Evaluation of semi-actuated signals and pedestrian push buttons using a microscopic traffic simulation model

Abstract

The typical geometry of many signalized intersections on national highways is that of a major street with a minor road of which traffic and pedestrian volumes are low in general, especially in rural areas. Such intersections generally show long green-lights for the through movements on the minor crossroad in order to serve pedestrian crossing time regardless of the volumes of pedestrians and vehicles. This research effort was initiated to solve this problem by introducing semi-actuated signals and pedestrian push buttons. To this end, this research effort evaluated the detailed effects of the introduction of semi-actuated signals and pedestrian push buttons using a calibrated microscopic traffic simulation model, VISSIM. This research effort evaluates three scenarios, including i) pretimed signal control in use at a selected test site (Scenario 1), ii) semi-actuated signal control (Scenario 2), and iii) semi-actuated signal control coupled with pedestrian push buttons (Scenario 3). From the results of evaluations through intensive simulation under diverse traffic conditions, the three scenarios showed a similar level of network-wide average delays. However, compared with Scenario 1, Scenario 2 showed 2.7% improvements on delay of a coordinated movement on average. In addition, compared with Scenario 1, Scenario 3 showed 13.0% improvements on average. Finally, Scenario 3 showed 10.5% improvements over Scenario 2. However, in terms of traffic safety, completely different results were found as follows. Scenario 1 showed the smallest frequency of traffic conflicts. Conclusively, the introduction of the semi-actuated signals coupled with pedestrian push buttons can increase the mobility on major streets by shifting unused green times from minor crossroads to the coordinated movements. However, more attention from traffic engineers is required when they introduce actuated signal control in terms of selecting actuated signal control parameters.