Traffic Simulation Models to Enhance Signal Timing in an Oversaturated Network: A Comparative Study of Optimizing Individual Intersections versus the Entire Network

Abstract

The objective of this study is to investigate the variations in performance of a network with multiple oversaturated intersections—particularly delays and queue lengths—generated by two different signal timing approaches, namely (i) the classical isolated signal timing approach that aims to optimize each intersection's signal timing independently and (ii) the network optimization approach that focuses more on the network's holistic performance. In doing so, two signal timing models are herein developed using Synchro—a powerful traffic simulation tool—based on the information of a real oversaturated network with six consecutive intersections located on a major arterial street of Bangkok, Thailand, during the weekday evening peak period. The results of this simulation indicate that optimal cycle lengths and the allocation of green intervals are two key success factors that help reduce average delays and queue lengths at these intersections. To this end, excessive green intervals tend to result in greater delays and queue lengths, as the remaining approaches would experience excessively long red intervals. Furthermore, the key factor that helps enhance the network's holistic performance is the allocation of coordinated green intervals considering vehicular flows on all traffic corridors. In this regard, we find that the network optimization approach is considerably more efficient, as it could help reduce average delays and queue lengths by 43.5% and 61.9% compared to the base case scenario—which is 9.7% and 9.4% better than the isolated signal timing approach, respectively.