Arterial Signal Timing Optimization Considering Speed Variation

Ideally, actual travel speed should be used in developing signal timing plans. However, actual travel speed could be affected by existing signal timing and presence of other traffic. This study examines impact of travel speed variation on a signal timing operation of an arterial. Actual travel times and travel speeds of links were collected using GPS tools. GPS trajectories can be drawn on the top of the time-space diagram with a GPS tool developed in our research. In GPS trajectory, actual travel speed between intersections can be clearly seen for three types of study runs. When actual travel speed is significantly different from the speed that is used for developing the timing, expected progression based on the time-space diagram would not be achieved. Offsets and phasing sequences were adjusted according to new speed data, with an improved bandwidth optimization algorithm from our previous study. Fine-tuning of initial signal timing plan was done to get optimal arterial and link progression bandwidth, generally link by link. The evaluation results of a case study about an arterial in Reno show that a rather significant improvement is achieved after the fine-tuning of initial signal timing plan with actual travel speed is done from simulation.