The objective of this paper is to identify some of the research issues involved in the analysis of the impact of changes in transportation costs on the long-term development of the city. From studies of the impact of new rapid transit systems it appears that the effects are fairly subtle. During the 1960s and early 1970s most of the transportation models that were developed ignored the feedback to the lane use allocation process. More recent developments in the fields of integrated models of the interrelationship between lane use and transportation and individual choice models go some way towards solving the problems, hut there are many outstanding issues. In the paper the role of transportation costs in the decision process of individuals and households making locational choices are considered. More specifically the following are discussed: whether the cost of travel to work is relevant in the choice of home and job, the number of stages that should be considered in the locational decision process, the required quality of the definition of the set of choices available, the interrelationships between locational and other household decisions, and the definition of the decision-making unit. These ideas are being investigated in the context of a study of the impact of rail fare increases on the choice of home and job in London and South-East England. The evidence about the changes from aggregate data is conflicting, in particular whether a recent small increase in the use of rail represents a reversal of the previous trend of decentralisation, or is a temporary shift partly brought about by changes in the relative cost of alternative modes. The objective of the study is. to examine the behaviour that is bringing about the observed changes. Consequently, surveys are being carried out of all workers at a number of larger employers in Central London and of current and former rail season-ticket holders in Hertfordshire to the north of London. This information will be used in the calibration of an existing aggregate model of the interrelationship of transportation and land use, and in the development of microlevel models of the locational choice process and other decisions. Those models will be run in parallel so that the forecasting abilities can be compared and the implications interpreted. Thus, the analysis will assist in both the development of new analytical methods, and the understanding of the policy implications of increasing the cost of travel. (Author/publisher)
Samenvatting