INTERACTIVE GRAPHICS SYSTEM FOR TRANSIT ROUTE OPTIMIZATION

A person-computer interactive graphics system for optimizing the routing structure on an urban transit network is presented. The system allows a user to design bus, streetcar, and subway routes on a display scope and to specify route frequencies and types of vehicles. The computer predicts the effects of the routing structure by assigning potential transit trips to the network and it displays the route loadings along with statistics on travel times, rolling stock use, and operating costs. After evaluation, the user can partially or totally modify his or her designs and thereby move toward routing schemes that come closest to planning objectives. The system is based on a multipath transit assignment model that is a further development of R. B. Dial's stochastic assignment algorithm. The model is implemented on a CDC 7326 series computer with a display scope, and it has been tested by being applied to the Lausanne, Switzerland, public transit system. A second implementation of the model has been realized on a small computer environment and is being used productively for optimizing the 24-route tramway and bus network of Basel, Switzerland. The methodology and some results of these applications are described.