Using the Impacts of Active Traffic Management Rollout Project to Discuss Wider Economic Benefits in Transport Appraisal
R Bose, T van Vuren, Mott MacDonald, UK; S Kohli, Steer Davies Gleave, UK
Using the impacts of active traffic management rollout project to discuss wider economic benefits in transport appraisal.
Traditionally it has been argued that direct benefits from transport investment could be used as a proxy for wider benefits, but it has been raised that the impact of transport investment on activity patterns and land use is potentially huge yet rarely considered in transport scheme appraisal and decision-making (Wenban-Smith, 1999). This paper uses the rollout of Active Traffic Management (ATM) scheme across the West Midlands (U.K.) motorway box as a case study to compare conventional benefits and wider economic benefits in transport appraisal, address this question whether or not these indirect impacts should be brought into transport scheme appraisals, and how this could be done.
Using the recent guidelines, issued by Department for Transport (DfT) of the U.K., to estimate these benefits, it has been suggested that wider economic benefits of transport schemes accounted for about an additional 25% benefit over the conventional benefits for various transport investment packages for Leeds city region (Marshall and Weber, 2007).
Transport Analysis Guidance given by DfT (2003), has provided a methodology to include in the appraisal of transport schemes the wider economic benefits, including impacts on GDP. We have implemented the guidance in our forecasting and appraisal work using the strategic model of West Midlands U.K. (PRISM). Commuting travel time saving is used as a proxy of estimating wider economic benefits. The scheme for which benefits have been estimated is the rollout of Active Traffic Management (ATM) across the West Midland motorway box.
One of the key drivers of wider economic benefits tends to be the employment location changes that the transport scheme or policy causes. Normally these changes are estimated by the use of Land Use Transport Interaction (LUTI) models or Spatially Computable General Equilibrium (SCGE) models. We have devised an innovative technique to estimate the impact of the transport schemes on employment density for singly constrained models where LUTI or SCGE models are not available. This technique is also discussed in this paper.
The study can only scratch the surface of this important area of development in appraisal. We suggest that it will comprise of the following tasks:
- More detailed literature review regarding this area;
- The methodology to estimate changes in employment location using a singly constrained modes in the absence of a land use model;
- description of the concepts behind the calculation of wider economic benefits and the associated data requirements;
- detailed discussion of the results for ATM rollout in West Midlands covering traditional economic benefits analysis and wider economic benefit analysis.
In discussing the test results we try to identify more general lessons that can be learned about the impacts on the direction and size of the additional impacts as a function of the types of scheme that are assessed and about the assumptions that are made.
Association for European Transport