Chapter 17: Spatial Data Issues: A Historical Perspective

Travel is a phenomenon that takes place in both time and space, as was clearly expounded by Hagerstrand (1970) and Lenntorp (1976). This work is also discussed at a little more length in Chapter 36 of this book. The temporal aspects of travel are relatively easily handled, and only brief mention of them is made in this chapter, but the spatial aspect of travel presents a number of challenges to the transport analyst. Transport planners need to know where travel will take place, and the amount of travel at different locations. In developing models to define this, transport planners need to know where people live and the travel that they undertake, by geographic location, and where the destinations are to which people travel. Traffic engineers need to know where congestion occurs in the system, where traffic signals and other traffic control devices are, and where there are changes in the supply of capacity for traffic. Bus planners need to know where bus stops are located, and where people who use the services originate, arrive, and where they transfer between services. Rail planners need to know at which stations passengers board and alight, where transfers are made, and how people get to and from the rail station. In short, all aspects of transport planning, traffic engineering, public transport operation and management, investment planning, etc., require information about various spatial aspects of the transport system.