MAXBAND-86: Program for optimizing left-turn phase sequence in multiarterial closed networks.

Abstract

Four variables are available to the traffic engineer that can be used to optimize the flow of traffic in signalized urban networks. Three of these--green phase time, offset, and cycle length--are well know, and a number of computer programs are available to determine them. A fourth variable, left-turn phase sequence, is less well known and can be computed only for arterial networks by existing software. Recognizing that the left-turn pahse sequence might be an important variable in multiarterial closed networks, the Federal Highway Administration (FHWA) contracted with Texas Transportation Institute (TTI) to extend the MAXBAND program, which was restricted to single arterials and triangular networks, to such general networks. The extensions made to the MAXBAND program resulted in MAXBAND 86; these extensions are described in this paper. The application of MAXBAND 86 to a study of the effect of the left-turn phase sequence in 10 multiarterial closed networks is described also. The study included comparison of MAXBAND-produced timing plans with and without phase sequence optimization and an analysis of the effects of using phase sequence patterns given by MAXBAND in the TRANSYT program. The results indicate that optimization of the phase sequence can often provide a substantial benefit in terms of reduced delay and stops.