Some Issues in Modelling the Impact of Changes in Transport Costs on Residential and Employment Locations.

This paper is written as part of a project on the effects of increases in rail fares on location and commuting decisions in London and South East England. The main theme of the paper is the relationship between accessibility and locational choice. The various factors determining the choice of residence, and to a lesser extent, job, are discussed, in particular, the importance of accessibility in the process. A wide variety of urban locational models are then discussed, in particular frm the point of view of how accessibility is taken into account. The models described are urban economic, spatial. interaction, regression, disaggregate and demographic. A model of the relationships between land use and transport that has already been applied elsewhere is then examined in terms of its suitability for analysis of the processes being studied in this project. A variety of possible extensions to the model are then put forward including the treatment of interaction with the rest of the country, the relationship between transport costs and the overall level of activity in the study area, the use of the different transport costs for different purposes, and an accounting framework including population, households and employment. The implication of these ideas for the survey are then discussed. The conclusion of this work is that the problem should be divided into a set of topics, with a variety of different analytical techniques being used, rather than a single comprehensive model of all the relevant decision processes involved in the impact of rail fares on location and commuting in London and South East England.