Problem 2: Moe Road

Discussion
What have we learned in this case study? We’ve learned about handling pedestrians and we’ve learned about the importance of accounting for lane utilization.

In the case of pedestrians, we’ve learned a little about how pedestrian timings are defined: an initial walk time plus an increment of flashing don’t walk time that allows a person to walk across the street. We’ve learned that these pedestrian timings are often in conflict with the vehicular timings in that the longer pedestrian timings tend to be associated with the side street, which typically has the shorter vehicular green. We’ve seen that to allow for these pedestrian times, the cycle length gets longer and the vehicular delays get larger. Or to put it another way, if the pedestrians weren’t present, the cycle length could be shorter and the vehicular delays smaller.

pedestrian push-buttons are particularly valuable where the pedestrian volumes are light. When pedestrian timings aren’t needed (that is, when the controller does not receive a call for pedestrian service), the vehicular-based timings can be used. That means that on those cycles when the pedestrian timings aren’t invoked, the delays will be shorter and the signal will be more responsive to the vehicular flows. Hence, pedestrian push buttons have great value.

In the case of lane utilization, we’ve seen what effect it can have on estimates of delays and queue lengths. We’ve seen that as the lane utilization gets poorer (i.e., more traffic in just one lane), delays and queue lengths increase. Not accounting for lane utilization, and using the defaults, can lead to overly optimistic assessments of intersection performance.