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Amey Report Template – CON-GEN/Template/001/01

Brent Swing BridgeOptions ReportDocument reference: CO04300132/02

Revision: 03

Issued: May 2014

Service is our passion. People, our strength

Project Name Brent Swing Bridge

Document Title Options Report

Doc. Ref.: CO04300132/02 Rev 03 - i - Service is our passion. People, our strengthIssued: May 2014

Executive Summary

The purpose of this report is to consider alternative options for replacing the existing Brent Swing Bridge,Faversham, Kent. The options considered are as follows:

Option 1 Fixed bridge

Option 2 Swing bridge

Option 3 Lifting bridge

Option 4 Dutch style bascule bridge

Option 5 Major maintenance and strengthening

In developing the estimated costs for the above options, account has been taken for the need to repairand strengthen the existing abutments and the provision of a temporary diversion route via Brent Hill andDavington Hill.

Option 1

The least cost option is a reinforced concrete bridge utilising precast elements for speed of construction.

A period of 6 weeks will be required for the construction works phase with a road closure of 4 weeks.

The estimated cost for the construction for this option is £390,000.

Option 2

The swing bridge will comprise a steel bridge deck supported on a strengthened south abutment similar inform to the existing bridge.


The estimated cost for the construction for this option is £970,000.

Option 3

The lifting bridge will require new foundations to be constructed behind the existing north abutment andwill comprise a steel bridge deck hinged at the north end.


The estimated cost for the construction for this option is £1,150,000.

Option 4

The Dutch style bascule bridge will require new foundations to be constructed behind the existing northabutment and will comprise a steel bridge deck hinged at the north end with steel A frames andcounterweight above road level.


The estimated cost for the construction for this option is £1,210,000

Option 5

Replacement of the existing opening mechanism and replacement with new. Strengthening of theexisting superstructure and abutments.

A period of 11 weeks will be required for the construction phase with a road closure for 9 weeks.

The estimated cost for the construction of this option is £642,000.



Doc. Ref.: CO04300132/02 Rev 03 - ii - Service is our passion. People, our strengthIssued: May 2014

Location Plan

The site plan has been reproduced from an Ordnance Survey map, with the permission of Her

Majesty s Stationery Office, Crown copyright reserved licence No. 100019238. 2013.

Figure 1: Brent Swing Bridge



Doc. Ref.: CO04300132/02 Rev 03 - iii - Service is our passion. People, our strengthIssued: May 2014

Contents

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

1.1 Client brief ...................................................................................................................... 1

1.2 Report Revision 02......................................................................................................... 1

1.3 Report Revision 03......................................................................................................... 1

1.4 Aims of the feasibility ..................................................................................................... 1

1.5 Background .................................................................................................................... 1

1.6 Detailed Description of the Structure ............................................................................. 2

1.7 Photographs of the structure.......................................................................................... 3

2 Design Considerations ................................................................................................ 4

2.1 General........................................................................................................................... 4

2.2 Foundations and Abutments .......................................................................................... 4

2.3 Temporary Road Bridge................................................................................................. 4

2.4 Land Acquisition............................................................................................................. 5

2.5 Site Compound .............................................................................................................. 5

2.6 Road closures ................................................................................................................ 5

2.7 Pedestrians and Cyclists................................................................................................ 5

2.8 Power Supply ................................................................................................................. 6

2.9 Statutory Undertakers Plant ........................................................................................... 6

2.10 Opportunities for Enhancement ..................................................................................... 6

2.11 Design Criteria ............................................................................................................... 7

3 Options.......................................................................................................................... 8

3.1 General........................................................................................................................... 8

3.2 Option 1: Fixed Bridge ................................................................................................... 8

3.3 Option 2: Swing Bridge ................................................................................................ 10

3.4 Option 3: Lifting Bridge................................................................................................. 12

3.5 Option 4: Dutch Style Bascule Bridge.......................................................................... 14

3.6 Option 5: Major Maintenance and Strengthening ........................................................ 17

3.7 Cost Summary ............................................................................................................. 19

4 Traffic Impact Assessment ....................................................................................... 20

4.1 Traffic Impact Assessment........................................................................................... 20

5 Environmental considerations ................................................................................. 21



Doc. Ref.: CO04300132/02 Rev 03 - iv - Service is our passion. People, our strengthIssued: May 2014

5.1 Emissions and Waste................................................................................................... 21

5.2 Air Quality..................................................................................................................... 21

5.3 Archaeology and Cultural Heritage .............................................................................. 21

5.4 Landscape.................................................................................................................... 21

5.5 Ecology and Nature Conservation ............................................................................... 22

5.6 Geology and Soils ........................................................................................................ 22

5.7 Material Use ................................................................................................................. 22

5.8 Noise and Vibration...................................................................................................... 23

5.9 Drainage and the Water Environment.......................................................................... 23

6 Geotechnical Considerations ................................................................................... 24

6.1 Background Geotechnical Information......................................................................... 24

6.2 Preliminary Geotechnical Advice ................................................................................. 25

6.3 Background information ............................................................................................... 25

7 Operation, Inspection and Maintenance.................................................................. 27

7.1 Operation of Moveable Bridge ..................................................................................... 27

7.2 Inspection and Maintenance ........................................................................................ 27

The above factors and the periods for inspection and maintenance have beenincluded in the appraisal of the whole life costs for each of the options. ..................... 28

7.3 Design Considerations ................................................................................................. 28

7.4 Health and Safety......................................................................................................... 28

8 Stakeholders............................................................................................................... 29

8.1 Stakeholder Consultation ............................................................................................. 29

8.2 Principal stakeholders .................................................................................................. 29

9 Discussion and Recommendations ......................................................................... 30

9.1 Cost comparison .......................................................................................................... 30

9.2 Time of construction..................................................................................................... 30

9.3 Operation and maintenance......................................................................................... 30

9.4 Advantages and Disadvantages .................................................................................. 30

9.5 Recommendations ....................................................................................................... 30

Appendix A Cost Estimate Coverage A-1

Appendix B Options Drawings B-1

Appendix C Temporary Diversion Route C.1

Appendix D M&E Inspection Report D.2Appendix E Bibliography E.1



Doc. Ref.: CO04300132/02 Rev 03 - 1 - Service is our passion. People, our strengthIssued: May 2014

1 Introduction

1.1 Client brief

A feasibility options study for the replacement of Brent Swing Bridge, Faversham, Kent has

been requested by KCC. The study is to consider fixed, swing, lifting bridge and Dutch style

bascule options for the bridge deck replacement and will include estimated capital and Whole

Life Costs for each option. The report has been reviewed by the Brent Bridge Working Group

and will be submitted to Brent Bridge Steering Group for their consideration.

1.2 Report Revision 02

Revision 02 of the report incorporated the comparison of a Dutch style bascule bridge (option 4)

with the previously considered options.

The estimated costs for all options were reviewed and the report was updated to include more

detailed costs for the mechanical and electrical elements.

1.3 Report Revision 03

This version of the report, revision 03, incorporates option 5, proposed strengthening and major

maintenance.

1.4 Aims of the feasibility

The purpose of this study is to consider practicability and engineering buildability of the

alternative options taking into account the reuse of parts of the existing facility.

The report will review the operation and maintenance of the alternative options taking into

account the costs for ongoing maintenance.

This report does not consider the Acts of Parliament relating to the navigation rights at this

location, similarly it does not consider the responsibilities for operation and maintenance.

1.5 Background

The existing bridge is a two span structure carrying Bridge Road over Faversham Creek in

Faversham, Kent. It was originally constructed in 1881 to replace a sliding footbridge. The

superstructure of the bridge was strengthened in 1941 and replaced again in 1976.




The bridge ownership is uncertain but it is believed that the hydraulic machinery and opening

mechanism is owned by Medway Ports Authority (now owned by Peel Ports) which is

responsible for navigation in the Creek. Kent County Council has an interest in the deck as it

supports a highway crossing.

Structural assessment of the bridge, carried out in 1993 and 2012, determined that the

superstructure does not have the capacity to support dead and superimposed dead loads when

in the open position. It was also noted in the 2012 assessment report that; further loss of

section to critical main steel members had occurred, however this had not reduced the

capability of the bridge to carry current highway loading and a weight restriction was not

required at this time.

With the cessation of commercial water borne traffic and the assessment result, it is understood

that the bridge has not been opened to boats since the late 1980’s/early 1990’s.

1.6 Detailed Description of the Structure

For the purposes of this report it is assumed that the bridge lies in a south to north direction.

Previous reports and records indicate that the substructure for the south abutment is formed by

mass concrete abutments supported on piled and spread foundations. No details are available

in the structure records for the north abutment.

The superstructure is a continuous deck formed of two steel girders and nine transverse beams.

The deck pivots about a pintle bearing located on top of the south abutment.

In the closed position the deck is a continuous two span structure, the tail end of the deck is

supported at the rear of the south abutment, an intermediate support at the front of the south

abutment and the deck nose is supported on the north abutment. When in the “open” position

the deck becomes a two span cantilever structure supported only by the south abutment on the

pintle bearing and the track at the tail end of the deck.

There are fenders fixed to the abutments and a pair of sluice gates at the west end of the

abutments.

The main elements of the superstructure are two 610 × 229 × 113 kg steel girders. There are

nine 356 × 127 × 39 kg steel beams fixed transversely above the lower flanges of the girders,

evenly spaced along the length of the deck. The deck surface is supported on six continuous

longitudinal inverted T beams on the transverse beams. The side cantilevers, supporting the

footways and parapets, are formed of nine built-up steel beams each side with single

longitudinal inverted T beams fixed at the top. The running surfaces of the road and footways

are formed of 15 mm thick steel deck plates.




The swing mechanism operates by lifting the deck off of the pier and north abutment using a

kentledge weight system at the south abutment and a hydraulic jack in the pintle between the

south abutment and the pier. The deck is then rotated about the pintle.

1.7 Photographs of the structure

Plate 1: Downstream Elevation

Plate 2: View across bridge from south




2 Design Considerations

2.1 General

A detailed inspection of the bridge has not been undertaken as part of this feasibility study. The

assumptions made in this report are based upon the findings and recommendations provided in

the previous reports undertaken for KCC.

The mechanical and electrical (M&E) equipment was inspected by a specialist employed by

Amey on 17th April 2014. The inspection report concluded that the M&E equipment is

unserviceable and unsafe and should not be operated. See Appendix D.

2.2 Foundations and Abutments

Inspection records indicate that the existing abutments and their foundations are in fair

condition. However the Principal Inspection (PI) report (dated 2011) records that there is

differential settlement apparent at the north abutment.

It is not known whether the apparent settlement is an ongoing issue or whether it occurred

historically, further investigation is required before it can be determined whether the existing

abutments can be utilised to support the proposed bridge options. An allowance of £80,000 for

underpinning of the foundations of the north abutment has been made for each of the

alternative options.

The 2011 PI report also notes that the bearing pad to west end of the north abutment is

displaced. It is proposed that new bearing seats will be provided therefore this defect will be

eliminated as part of the design for the relevant alternative options.

The abutment walls exhibit eroded joints, cracks in the masonry and brickwork and isolated loss

of brick faces due to erosion. These repairs should be undertaken in conjunction with all four

proposed alternative options and costs of £23,000 have been allowed for undertaking this work

in each of the construction works estimates.

2.3 Temporary Road Bridge

Consideration has been given to providing a temporary bridge to minimise traffic disruption

whilst the construction works are being carried out. However there is insufficient space to allow

for the installation of a bridge at the existing bridge site.




Alternative locations for a temporary bridge have also been looked into, these would require the

diversion of traffic and significant civil engineering works to achieve a suitable solution. The

most likely locations would be upstream of the existing bridge, but the anticipated cost for

providing the temporary structure is disproportionate to the permanent replacement bridge

therefore it is not considered to be viable.

2.4 Land Acquisition

A land search has not been undertaken for the bridge replacement options. It is understood that

all land within the footprint of the existing structure is either designated as highway or owned by

the Port Authority.

All four of the alternative options are within the existing highway boundaries therefore no

additional land is required for the permanent works.

2.5 Site Compound

Space will be required for a site compound to accommodate site offices, messes and stores etc.

There is an area of land at the north-west corner of the bridge which could be used for this

purpose. Ownership of this area of land will need to be determined and the appropriate

arrangements agreed before commencement of the works.

2.6 Road closures

The proposed bridge replacement works will require a temporary road closure for part of the

duration of the construction works. A diversionary route can be provided via Brent Road and

Brent Hill, details of the proposed diversion are shown in Appendix C.

In addition, once the bridge has been reinstated to allow opening to river traffic there will be an

impact upon the local road network albeit only for a short period (not in excess of 10 minutes

per bridge opening assuming marine traffic can be controlled effectively).

There are currently no available traffic flow figures for Brent Road therefore an assessment of

the effect of these closures is not known.

Closure of the road to facilitate the works will require significant local consultation as the project

progresses.

2.7 Pedestrians and Cyclists

The existing bridge is the main route for pedestrians from the Brents area of Faversham to the

town centre, the bridge is also part of the National Cycle Route 1 (NCR1) which runs from

Dover to Scotland and crosses the bridge.




Access for pedestrians and cyclists will need to be maintained throughout the period of

construction. This could be achieved either by the provision of a footbridge adjacent to the

existing swing bridge or alternatively providing a pedestrian diversion via Flood Lane. Providing

a footbridge through the construction site will have significant health and safety implications and

the preferred alternative would be to divert pedestrians via Flood Lane. Improvements will be

required in Flood Lane to provide a suitable footway.

A Public Right of Way (PRoW) starts at the north-east corner of the bridge and runs along the

north bank of the creek to the east of the bridge. It is not envisaged at this stage the PRoW will

be affected by the construction works however it needs to be considered in future development

of the project.

2.8 Power Supply

It has been assumed that electricity supplies are available at either side of the bridge and that

these will be sufficient to power the plant and equipment required for the moveable bridge

options.

The condition, type and location of electricity supply will need to be confirmed for the

subsequent stage of design development.

Costs for connection to the existing supply have been allowed for in the options cost estimates

but no cost allowance has been made for providing new power supply.

2.9 Statutory Undertakers Plant

Responses to notices have been received from all of the statutory undertakers.

None are likely to be affected by any of the alternative options being considered.

2.10 Opportunities for Enhancement

Parts of the existing bridge are to be retained and brickwork repairs will be required. At this time

there would be the potential for replacing previous repairs with materials more sympathetic to

the original structure.

The three existing buildings adjacent to the bridge which house the existing M&E equipment

and controls for the bridge and lock gates may no longer be required, in whole or part. The

buildings no longer required for use could be demolished allowing greater space around the

bridge.

There would be the added benefit of widening the footways, improving safety for pedestrians.

However formal crossing points may be required at both ends of the bridge to allow pedestrians

to cross the road safely where the footway is only being widened on one side.




There is currently no fendering provided on either the upstream or downstream approaches to

the bridge. The consideration of use of the bridge by river traffic is not included in the scope of

this feasibility report and the cost for providing fendering has not been included in the option

costs. It is recommended that this should be considered if either of the moveable bridge options

is taken forward, the requirements for navigation lighting should also be considered.

2.11 Design Criteria

All options minimum 3.0 m wide carriageway

Minimum desirable footway width 1500mm

Minimum offset to parapet 0.45 m

Type N1 parapets with vertical infill to be used for options 1 to 4

Single-way traffic to be maintained as existing usage

Minimum headroom – 5.70 m




3 Options

3.1 General

All of the following options include costs for underpinning of the abutment foundations and

significant repairs to the abutment wall brickwork and masonry.

Also included is the need to provide temporary access for pedestrians, the cost for providing a

temporary diversion via Flood Lane has been included in each of the options.

Tidal variations will have a significant effect on the construction works, careful planning will be

required to programme the individual work phases to avoid disruption to the works.

3.2 Option 1: Fixed Bridge

3.2.1 Description of the proposed works

This alternative comprises the construction of a single span square deck over Faversham

Creek.

The bridge will utilise the existing abutments to support a precast reinforced concrete beam and

in situ deck slab. The deck will be seated upon precast reinforced concrete bank seats

constructed on top of the existing abutments.

Use of precast reinforced concrete elements has been selected for this option to reduce the

construction period thereby reducing the length of time required for closure of the road

compared with an in situ reinforced concrete deck form of construction.

Fill will be required to support both approaches to the bridge.

Alternative designs for the fixed bridge span have been investigated. The installation of a steel

deck would reduce the period for the site construction works, although its cost would be similar

to that for the precast beam option, the durability would be less than the concrete deck and the

whole life costs would be greater therefore this option has not been developed further.

3.2.2 Drawings and sketches

A sketch showing details of the proposed structure is included in Appendix B.

3.2.3 Estimated costs for design and construction

A summary of the items included in the following cost estimate is included in Appendix A.

The estimated scheme design and construction cost are detailed below:




ItemCost£

Preliminaries 51000

Site Clearance 55500

Fencing 1000

Road Restraint Systems 8000

Earthworks 13500

Pavements 11500

Kerbs, Footways and Paved Areas 5500

Traffic Signs and Road markings 500

Street Lighting 500

Piling and Embedded Retaining Walls 96000

Structural Concrete 62000

Waterproofing to Structures 2000

Bridge Bearings 9500

Bridge Expansion Joints 10500

Brickwork, Blockwork & Stonework 23500

Contingencies (10%) 35050

Total 385,550

3.2.4 Whole life costs

The whole life costs for option 1 are as follows:

Option 1 60 Years 120 Years

Net Present Value (£) 431,000 451,000

3.2.5 Outline timescale for delivery

It is estimated that the bridge will take up to 6 weeks to construct.

If weekend working is permitted by the local authority it may be possible to reduce the

construction period for the bridge and hence reduce the amount of time required for closure of

the road. The programme indicates that a road closure will be required for approximately four

weeks.




3.2.6 Advantages

The main advantages of this option is that it will be the cheapest option to construct and

maintain it also has the shortest construction programme therefore is the least disruptive to the

travelling public and local businesses.

The bridge is located within a marine environment and is likely to be subjected to occasional

high water levels. Due to its reinforced concrete form of construction option 1 will be more

durable, in this type of environment, than the other options considered.

3.2.7 Disadvantages

The fixed bridge option will limit the size of watercraft on the navigable waterway and would

prevent the upper creek from effectively functioning as a navigable waterway.

3.3 Option 2: Swing Bridge


The swing bridge alternative will be a like for like replacement of the existing structure but

increased in width.

For closure of the bridge; vehicle, cycle and pedestrian traffic will be controlled by automatic

lights and barriers at either end of the deck.

The bridge superstructure will be of steel construction similar in form to the existing structure, it

will pivot about a new pintle bearing located in the same position as the existing bearing.

The top of the south abutment will be reconstructed as a reinforced concrete slab this will

ensure safe access to inspect and maintain the new superstructure and mechanical and

electrical equipment. The new abutment slab will support the pintle bearing, tail wheel running

track and rear hydraulic wedges and jacking system. Around its perimeter the abutment slab will

be provided with a reinforced concrete wall perimeter this will protect the structure from sea

water ingress and protect the water environment from possible hydraulic oil spillages.

Hydraulic jacks and the motor drive unit will be located at the rear end of the tail span with

hydraulic operated stabilising wedges at the tail end of the deck.

Movement of the bridge deck will be automatically controlled in the following sequence:

Stop cars, pedestrians and cyclists

Release tail wedges and lower deck on the rear jacks so load is taken up on the tail

wheels

Engage motor drive and manoeuvre bridge deck into open position

Apply braking system and arrest movement of deck




Closing the bridge will be a reversal of the above procedure.



3.3.3 Estimated initial capital costs of carrying out the works


The estimated scheme design and construction costs for option 2 are detailed below:

ItemCost

£

Preliminaries 56500


Fencing 1000


Drainage and Service Ducts 2500

Earthworks 2500

Pavements 11000



Street Lighting 500

Electrical 68000



Protection of Steelwork Against Corrosion 15000




Special Structures Designed by the Contractor

Breakdown of costs:

• Superstructure design, fabrication and installation:

• Fabrication and supply of M&E equipment

• Design, Installation and commissioning of M&E equipment

460500

(175000)

(125500)

(160000)


Total 962,500







Net Present Value £1,246,000 £1,379,000


It is estimated that the bridge will take up to 13 weeks to construct with a road closure required

for approximately 12 weeks.

3.3.6 Advantages

In case of a mechanical failure during either opening or closing of the bridge it would be

relatively easy to manually manoeuvre the bridge back into position.

This option would provide navigation access to the upper basin of Faversham Creek.

3.3.7 Disadvantages

There will be ongoing costs for management and maintenance of the mechanical and electrical

equipment.

3.4 Option 3: Lifting Bridge


This alternative will require the construction of a large retraction pit to accommodate the lifting of

the deck at the tail end of the bridge. Due to the extent of the existing south abutment

foundations and the proximity to existing buildings at the south end of the bridge it is considered

that the most practicable location for the retraction pit is behind the existing north abutment. The

pit will need to be sufficiently large enough to allow for the movement of the tail end of the deck

and to accommodate the bearings and hydraulic lifting equipment.

The bridge superstructure will be of steel construction similar to that proposed for the swing

bridge option. Raising the deck will be achieved by hydraulic rams pushing up on the soffit of

the deck just in front of the pivot resulting in the main span lifting clear of the water way.



Operation of the bridge will be automatically controlled in the following sequence:

Stop road, cycle and pedestrian traffic

Engage hydraulic rams and raise bridge deck into open position

The control system slows the bridge down as it reaches the fully raised position.




Closing the bridge will be a reversal of the above procedure. The deck will land on a shock

absorber to bring the deck to a controlled stop as it reaches the fully lowered position.






ItemCost£

Preliminaries 66000


Fencing 1000



Earthworks 12500

Pavements 11000



Street Lighting 500

Electrical 68000








Breakdown of costs:




547000

(150000)

(247000)

(150000)


Total 1,143,500











3.4.6 Advantages


3.4.7 Disadvantages

Deep foundations required for retraction pit will require special measures for confined space

working during construction and maintenance. In addition continuous pumping is likely to be

required to ensure the construction works are free of water.


equipment.

3.5 Option 4: Dutch Style Bascule Bridge


This alternative is similar to option 3 however the counterbalance for the deck will be positioned

at high level carried by balance beams located on each side of the bridge. The balance beams

will be supported on steel “A” frames.

The bridge superstructure will be of steel construction similar to that proposed for the previous

bascule bridge option. Raising the deck will be achieved by hydraulic rams pushing up on the

balance beams located in front of the “A” frame pivot resulting in the main span lifting clear of

the water way.

Due to the extent of the existing south abutment foundations and the proximity to existing

buildings at the south end of the bridge it is considered that the most practicable location for the

retraction pit is behind the existing north abutment. The pit will need to be sufficiently large

enough to allow for the movement of the tail end of the deck and to accommodate the bridge

bearings.



Operation of the bridge will be automatically controlled in the following sequence:




Stop road, cycle and pedestrian traffic

Engage hydraulic rams and raise bridge deck into open position

The control system slows the bridge down as it reaches the fully raised position.

Closing the bridge will be a reversal of the above procedure. The deck will land on a shock

absorber to bring the deck to a controlled stop as it reaches the fully lowered position.






ItemCost

£

Preliminaries 66000


Fencing 1000



Earthworks 7000

Pavements 11000



Street Lighting 500

Electrical 68000










ItemCost£


Breakdown of costs:




614500

(190000)

(259500)

(165000)


Total 1,202,000








3.5.6 Advantages


3.5.7 Disadvantages

Deep foundations required for retraction pit will require special measures for confined space

working during construction and maintenance. In addition continuous pumping is likely to be

required to ensure works are free of water.

Maintenance of the hydraulic cylinders and balance beam bearings will entail working at height.

In addition to gain access to these elements it will be necessary to close the road to traffic which

may require maintenance work being undertaken outside of normal working hours (i.e. at during

night time road closure).


equipment.




3.6 Option 5: Major Maintenance and Strengthening


This option would require a complete refurbishment of the bridge and strengthening of the

lateral steel joists to ensure that the structure could bear the dead and superimposed dead

loads when in an open position. It would also require replacement of the M&E equipment,

which was last tested in June 2006.

The refurbishment and major maintenance of the bridge would require repainting, resurfacing,

abutment strengthening, replacement of the bearings and strengthening of the transverse

members and kentledge area. This option would not include containments parapets.

It would be necessary to close Bridge Road while the works were carried out and a temporary

diversion for HGV traffic and pedestrians provided. This would require accommodation works

on Brent Road, Brent Hill and Flood Lane.

An inspection of the M&E equipment has been carried out by Amey. The inspection found that

whilst the equipment appears to be in reasonably good condition externally, its operational

integrity could not be determined. It was noted that the bridge deck has moved toward the north

abutment, probably due to braking effects from heavy vehicles, and the lifting piston and pintle

bearing are misaligned.

The inspection highlighted safety issues regarding operation of and the protection around the

pressure weights and operation of the pump wheel. The report also cast doubt on the level of

manual handling required to open the bridge. The report concluded that due to these

uncertainties and doubts regarding the method of closing the road for opening, the bridge in its

current condition should remain closed to navigation.

Previous preliminary design proposals by Jacobs have also recommended that access to the

kentledge area and operating mechanisms for inspection and maintenance should be improved

by the provision of an access manhole in the deck of the south span and a gallery area on the

south abutment.

It is estimated that the bridge has a remaining life of 40 years, after which it will require

replacement. This has been included in the whole life cost shown below, assuming a

replacement cost similar to that of option 2.


A drawing showing details of the existing structure is included in Appendix B.







ItemCost£

Preliminaries 44000

Site Clearance 1000

Fencing 1000

Pavements 11000


Electrical 68000




Bridge Bearings 20000



Breakdown of costs:



285500

(125500)

(160000)


Total 642,000






It is estimated that the strengthening and maintenance works will take up to 11 weeks to

construct with a road closure required for approximately 9 weeks.

3.6.6 Advantages

In case of a mechanical failure during either opening or closing of the bridge it would be

relatively easy to manually manoeuvre the bridge back into position.





3.6.7 Disadvantages


equipment. The maintenance of any reused parts of the existing M&E equipment might require

a higher number of site visits than for options 2, 3 and 4.This option does not provide any

improvements to the bridge i.e. widened footways and carriageway; containment parapets;

replacement pedestrian fencing.

3.7 Cost Summary

The estimated budget costs and whole life costs are summarized in the table below.

Option DescriptionBudget works

estimate60 year WLC 120 year WLC

1 Single span fixed bridge £385,550 £431,000 £451,000

2 Replacement swing bridge £962,500 £1,246,000 £1, 379,000

3 Lifting bridge £1,143,500 £1,455,000 £1,537,000

4 Bascule bridge £1,202,000 £1,531,000 £1,655,000

5 Maintenance and strengthening £642,000 £1,267,000 £1,365,000




4 Traffic Impact Assessment

4.1 Traffic Impact Assessment

Initial consultation with KCC’s officer responsible for Swale District, has been undertaken to

discuss the scope for the Traffic Impact Assessment (TIA).

It was agreed at the scoping meeting that a fully classified traffic count should be undertaken on

the existing bridge to determine existing traffic levels during peak periods. This work isn’t

required at this feasibility stage of project development but will be required for subsequent

preliminary and detail design stages. This would allow an initial appraisal of the likely impacts of

closing the bridge for the following scenarios:

Full closure of the bridge during the construction period;

Temporary closure of the bridge when operation has been reinstated.

It was also agreed that following this initial appraisal a further meeting would be held with KCC

to determine whether any further assessment would be required to determine potential impacts

on surrounding junctions and/or diversion routes.




5 Environmental considerations

An initial environmental scoping assessment has been undertaken as part of this feasibility

study.

The following sections are a brief summary of the findings of the desk study which will need to

be considered and addressed by the designer and contractor at the subsequent stages of the

scheme’s development.

5.1 Emissions and Waste

As it is likely that the overall cost of the works for this scheme will exceed £300,000 a site waste

management plan (SWMP) will be required.

5.2 Air Quality

The site does not lie within an Air Quality Management Area (AQMA).

The works will take place on Bridge Road; the site is therefore impacted by vehicle exhaust

emissions and the local residents could be affected.

5.3 Archaeology and Cultural Heritage

The bridge site lies within the Faversham designated conservation area and a search of the

English Heritage website indicates that there are several Listed Buildings located within 300m of

the site. However the search has not identified any Scheduled Ancient Monuments, Registered

Parks and Gardens, Registered Battlefields or World Heritage Sites within the search radius.

Further assessment will be required for subsequent stages of scheme development and the

local Conservation Officer should be contacted to determine as to whether consent is required

as the works lie within a designated conservation area.

5.4 Landscape

The site does not lie within an Area of Outstanding Natural Beauty (AONB).

The scheme will involve aesthetic changes, although the visual impact will vary depending on

what option is chosen. Options 3 and 4 both have visual impact due the lifting of the bridge deck

during the opening phase. Option 4 will have the greatest visual impact due to the elements

which will be permanently visible further afield

The site lies in an area covered by the Landscape Information System (K-LIS) and is

characterised as Eastern Swale Marshes. This landscape character area commonly has the

following features:




Remote, wild and exposed;

Broad skies. Pervasive influence of sea and sky. Creeks, ditches, sea walls.

Grazing marsh; wild birds and grazing animals;

Creekside townscape and waterside buildings; and

Poorly managed fences. Intrusion of power lines.

The site lies within a relatively low lying area and it is predicted that landscape impacts will vary

depending on which bridge design option is chosen. It could be argued that options 3 and 4

(lifting bridge options) will have the most impact upon local landscape as both visible further

afield when raised and option 4 will have structural elements permanently visible.

5.5 Ecology and Nature Conservation

There are no Special Areas of Conservation (SACs) within the a 2km radius of the site however

the Swale is a Site of Special Scientific Interest (SSSI), Special Protection Area (SPA) and is

also a Ramsar. The south bank of the Swale is also a Local Nature Reserve (LNR).

N.B. SPA’s and Ramsar Sites are classed as Designation European Conservation Sites.

Natural England will need to be consulted at subsequent stages of scheme design

development.

According to the National Biodiversity Network (NBN) there are records of bats being present

within the vicinity of the proposed works. Before any works are undertaken an ecologist should

visit the site to determine whether further surveys are required in relation to the presence of

bats.

5.6 Geology and Soils

Further assessment of contamination of the proposed bridge site will be required to determine

as to whether any remediation may be required before the bridge construction works can go

ahead.

5.7 Material Use

No further assessment is envisaged however the following should be considered as the scheme

is further developed:

Sourcing local materials to minimise associated transportation costs.

All waste should be segregated appropriately and stored in a safe manner.

Sub-contractors removing waste from site must possess a current waste carriers license

and all waste processing/disposal sites must also be appropriately licensed.




Consider whole life cost of materials as those that require less maintenance are more

durable.

Consider the presence of Asbestos particularly in the historic mechanical and electrical

equipment.

5.8 Noise and Vibration

Noise sensitive receptors within close proximity to these works include residential properties

and a place of worship The Parish Church of St Mary of Charity which is located approximately

275m to the east of the bridge site.

The following mitigation measures need to be considered:

Noise and vibration should be controlled and limited as far as reasonably practicable so

that sensitive receptors are protected from excessive noise and vibration from

construction.

Best Practicable Means shall be employed to minimise noise levels during construction.

Working hours should be strictly followed.

Advance notice of works should be given to local businesses and residents.

Where local residents are affected by the works, timing and phasing of work during the

construction phase should be considered.

5.9 Drainage and the Water Environment

The site does not lie within a Groundwater Source Protection Zone (SPZ), although a zone III

SPZ lies approximately 25m southeast of the site. The site does however lie within a

Groundwater Vulnerability Area classed as a principal aquifer.

The site also lies in an area vulnerable to flooding every 1 in 100 years.

As the works will take place within 10m of a primary river, consultation with the Environment

Agency must be undertaken to determine as to whether consent will be required for the works to

go ahead.




6 Geotechnical Considerations

6.1 Background Geotechnical Information

No historical information is available for the bridge however geotechnical investigation work has

been undertaken in the vicinity of the bridge location and has been reviewed for this report.

It is understood that the ground investigation was located a short distance to the west of the

site, on the northwest side of Faversham Creek, but the exact location is unknown. The

investigation comprised one percussive borehole to 22m depth and five 3m deep trial pits.

The strata encountered in the borehole is summarised in the table below:

Strata Description Thickness

(m)

SPT / CPT

values

Comments

Made

ground

Concrete and brick

rubble over clay with

flint and brick gravel

1.8 - Hydrocarbon contamination

was noted at 0.75m depth.

Alluvium Soft / firm clay

becoming very soft

2.7 7 at 1.8m

1 at 4m

Hydrocarbon contamination

was noted at 2.5m depth.

Head /

Alluvium?

Shattered flint sand,

gravel, cobbles and

boulders

0.8 22 at 5m

Thanet

Beds

Medium dense fine

sandy clay/silt with

occasional coarse

sand and fine flint

gravel at the top

4.2 26 at 8m

Upper

Chalk

Weak to very weak

white Chalk with

shattered flints.

Becoming hard

below 17.5m

12.5 41 at 9.5m

21 at 11m

22 at 12.5m

40 at 15.5m

50 at 17m

81 at 20m

>50 at 21m

Unfortunately the SPT values are not energy corrected so should be used for guidance only.

Groundwater strikes were recorded at depths of 4.6m rising to 4.45m, 7.2m rising to 5.55m and

9.3m rising to 1.4m. Subsequent monitoring indicated that groundwater was at between 1.25m

and 2.89m depth.




The trial pits encountered between 0.7m and 3.0m of made ground over alluvium. The made

ground varied in composition from sandy / gravelly brick and clinker to dark slightly organic clay

with some flint and brick gravel. A concrete slab was also encountered in TP2 between 0.57m

and 0.7m depth and the remnants of buried walls were recorded in TP1 and TP3. The alluvium

is described as soft to very soft organic clay with occasional flint gravel. Hydrocarbon odour

was recorded in TP2 at 0.7m.

Near neutral pH levels were recorded during the ground investigation and all of the soluble

sulphate levels were less than 0.5g/l.

6.2 Preliminary Geotechnical Advice

Shallow foundations bearing on the made ground and or alluvium are not recommended and

therefore a piled foundation, founding in the underlying Thanet Beds / Upper Chalk, will be

necessary.

Some difficulty may be experienced during excavation / piling if buried obstructions (remnants of

walls, or concrete slabs etc.), or if flint gravel / cobbles / boulders are encountered.

The piles may need to be temporarily or permanently cased through the made ground and

alluvium to ensure the bores stay open.

Excavations are likely to encounter groundwater at relatively shallow depth and therefore a

cofferdam or an appropriate method of controlling groundwater is likely to be required to keep

the excavations dry. It may also be necessary to case the pile bores to seal out the

groundwater.

If hydrocarbon contamination is suspected at the site then a phased contamination assessment

is likely to be required to assess the risk to site workers, the water course and groundwater.

A ground investigation is recommended in order to determine the ground and groundwater

conditions at the site. For preliminary design, this should comprise two 25m deep boreholes,

one either side of the water course, with in situ testing and sampling. Standard geotechnical

laboratory testing (likely to be moisture content, plasticity, grading, pH and sulphate) and

contamination screening should be undertaken.

6.3 Background information

A drawing dating from 1988 indicates that foundation to the south bearings comprises timber

piles, with cast iron shoes, founding in gravel. Unfortunately the length of the piles is not shown

on the drawing.

The records of the British Geological Survey (BGS) indicate that the site is underlain by

superficial alluvium and head brickearth over solid geology comprising Thanet Sand Formation

over the Seaford Chalk Formation.




The BGS records also indicate that there a number of historic boreholes near the site, dating

from 1962 and older. None of the logs for these boreholes contain engineering descriptions or

in situ test results. They do however indicate that the strata present in the vicinity of the site

comprises;

Strata Thickness (m)

Made ground 0.45 to 0.9

Alluvium 2.1 to 4.3

Head Brickearth 0.9 to 4.5

Thanet Beds Below 10.85m in one exploratory hole

Upper Chalk Below 15m in one exploratory hole

According to the records of the Environment Agency the site lies immediately adjacent to an

Inner Zone (zone 1) groundwater catchment area. The site overlies a major aquifer of high

leaching potential. The superficial deposits are designated as being secondary A aquifer, as is

the Thanet Sand. The chalk bedrock is a principal aquifer.

There are a number of small historic landfill sites and an authorised landfill in fairly close

proximity to the site, but no further records are available on the EA website (see screen print

below).

The site plan has been reproduced from an Ordnance Survey map, with the permission of

Her Majesty’s Stationery Office . Crown copyright reserved licence No. 100019238. 2013.

The site lies in an EA designated flood area, at risk from rivers or sea without defences.

.




7 Operation, Inspection and Maintenance

7.1 Operation of Moveable Bridge

It is understood that the operation of the moveable bridge options will be the responsibility of

Medway Ports ltd (part of Peel Ports Group).

Discussion with fabricators suggests that the period of time required for a bridge opening will be

approximately 8 to 10 minutes but this will be dependent upon the type of control system

implemented. A fully automated system with “single button” operation of the signals, barriers

and moveable bridge has been allowed for in the estimated costs.

7.2 Inspection and Maintenance

All five alternative options will require General Inspections (GI) undertaken on a biennial basis

and Principal Inspections (PI) undertaken every six years.

Options 2, 3, 4 and 5 will also require regular inspection and maintenance of the M&E

equipment. The requirements for inspections and maintenance are shown in the table below:

Type Period Estimated Cost

Inspection, and maintenance,

including greasing of moving

parts.

6 months £1000

As above, plus a full review of

electrical components

Annually £2000

Full inspection and Report Every 5 years £6000

Option 4 will require special arrangements for the maintenance and inspection of the M&E

equipment due to some of the elements being at height, requiring either a mobile elevated

working platform or scaffold tower to gain access to the equipment. It would be necessary to

close the road whilst this work is undertaken and it is envisaged that the maintenance work may

need to be undertaken at night to avoid disruption to vehicular traffic. This would add in the

region of £1000 cost to each maintenance visit.

It is possible that installing replacement M&E equipment into the existing footprint will

necessitate additional maintenance work for option 5.




The bridge is located in a low lying area and is liable to be inundated with flood water under

extreme climatic and cyclic tidal conditions. This will result in some elements/ components of

the structure being subjected to contamination with water borne chlorides from seawater. The

structure is deemed to be located in a severe exposure environment which may result in the

early replacement of some of the structures components.

The above factors and the periods for inspection and maintenance have been included in the

appraisal of the whole life costs for each of the options.

7.3 Design Considerations

When designing the M&E equipment for controlling and moving the bridge due consideration

shall be given to providing access to inspect, maintain and replace the equipment.

If necessary, jacking points need to be included in the design to allow for these operations to be

carried out safely. Repainting of the structure will be required on a number of occasions

throughout the service life of the structure and this will need to be considered at the detail

design stage to avoid undertaking in a confined space.

7.4 Health and Safety

The moving bridge options present significant hazards to operation, inspection and

maintenance, hazard management will need to be fully developed in co-ordination between the

civil engineering and M&E designers at future stages of design development.

Of particular concern will be the restriction of public access to the bridge site whilst the bridge is

moving. A closed circuit television system (CCTV) is considered necessary to ensure that the

operator has full visibility of sight restricted areas when opening or closing the bridge. A cost of

£30,000 has been allowed for provision and installation of the CCTV in the relevant option cost

estimates.

Maintenance and inspection for option 4 would entail working at height requiring special

equipment and possibly working outside of normal working hours. In addition there is a risk that

failure of the hydraulic rams or pipes could result in an oil spillage, consideration would need to

be given during the detailed design stage to investigate mitigation for this risk e.g. provide

containment to the items of equipment which could fail or leak oil. The designers will also be

required to provide a manual for operation and maintenance for the structure.




8 Stakeholders

8.1 Stakeholder Consultation

Stakeholder liaison was excluded from the scope for this report. However local businesses have

been contacted to discuss the implications of closure of the road due to the construction works.

The effects of proposed work should be planned with full consideration of the impact on all

stakeholders and all reasonable measures to eliminate or mitigate detrimental effects should be

taken.

It is recommended that a full public consultation exercise should be carried out during the

preliminary design stage for the scheme.

8.2 Principal stakeholders

The principal stakeholders identified at this stage include the following organisations and

groups:

Road users

River users

Kent CC Education & Learning Department

Swale District Council

Faversham Town Council

Environment Agency

Natural England

Medway Ports Ltd (Peel Ports)

Emergency services (Police, Fire and Rescue and Ambulance )

Statutory Undertakers

BMM Weston

Shepherd Neame Brewery

Brents Tavern PH

The Albion PH

Little Moon Beams (Day Nursery)

Brent Industrial Estate




9 Discussion and Recommendations

9.1 Cost comparison

It can be seen from the cost summaries included in Section 3 above that Option 1 has the

lowest capital and whole life costs. It is also considered that this option would require the least

ongoing maintenance.

For the moving bridge options; option 5 has the lowest budget cost for design and construction.

However, the whole life costs for options 2 and 5 are very similar such that the cost for option 2

is marginally lower over 60 years and marginally higher over 120 years. There is little to choose

between options 3 and 4, both have similar costs for design and construction however the

whole life costs for option 4 are the greatest of all the considered options.

9.2 Time of construction

Option 1 will be the quickest of the three options to construct and therefore will result in less

disruption to the public.

Options 2, 3, 4 and 5 have similar construction periods and also require a road closure for a

similar length of time.

9.3 Operation and maintenance

Options 2, 3, 4 and 5 will require significantly more attendance for inspection and maintenance

than option 1. The cost for this work has been included in the whole life costs for each option.

9.4 Advantages and Disadvantages

Options 2, 3, 4 and 5 would enable access for water craft access the upper basin of Faversham

Creek however the fixed bridge (option 1) will limit the size of watercraft on the navigable

waterway and would prevent the upper creek from effectively functioning as a navigable

waterway.

9.5 Recommendations

If the scheme is to be developed to preliminary and detail design stages it is recommended that

the following information is obtained:

Topographical survey

Geotechnical investigation and report




Environmental assessment

Traffic impact assessment

In addition the costs for the following will need to be considered:

Provision of power supply

Fendering

Dredging of the basin

Repair to lock gates



Doc. Ref.: CO04300132/02 Rev 03 - A-1 - Service is our passion. People, our strengthIssued: May 2014

Appendix A Cost Estimate Coverage




Item Coverage

Preliminaries Construction site accommodation, offices

stores etc.

Traffic and pedestrian diversions.

Site Clearance Clearing site.

Demolition of existing structures.

Fencing Temporary fencing to secure site.

Road Restraint Systems Parapets and pedestrian guard railings.

Drainage and Service Ducts Drainage system.

Earthworks Excavation, Fill material and topsoiling.

Pavements Road construction.

Kerbs, Footways and Paved Areas Kerbing and footways.

Traffic Signs and Road markings Re-erection of signs and new white lines.

Street Lighting Re-erection of lighting columns.

Electrical Connection to electricity supply.

Automatic barriers and lights.

CCTV.

Underwater power/ communications link.

Piling and Embedded Retaining Walls Underpinning of existing abutment

foundations.

Piling for retraction pit foundations.

Structural Concrete Reinforced concrete (RC) elements

including:

In situ RC deck slab.

Precast bridge beams, bank seats

and walls

In situ RC retraction pits

Protection of Steelwork Against Corrosion Protective paint system to steel members

Waterproofing to Structures Waterproofing system to reinforced

concrete members i.e. retraction pits and

bridge deck

Bridge Expansion Joints Nosing joints at abutments

Brickwork, Blockwork & Stonework Masonry repairs to existing abutment walls




Item Coverage

Special Structures Designed by the

Contractor

Design, fabrication, installation and

commissioning of the following:

Steel bridge deck.

Steel frames and counterweights

Mechanical equipment

Electrical control system

The cost estimates do not include the following:

Scheme design development

Land licences or acquisition

Provision of power supply

Fendering

Dredging of the basin

Repairs to lock gates



Doc. Ref.: CO04300132/02 Rev 03 - B-1 - Service is our passion. People, our strengthIssued: May 2014

Appendix B Options Drawings

500 1500 3000 1500 500

150

11 No. Precast Prestressedbeams (Type SBB S8)

500

300

7980 (clear span)3520 3520

Masonry / Brickwork repairsrequired to both abutments

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Drawing Title

Original Drg Size :Scale :

Client

Dimensions :A3

Rev

Revision details

Date:

Drawn:

Chkd:Appd:

Design:

Rev

As constructedFor constructionFor tenderFor comment

Chkd Appd Date

Preliminary

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JWSLRCSL14.11.2013

Other

BRENT SWING BRIDGEKCC Structure No. 1277

STRUCTURES

OPTION 1:FIXED BRIDGE

As Shownmm

CO04300132/30/101 02

PLANScale 1:100

EAST ELEVATIONScale 1:100

TYPICAL CROSS SECTION LOOKING SOUTHScale 1:50

1000 high vehicle parapetN1/W2 with vertical infill

100 slab100 surfacing1:40 1:40

Spray applied waterproofing membrane

Kerb lines to be tied intoexisting kerbs at both ends

1000 high guardrailing at approaches

NOTES1. All measurements are in millimetres unless

stated otherwise. All levels are in metres.2. Do not scale from this drawing, use written

dimensions only.

01 Minor amendments RC SL 15.11.1302 Elevation revised RC SL 14.02.14

5500 11000

Pintle bearing

Nose bearings

Tail wheel track

LC of pintlebearing

Masonry / Brickwork repairsrequired to both abutments

Automatic barrierand warning lights

15003000450

Deck plate

UB main beamsTransoms @ 2000 c/cTee stiffeners

Proprietary combined water-proofing and anti-skid surfacing

Stiffeners at 2000 crs.

LC of pintle bearing

Insitu reinforced concreteabutment slab

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STRUCTURES

OPTION 2:SWING BRIDGE

As Shownmm

CO04300132/30/102 03

Nose bearing

Precast reinforced concretebearing beam and ballast wall

1000 high vehicle parapet N1/W2 with vertical infill

Kentledge

PumpHouse

Hydraulic wedgesand jacks



dimensions only.

Kerb lines to be tied intoexisting kerbs at both ends

1000 high guardrailing at approaches

01 Minor amendments RC SL 15.11.1302 Sect. B-B amended AJM SL 19.11.13

PLANScale 1:100

EAST ELEVATIONScale 1:100

TYPICAL CROSS SECTION LOOKING SOUTHScale 1:50

02 Redrawn AJM SL 18.02.14

Deck to lift clear of watercourse

Line of handrail stepped toallow for rotation of deck



dimensions only.

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STRUCTURESOPTION 3:

LIFTING BRIDGEEAST ELEVATION Sht 1

As Shownmm

CO04300132/30/107 01

EAST ELEVATION (OPEN)Scale 1:100

EAST ELEVATION (CLOSED)Scale 1:100

01 Power pack &hydraulic ram movedinto retraction pit

RC SL 25.02.14



dimensions only.

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Other


STRUCTURESOPTION 3:

LIFTING BRIDGEEAST ELEVATION Sht 2

As Shownmm

CO04300132/30/108 01

EAST ELEVATION (HALF OPEN)Scale 1:100

01 Power pack &hydraulic ram movedinto retraction pit

RC SL 25.02.14



dimensions only.

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STRUCTURESOPTION 4:

BASCULE BRIDGEEAST ELEVATION Sht 1

As Shownmm

CO04300132/30/109 P0

EAST ELEVATION (CLOSED)Scale 1:100

Deck to lift clearof watercourse



dimensions only.

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STRUCTURESOPTION 4:

BASCULE BRIDGEEAST ELEVATION Sht 2

As Shownmm

CO04300132/30/110 P0

EAST ELEVATION (OPEN)Scale 1:100



Doc. Ref.: CO04300132/02 Rev 03 - C.1 - Service is our passion. People, our strengthIssued: May 2014

Appendix C Temporary Diversion Route

Brent Swing Bridge

Two way

Single way working undertraffic signal control

3 way signals required atBrent Hill/Davington HillJunction

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AJMSLRCSL19.11.2013

Other

BRENT SWING BRIDGEKCC STRUCTURE

No. 1277

STRUCTURES

DIVERSION ROUTE

As Shown-

CO04300132/30/105 01

Ordnance Survey Map with the permission

of the Controller of Her Majesty's Stationery Office.

Based upon or reproduced from the TR06SW1:10,000

01 Redrawn AJM SL 19.11.13



Doc. Ref.: CO04300132/02 Rev 03 - D.2 - Service is our passion. People, our strengthIssued: May 2014

Appendix D M&E Inspection Report



Doc. Ref.: CO04300132/02 Rev 03 - E.1 - Service is our passion. People, our strengthIssued: May 2014

Brent Swing Bridge, structure ref. 1277 – Visual Inspection 17th April 2014

Review comments of Medway Ports - Bridge Operations Document and Peel Ports – Marine

Operations - Report on Lifting Mechanism

The brief was to review the Mechanical and Electrical operating system of the Brent Swing

Bridge. The review was undertaken by Derek Cox (Amey). Also present were

representatives from Kent County Council (KCC), Peel Ports and Dave Dale (Amey)

While it was possible to gain access to most areas, any information regarding the principle of

operation, in relation to what was clearly pumping equipment, was not readily available on the

day of the site visit.

However, various Internet searches and the Jacobs Principle Inspection of November 2011

indicate the lifting mechanism is hydraulic, although anecdotal information gained from

engineers familiar with the bridge suggests that the lifting action is achieved by utilising water

pressure.

Documents supplied by Peel Ports provided information on the operation of the mechanism.

Medway Ports Marine Department – Bridge Operations

It would appear that the purpose of the hand-operated pump is to raise the

accumulator. (Large weights in the pump house)

The opening process/raising of the bridge is achieved by movement of hydraulic

water pressure that is applied to the lifting ram located under the bridge after opening

and closing a series of hand-valves in the pump-house.

There appear to be options of gaining bridge movement from fully open to fully closed

by utilising the winch located close to the pump house and a travelling block. This

seems to involve relocating the winch hook to different locations of the bridge and

handrail during its rotation and securing the travelling block to the storeroom opposite

the pump house. In all likelihood the winch would only be used if it proved difficult to

move the bridge manually.

Review Comments:

The current method of closing the highway is outdated when compared to modern

standards and it is unlikely that the current gates and red-lamp for nighttime closures

could be accepted under current standards.

The integrity of the associated pipework and operational readiness of the control

valves and the lifting ram mentioned in the procedure are unknown.

The accumulator lowering area within the pump house is unguarded.




Report Findings:

The Brent Swing Bridge has not been operated for over 15 years and whilst the

pumping equipment in the pump house at the south east corner of the bridge looks

in fairly good external condition, its operational integrity is unknown.

The principle of operation also remains unknown, but it would appear that the piston

inside the large ram sited below the pintle bearing engages with the bearing when

pressure is applied and raises the structure off of the north and south abutments and

central bearing points.

The structure, when raised, balances on the ram piston and it is assumed that the

rotation/swinging motion is manually applied to the southern end of the bridge. It is

unclear if this is a single man operation, but there is a cable winch in the pintle area

close to the pump house and a hook locating ring fixed to the south west kerb area

beneath the pedestrian railing and it is understood that this was used to overcome

any difficulties initially encountered when moving the structure.

Also located at the southern end of the structure are the Kentledge box and bridge

tilt wheels.

The deck superstructure appears to have moved and is now in contact with the

northern abutment face. Consequently there is a visible misalignment between the

lifting ram piston and pintle bearing such that the ram is no longer in contact with the

pintle bearing.

Although not clearly visible, it is understood that there is uncertainty regarding the

integrity of the steelwork securing the pintle bearing to the bridge deck.

Housed in the north west building is a 12 Volt DC hydraulic power pack, batteries,

charger and a small quantity of electrical relays and timers that when triggered by

float switches, control the small flap/gate situated at the base of the north sluice gate.

Both the south east and north west buildings have a single-phase 240-volt AC power

supply. Both are metered, which would indicate they are separate incomers.

Summary:

The importance of the structure from a highway access perspective was emphasised by KCC

and while a live test of the equipment might be considered worthwhile, the potential disruption

would likely be unacceptable.

As documented above, the operational procedure is unknown, but clearly within the pump

house there are large weights currently at ceiling height and it is assumed that these lower

imparting pressure into the hydraulic lifting system. From a health and safety perspective, if

these weights do lower then this area must be securely protected. It is also unclear what the

function of the pump is and how much effort is needed to operate it, but there is clearly limited

space to turn the hand-wheel and the grip appears to be fixed, and would therefore not rotate




within the operators grip. It is also doubtful that the manual effort needed to rotate the

structure would meet current manual handling regulations.

Given the clear uncertainties regarding the integrity of the installed equipment, the tranverse

joists, the operational procedure, the associated pipework and the current method of closing

the highway, it is recommended that the bridge remains closed to navigation.

The extract from the Jacobs PI report of 2011 is included below.

8.0 – Jacobs Conclusion

The structure is in fair to poor condition and several significant faults have been identified.

Intrusive investigation works and remedial works have been recommended for different

elements of the structure, depending upon whether or not the bridge is to be opened in future.

It is a matter of concern that several inaccessible items, which must be assumed to be in poor

condition, as explained in the commentary on section 7.1, and cannot readily be inspected or

maintained.

For example the south bearings might be visible with the aid of an endoscope, but it is not

possible to assess their condition, or to maintain them.

It must be noted also that the paint system is known to be lead based, so that any

strengthening and maintenance operations will require special protection to be put in place for

the safety of the workforce and the environment.

The recommendations tabulated in section 7.1 are the basic measures needed to maintain

the stability of the existing structure.

A full list of recommendations will form part of the Feasibility Report referred to in item 2.2

because the work recommended will depend to some extent upon the results of the structural

assessment, residual life and fatigue life assessment.




Peel Ports – Marine Operations 23rd October 2007

Report on Road Lifting Mechanism at Faversham

Pump and accumulator proved operational under local test within the pump house.

The ram under the bridge was not tested, as this would require raising the bridge.

Poor condition of road closure barriers

The wheels on the turntable are covered in debris and would need testing before any

movement of the bridge was attempted

Review Comments:

The report confirms the hydraulic fluid is a 50/50 mixture of water and antifreeze that

should be drained and replaced. It does not establish if there is a mains water

supply. In addition and when drained, the current fluid would be classed as

hazardous waste and therefore need to be disposed of accordingly.

It is assumed that the 20mm deflection of the bridge at the northern abutment when

heavy vehicles pass over has now been addressed.

Conclusion:

The condition of the structure is documented in the Jacobs Principal Inspections Report of

November 2011. Peel Ports reported the condition of the Road lifting mechanism in October

2007.

Both reports cast doubt on the integrity of certain areas of the structure, its operational

readiness in relation to the installed equipment and compliance with current traffic

management requirements.

It is also unclear if there has been a recent risk assessment carried out in relation to the

operating procedure and whether there would be manual handling issues relating to moving

the structure.




Appendix E Bibliography




STRUCTURE RECORD REPORTS:

Brent Swing Bridge – Feasibility Report (April 2012) - Jacobs

Brent Swing Bridge - Principal Inspection Report (November 2011) – Jacobs 2011

Historical Report on Brent Swing Bridge – KCC Structure No. 1277 (October 2004)

Hydraulic Mechanism(s) Testing Report (Untitled). Medway Ports memorandum 7th June 2006.

Report on Road Lifting Mechanism. Medway Ports unreferenced report 23rd October 2007.