This paper is based on a research study carried out at TRL into the problems of, and possible solutions to, suburban and ex-urban congestion. To examine these problems in a consistent fashion it is necessary to use a multi-modal transport model able to incorporate the behavioural choices made by people in response to a wide variety of generalised transport costs and supply-side effects. A number of such models have been developed in the 1980s and 1990s and one of these, the TRL Strategic Transport Model, was adopted for this study. The model has been employed to assess the effects of six potential policies aimed at reducing car use using the cities of London and Manchester as case studies. Analysis of the model output has focused on traffic levels, changes in modal share and mean road speeds. Three of the policies contain elements which apply globally and the other three only directly affect travel costs to the city centre. These policies, and especially those focused upon the central area, represent a plausible range of possible actions which might be adopted to combat rising car use and congestion. The policies represent rather extreme changes in costs so as to bring out the results more clearly. (A)
Abstract