Urban congestion management: the impact of demand management proposals

It is now generally accepted that urban transport problems cannot simply be solved by providing additional infrastructure or managing the existing infrastructure more effectively. In addition, measures are required to manage the demand for road use, and the Department of Transport now advocates demand management as a key element of Package Approach submissions (DoT, 1995). There is rather less guidance as to the forms which demand management might take, or the levels which might be required. While successful demand management measures will reduce pressures on the transport system, they will certainly not remove the need for effective management of system. Moreover, by changing the pattern of demand, they are likely to introduce a new set of congestion management requirements. This paper discusses this set of issues. It starts by considering the objectives of demand management, and the target reductions which others have sought. It then reviews the strengths and weaknesses of the main types of demand management measure which are potentially available. Finally it discusses, for the three main contenders, the changes in congestion management strategy which are likely to arise if they are successfully implemented.