Scottish Trunk Road Infrastructure Project Evaluation - Evaluation Report for Trunk Road Projects Opened between April 09 and March 10
1.1 Background to Project Evaluation
Road infrastructure projects normally take a minimum of 5 to 7 years to plan prior to the commencement of construction and it is not possible to know exactly what will happen when a project is opened, nor what would have happened had the project not been built, particularly when the project is opened a number of years after its assessment.
The aims of evaluation, as set out in the Design Manual for Roads and Bridges (DMRB), Volume 5, SH 1/97 'Traffic and Economic Assessment of Road Schemes in Scotland', are as follows:
- to satisfy the demands of good management and public accountability by providing the answers to questions about the effects of a new or improved road;
- to identify the strengths and weaknesses in the techniques used for appraising projects, so that confidence in the roads programme is maintained;
- to allow the predictive ability of the traffic or transport models used to be monitored to establish whether any particular form of model is consistently more reliable than others when applied to particular types of projects; and
- to assist in the assessment of compensation under Part 1 of the Land Compensation (Scotland) Act 1973 for depreciation due to the physical factors caused by the use of public works.
The evaluation of trunk road projects is evolving as Transport Scotland improves its process and reporting to reflect the principles of monitoring and evaluation set out in the Scottish Transport Appraisal Guidance (STAG).
STAG advocates evaluation against indicators and targets derived for the Transport Planning Objectives originally set for the project, STAG criteria (Environment, Safety, Economy, Integration and Accessibility & Social Inclusion) and relevant policy directives, the aim of which is to identify:
- whether the project is performing as originally intended;
- whether, and to what extent, it is contributing to established policy directives; and
- whether the implemented project continues to represent value for money.
1.2 Projects Reported
The Evaluation Report for Trunk Road Projects Opened between April 09 and March 10 presents the evaluations undertaken for projects costing over £5m that were completed and opened to traffic in the 2009/10 financial year.
The projects evaluated in this report are listed in Table 1.1 and their locations are shown in Figure 1.1.
The A830(T) Arisaig and Loch Nan Uamh project involved the upgrade of 7.5 kilometres of single track road with passing places to 2-lane single carriageway standard. The A7(T) Auchenrivock project involved the off line construction of 1.6 kilometres of single 2-lane carriageway and 1.7 kilometres of wide single 2‑lane carriageway. The A9(T) Bankfoot junction improvement was delivered as part of a series of improvement along the A9(T) corridor and included the removal of right turn manoeuvres across the main carriageway through improvements to the existing A9(T)/B867 junction and the realignment of a minor road to the north.
Chapter 2 of this report presents the methodology and data sources used in the evaluations of projects that opened between April 09 and March 10. Chapter 3 provides a summary of the evaluations and the key findings are presented in Chapter 4.
Full details of the evaluations for the projects are contained in Appendix A.