In traditional transport planning the changes in the spatial structures of urban areas are often assumed to be exogenous. Research into the urban development of Europe has shown they are so only in the short run. In the development of towns different stages can be distinguished, succeeding one another as economic circumstances evolve, each stage showing its own spatial structure and transportation patterns. In the long run, both the spatial structure of towns and transportation structures become part of an interdependent system, that is, they become endogenous. Urban policies and income are among the factors that govern urban dynamics, the latter factor being by far the most important. In periods of income growth, urban structures tend towards spatial deconcentration; in periods of economic decline they tend towards spatial concentration. Through urban dynamics, changes occur in the average travel distance and in the spatial and temporal structure of traffic. Should the present economic recession continue, then the future urban development is likely to be marked by progressive spatial concentration, probably attended by decreasing travel distances. Average travel time may not decrease in proportion, however, for spatial concentration may well entail increasing congestion.(a) for the covering abstract of the conference see IRRD 276520.
Samenvatting