3 Description of Route Corridor Options 3.1 Introduction 3.2 Capacity Management Strategy 3.3 Access Strategy 3.4 Bus Priority and High Occupancy Vehicles (HOVs) 3.5 Intelligent Transport Systems Strategy 3.6 Multi-modal Strategy 3.7 North Corridor Option 1 3.8 North Corridor Option 2 3.9 South Corridor Option 1 3.10 South Corridor Option 2 3.11 Do-Minimum Option 3.12 Cost Estimates 3.13 Proposed Replacement Bridge 3.14 References
3 Description of Route Corridor Options
3.1 Introduction
3.1.1 The development of the proposed replacement bridge and its associated connections has been undertaken according to capacity management and access strategies. Each of these strategies has been developed for the Forth Replacement Crossing Project based on the requirements of current and national transport policy.
3.1.2 The capacity management and access strategies will be supported and complemented by a subsidiary strategy for Intelligent Transport Systems (ITS). The multi-modal strategy considers the future implementation of public transport systems such as Light Rapid Transit (LRT), Bus Rapid Transit (BRT), guided buses and trams.
3.1.3 Whilst providing a description of the route corridor options assessed within this DMRB Stage 2 Corridor Report, this chapter also provides an overview of the past assessment work undertaken and the strategies and criteria used in the development of roads infrastructure to complement the proposed replacement bridge.
Route Corridor Option Sifting
3.1.4 The Jacobs Arup report "Forth Replacement Crossing, Route Corridor Options Review" details each of the corridor options considered in the provision of road connections to the proposed replacement bridge. A two staged assessment was undertaken as a part of this process including an initial assessment, where a high level study allowed the least favoured options to be removed from further consideration, and a further assessment, where the remaining options were considered in greater detail.
Initial Assessment
3.1.5 As a part of the initial phase of assessment, a total of nine route corridor options were identified for consideration, three to the north of the Firth of Forth and six to the south of the Firth of Forth.
3.1.6 The three available route corridor options north of the Firth of Forth were all considered viable during this initial period of assessment and hence were taken forward for further assessment.
3.1.7 South of the Firth of Forth, three of the route corridor options were carried forward, each providing an alternative connection to the existing road network via the A90, M9 or M9 Spur. In addition, a combination option providing a direct connection from the proposed replacement bridge to the M9 and the A90 was also carried forward for further consideration.
3.1.8 The three remaining route corridor options south of the Firth of Forth were removed from further consideration on the basis that they did not best meet the scheme objectives. Furthermore, it was deemed that each of these route corridor options would require significant additional costs to implement taking into consideration land acquisition, the requirement for sizable junction arrangements and the possible requirement for substantial geotechnical investigation and consolidation of existing mine workings.
Further Assessment
3.1.9 The mainline route corridor options considered for further assessment were developedtaking cognisance of carriageway provision, junction connectivity and relevant design standards as set out within the DMRB. Each corridor was designed to current standards over its full length. It is recognised that shorter improvements are feasible in each corridor. Following the consideration of the mainline carriageway design, the suitability of each route corridor option was assessed considering environmental, geotechnical, structural and traffic impacts.
3.1.10 North of the Firth of Forth, it was deemed that North Corridor Option 1 and North Corridor Option 2 should be taken forward as a part of the DMRB Stage 2 assessment process. These options are detailed in Figure 3.1 and Figure 3.2 (Volume 2).
3.1.11 North Corridor Option 3, the remaining route corridor option and a combination of North Corridor Option 1 and North Corridor Option 2, was not deemed to provide any additional benefits. It is the least effective in meeting the scheme objectives and provides the least amount of junction functionality. In addition, it generates a deterioration of local air quality to the highest number of properties.
3.1.12 South of the Firth of Forth, it was deemed that South Corridor Option 1 and South Corridor Option 2 should be taken forward as part of the DMRB Stage 2 assessment process. These options are detailed in Figure 3.3 and Figure 3.4 (Volume 2).
3.1.13 South Corridor Option 3, the remaining route corridor option, was deemed to have the greatest level of impact with regards to residential property demolition. The provision of connectivity to the existing road network also presented difficulties with a requirement for large junctions and significant land acquisition. In addition, the complexity of the junction interface with the M9 Spur raised a number of design standard concerns and highlighted the need for a number of new structural crossings of road and rail at significant cost.
3.1.14 The combination option, South Corridor Option 4A, encompassing South Corridor Option 1 and South Corridor Option 2, was also removed from further consideration at this stage. The requirement for significant land acquisition, the effects that the option would have on the existing landscape and the cost of its implementation were all key factors in it not being carried forward to DMRB Stage 2 assessment.
3.2 Capacity Management Strategy
3.2.1 A strategy for the management of capacity associated with the Forth Replacement Crossing Project has been developed, consistent with national transport planning policy, as defined by:
- The Government Economic Strategy
- The National Transport Strategy (NTS, 2006).
3.2.2 The Scottish Government’s National Transport Strategy (NTS) sets out three strategic outcomes designed to meet the key challenges facing transport in Scotland over the next 20 years.
- Improve journey times and connections, to tackle congestion and the lack of integration and connections in transport which impact on our high level objectives for economic growth, social inclusion, integration and safety.
- Reduce emissions, to tackle the issues of climate change, air quality and health improvement which impact on our high level objective for protecting the environment and improving health.
- Improve quality, accessibility and affordability to give people a choice of public transport, where availability means better quality transport services, value for money and a realistic alternative to the car.
3.2.3 The Strategic Transport Projects Review (STPR) has been taken forward based on these strategic outcomes for the NTS to enhance Scotland's strategic transport network. As an early priority project of the STPR, the proposed replacement bridge is expected to contribute to the NTS strategic outcomes and form part of the overall strategy for investment in Scotland’s transport network.
3.2.4 Through the STPR, Transport Scotland has defined the following hierarchy for investment in transport infrastructure:
- Firstly, at maintaining and safely operating existing assets;
- Secondly, at promoting a range of measures, including innovative solutions, to make better use of existing capacity (Interventions may include technology based, fiscal and ‘soft measures’ in addition to engineering solutions); and
- Thirdly, at promoting targeted infrastructure improvements.
3.2.5 As an early priority project of the STPR, option development for the proposed replacement bridge is guided by this investment hierarchy. The proposed replacement bridge, as a ‘level 3’ targeted infrastructure improvement, is under consideration because the continued maintenance and safe operation of the Forth Road Bridge (a preferred ‘level 1’ solution) is known to be subject to significant uncertainty.
3.2.6 However, this targeted investment must also be seen in the context of other complementary investments being promoted in the potential absence of the Forth Road Bridge. These aim to make best use of existing cross-Forth capacity (‘level 2’ solutions) in order to manage demand for cross-Forth travel and access. Many of these are being considered within the STPR framework as described above. Others are being promoted and developed by local authorities in the Forth catchment area and the South East of Scotland Transport Partnership (SEStran). These include rail and tram improvements, Intelligent Transport Systems (ITS), ferry options, and public transport priority schemes and interchanges.
3.2.7 A key element of the option development process is therefore to prioritise proposed replacement bridge options which provide targeted infrastructure replacement, sufficient to meet continuing demands for its use, in the context of the potential contribution to be made by more preferable ‘level 1’ and ‘level 2’ solutions for investing in cross-Forth transport systems, and in such a way that the viability of these preferred alternatives are not undermined.
3.2.8 In practice, this means generating preferred configurations for the proposed replacement bridge and its connections at no more than replacement levels of road capacity. Consequently, as the Forth Road Bridge and its immediate connections are designed utilising dual two lane all purpose carriageway/dual two lane motorway, the assumption is that any replacement infrastructure should be provided to the same or equivalent specification. Any additional capacity is only considered where, consistent with scheme objectives, it is either:
- reserved for priority users (e.g. public transport, emergency vehicles); or
- forms part of an existing and transferable commitment for improvements to the Forth Road Bridge and its associated direct connections; or
- where there are other requirements (e.g. safety, transport/land use/policy integration, design standards) for additional investment over and above that required for replacement purposes. This excludes providing for forecast growth in non-priority traffic (e.g. single occupancy vehicles) beyond a level that would have been provided for by the Forth Road Bridge.
3.3 Access Strategy
3.3.1 In addition to the Capacity Management Strategy, an Access Strategy has also been developed to ensure the integration of options with key schemes and policies in the region. The Access Strategy for the Forth Replacement Crossing Project has been developed taking cognisance of the following transport planning policies, and a detailed interpretation of the Scheme Objectives.
- The National Planning Framework 2 (NPF2) discussion draft (2008).
- The West Edinburgh Planning Framework;
- SEStran draft Regional Transport Strategies;
- FETA Local Transport Strategy; and
- Fife Structure Plan/Edinburgh and Lothians Structure Plan.
3.3.2 The resulting access strategy objectives are set out in Table 3.1.
Table 3.1: Access Strategy for Option Development
Scheme Objective |
Access Strategy Objectives |
|---|---|
Maintain cross-Forth transport links for all modes to at least the level of service offered in 2006 |
|
Connect to the strategic transport network to aid optimisation of the network as a whole |
|
Improve the reliability of journey times for all modes |
|
Increase travel choices and improve integration across modes to encourage modal shift of people and goods |
|
Improve accessibility and social inclusion |
|
Minimise the impacts of maintenance on the effective operation of the transport network |
|
Support sustainable development and economic growth |
|
Minimise the impact on people, the natural and cultural heritage of the Forth area |
(See also prioritisation of road space criteria for sustainable development objective) |
3.4 Bus Priority and High Occupancy Vehicles (HOVs)
3.4.1 Based on the access strategy objective to support sustainable development and consistent with the investment principle of making best use of existing assets, one of the features relevant to the function of the proposed replacement bridge includes the consideration of bus and HOV lanes.
3.4.2 The consideration within the overall access strategy to implement priority use of the proposed replacement bridge and associated roads infrastructure by buses and, potentially, HOVs has therefore been developed to guide option development. Bus priority measures developed by SEStran include ‘Park & Choose’ bus/rail/car-sharing interchange facilities along the A90/M90 corridor in Fife at Ferrytoll, Rosyth, Halbeath, Dalgety Bay, and Inverkeithing. These would also integrate with a number of existing facilities for priority vehicle use within the immediate Forth catchment, including:
- City of Edinburgh radial bus priority infrastructure along the A90, A8 and A71; and
- a car-sharing database, operated by SEStran to match drivers to potential passengers undertaking the same or similar journeys.
3.4.3 In this context, bus and HOV considerations are:
- To consider the potential for bus priority and HOV measures along the A90/M90 corridor between Halbeath Interchange (M9 Junction 3) and North Queensferry.
- To consider the potential for the linked provision of bus priority and HOV measures between South Queensferry, west Edinburgh, and central Edinburgh.
3.4.4 These considerations are consistent with the other access strategy objectives presented in Section 3.3, in particular:
- Facilitating improved connections with Park & Choose facilities to meet scheme objectives to increase travel choices, improve integration and encourage modal shift of personal travel.
- Facilitating improved public transport accessibility in west Edinburgh to meet the scheme objective of improved accessibility and social inclusion.
- Positively contribute to the management of road congestion in west Edinburgh along the A90 to address the scheme objective of network optimisation.
3.5 Intelligent Transport Systems Strategy
3.5.1 An Intelligent Transport Systems (ITS) strategy has been developed for the proposed replacement bridge in support of the overall access strategy defined in Section 3.3. ITS is also a key component of Transport Scotland’s investment hierarchy and will also therefore contribute to the capacity management strategy defined in Section 3.2.
3.5.2 For the Forth Replacement Crossing Project the ITS strategy addresses:
- Public Transport Measures
- Priority Vehicle Operation
- Journey Time Reliability
- Safety Management
- Emissions Management
- Demand Management
- Network Operation
- Integration
3.5.3 The strategy will propose ITS measures according to the following five integrated and overlapping categories of use:
- General provision – universal measures required for the route corridor
- Mainline junctions and local network – measures targeted at the interface between the mainline, strategic and local roads
- Public Transport – measures to manage bus, train and LRT movements
- Priority Vehicles – measures to manage priority vehicles
- Mainline Route Corridor – measures targeted at the management of mainline traffic movements
3.5.4 Within each of these categories, a suite of ‘mature’ and ‘emerging’ ITS measures are proposed for further development and consideration as the scheme progresses. These are summarised in Table 3.2.
Table 3.2: ITS Strategy – Technologies for Potential Adoption
Use Category |
Mature technologies |
Emerging technologies |
|---|---|---|
General Provision |
Traffic/Transport Management Centre |
Journey Time Measurement (JTM) |
Mainline junctions and local network |
Variable Message Signs (VMS) |
Mobile ITS |
Public transport |
Vehicle Detection |
Exit Queue Management |
Priority vehicles |
Lane Control Signals (LCS) |
Intelligent Road Studs |
Mainline Route Corridor |
Lane Control Signals (LCS) Variable |
Mobile ITS |
3.6 Multi-modal Strategy
3.6.1 The Forth Replacement Crossing Project shall make provision for public transport and traffic management practices. In its provision, the proposed replacement bridge must not preclude the implementation of future transport systems such as Light Rapid Transit (LRT), Bus Rapid Transit (BRT), guided buses or trams.
3.6.2 To future-proof the scheme for the implementation of possible future transport modes, a multi-modal corridor is to be provided.
3.6.3 In the initial phase of operation it is possible that the multi-modal corridor could be used for the running of road based public transport or HOV traffic, although this would increase overall road capacity. On approach to the proposed replacement bridge, this traffic would be directed into the multi-modal corridor to cross the Firth of Forth. On departure from the multi-modal corridor at the opposing ends of the proposed replacement bridge, it would rejoin the main carriageway.
3.6.4 On the implementation of a system such as LRT or BRT, the interim priority given to buses or HOVs would be removed and this traffic would utilise the same carriageway used by general traffic on the proposed replacement bridge, allowing the LRT/BRT system to be isolated from normal vehicular traffic.
3.6.5 To safeguard the connectivity of future LRT/BRT systems and taking cognisance of potential infrastructural requirements, it is necessary that access and egress points for the LRT/BRT system be catered for within the design at an early stage, ensuring minimum disruption to local and strategic routes upon its implementation.
3.6.6 The potential termination points for the implementation of such a system have been defined in line with the scheme objectives and access strategy objectives detailed in Table 3.1 and following a review of public transport infrastructure being implemented or considered by local authorities.
3.6.7 North of the Firth of Forth, it is deemed appropriate that LRT/BRT provision be terminated at Ferrytoll Junction enabling the system to interact with future public transport initiatives being considered by Fife Council and SEStran. Termination at this point would enable interaction with the Ferrytoll Park and Ride site, and local communities in west Fife including North Queensferry, Rosyth, Inverkeithing, Dalgety Bay and Dunfermline.
3.6.8 South of the Firth of Forth, it is considered that the potential LRT/BRT connections would be established through a new interface with the A904. Termination at this point would enable interaction with any future expansion of the Edinburgh Tram Project to West Lothian, providing alternative direct public transport links between Fife and Edinburgh.
3.6.9 There are currently no committed proposals for a cross-Forth LRT or BRT system. As a consequence the connecting roads to the proposed replacement bridge will be designed such that they will not preclude the future construction of a LRT or BRT system as far as is reasonably practicable.
3.7 North Corridor Option 1
3.7.1 Details of North Corridor Option 1 are provided in Figure 3.1 (Volume 2).
3.7.2 At 7.1km in length, North Corridor Option 1 utilises much of the existing A90/M90 corridor between Ferrytoll Junction and Halbeath Interchange, passing east of Rosyth and west of Inverkeithing. In the provision of this option, the A90 and M90 would be reconstructed to dual three lane motorway standard, and provision could be made for HOVs in the outer of the three trafficked lanes. As noted in Section 3.6.3, this arrangement would have the disadvantage of increasing capacity and could lead to induced traffic and wider network impacts.
3.7.3 Whilst utilising much of the existing A90/M90 route corridor, the construction of a new section of carriageway is required between the proposed replacement bridge and the A90/M90. Descending in a north easterly direction from the north bridgehead at St Margaret’s Hill toward Ferrytoll Junction on viaduct, the route corridor clips the edge of St Margaret’s Marsh, before crossing the B981 east of Dunfermline Waste Water Treatment Works. This section shall be operated as an all purpose carriageway with hardshoulder to maintain cross-Forth links for non-motorway traffic.
3.7.4 Whilst tying into the existing horizontal and vertical geometry of the A90 at Ferrytoll Junction, the change in bearing associated with the provision of the new section of carriageway necessitates the reconstruction of the existing junction arrangement. As part of its reconstruction, a number of new structures will be required. Existing structures shall be retained or widened as appropriate. The new junction shall cater for non-motorway traffic and local traffic with links being provided to the B980, B981 and Ferry Toll Road.
3.7.5 North of Ferrytoll, motorway restrictions are implemented. The corridor retains the horizontal and vertical geometry associated with the existing A90/M90 crossing beneath Dunfermline Wynd before cresting on Muckle Hill. The corridor then descends toward Admiralty Junction, located east of Rosyth, where the existing junction arrangement is to be reconfigured to improve operational safety. The measures to be implemented would include the closure of the north facing slip roads.
3.7.6 Continuing north, the corridor crosses Brankholm Burn west of Belleknowes Industrial Estate before crossing the Fife Circle Railway Line and swinging northeast through Masterton Junction. Located within the junction area, Masterton Viaduct which carries the M90 over the railway line and the existing southbound M90 link to the A823 will be widened to accommodate the proposed dual three lane motorway. Masterton Junction itself will be reconstructed, in part, to improve operational safety and also to provide additional links, compensating for the removal of the north facing slip roads at Admiralty Junction.
3.7.7 From Masterton Junction, the dual three lane motorway continues northeast passing beneath Masterton Road and the B981 before swinging north towards Halbeath Interchange. Located east of Fife Leisure Park, Halbeath Interchange is where the scheme terminates, the proposed dual three lane motorway reducing to dual two lane motorway standard, via a lane drop, so to comply with existing M90 carriageway cross section. In the implementation of North Corridor Option 1, it is proposed that any HOV lanes would terminate five hundred metres north of Masterton Junction.
Junction Arrangements
3.7.8 In the provision of North Corridor Option 1, the reconfiguration or reconstruction of the following junctions has been considered. The junction configurations are indicative at this stage, the requirements for each being considered in detail should this option be taken forward for DMRB Stage 3 assessment.
Ferrytoll Junction
3.7.9 The provision of a new junction at Ferrytoll is a key requirement in the maintaining of access between the mainline carriageway, Ferrytoll Park and Ride, Rosyth Dockyard and west Fife.
3.7.10 The current layout, taking the form of a roundabout is to be partially retained for use in the new junction design, its eastern extents being utilised in the provision of southbound merge/diverge movements to the mainline carriageway. It shall also serve the existing Ferrytoll Park and Ride facility. Northbound, merge/diverge movements to the mainline carriageway are catered for through a new roundabout located north of the existing junction on the line of the existing B980 Castlandhill Road. The position of this new roundabout is dictated by the level difference between the mainline departing the proposed replacement bridge and the existing local road network.
3.7.11 Whilst the future of the Forth Road Bridge remains undefined, to ensure that any future reconnection proposal can be accommodated, new slip roads have been designed to provide access. Dedicated links can be constructed to the M90 with local connectivity being maintained through the construction of additional links to Ferrytoll Junction.
3.7.12 The new Ferrytoll Junction also takes into consideration the possible future developments of a LRT system or BRT system.
3.7.13 The multi-modal requirements of the project dictate that the provision of a system such as LRT or BRT must have an entry/exit point. North of the Firth of Forth, Ferrytoll Junction shall be designed such that it will not preclude this feature, the multi-modal corridor dropping beneath the mainline into the junction area allowing local connections to be established in future years.
Admiralty Junction
3.7.14 In the provision of North Corridor Option 1, the existing Admiralty Junction is retained in part, with access maintained between Rosyth (A985) and Inverkeithing (A921).
3.7.15 To address the safety concerns associated with the proximity of Admiralty and Masterton Junctions, the north facing slip roads linking the existing M90 to the local road network are to be closed. Under North Corridor Option 1, additional functionality is provided at Masterton Junction to cater for their closure. Through the implementation of this measure, the short weaving distance currently experienced between the junctions on the M90 is addressed.
3.7.16 The existing south facing slip roads at Admiralty Junction are to be retained. The merge and diverge noses to the M90 shall be adapted to accommodate the proposed dual three motorway.
Masterton Junction
3.7.17 In the reconstruction of Masterton Junction, a new partial cloverleaf arrangement is provided serving southbound traffic movements between the M90 and A823(M). To facilitate this connection, the A823(M) is carried on structure over the M90 with improved horizontal and vertical geometry implemented to remove existing operational safety concerns.
3.7.18 In addition to the new A823(M) links, a new arrangement is provided to the A921. The new layout facilitates access between Inverkeithing and the M90 to the north. This additional functionality is provided to compensate for the closure of the north facing slip roads at Admiralty Junction.
3.7.19 The existing M90 to A823(M) northbound merge and diverge layouts are retained as a feature of the new junction layout. Modifications to the merge and diverge noses to the M90 will be required to accommodate the proposed dual three lane motorway.
3.8 North Corridor Option 2
3.8.1 Details of North Corridor Option 2 are provided in Figure 3.2 (Volume 2).
3.8.2 At 7.0km in length, North Corridor Option 2 is an offline solution which enables much of the existing A90/M90 associated with the Forth Road Bridge to be left in-situ between Ferrytoll Junction and Masterton Junction. Utilising the existing A90/M90 as a local distributor road, North Corridor Option 2 is to be constructed to dual two lane motorway standard, a combination of the new corridor and the existing A90/M90 serving to provide local access and any desired HOV functionality.
3.8.3 Connecting to the north bridgehead at St Margaret’s Hill, the new carriageway descends on viaduct in a northerly direction passing through the eastern extents of St Margaret’s Marsh before crossing the B981 southeast of Dunfermline Waste Water Treatment Works. This section shall be operated as an all purpose carriageway with hard shoulder to maintain cross-Forth links for non-motorway traffic. Located west of the existing A90 through Ferrytoll, North Corridor Option 2 requires the provision of a new junction at this location, providing access and egress between the proposed replacement bridge, B980, B981 and Ferry Toll Road. In the provision of this junction a significant number of structural crossings are required of both road and rail, the Rosyth Dockyard Branch Line Railway traversing the corridor at this location.
3.8.4 North of Ferrytoll, motorway restrictions are implemented as the corridor climbs on a shallow gradient towards Castlandhill. Clipping the corner of Castlandhill Woods, the corridor sweeps northeast, a cut and cover tunnel solution being utilised east of Castlandhill Steadings to mask its presence. Crossing the existing A90 on structure south of Admiralty Junction, the corridor continues on a north easterly bearing towards Belleknowes Industrial Estate north of Inverkeithing.
3.8.5 Passing through a valley, a further structure is required in the form of a viaduct so to clear the railway sidings located at Inverkeithing Junction, north of Belleknowes Industrial Estate. The viaduct commences south of the A921 and terminates having crossed the railway line.
3.8.6 North of the viaduct, the corridor climbs to intersect the existing M90, 1.2km north of Masterton Junction. In achieving this, the corridor passes through broadleaved woodland west of Pinkerton Burn. It then passes to the west of Dales Farm on embankment requiring the realignment of the B981 through this section.
3.8.7 Connection to the existing M90 is achieved east of Duloch Farm.
3.8.8 Given the offline nature of North Corridor Option 2, as described in 3.8.2, it is proposed that the existing A90/M90 be retained as a local distributor road. To facilitate access between the existing road network and the M90 to the north of the scheme, north facing slip roads will be provided northeast of Masterton Junction maintaining local access to west Fife.
Junction Arrangements
3.8.9 In the provision of North Corridor Option 2, the construction of the following junction has been considered. The junction configuration is indicative at this stage, the requirements for its implementation being considered in detail should this option be taken forward for DMRB Stage 3 assessment.
Ferrytoll Junction & M90 Connectivity
3.8.10 As with North Corridor Option 1, a new junction at Ferrytoll in the provision of North Corridor Option 2 is a key requirement, maintaining access between the proposed mainline, Ferrytoll Park and Ride, Rosyth Dockyard and west Fife. Located to the west of the existing Ferrytoll Junction, the new junction consists of a grade separated dumb bell arrangement facilitating all movements.
3.8.11 In the provision of the northbound diverging lane from the proposed mainline, a significant structural requirement exists, the new slip road descending on viaduct from St Margaret’s Hill through St Margaret’s Marsh to its interface with a new roundabout situated southeast of Castlandhill Woods. On approach to the new roundabout, diverging traffic from the proposed replacement bridge merges with local traffic utilising the B981 from North Queensferry.
3.8.12 In the connection of this link, a further structural crossing of the Rosyth Dockyard Branch Line Railway is required northeast of Dunfermline Waste Water Treatment Works.
3.8.13 Through the provision of a new roundabout, northbound connections are also catered for. Rather than connecting to the new mainline carriageway, strategic northbound traffic and local traffic wishing to commute between North Queensferry, Rosyth, Inverkeithing and Dunfermline is routed via the existing A90/M90. The existing junctions at Admiralty and Masterton are retained and continue to operate in their current form. Connection to the M90 is achieved north of Masterton Junction where simple north facing merge and diverge links are provided.
3.8.14 Southbound, traffic from the A823(M), Rosyth and Inverkeithing is routed via the A90/M90 to Ferrytoll Junction where new slip roads facilitate movements between the new dual two lane motorway and the existing local road network. A direct link from the existing A90/M90 to the proposed replacement bridge is provided through the junction area as a free flow link.
3.8.15 As per North Corridor Option 1, the Ferrytoll Junction layout associated with North Corridor Option 2 takes into consideration the potential future development of a LRT system or BRT system, the multi-modal corridor dropping beneath the new M90 into the junction area enabling future connections to be made to a number of local destinations.
3.8.16 As per North Corridor Option 1, any future reconnection proposals for the Forth Road Bridge could be accommodated through the utilisation of the new junction at Ferrytoll, the provision of further links facilitating partial free flow connectivity.
3.9 South Corridor Option 1
3.9.1 Details of South Corridor Option 1 are provided in Figure 3.3 (Volume 2).
3.9.2 At 2.75km in length, the mainline carriageway associated with South Corridor Option 1 provides a link between the proposed replacement bridge west of South Queensferry and the existing A90 southeast of Echline Junction. In the provision of this option, best use is made of the existing roads infrastructure associated with the Forth Road Bridge including the A90 and recently completed M9 Spur Extension. Building on past improvements to the road network, further connectivity enhancements are proposed with the full reconstruction of M9 Junction 1a, connecting the M9 to the M9 Spur, and a reconfiguration of Scotstoun Junction.
3.9.3 Commencing approximately 250m east of the A8000, South Corridor Option 1 has been developed as a dual three lane carriageway with hardshoulder. As with North Corridor Option 1, provision could be made for HOV functionality in the outer of the three trafficked lanes.
3.9.4 Passing beneath the A8000, requiring a reconstruction of the existing A8000 overbridge, the corridor departs the existing A90 in a westerly direction towards the fields of Dundas Home Farm. Through this area, the corridor is to be constructed on moderate embankment for part of its length so to accommodate the existing BP Pipeline situated below ground level.
3.9.5 Continuing west through Dundas Home Farm, a new junction is provided to facilitate local access between the proposed replacement bridge, the A904, the A90 and the M9 Spur. Beyond the new junction, the corridor swings north through Dundas Estate before crossing beneath the A904, the vertical geometry descending throughout so to provide adequate headroom clearance to the local road above.
3.9.6 On approach to the proposed replacement bridge, the corridor passes to the west of South Queensferry through Scottish Ministers land, the existing topography of the area descending towards the Firth of Forth. Through this section, the corridor transitions from cutting to embankment, the vertical geometry rising to meet the approach structure associated with the proposed replacement bridge, east of Inchgarvie House.
3.9.7 With reference to any potential future transportation developments such as the introduction of LRT or BRT, the A904 located to the south would be used as the interface for such a system. Routing via the A904 would enable future connections to be established with a number of local destinations.
Junction Arrangements
3.9.8 In the provision of South Corridor Option 1, the provision of the following new and reconstructed junctions has been considered. The junction configurations are indicative at this stage, the requirements for each being considered in detail should this option be taken forward for DMRB Stage 3 assessment.
M9 Junction 1a
3.9.9 In the facilitation of improved cross-Forth connections, M9 Junction 1a is to be reconstructed under South Corridor Option 1, becoming a free flow junction with all ways functionality between the M9 and the M9 Spur.
3.9.10 The existing loop arrangement is to be removed and replaced with a new link, improving junction connections between the M8, M9, A8, South Queensferry and the proposed replacement bridge.
3.9.11 Increased accessibility being a key strategic aim, west facing slip roads connecting the M9 to the M9 Spur are included within the new M9 Junction 1a arrangement, a movement not currently provided for.
Echline/Scotstoun Combination Junction
3.9.12 Echline/Scotstoun Combination Junction facilitates access between South Queensferry, the M9 Spur, A90 and the A904.
3.9.13 The South Corridor Option 1 mainline and the proposed replacement bridge will have priority through the junction area with a through connection to the M9 Spur. Connections to the A90 and the north of Edinburgh are maintained through the use of Scotstoun Junction.
3.9.14 Traffic wishing to access South Queensferry from Edinburgh and the M9 Spur will be catered for through the provision of additional slip road arrangements to Scotstoun Junction. A new link will cross the proposed mainline on structure, north of Dundas Home Farm, before interfacing with the A904 and A8000 at Echline Junction.
3.9.15 Traffic wishing to access the proposed replacement bridge, the A90 or the M9 Spur from the A904 or A8000 is catered for with the provision of a new grade separated junction to the west of the existing Echline Junction. The existing junction arrangement will only serve local traffic and northbound traffic from Edinburgh and the M9 Spur.
3.10 South Corridor Option 2
3.10.1 Details of South Corridor Option 2 are provided in Figure 3.4 (Volume 2).
3.10.2 At 5.1km in length, South Corridor Option 2 provides a direct connection between the M9 and the proposed replacement bridge.
3.10.3 To be constructed as a dual three lane motorway, connection to the M9 is achieved to the northeast of Winchburgh through the provision of a new free flow junction arrangement with all ways functionality.
3.10.4 As with other options, provision could be made for the running of HOVs in the outer of the three trafficked lanes.
3.10.5 Departing the M9, the new dual three lane motorway climbs on embankment crossing the B9080 and the Falkirk-Fife Railway Line. Cresting on approach to Swine Burn, the corridor continues in a northerly direction descending into cutting as it passes to the east of Westmuir Riding Centre.
3.10.6 Continuing north along the boundary of Dundas Estate, the corridor continues to descend in cutting, crossing beneath Builyeon Road on approach to the A904. At the A904, motorway restrictions cease on the mainline with north facing slip roads being provided to the A904 facilitating cross-Forth travel for non-motorway traffic and local traffic.
3.10.7 On approach to the proposed replacement bridge, the corridor passes to the west of South Queensferry through Scottish Ministers land, the existing topography of the area descending toward the Firth of Forth. Through this section, the corridor transitions from cutting to embankment, the vertical geometry rising to meet the approach structure associated with the proposed replacement bridge, east of Inchgarvie House.
3.10.8 With reference to any potential future transportation developments such as the introduction of LRT or BRT, the A904 located to the south would be used as the interface for such a system. Interacting with the provision of a new junction on the A904, future connections would be possible to a number of local destinations.
Junction Arrangements
3.10.9 In the provision of South Corridor Option 2, the provision of the following new and reconstructed junctions has been considered. The junction configurations are indicative at this stage, the requirements for each being considered in detail should this option be taken forward for DMRB Stage 3 assessment.
M9 Junction
3.10.10 The M9 Junction arrangement associated with South Corridor Option 2 consists of a complex layout, a number of slip roads being required to establish free flow connections between the M9, M9 Spur and proposed replacement bridge.
3.10.11 Similar to the layout proposed under South Corridor Option 1, all ways functionality is offered to road users of the M9 and M9 Spur with the existing loop arrangement being removed in favour of a simple link arrangement and the addition of west facing slip roads.
3.10.12 In addition and so to provide all ways functionality between the proposed replacement bridge and the M9, further link roads are provided, a large junction footprint being required to accommodate them. East facing slip roads are provided in the vicinity of the M9 Spur, south of Humbie Farm, enabling traffic to access both the M9 and M9 Spur.
3.10.13 To facilitate westbound movements between the proposed replacement bridge and the M9, a diverging slip road from the new dual three lane motorway is provided to the east of Humbie Reservoir. The opposing slip road, merging to the new dual three lane motorway from the M9, clips the eastern extents of Muiriehall Wood. In the provision of these links, a further 2 structural crossings of the Falkirk-Fife Railway Line are required.
A904 Junction
3.10.14 In the provision of a half diamond junction on the A904, local access connectivity is provided to the proposed replacement bridge. The provision of this junction also provides the functionality required to remove non-motorway traffic from the mainline carriageway prior to motorway restrictions commencing south of the A904.
3.10.15 The junction, proposed in a dumbbell roundabout configuration will require a minor reconfiguration of the A904, the existing local road crossing the proposed mainline carriageway on structure.
Scotstoun Junction
3.10.16 In addition to the required junctions on the M9 and A904, a reconstruction of Scotstoun Junction is also proposed as part of South Corridor Option 2.
3.10.17 The revised layout will provide all ways functionality between the A90 and the M9 Spur. In the provision of these additional movements, the priority route through Scotstoun Junction is changed from M9 Spur – A90 Westbound to M9 Spur – A90 Eastbound, new slip road arrangements maintaining access to South Queensferry and the existing Forth Road Bridge should there be a desire for its reconnection.
3.10.18 The provision of the new eastbound link from the M9 Spur to the A90 will complement the increased level of service offered by the new junction on the M9, facilitating direct access to the north of Edinburgh.
3.11 Do-Minimum Option
3.11.1 As indicated in the Forth Replacement Crossing Study, the do-minimum option for the Forth Replacement Crossing Project has to reflect what would happen if the proposed replacement bridge was not built.
3.11.2 At present, the future of the Forth Road Bridge is uncertain. Whilst it might continue to operate without the need for a high level of disruptive maintenance, the success of the dehumidification work, scheduled for completion in 2009, will not be known until 2012. A likely scenario is that the Forth Road Bridge will require a sustained period of refurbishment, causing significant disruption to cross-Forth travel through a requirement for partial or full closures. In light of this uncertainty and for the purposes of economic assessment, the route corridor options were assessed against a do-minimum which assumed that the existing Forth Road Bridge would be permanently closed to all traffic.
3.11.3 To effectively report the environmental impacts of the Forth Replacement Crossing Project, the continuing operation of the Forth Road Bridge at its present level of service will be considered as the do-minimum within this DMRB Stage 2 Corridor Report, providing an understandable baseline from which to undertake relevant assessment.
3.12 Cost Estimates
3.12.1 The cost estimates for each of the northern and southern route corridor options have been based on Quarter 4 2006 cost information and have been derived from historical tender information.
3.12.2 The figures quoted are for comparison purposes only. These are not to be mistaken for construction costs or final scheme outturn costs. Furthermore, the costs associated with each option do not take into consideration the costs associated with the proposed replacement bridge.
3.12.3 No cost estimate has been prepared for the do-minimum option. Should the Forth Road Bridge be closed, cross-Forth traffic will be redirected via existing roads infrastructure such as the M9, A977 and Kincardine Bridge.
3.12.4 The main roads infrastructure elements considered for cost estimation are detailed in Table 3.3. In the preparation of these cost estimates, the areas required to establish site clearance and road pavement have been calculated from the developing alignment designs associated with the northern and southern route corridor options. The requirements for fencing, earthworks and structures have also been calculated.
3.12.5 The bulk earthworks quantities calculated have been adjusted to reflect the presence of a capping layer and road pavement. It is assumed that a certain proportion of excavated material will be acceptable for use as engineering fill or landscape fill. This is based on a brief interpretation of the earliest results from the initial ground investigation work undertaken during 2008.
Table 3.3: Cost Estimate Assumptions
Road Works |
Assumption |
|---|---|
Site Clearance |
Area of influence assumed to be 10 metres beyond proposed earthworks interface with existing ground level. |
Fencing |
Boundary fencing assumed to be sited 5 metres from earthworks interface with existing ground level. |
Road Restraint Systems |
Road restraint systems provided where embankments are ≥6 metres in height, at road, rail or watercourse crossings, structures and in central reservation |
Drainage |
Pre-earthwork drains located at top of significant cut slopes |
Earthworks |
Topsoil assumed at 300mm thick |
Road Pavement |
Area based on length multiplied by cross section. |
Kerbs, Footways & Paved Areas |
No kerbing to mainline (except structures) |
Traffic Signs & Road Markings |
Cost of gantries to fall within Integrated Traffic System costs |
Road Lighting |
Junctions and mainline approaches to junctions lit from nearside. 36 metre column spacing assumed on mainline and in junction areas. 30 metre column spacing assumed on side roads |
Structures |
Structural requirements to include Bridge Works, Structural Retaining Walls, Culverts and Viaducts. |
3.12.6 A risk allowance of 10% has been factored in to the cost estimates provided for each route corridor option. This figure is derived from the sum total of the total construction cost, Employers Costs and Statutory Undertakers Costs. Contingency costs are taken account of with the risk allowance.
3.12.7 Optimism Bias is assumed at a level of 25%, in accordance with Her Majesty’s Treasury Guidance.
3.12.8 The total cost quoted for each route corridor option is exclusive of Value Added Tax (VAT).
3.12.9 Land acquisition and compensation agreements have not been considered within the cost estimates provided.
3.12.10 The cost estimate for each northern and southern route corridor option is provided for comparison in Table 3.4.
Table 3.4: Route Corridor Options - Cost Estimate Comparison
Route Corridor Option |
Cost Estimate (Excluding VAT) |
|---|---|
North Corridor Option 1 |
£518,760,000.00 |
North Corridor Option 2 |
£671,500,000.00 |
South Corridor Option 1 |
£318,260,000.00 |
South Corridor Option 2 |
£454,150,000.00 |
3.13 Proposed Replacement Bridge
3.13.1 Whilst the form of the proposed replacement bridge has no influence on the route corridor option selection process, for reporting completeness, an overview of the designs being considered as part of the ongoing assessment work is provided below.
3.13.2 The proposed replacement bridge is likely to encompass two cable stayed spans, each of approximately 650 metres, and three support towers, the central tower being located on Beamer Rock.
3.13.3 The landing points for the proposed replacement bridge to the north and south of the Firth of Forth are as follows:
- North – St Margaret’s Hill, east of Rosyth
- South – Fields at Echline, west of South Queensferry
3.13.4 Further development of the bridge design is ongoing and will be reported upon as part of the continuing scheme assessment process.
3.14 References
Forth Estuary Transport Authority. www.feta.gov.uk
The Highways Agency. The Design Manual for Roads and Bridges (May 2008)
Jacobs UK Ltd, Faber Maunsell, Grant Thorton and Tribal
Consulting.
- Forth Replacement Crossing Study, Report 1: Access Existing, and Forecast Future, Conditions of the Transport Network within the vicinity of the Forth Road and Rail Bridges, February 2007
- Forth Replacement Crossing Study, Report 2: Gaps and Shortfalls, February 2007
- Forth Replacement Crossing Study, Report 3: Option Generation and Sifting, February 2007
- Forth Replacement Crossing Study, Report 4: Appraisal Report, June 2007
- Forth Replacement Crossing Study, Report 5: Final Report, June 2007
The Scottish Government. The Government Economic Strategy, November 2007
The Scottish Government. The National Transport Strategy (NTS), December 2006
The Scottish Government. Key Road Accident Statistics 2007
The Scottish Government. The National Planning Framework 2 (NPF2) discussion draft, January 2008
The Scottish Government. Choosing our future: Scotland's sustainable development strategy, December 2005
The Scottish Government. New Purpose and Strategic Objectives
The Scottish Executive (Scottish Government). The City of Edinburgh Council and Scottish Enterprise Edinburgh and Lothian: The West Edinburgh Planning Framework, 2003
SEStran, draft Regional Transport Strategies
Forth Estuary Transport Authority (FETA). Local Transport Strategy, June 2005
The City of Edinburgh Council, East Lothian Council, Midlothian Council, West Lothian Council. Edinburgh and Lothians Structure Plan 2015
Fife Council. Fife Structure Plan 2006 – 2026
Jacobs Arup – Jacobs UK Limited and Ove Arup & Partners International Limited Consortium. Forth Replacement Crossing, Route Corridor Options Review – January 2009
Transport Scotland. Structures As-Built Record Information
Transport Scotland. 2008 Automatic Traffic Count (ATC) Data
Transport Scotland. Forth Replacement Crossing Sustainable Development Policy, 2008
The City of Edinburgh Council. Structures As-Built Record Information
Fife Council. Structures As-Built Record Information