A modified cell transmission model considering queuing characteristics for channelized zone at signalized intersections

Abstract

This paper focuses on traffic flow modeling of signalized intersections with entrance widening lanes and shared lanes. The link of the signalized intersection is divided into the upstream mixed zone, the transition zone, and the downstream channelized zone. The development of the modeling framework is motivated by the need to model realistic flow dynamics, especially regarding the complex interactions in the channelized zone. To describe the evolution of traffic flow, a modified cell transmission model is developed, which jointly captures features of the queue discharge process, diverge process, optional lane-changing, and shared lanes. Furthermore, a queue length calculation method based on cell densities is proposed to obtain the queue profile. Finally, the performance of the proposed modified CTM is tested using both VISSIM simulation data and empirical data on actual intersections. Numerical experiments are conducted to illustrate the importance of capturing each of these realistic queuing features for queue estimation. It is observed that our modified CTM can estimate the lane-group based queue length, and it has good estimation accuracy on both under-saturated and over-saturated traffic conditions. With the increase of the proportion of through vehicles, the estimation error decreases. The mean values of the weighted mean absolute percentage error (WMAPE) of the link maximum queue length estimation in all cases are less than 13.73%. Compared with the benchmark method, the proposed method shows better accuracy. The improvement of the modified CTM is more significant under heavy traffic conditions.