A rationale for incorporating its applications' effect into the HCM signalized facilities analysis procedure

The signalized intersection methodology in the Highway Capacity Manual 2010 (HCM) deals with saturation flow rate and control delay estimations. The HCM currently does not explicitly consider the impact of Intelligent Transportation Systems (ITS) applications in its signalized intersection methodology. This paper attempted to quantify the impact of saturation flow rates and delay performance under a few selected ITS applications at the signalized intersection. The purpose was to investigate whether the HCM procedure should be revised to account for the ITS strategies. A microscopic simulation modeling approach was utilized to quantify the impact of advanced operational strategies supported by ITS. The results demonstrated that the Cooperative Adaptive Cruise Control (CACC), due to reduction in headway, resulted in significantly increased capacity over the base scenario. Immediate departure application improved capacity due to better use of effective green time. Pedestrian responsive signal operations reduced capacity due to the use of signal optimization. The simulation results clearly suggests that a procedure accommodating increased capacity or saturation flow rate from the ITS strategies should be developed to properly reflect the impacts of ITS strategies at the signalized intersection analyses.