2 The Proposed Scheme and Alternative Design Options · PDF file2 The Proposed Scheme and Alternative Design Options ... thrust bored culvert below ... for the west interchange junction

4 715/M8 MOTORWAY & GREENOCK ROAD (A8), INCHINNAN CASS ASSOCIATES ROYAL ORDNANCE, BISHOPTON MARCH 2015

2 The Proposed Scheme and Alternative Design Options 2.1 This chapter will examine the need for the scheme, alternative design options and the selection of the preferred

scheme. It will also give a full description of the scheme and the benefits that will be derived and will give a commentary on construction programme, construction methods and operational requirements.

Need for the Scheme

2.2 The Transport Assessment for the mixed use regeneration project at the BAE Systems site identifies the constraints on the local road network at different stages of the development. The assessment concludes that there is capacity for a limited amount of development without significant intervention but that beyond a threshold there is a clear requirement for a new connection to the trunk road network.

2.3 The need for the scheme is linked to the delivery of a regeneration project which is of national significance. Bishopton is recognised as a strategic location for growth in National Planning Framework (NPF) and is the key Community Growth Area to the west of Glasgow (Glasgow and the Clyde Valley Joint Structure Plan).

Scheme Description

2.4 The proposed M8 / Greenock Road interchange will incorporate direct Eastbound on and Westbound off ramps between the A8 Greenock Road and the M8 motorway constructed as a half diamond south of the A8 underbridge. Design year traffic forecasts (weekday AM and PM peak) for the new interchange including the development generation have been extracted from the Transportation Assessment Report and are summarised below in Table 2.1.

Table 2.1: 2027 Design Year AM & PM Peak Interchange Traffic Flows

AM Peak Eastbound Westbound Total

Greenock Road west of Interchange 1186 722 1908

M8 Off Ramp 591

M8 Overbridge 1217 163 1380

M8 On Ramp 883

Greenock Road east of Interchange 418 246 664

PM Peak

Greenock Road west of Interchange 842 863 1705

M8 Off Ramp 691

M8 Overbridge 923 251 1174

M8 On Ramp 758

Greenock Road east of Interchange 305 389 694

2.5 The design of the interchange merge and diverge tapers has been assessed utilising Technical Memorandum TD22/06 from the Design Manual for Roads & Bridges (DMRB). The M8 motorway at the location of the Greenock Road Interchange has a two lane carriageway with hardshoulders. Utilising the peak hour traffic demand figures the specification of the merge taper has been established using Figure 2/3 and Table 4/3 of TD 22/06 as a Type B parallel merge. Similarly the specification of the diverge taper has been established using Figure 2/5 and Table 4/4 of TD22/06 as a simple Type A taper diverge.


2.6 The specification of the carriageway width (cross section) for the interchange slip roads are detailed in Figure 4-1b of TD 27/05. On a rural motorway slip road a diverge ramp with a single lane (3.70m wide with 2.30m hard shoulder) can accommodate a design flow up to 900 vehicles per hour. A design flow of up to 1350 veh/hr on a merge (on ramp) can be accommodated on a single lane ramp (3.70m wide lane with 3.30m hard shoulder). Single lane on and off-ramps would therefore provide adequate capacity to cater for predicted peak hour traffic demand.

2.7 In its current condition, Greenock Road crosses the M8 on a reinforced concrete underbridge which is to be retained. The road is essentially straight, and rises gently from either direction towards the underbridge. Greenock Road is a rural road at this location, subject to the national speed limit (60mph). As part of the proposals, the speed limit through the interchange will be reduced to 40mph.

2.8 The proposed interchange will incorporate direct Eastbound on and Westbound off ramps between Greenock Road and the M8 Motorway. Connections to Greenock Road will be by means of roundabouts. The on and off ramps measured from the physical nose points are approximately 360m and 525m long respectively. The ramps are one lane wide with hardshoulders.

2.9 The west roundabout comprises four arms, serving Greenock Road west and east, the new off ramp and a new access road to Craigmuir Farm, the existing link to which becomes severed due to the road realignment. The east roundabout comprises three arms, serving Greenock Road west and east and the new on ramp.

2.10 Pedestrians will be accommodated by footways to the north of the A8 alignment with a provision for cyclists. The roundabouts will be lit by street lighting.

2.11 Road Restraint Systems will be provided as determined by the risk assessment procedures laid down in the DMRB supplemented as necessary by the Designer’s individual assessment. High Friction Surfacing will be located on all approaches to both roundabouts and on the bend of the off ramp as per DMRB requirements.

2.12 The interchange will comprise elements which fall under the maintenance burden of both Transport Scotland and Renfrewshire Council, and as such separate drainage systems incorporating SUDS treatments and attenuations will be provided at strategic locations adjoining the junction discharging to the existing or diverted watercourses.

2.13 Local diversion of minor watercourses and drainage ditches will be required to accommodate the new road alignments, as well as a new thrust bored culvert below the M8.

Alternative Design Options and the Preferred Design Solution WEST INTERCHANGE JUNCTION

2.14 In relation to the design of the junctions between Greenock Road and the motorway ramps the total traffic volume entering the junction and the relative size of the traffic movements that have to be accommodated were considered along with the physical constraints.

2.15 At the west interchange junction (off-ramp junction) the predominant traffic volumes are Greenock Road (eastbound) and M8 off-slip to Greenock Road (westbound).

2.16 Other than land ownership the most important physical constraint imposed on the design of the west interchange was the necessity to avoid intrusion into the former landfill site located south of Greenock Road and west of the M8 motorway.

2.17 Optional layouts considered for the design of the west interchange junction including a channelised priority controlled junction, traffic signals, roundabout and merge taper were discussed with the Local Roads Authority and Transport Scotland.


West Interchange Junction – Channelised Priority

2.18 A channelised priority junction was initially considered where priority was maintained on the major dominant traffic movements (Eastbound A8 and M8 off Slip-A8 westbound) to maximise capacity and minimise the overall level of delay at the junction. This would produce an unconventional junction layout where traffic on Greenock Road westbound would have to ‘giveway’ to the albeit larger traffic movement flowing between the M8 off-ramp and Greenock Road (west).

2.19 In order to maintain appropriate geometry for the speed of traffic on the Link Road between the M8 Off-ramp and Greenock Road (west) the alignment of the off-ramp slip road would encroach into the landfill site. This would require the excavation of waste material, new retention measures and the containment of ground water leachates.

2.20 The Roads Authority was concerned that this junction configuration would encourage high speeds through the junction. In addition the Roads Authority were of the opinion that the level of traffic attracted to the new Bishopton Interchange (destined for Inchinnan) was underestimated and the channelised layout would not cater adequately if this demand arose.

West Interchange Junction -Traffic Signals

2.21 The provision of a simple traffic signal controlled junction was also considered. This method of junction control could be tailored to provide adequate capacity (greentime) to the dominant movements thereby minimising junction delays. The conventional junction layout incorporating a stop condition between the M8 off-ramp and Greenock Road (west) can accommodate a tighter geometry compared to the channelised priority junction and therefore a more compact junction layout could be produced. However, the off-slip would still encroach into the landfill site.

2.22 There are specific regulations in the DMRB regarding the installation of traffic signals on high speed roads. Gap accepting right turn manoeuvres are not acceptable and anti-skid surfacing is required on the junction approaches. In addition the Roads Authority is required to comply with a strict maintenance regime including frequent and regular inspections of the installation.

2.23 The Roads Authority, because of the safety issues relating to traffic signal installations on high speed roads, takes the view that this form of junction control should be seen as a last resort solution and would only be considered if there was no suitable alternative.

West Interchange Junction - Roundabout

2.24 Roundabout junctions operate more efficiently when traffic demand on all approaches are in balance and there are no dominant movements. Four arm junctions are more efficient than three arm roundabouts for this reason. At the proposed Greenock Road West Interchange junction because of the restricted connections to the motorway (east facing ramps only) and the one way nature of the on and off ramps there are dominant unopposed movements.

2.25 The operational assessment of a roundabout for the west interchange junction indicated that two lanes of traffic on approach to and through the junction would be required to accommodate the major traffic movements (A8 eastbound) during the AM peak.

2.26 Single lane approaches flaring to two lanes on entry and through the junction (A8 eastbound & off-slip to Bishopton) with extended merges (two lanes back into one) on the eastbound A8 Greenock Road exits would be required to accommodate predicted traffic demand.

2.27 The provision of the merge on the eastbound exit dictates the position of the roundabout some 300m west of the existing M8 overbridge. A roundabout with an Inscribed Circle Diameter (ICD) of ~40m centrally located on


Greenock Road would be required to achieve entry path deflection and forward Stopping Sight Distance in compliance with the DMRB. In this location the off-ramp slip road would encroach into the landfill site.

2.28 The Roads Authority were of the opinion that a roundabout solution incorporating single lane approaches flaring to two lanes on entry and through the junction with merges (two lanes back into one) on the eastbound A8 exit would be acceptable and were aware of existing junctions incorporating this feature which they considered operated safely and efficiently.

West Interchange Junction – Merge Taper

2.29 A simple merge taper between the M8 off-slip and the A8 westbound carriageway was also considered. This solution would essentially remove the west interchange junction and any significant delays to the A8 and M8 off-slip traffic. The minor movement of traffic between the M8 and Inchinnan would be accommodated as a u-turn manoeuvre at the proposed Bishopton South Access roundabout to be located on Greenock Road ~500m west of the Motorway. This solution would enable the off-slip ramp to be constructed close to the motorway and consequently would have minimal intrusion into the landfill site.

2.30 The Roads Authority did not like the diversion imposed on Motorway to Inchinnan traffic and were concerned that the omission of the west junction could preclude the simple improvement of the Interchange in the future to provide north facing ramps. It also expressed concern that the merge taper would present a danger for cyclists and could not support a solution with this feature.

West Interchange Junction – Preferred Solution

2.31 Considering all options it was apparent that a solution based on a roundabout junction was the preferred solution. A roundabout incorporating single lane approaches through the junction with extended merges (two lanes back into one) on the eastbound A8 Greenock Road exit to cater for the AM Peak Flows would be acceptable in capacity terms.

2.32 This solution would still have an impact on the landfill site however offsetting the roundabout to the north of Greenock Road would allow the alignment of the off-ramp to be constructed close to the motorway and consequently minimise intrusion into the landfill site.

2.33 The Roads Authority has advised that in association with the new interchange they would consider imposing a 40mph speed limit west from the proposed east interchange junction and a 50mph speed limit between the east interchange junction and the Red Smiddy roundabout.

2.34 The vertical alignment of the off-ramp has also been designed to position the carriageway above existing ground levels to maintain forward visibility and thereby further avoid the possibility of intrusion into the landfill.

2.35 The preferred west interchange junction layout is shown in Figure 2.1. The overall junction ICD has increased to 80m in order to accommodate the flared dual carriageway approaches on Greenock Road and ensure the requisite entry path curvature in accordance with the DMRB.

GREENOCK ROAD - EAST INTERCHANGE JUNCTION

2.36 In relation to the design of the east interchange the total traffic volume entering the junction is significantly less than the west interchange junction. The major eastbound traffic flow on the Greenock Road (west) approach is distributed at this junction between the Greenock Road (east) and M8 on-ramp exits with the predominant traffic movement taking place between Greenock Road (west) and the M8 on-ramp.

2.37 A priority junction would not be suitable in operational terms due to the high predominant right turn manoeuvre between Greenock Road (west) and the M8 on-ramp and the Roads Authority would have concerns that this method of junction control would maintain high vehicle speeds in the vicinity of the junction.


2.38 A traffic signal controlled junction solution is seen as a last resort solution by the Roads Authority for a new junction on a high speed road and would only be considered if there was no suitable alternative.

2.39 In common with the west interchange design a roundabout solution would be the preferred solution. The operational assessment of a roundabout for the east interchange junction indicated that simple flared approaches would be adequate to cater for predicted traffic demand. Individual traffic movements can be accommodated in single lanes and therefore extended merge areas on the junction exits are not required. Consequently a roundabout with an ICD of 60m would be adequate to accommodate appropriate entry path deflection. The preferred east interchange junction layout is shown in on Figure 2.1.

General Design and Construction

Land Take

2.40 All land required for the interchange will be under the control of the developer once the requisite land agreements are crystallised into land transfers. The total land take required for the scheme is 12.4 ha, of which 5.0 ha is under the ownership of the Scottish Ministers, and the remainder – including the adopted A8 carriageway maintained by Renfrewshire Council – belongs to private landowners. The land owned by the Scottish Ministers comprises narrow strips adjacent and parallel to both carriageways of the M8 motorway, as well as an area to the west of the motorway where a former slip road was located. Renfrewshire Council maintain narrow strips to either side of the A8 Greenock Road. Those private parcels are generally in agricultural land, although the western extents of the scheme will occupy the periphery of a former landfill which has now been closed, capped and returned to agricultural use.

2.41 Some gross areas for the scheme (excluding off-site sign works) are as follows:

• Area within permanent fence boundaries – 9.42 ha

• Areas for attenuation ponds – 1.03 ha

• Servitude area for contractor’s site compound/temporary stockpiles, etc. – 1.95 ha.

2.42 All construction work will take place within the limit of the land made available.

2.43 Due to the nature and extent of the roadworks proposals diversions for Scottish Power (existing 11kv overhead line) and British Telecom (existing underground duct and cable network) will be required. All other public utility services, including gas and water are unaffected by the proposals.

2.44 Motorway communications will also require to be diverted prior to construction of the slip road tie-ins.

Structures

2.45 The existing A8 Greenock Road underbridge is to be retained in its entirety.

2.46 A new earthworks embankment is to be constructed over a length of the new on ramp.

Road Drainage

2.47 The proposed drainage system will comprise a Sustainable Drainage System (SUDS) to provide treatment and attenuation to run off from the interchange (see SUDS Masterplan Figure 2.2). The SUDS will also facilitate the management of accidental spillages by enabling the isolation of run off to prevent potential pollutants from discharging to controlled waters. In addition to retention ponds, source control methods such as filter and off-edge drains will also be incorporated. Three new retention ponds are to be constructed as part of the proposed works, and existing ponds located immediately to the west of the M8 are to be reconfigured but in the main retained as they provide important treatment to surface water run offs from the historic landfill site. All drainage will ultimately run to existing outfalls and watercourses, the most significant of which is the Linn Burn, a tributary of the River Gryffe.


2.48 Principal quantities are:

• 150mm diameter pipe – 3,920m

• 225mm diameter pipe – 2,105m

• 300mm diameter pipe – 805m






2.49 An existing 900mm diameter culvert requires to be extended below the new on slip under the proposed scheme and a new surface water crossing below the M8 is required.

2.50 Existing bridge deck drainage from the Greenock Road over bridge will be tied into the new system.

Earthworks

2.51 Earthworks will involve the creation of embankments as well as the construction of the drainage attenuation ponds mentioned above and local watercourse/drainage ditch realignments.

2.52 Tar materials and site clearance items will be removed off site for disposal.

2.53 Due to the presence of soft underlying material, the new embankments will be built in advance of the main works to encourage a controlled but accelerated ground settlement. The embankments may be surcharged. The settlement will be aided by the introduction of band drains and the embankments will be monitored for settlement. This will effectively create a two stage construction period where enough time will be allowed to facilitate the majority of settlement to take place.

2.54 The surcharge material for the embankments – if required – will comprise a mix of topsoil and excavated unsuitable material which will be segregated from the permanent embankment material by use of a membrane to alleviate cross contamination. Following the completion of settlement period the surcharge will be removed to form landscape fills on site.

2.55 It is assumed that the majority of the structural fill material will be imported and that excavated material will generally be unsuitable for re-use as fill, although some of the arisings from the attenuation pond excavations may be suitable.

2.56 Approximate bulk earthworks quantities for the scheme are as follows:

Element Cut Material Volume (m3)

Fill Material Volume (m3)

Off-slip incl. roundabouts and A8 realignment 25,830 73,080 On slip including roundabout 8,860 65,350 SUDS ponds 7,040 1,570 Total 41,730 140,000

2.57 Note these figures make allowances for topsoil placement and local removal/deposition of landscape fills (approximately 33,000 cubic metres) but do not include for drainage fills or road construction above formation (underside of sub-base) levels.


2.58 Pre-earthworks drainage will be constructed before commencing topsoil stripping and bulk filling. Fill will generally be spread and compacted using dozer and roller.

2.59 Soft landscaping will be carried out during the appropriate planting season and to suit the placing of landscape fills. Realignment of watercourses will be carried out in periods of low flows and to minimise disruption to main earthworks. Ditches will be installed with local pollution control measures, eg. straw bales/terram fences to minimise pollution.

Lighting and Fencing

2.60 The roundabouts will be lit locally by street lighting, designed to maintain safety of the road user whilst minimising light pollution effects in this rural area and to minimise the impact on flight operations from Glasgow Airport.

2.61 Temporary and permanent fencing will be required during construction and operation of the junction to contain working areas and subsequently prevent unauthorised access and stock movements, maintaining safety for the public and road users.

2.62 The principal requirements are:

Permanent fencing:

• On all new permanent land boundaries, post and five rail fences are to be constructed.

• Additionally Rylock Stock proof fences are to be installed around new SUDS ponds.

• On existing boundaries, post and wire fences are to be retained.

Temporary fencing:

• Contractor’s areas including site compounds to be fenced for the duration of the works utilising Chestnut Paling or re-locatable Heras fencing dependant on location.

Landscaping

2.63 A landscape design has been developed for the proposed scheme which minimises adverse visual effects on the local landscape character. Landscape mitigation and enhancement includes: recommendations in relation to earthworks and SUDS design; public access reinstatement considerations and landscape planting. The proximity of Glasgow Airport has also been considered in planting selection to discourage large numbers of birds, particularly around and on the open water bodies.

CONSTRUCTION

Construction Programme and Working Hours

2.64 It is anticipated that the construction of the interchange would commence with an initial advance earthworks package at the interface with the landfill to the west of the junction. The detail and environmental implications of these works are addressed in Chapter 12 of the ES.

2.65 Phase 2 would encompass ground stabilisation and embankment construction works designed to expedite settlement of the embankments to tolerable levels prior to completion of the road corridors. It is envisaged that a settlement period of around 1 – 2 years may be necessary to induce the necessary degree of settlement to safeguard the road construction prior to the final drainage, surfacing and finishing works being undertaken.

2.66 Phase 3 encompassing the completion works for the junction is expected to run over a period of 15 months.

2.67 Working hours for those activities requiring the use of heavy plant and equipment are stipulated by the planning consent to be limited to:


07.30 – 18.00 Monday to Friday

07.30 – 13.00 Saturday

2.68 Extensions to these times and works on Sundays and Bank Holidays are prohibited unless by prior consent is approved by the planning authority.

2.69 Some working outwith the designated hours will be required due to traffic restrictions on the M8 and these will require to be planned and agreed in advance. Noise restrictions by Renfrewshire Council will also apply..

Construction Activities and Plant Requirements

2.70 Construction of the proposed interchange will involve the following elements of work which are set out in anticipated chronological order:

• Advance landfill interface to roads corridor.

• Advance earthworks comprising ground stabilisation and embankment construction as well as associated public utility diversions.

• Advance works – M8 communication ducts re-aligned or protected.

• Fencing.

• Realign existing watercourses.

• Pre-earthworks drainage and attenuation ponds.

• Construction of embankments including drainage blanket, band drains and surcharge material.

• Settlement period.

• Remove surcharge material to landscape areas/off site.

• Install drainage, formation, sub-base and roadworks.

• Roadwork finishes, lighting, safety barrier, signing and lining.

• Landscaping.

2.71 Careful consideration is required in the sequencing of the construction of the new roundabouts on the A8 Greenock Road to ensure a free flow of traffic through the junctions is maintained at all times. Access to Craigmuir Farm will also be maintained at all times.

2.72 Plant requirements for the construction operations will include:

• 360° excavators (tracked and rubber tyred).

• Articulated dump trucks.

• Bulldozers and grading equipment.

• Tipper and articulated trucks of various sizes.

• Hyab type trucks.

• Agricultural tractors and trailers including water.

• Light commercial cars and vehicles.

• Tar laying equipment.


Construction Site Access

2.73 Generally construction access will be taken off strategic locations on the existing A8 Greenock Road and all vehicles will be strictly controlled to ensure that access and egress in the wider context to/from the site will be via Junction 29 St James interchange and Barnsford Road thereby ensuring no construction traffic affects the Bishopton Village road network. There will be additional access required directly off the M8 during tie-in works but this will be kept to a minimum.

2.74 Due to the logistics of the construction it will be necessary to create three access points off the A8 Greenock Road servicing the individual sector construction making up the project scope. ie.

• Access 1 – East of the M8 adjoining the proposed SUDS ponds. This will form the main site compound for the construction of Phases 2 and 3 of the works.

• Access 2 (North) – West of the M8 directly opposite the existing farm access, this will form the main access to the satellite site compound to be formed between the existing and proposed accesses to Craigmuir Farm.

• Access 3 (South) – Directly opposite Access 2, this will utilise the existing farm access and redundant A8 roadway to service the off-ramp construction. It is envisaged that with limited space this access will feature a security gate area only and all messing facilities will be based in the compounds either off Access 1 or Access 2.

2.75 Short term access from the M8 corridor to service the local tie-ins will be necessary during certain tarring and other finishes operations. These will be negotiated with Transerve as they will be dependent on the operating company’s specific requirements and whether other roads operations are being carried out in the vicinity of the tie-in works.

2.76 A Logistics Management Plan compiled under the control of a Traffic Safety Control Officer employed by the successful contractor will plan details of measures to control and monitor vehicles engaged in deliveries to and removals from site and additionally measures to control and maintain road cleanliness. Such measures will include, inter alia, the installation of wheel wash facilities at site entrances and the review and implementation of further road cleaning measures on the existing A8 and adjoining road corridors.

Temporary Compounds

2.77 Site compound locations and layouts are generally designed by the Contractor prior to site start and should not only be functional but take due cognisance of the permanent works construction to minimise the interaction between these temporary and permanent works installations.

2.78 Sufficient space should be made available to accommodate site office and messing facilities as well as minor materials storage, access and adequate parking facilities for construction operatives and site visitors. They should also be secured by a controlled entrance, fenced to minimise intrusion and the layout should also be designed to minimise interaction between site and pedestrian traffic and if possible all heavy machinery routes should be constrained to areas remote from the site compound to minimise safety issues.

2.79 It is envisaged that the main site compound will be serviced off Access 1 and will encompass approximately 7 portakabin units housing meeting rooms and offices with a separate, but linked, facility encompassing toilets, drying rooms and mess facilities within a further 3 units.

2.80 Parking is envisaged to be required for approximately 30 – 40 people and would be arranged in standard aisle format adjoining the cabins.

2.81 A light material and fuel/generator storage area would make up the balance of the temporary site compound area.


2.82 The satellite compound serviced off Access 2 could be smaller as it is not anticipated to accommodate meeting facilities or large numbers of visitors and may therefore be scaled down to an area of approximately 30m x 30m.

2.83 Utility connections may be required from external sources but the compounds will be self-contained with electricity taken from site generators, toilets discharging to septic tanks and soakaways and water supplies derived from browsers feeding header tanks. Telecommunications will be either via landline or by mobile phone communication.

Storage Areas

2.84 To minimise the work associated with the contract, double handling and hence storage area requirements can be reduced significantly by prudent implementation of the project logistics.

2.85 As such, storage areas are generally limited to those associated with the bulk handling of topsoil and landscape surcharge fill for re-use. There may also be a requirement for local short term bulk storage of SUDS bases and granular fills associated with the road construction but these will be kept to a minimum to avoid site congestion issues.

2.86 Many building materials are generally offloaded at points on site local to their permanent location albeit some may be stored on pallets within the site compound storage area for short periods prior to installation. These include, but are not limited to:

• Geotextiles

• Drainage pipes/manhole rings/covers and bedding/backfill materials (generally single loads deposited locally to work sections)

• Kerbs and edgings

• Traffic sign poles and signs

• Streetlighting cable, columns and lanterns.

2.87 The final major element of storage relates to fuel oils for construction plant and generators.

1 Bulk Storage Areas

2.88 It is envisaged that there will be limited scope for recovery of reusable topsoils and these will be limited to the on-ramp and the two SUDS ponds areas between the on-ramp and the existing watercourse.

2.89 The estimated quantity of the topsoil arisings based on a 300mm strip is approximately 6,500 cubic metres which – to minimise loss – should be stockpiled at depths not exceeding 2m yielding an area requirement of around 3,250 square metres which can be accommodated in the area of one of the two on-ramp SUDS ponds temporarily and around the main site compound area between the on-ramp and the SUDS ponds.

2.90 Bulk earthworks items consisting of excavated unsuitable materials and embankment fills will be controlled to facilitate immediate removal or deposition respectively thereby minimising double handling.

2.91 It is envisaged that there may be a requirement to pre-load the embankments with additional fills to minimise the time period required for acceptable settlements to occur and, as this can be unacceptable materials, this material would come from the unsuitable arisings generated by the initial earthworks. This material would be temporarily stockpiled adjoining both sections of the works and placed on the structural embankment (with suitable separation membranes to avoid cross contamination) after completion of the initial earthworks phase.

2 Non-Earthworks Construction Materials

2.92 The bulk of these will be contained within the site compound areas or delivered directly to the area of work for immediate placement in the permanent works.


2.93 The locations of these deposition areas is dependent on the Contractor’s method of works/logistics plan.

2.94 It is not envisaged that any of these temporary stockpiles will cause any inconvenience to the travelling public or adjoining landowners either from a noise or a pollution viewpoint.

3 Fuel Storage/Pollution Prevention

2.95 Fuel storage will be rigidly controlled by the contractor and all storage facilities will be bunded to ensure accidental spillages are contained locally for early treatment/removal.

2.96 The contractor must comply at all times with the requirements of the contract specification in respect of pollution prevention in order to ensure that watercourses are protected from accidental spillage and other discharges. This will include keeping noise and dust to a minimum. The contractor should adopt best working practices and measures to safeguard the environment as set out in the Scottish Environment Protection Agency (SEPA) Pollution Prevention Guidelines (PPG) notes.

2.97 A monitoring plan detailing sampling and testing measures for groundwater, surface water, dust, vapour, gas and odour shall be prepared and agreed by the Local Planning Authority prior to commencement. Likewise a Water Management Plan will be prepared and agreed prior to commencement.

2.98 Specific controls and monitoring will also be required for working in the vicinity of the former landfill site to the west of the site.

Protection of Ecology

2.99 Due care should be exercised to ensure the effects on the flora and fauna in the area of the site are minimised. This should include ensuring vegetation is not cleared during bird nesting season.

Typical Truck Movements

2.100 Although the final design is nearing completion it is very difficult to be completely accurate about the amount of road traffic which is expected. Soil parameters of excavated materials will dictate their re-use within the site and good materials management will be used to minimise the impact on imported fill and removal of unsuitable material from site. Site storage will be considered to double handle materials and this will reduce the number of vehicle movements from outwith the site boundaries.

2.101 The following is a guide to what movements can be expected:

1 Imported fill 15,000 trucks

2 Drainage fills 600 trucks

3 Concrete deliveries 150 trucks

4 Off-site tipping 2,000 trucks

5 Plant movements 100 trucks

6 Janitorial deliveries 100 vans

7 General materials 150 vans

2.102 As can be seen this equates to around 18,000 truck movements which underlines the need for a strong management plan to control and monitor the vehicle movements. A helpline phone number will be considered (if appropriate) which will help generate local support for our aim and goals. General good neighbour principles will be applied to build stakeholders’ confidence and support.


Traffic Management

2.103 Wherever possible disruption to existing traffic will be avoided, although during the construction phase some traffic management will be necessary and the contractor will produce a detailed traffic management plan.

2.104 The construction of the new on and off-ramps will involve work alongside and on the existing M8 motorway. Whilst the majority of the works may be carried out with hard shoulder closures, lane narrowing and speed restrictions may be required at some points, for example, tie-ins of merge and diverge slip roads. Traffic management measures shall be implemented in accordance with Chapter 8 of the Traffic Signs Manual (Department of Transport 2006). The requirements of Transport Scotland’s term maintenance contractor for trunk roads (Transerve) should also be met. This will be implemented with regular meetings to agree and plan the measures required.

2.105 Site accesses will be clearly marked and signed in accordance with Chapter 9 requirements.

243

715/M8 MOTORWAY & GREENOCK ROAD (A8), INCHINNAN CASS ASSOCIATES ROYAL ORDNANCE, BISHOPTON MARCH 2015

Figures

Figure 2.1

Documents

2 The Proposed Scheme and Alternative Design Options · PDF file2 The Proposed Scheme and Alternative Design Options ... thrust bored culvert below ... for the west interchange junction