Impact of left-turn waiting areas on arterial coordination: a signal performance assessment

Whether to deploy left-turn waiting areas (LTWAs) in arterial coordination remains debated as the required fixed phasing sequences may constrain signal flexibility. To fill this gap, a Vissim-based corridor synchronisation performance tool (V-CSPT) was developed based on signal timing performance measure methodology to evaluate the impacts of LTWAs on arterial coordination. This tool enables the collection of vehicle trajectories from microscopic traffic simulation software, facilitating performance analysis and evaluation. To assess the impacts of LTWAs on arterial coordination, a case study was conducted on an arterial with LTWAs in Wuhan city, China. The results indicated that LTWAs did not deteriorate the traffic operations of an arterial system under adequately designed signal timing plans, and could reduce the probability of left-turn traffic queue overflow and the subsequent negative effects on through traffic. According to the results of the analysis, there was no difference between deploying and not deploying LTWAs. Compared with scenarios without LTWAs, in the scenarios with LTWAs, delays were reduced by 35.65% and 23.94% and the stop ratio was reduced by 8.28% and 1.01%. In addition, it was found that the V-CSPT could simplify the signal performance measurement process and potentially reduce performance measurement costs.