Queue length is a basic element of urban traffic control for advanced analysis or applications. An algorithm for estimating queue lengths and stop delays at signalized intersections has been developed. The algorithm can be used to predict the queue length and the number of queueing vehicles on each approach or block to reflect actual traffic conditions by every second or other assigned time interval depending on the requirement of each traffic control center. A simulation program based on this algorithm is developed to calculate thesevalues by considering the status of real-time traffic lights, the number of queuing vehicles left, and the location of a designated vehicle detector. Field and video measurements were made at four lanes of three intersections in taiwan to test the predictions of this time-dependent queuing model. The preliminary results of comparisons between observed and estimated queue lengths and stop delays are encouraging and interesting. This simulation program has been installed at five trusts (traffic responsive and uniform surveillance timing systems) in taiwan for controlling urban traffic effectively. This paper appears in transportation research record no. 1324, Communications, traffic signals, and traffic control devices 1991
Abstract