in metres n is the power rate of attenuation

Table 8C2 below lists the values A and n determined using measurements from all 4 measured locations (i.e. covering distances between 2m and 17m from the impact) and from the 3 furthermost locations (i.e. covering distances between 7m and 17m from the impact). The analysis was repeated with the closest vibration reading removed because the surface or Rayleigh waves generated by the impact does not fully form until some finite distance from the impact. Therefore, the effect of excluding the reading at 2m on the model coefficients could be investigated.



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Table 8C2: Predictor curve coefficients A and n

Impact Hammer

Fitted Predictor Curve Coefficients

A n

(2m-17m) (7m-17m) (2m-17m) (7m-17m)

Sandbag 0.48 0.44 -1.30 -1.19

Metal Rail 5.75 0.87 -2.73 -1.27

With reference to Table 8C2, it will be observed that when the sandbag is used as the impact hammer there is not a significant change in model coefficients irrespective if all of if just the three furthermost readings are utilised. Also, there is good agreement between the sandbag derived value of power rate of attenuation (n) and that derived with the metal rail using the three furthermost data points. However, Table 8C2 highlights that the value of coefficient A is very much related to the nature of the impact, with the metal rail giving values 2 to 12 times greater.

On the basis of the results presented in Table 8C2, the sandbag was selected as the preferred impact hammer for drop tests because, unlike the metal rail, estimates of the power rate of attenuation were not greatly influenced by the distance to the closest measurement location. The other advantages of the sandbag were:

• less scatter in the measured PPV values

• no bounce on impact to affect the readings

• less likelihood of damage to surfaces

However, there is need to exercise care when applying predictor curves derived from sandbag tests as the estimates of expected vibrations, while being realistic, are unlikely to be at the upper bound.



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Appendix 8.D: Accelerometer calibration data

Calibration data provided by the manufacturer of the accelerometers, Colibrys Inc., is summarised in the table below for each of the accelerometers used in making the ground vibration measurements for the Basin project. To ensure that each channel of the accelerometers was operating properly, an acceleration level of ±1g (=9.81m/s2) was applied at the start and end of each monitoring period and the resulting output voltage compared with that expected from Table 8D1.

Table 8D1: Manufacturer supplied calibration data

Accelerometer ID

Serial No. Axis Offset

(K0) g’s Scale Factor (K1) Volts/g

2nd Order non-linearity

(K2) g/g 2

3rd Order non-linearity

(K3) g/g 3

A 602

X -1.08E-03 1.216 -5.92E-05 -1.70E-03

Y -7.65E-02 1.270 -2.38E-04 -1.58E-03

Z -1.24E-01 1.245 -3.24E-04 -8.29E-04

B 604

X -3.43E-02 1.243 -1.44E-04 -2.16E-03

Y 9.31E-02 1.233 -4.31E-04 -2.98E-03

Z -1.03E-01 1.176 -2.12E-04 -1.65E-03

C 779

X -0.051 1.265 -1.508E-04 -1.403E-03

Y -0.183 1.260 -4.906E-04 1.503E-03

Z -0.152 1.247 1.897E-04 -6.218E-04

D 780

X -0.138 1.256 -6.450E-04 -5.614E-04

Y -0.150 1.257 2.821E-04 1.276E-03

Z -0.138 1.278 -3.778E-04 -9.689E-04

V=output in volts g=Acceleration in g’s peak

Basic Output Equation: g=V/K 1-K0

High Accuracy Equation: g corrected =g-K2×g2-K3×g3

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