The pressure of excessive flows of motorised traffic upon urban road networks is the principal component of the urban transport problem in most towns and cities of the Western and the developing world. The identification of the difficulties caused by vehicle movements in urban areas and the efforts made to apply effective solutions form the basis of this chapter, but urban transport also has a significant impact upon many aspects of the urban environment, such as air pollution and landscape conservation, which are discussed elsewhere in this volume.
The continually increasing rates of transport congestion and its detrimental impact upon the social and economic functions of towns and cities has stimulated the production of a wide range of problem-solving exercises, which constitute the urban transport planning process (Pass 1995) (see Figure 34.1). This varies in complexity and scope according to the urban area involved, and the efficacy of the planning process has increased with the number of disciplines that have contributed to the production of plans and policies (Dimitriou 1990a). In recent years, the environmental impact both of urban transport problems and of the solutions advanced has received particular attention (Banister 1994).
The earliest comprehensive urban transport plans date from the mid-twentieth century and were applied to large North American cities, where rapidly increasing volumes of motorised traffic were causing severe congestion. A demand-driven solution was commonly
Figure 34.1 Stages In the urban transportation planning process.
adopted, with the construction of new high-capacity urban expressways in city centres and suburbs (Muller 1995). By the early 1950s, car