Estimating Impact of Signal Hardware Improvements

Abstract

Signal equipment upgrades (e.g., multiple timing plan capability and signal interconnection) are commonly used to improve the quality of traffic flow in urban arterials and networks. The findings of the assessment of the effects of alternative control scenarios to assist practicing engineers in conducting analyses to determine the effectiveness of proposed signal equipment upgrades are presented. The effectiveness of hardware improvements was evaluated against the optimal timings with the available equipment to differentiate the benefits from installing hardware from the benefits from signal timing optimization. Alternative signal operations strategies were simulated through the NETSIM model on eight real-world test networks. Field data on traffic performance were collected before and after the installation of improved hardware in three demonstration projects. The analysis of the results quantified the effects of design and traffic characteristics on the expected benefits from hardware improvements. Comparison with field results from several hardware projects in California indicates that the study procedures and recommendations provide reasonable estimates of the improvements likely to be achieved from signal control upgrades.