Part 1: The Scheme
1. Scheme Background
1.1 Forth Replacement Crossing
1.1.1 This is the DMRB Stage 2 Corridor Report for the Forth Replacement Crossing, one of twenty nine strategic transport interventions identified within the Strategic Transport Projects Review (Section 1.2) which reflect the diversity of the country whilst addressing the issues that currently exist or are expected to exist in the future.
1.1.2 The Forth Replacement Crossing is a fast tracked component of the Strategic Transport Projects Review, and will ensure that this key river crossing is maintained, protecting the economies of Fife, Edinburgh and beyond from the disruption stemming from the uncertainty over the long term viability and operation of the Forth Road Bridge and concerns over the current operational characteristics of the surrounding road network.
1.2 Strategic Transport Projects Review
1.2.1 The Strategic Transport Projects Review (STPR) is a body of work which has been undertaken by Transport Scotland to define the most appropriate strategic investments in Scotland’s national transport network between 2012 and 2022.
1.2.2 The review, which commenced in the summer of 2006, has culminated in the publication of a report detailing a portfolio of land based interventions to be taken forward, further developing Scotland’s transport infrastructure to meet the demands of the 21st century.
1.2.3 The focus of the STPR is in the identification of those interventions that most effectively contribute towards the Government’s purpose of increasing sustainable economic growth. Its objective led evidence based approach enables transport issues to be appraised and addressed effectively. This system of assessment is comparable to that implemented in STAG and ensures that the national priorities of a Wealthier and Fairer, Healthier, Safer and Stronger, Smarter and Greener Scotland are met and that investment is targeted on the measures which will best assist in the promotion of Scotland’s sustainable economic development.
1.2.4 The outcome of the STPR is based on a tiered system of investment structured around the following priorities:
- Maintaining and safely operating existing assets;
- Promoting a range of measures, including innovative solutions that make better use of existing capacity; and
- Promoting targeted infrastructure improvements where these are necessary, affordable and practicable.
1.2.5 Through the implementation of this approach, best use can be made of the limited resources available, ensuring that new infrastructure is identified only after other interventions have been appraised and considered.
1.2.6 This has been achieved through:
- Looking at what the picture of transport might look like in the future and identifying the issues this creates in terms of achieving the Government’s Purpose;
- Allowing a range of interventions, covering a variety of modes across Scotland, judged comparatively on their merits; specifically in terms of their ability to address these issues and support the Government’s Purpose; and
- Prioritising investment to meet the Government’s Purpose and the complementary objectives of the National Transport Strategy.
1.2.7 Taking the above into consideration, the Forth Replacement Crossing forms a key piece of infrastructure investment in Scotland.
1.2.8 The Forth Replacement Crossing Study (Section 1.3), undertaken as part of the STPR, was brought forward as a result of the findings relating to the deteriorating condition of the Forth Road Bridge and considered potential options in the provision of a replacement crossing of the Firth of Forth.
1.3 Previous Studies: Forth Replacement Crossing Study
1.3.1 The Forth Replacement Crossing Study was commissioned by Transport Scotland in 2006. Its purpose was to identify the scope, form and function of any potential replacement to the Forth Road Bridge. Reports 1 to 5 containing the findings of the study were published in 2007.
1.3.2 The need for a replacement crossing was justified for the following reasons:
- There is a lack of certainty that the existing Forth Road Bridge is going to be available in the future; and
- The repair/refurbishment of the existing crossing has too severe a set of impacts on the east of Scotland economy if it were to be closed (or even severely restricted) for a period of time.
1.3.3 In the consideration of potential locations for a replacement crossing of the Firth of Forth, a list of sixty five potential options was generated. These options were assessed through an initial sifting process with options which did not satisfy national and regional policy objectives or the study objectives being eliminated. The study objectives are reflected within the Forth Replacement Crossing Project’s Scheme Objectives (Section 1.4). Following this initial sifting exercise the provision of a replacement crossing was considered in the following corridors:
- A – Grangemouth
- B – East of Bo’ness
- C – West of Rosyth
- D – East of Rosyth/West of Queensferry
- E – East of Queensferry
1.3.4 Each of these corridors is displayed graphically in Figure 1.1.
Figure 1.1: Forth Replacement Crossing Study – Replacement Crossing Corridors
1.3.5 The suitability of each corridor was assessed for a bridge or tunnel crossing. Through the undertaking of this work, it was established that Corridors A and B did not meet the scheme objectives and as such these were rejected. Corridors C, D and E were deemed to perform well against the objectives and were taken forward for assessment as part of a STAG Part 1 Appraisal, with both bridge and tunnel options being considered for all three corridors.
1.3.6 The outcome of the STAG Part 1 Appraisal resulted in bridge options for Corridors C and E being set aside from further consideration due to their impact on Forth Special Protection Areas (SPA). Corridors C (Tunnel), Corridor D (Bridge or Tunnel) and Corridor E (Tunnel) were taken forward for further development.
1.3.7 Through the undertaking of a STAG Part 2 Appraisal, the principal factors differentiating the options were implementation, environmental impact and economic efficiency.
1.3.8 The recommendation from this appraisal was that Corridor E should not be considered further on the basis of environmental impact, the implementation risk associated with tunnels, the impact of drill and blast construction techniques on Hound Point (Marine Terminal for Oil Export), mine workings and the high costs involved.
1.3.9 Of the remaining tunnelling options, little difference was reported between Corridors C and D, both taking the same time to construct and requiring similar budgets. Corridor D did perform marginally better economically but considering the replacement crossing as a whole, the provision of a tunnel did not provide the same level of service as a bridge, with access being restricted to motorised vehicles only.
1.3.10 The Forth Replacement Crossing Study concluded that a cable stayed bridge in Corridor D was the best overall performing option in relation to:
- Cost - It is significantly cheaper than the tunnel options;
- Construction Programme - It can be delivered quicker;
- Construction Risk - It has fewer risks associated with its construction; and
- Economics - It has the best Benefit to Cost Ratio (BCR).
1.3.11 The findings of the Forth Replacement Crossing Study were the basis for the decision of the Scottish Government, announced by the Cabinet Secretary for Finance and Sustainable Growth on 19 December 2007.
1.4 Scheme Objectives
1.4.1 The scheme objectives outlined from the conception of the Forth Replacement Crossing Study are as follows:
- to maintain cross-Forth transport links for all modes to at least the level of service offered in 2006;
- to connect to the strategic transport network to aid optimisation of the network as a whole;
- to improve the reliability of journey times for all modes;
- to increase travel choices and improve integration across modes to encourage modal shift of people and goods;
- to improve accessibility and social inclusion;
- to minimise the impacts of maintenance on the effective operation of the transport network;
- to support sustainable development and economic growth; and
- to minimise the impact on people, and the natural and cultural heritage of the Forth area.
1.4.2 In relation to the above, the announcement made by the Cabinet Secretary for Finance and Sustainable Growth on 19 December 2007 stated that the Forth Replacement Crossing Project would provide:
- a replacement for the Forth Road Bridge;
- a dual carriageway with hard shoulders and facilities for cyclists and pedestrians;
- provision for future multi-modal public transport;
- connecting roads to allow greater choices and opportunities to West Lothian and to protect and promote development areas in Fife.
1.4.3 The provision of a multi-modal transport corridor will allow future consideration to be given to the introduction of Light Rapid Transit (LRT), Bus Rapid Transit (BRT), guided buses or trams in future years if required.
1.5 Sustainable Development Objectives
1.5.1 One of the main commitments made in the scheme objectives is ‘to support sustainable development and economic growth’ making it clear that the concept of sustainability is at the heart of the Forth Replacement Crossing Project.
1.5.2 Transport Scotland recognises this and has set out a sustainable development policy for the scheme including a vision statement and objectives. The vision is ‘To deliver an iconic project that respects the environment, contributes to the regional and Scottish economy and facilitates efficient public transport whilst minimising disruption to the community and reducing the use of non-renewable resources during its construction and throughout its life’.
1.5.3 Beneath this vision is a set of sustainable development objectives and the reader is referred to Transport Scotland’s ‘Forth Replacement Crossing Sustainable Development Policy’ for more details about the objectives and how these relate to the Government’s Sustainable Development Strategy for Scotland and the Scottish Government’s ‘New Purpose and Strategic Objectives’.
1.5.4 Consideration of sustainable development will form a core thread throughout all the activities of the project team and stages in the project life cycle including:
- Project design and appraisal;
- Preparation of contract documents, and hence tenderers’ designs (dependent on procurement method);
- Tender evaluation;
1.5.5 An overview of the sustainability assessment that underpins the DMRB Stage 2 assessment is presented in Part 5 of this report.
1.6 DMRB Stage 2 Corridor Report Methodology
1.6.1 This DMRB Stage 2 Corridor Report has been prepared in accordance with TD37/93, Scheme Assessment Reporting, of the Design Manual for Roads and Bridges (DMRB).
1.6.2 The purpose of this report is to document the factors that have been taken into account in the provision of alternative route corridor options, considering the scheme objectives and the engineering, environmental, traffic and economic advantages/disadvantages and constraints associated with each.
1.6.3 To demonstrate the possible extent of the improvements (subject to further scheme definition work), preliminary layout drawings have been prepared and are included within Volume 2 of this report.
1.6.4 It should be noted that whilst the proposed replacement bridge forms a significant element of the Forth Replacement Crossing Project, its alignment has no effect on the route corridor option selection process, its position and bearing having been fixed to allow the effective design of associated roads infrastructure.
1.6.5 For the purposes of DMRB Stage 2 assessment, the route corridor options discussed within this report have been considered over the full extents of the Forth Replacement Crossing
1.6.1 study area. As a part of the next stage of design and assessment, further detailed consideration shall be given to the form and function of the junctions required and the extent of the optimal road infrastructure improvement provided within the preferred corridor. The developing design shall also reflect future consideration of the use of the Forth Road Bridge.
1.6.6 Whilst following the format prescribed in TD 37/93 to the extent practicable, the volume of information presented within this DMRB Stage 2 Corridor Report dictates that it be presented in the following chapters:
- Part 1: The Scheme
- Part 2: Engineering Assessment
- Part 3: Environmental Assessment
- Part 4: Transport and Economic Assessment
- Part 5: Sustainability Assessment
- Part 6: Southern Route Corridor - Combination Option Assessment
- Part 7: Conclusion and Recommendation
- Part 8: Appendices