Estimation of Travel Times in Multiple Mode Systems^†

Abstract

This paper describes a procedure for generating estimates of the minimum travel times (shortest distances, least cost routes) between pairs of points on a standard map. The procedure exhibits substantial improvements in accuracy over the traditional generation methods involving simple orthogonal and vector-directed distance metrics. These improvements are achieved by combining the traditional methods with algorithms which find shortest routes in networks. The new procedure is particularly appropriate to the analysis of transportation or distribution systems which entail "multiple-mode travel", e.g. surface road vs. expressway travel, or railway vs. air travel. The advantages of the procedure are illustrated with empirical evidence from a simulation study of travel times in a large urban area. Finally, the generality of this procedure to a wide class of problems is discussed.