The results from the Wider Economic Benefits calculations should be presented as an additional sensitivity to the TEE results. The current position of Transport Scotland is that WEBs should not be included in the standard calculation of an NPV and BCR as detailed above. However, a second NPV, termed NPVWEB, and BCR, termed BCRWEB, that sum the standard TEE and WEB results may be presented.
It is important to note that this must, at this stage, be clearly labelled as a sensitivity and the standard TEE results should remain the core reported figure. It is anticipated that this position may change in the future but remains guidance at present. If only a single figure is reported it should remain as the standard value.
The primary driver for this distinction is the difficulties associated with Monitoring and Evaluating the outturn of WEBs. The view is that a stronger focus on WEBs at this stage would undermine the monitoring and evaluation of schemes put forward under STAG.
A suggested approach is shown below:
|
NPV |
|
| BCR | |
| Agglomeration Impacts WB1 | From equation 5 |
| Imperfect competition impacts WB3 | 10% of business time savings |
| Total Wider Economic benefits | Sum of WB1 +WB3 |
| Adjusted NPV (NPV web) | |
| Adjusted BCR (BCR web) |
Transport Scotland recognises that the calculation of agglomeration benefits is an emerging science, and that innovative methodologies are frequently applied. Whichever methodology is employed, practitioners should ensure that their results are reported in a transparent manner. Supporting technical information should be provided, either as part of the Economy AST or as a separate technical annex. Examples of technical data that practitioners may wish to supply are changes in generalised cost, income per worker, and agglomeration elasticities for key zones; however the choice of data deemed most appropriate to support the calculations is left up to the judgement of individual practitioners.
