The Effects of Appraisal Methodology on the Specification of Optimal Urban Transport Strategies

ABSTRACT The concept of integrated urban land-use and transport strategies has been promoted for more than a decade. In most cases, strategy appraisal is conducted by maximizing some measure of total welfare based on a cost–benefit analysis (CBA). In other cases, a multicriteria approach is adopted whereby monetized and nonmonetized effects are taken together. More recently, there has been a move toward the use of targets at both national and local levels first for monitoring purposes but also for the appraisal of strategies against outcomes. The aim of this paper is to present optimal transport strategies resulting from the application of different appraisal frameworks. We apply and compare a standard CBA appraisal and a target-based approach. We also look at constrained optimization solutions, adding constraints on finance, CO2 emissions, and cost of accidents to the CBA approach. The results are presented and discussed for two UK cities: Edinburgh and Leeds. This research configuration allows us to identify and explain similarities and differences in the optimal strategies and to decide whether they stem from the application of the different appraisal methods or if they are city specific. Our results indicate that there is a discrepancy between the targets set and the monetary values used in the CBA approach. When constrained to meet certain targets, the impact on policy can be significant; in the extreme case, it can reverse the policy for capacity increases. The constrained CBA approach can find solutions that maximize welfare while satisfying the targets, but this still leaves open the issue of whether targets and monetary values can be set that are consistent with one another.