SIMULATION TECHNIQUES FOR FREEWAY DESIGN

Freeway design skills are being tested to the utmost by the wave of improvements required for the interstate highway system. Many segments of the aging interstate system are overloaded. Standard geometrics are causing bottlenecks at many locations. The analysis of freeway operations for design purposes has to cope with closely spaced interchanges, short weaving sections, and very complex weaving sections. The complexities of design problems are well beyond the level of analysis that can be achieved using equations and graphs such as those employed in the current Highway Capacity Manual. The most promising tool, today, for the analysis of complex interchange problems, is the process of microscopic simulation. The state-of-the-art microsimulation model for freeway operations analysis is the FRESIM microsimulation model, which was developed by the Federal Highway Administration. The objective of this brief paper is to illustrate the opportunities offered by microsimulation, by means of examples of recent design studies.