New Approach for Calibrating Robertson’s Platoon Dispersion Model

Abstract

A new approach for calibrating Robertson’s platoon dispersion model (RPDM) is proposed for addressing the issue of overestimation of time span of downstream vehicle arrival as predicted by the model Instead of comparing the observed and predicted vehicle arrivals during different modeling time intervals, the new approach for calibrating RPDM concentrates on the time span of downstream vehicle arrivals to model the vehicle platoon dispersion. The new approach is demonstrated using vehicle platoon data collected from a signalized urban arterial. Vehicle arrival profiles as obtained using the new approach for calibrating RPDM and the traditional approach are further compared. The error related to overestimation of time span of downstream vehicle arrival is found to be lower for the new approach for calibrating RPDM than the traditional approach. Microsimulation models were used to evaluate the implications of the new approach to calibration on signal design. Three scenarios (SC-I, SC-II, and SC-III) were hypothesized with variations in link length between a pair of coordinated traffic signals. All three scenarios resulted in the reduction of vehicle delay along the coordinated links while adopting the new approach for calibrating RPDM to develop the signal timing plan using TRANSYT-7F. Although these are case-specific findings, they encourage further testing of the new approach to calibration on the design of coordinated traffic signal systems for several corridor and traffic conditions.