Simple Method of Predicting Travel Speed on Urban Arterial Streets for Planning Applications

Abstract

Travel speed is a key measure of effectiveness in evaluating urban arterials. The Highway Capacity Manual (HCM) methodology of predicting speeds along urban streets requires complex calculations and input not typically available in long-range planning. The use of default values is therefore necessary. This paper demonstrates that a simple and practical method of estimating travel speed along urban arterial streets is possible. An equation derived from the HCM delay formula and calibrated with the results obtained from CORSIM, a microsimulation model, is proposed. The equation requires neither signal characteristics nor detailed traffic and geometry information about arterial intersections. The proposed model of travel speed along urban arterials uses only input available to planners. The model is evaluated with the results obtained from a field study in Lafayette, Indiana. Despite its limited scope of input and simple structure, the model properly replicates the trends found in the field. The model overestimates the actual speeds by 18%, and a simple adjustment factor removes the bias.