Moving Queues in Freeway Traffic Networks

This paper presents the basic building block and some illustrations of a computer program that is currently being developed to predict the behavior of freeway traffic with a macroscopic model. The program, which keeps track of traffic destinations, is based on an approximation of the hydrodynamic theory of traffic flow in which time and space are treated as discrete variables. The program automatically tracks shocks and acceleration waves, and can realistically locate the front and rear end of moving queues within every link. The basic building block is illustrated by means of a computer spreadsheet that produces numerical output in the form of a time-space table. An example is given in which the table can be seen at a glance to exhibit the shock-wave pattern obtained with the hydrodynamic analysis. An appendix documents the spreadsheet, which can be constructed in a few minutes; with this spreadsheet the reader can easily verify the results and solve other (single link) problems.