COMPUTATIONAL REALIZATIONS OF THE ENTROPY CONDITION IN MODELING CONGESTED TRAFFIC FLOW. FINAL REPORT

Existing continuum models of traffic flow tend to provide somewhat unrealistic predictions for conditions of congested flow. Previous approaches to modeling congested flow conditions are based on various types of "special treatments" at the congested freeway sections. Ansorge (Transportation Research Part B, 24B, 1990, pp 133-143) has suggested that such difficulties might be substantially alleviated, even for the simple conservation model of Lighthill and Whitman, if the entropy condition were incorporated into the numerical schemes. In this report the numerical aspects and effects of incorporating the entropy condition in congested traffic flow problems are discussed. Results for simple scenarios involving dissipation of traffic jams suggest that Godnunov's method, which is a numerical technique that incorporates the entropy condition, is more accurate than two alternative numerical methods. Similarly, numerical results for this method, applied to simple model problems involving formation of traffic jams, appear at least as realistic as those obtained from the well-known code of FREFLO.