URBAN LAND USE BUDGETS: A SMALL HOMAGE TO SMEED AND MOGRIDGE

This paper discusses the importance and continued relevance of two publications: The space requirements for traffic in towns (1962) by R J Smeed (in Williams, T E H (Ed) Urban survival and traffic, Spon) and Travel in towns: Jam yesterday, jam today and jam tomorrow? (1990) by M J H Mogridge, MacMillan (IRRD 832806). Smeed's paper provides a simplified model of a city, assuming it to be non-residential and that all workers live a similar distance from the city. It concluded that the proportion of a town's area dedicated to transport increases with increasing size and that the size of a town is affected far more by the mode of travel as it increases in size. Travel by car to small towns requires an area to park greater than the area required for the traffic to move, even if multi-storey parking is introduced. Mogridge's closely-argued book suggests that changes in traffic volume and changes in speed are interdependent variables capable of changing places. Public transport costs are reduced by the quantity of users whereas private transport costs increase as the number of users increase. This results in a point of convergence at which the increasing costs of car use equal those of public transport use. Consequently any improvement of the road network will encourage the use of cars unless improvements to public transport are made. However journey speeds in urban areas are constrained by the presence of buses and still remain more or less constant. These ideas are complicated by changes in urban form, whereby employers move out from the business districts to the peripheries of towns. It is suggested that Mogridge's conjecture that access costs by public transport act as a glass ceiling to car costs is incorrect, or would be correct only if the trip matrix is fixed. In practice the trip matrix can only be regarded as fixed in the short term. For the covering abstract see ITRD E121926.