Multicriteria-Based Guideline for Pedestrian Timing Accommodation in Signal Coordination

At coordinated intersections, when the side-street required green time is less than the required pedestrian time (RPT) to cross the main street, there are two options to consider when implementing RPT into side-street green time. One option is to add RPT to the side street at all cycles whether or not there is a pedestrian call. This method is sometimes referred to as accommodation (A) of RPT. With this method, the signal remains coordinated at all times with side-street green time even when that much green time is not needed. Another option is to extend the side-street green time interval only when it is required, that is, when there is a pedestrian call to cross the main street, and brings the signal into coordination by one of the transition methods. This method is called nonaccommodation (NA) in this paper. It keeps side-street green time to its minimum required green time at the expense of disturbing coordination when there is a pedestrian call. The optimum method depends on several factors including cycle length, vehicle and pedestrian volume, the value of RPT compared with required side-street green time, transition method, and other signal parameters. This research provides a guideline to determine when accommodation (A) is preferable over NA under each condition. In cases where the cycle length is not long enough to accommodate RPT into side-street green time without extending it, a threshold for pedestrian volume is provided. If pedestrian volume is higher than this threshold, pedestrian timing will be accommodated. If pedestrian volume does not warrant accommodation, practitioners can use several graphs, which are extracted from simulation to determine the optimum method for a wide range of conditions. To provide these graphs, 7,776 scenarios were simulated for both A and NA methods, forming a total of 15,552 cases. Then, at the end, the guideline is tested on one intersection.