The effects of pedestrian countdown timers on safety and efficiency of operations at signalized intersections.

PDFTech ReportSPR-P1 (09) P332Pedestrian clearance interval (Traffic signals)Signalized intersectionsPedestrian trafficBefore and after studiesTimersData collectionTraffic safetyDriversNebraskaNebraska. Dept. of RoadsSharma, AnujSchmitz, JacobNebraska Transportation CenterUnited States. Federal Highway AdministrationNTL-OPERATIONS AND TRAFFIC CONTROLS-Traffic Control DevicesNTL-PEDESTRIAN AND BICYCLES-PedestriansNTL-SAFETY AND SECURITY-SAFETY AND SECURITYUS Transportation CollectionPedestrian countdown timers are becoming common at urban and suburban intersections. The added information thatpedestrian countdown timers provide to pedestrians can also be used by approaching drivers. A before-and-after case studyon the effects that pedestrian countdown timers have on safety and efficiency of operations was performed at twosignalized intersections in Lincoln, Nebraska. The effects on both drivers and pedestrians were analyzed. Performancemeasures for pedestrian analysis include pedestrian compliance and average pedestrian walking speed. Performancemeasures for the driver analysis include probability of stopping and speed gain of vehicles at the stop bar during the yellowphase (vehicles passing through the intersection during the yellow phase) and queue discharge headway. Data wascollected using a Wide Area Detector (WAD), point detector at the stop bar and a Pan-Tilt-Zoom (PTZ) video camera.Data was collected using state-of-the-art data collection software, Wonderware, which displayed all traffic and pedestriansignal information, vehicle detections, individual vehicle speeds, vehicle distances from stop bar, and the video from thePTZ camera all on one computer screen. Statistical models were estimated to understand the effects that pedestriancountdown timers have on the performance measures. The resulting models identified statistically significant factors thataffected the performance measures. Pedestrian countdown timers were found to increase pedestrian walking speed by 0.2ft/sec, and decrease the probability of pedestrian violations. Impact of PCT on driver safety and efficiency was not found tobe statistically significant at 95% level of confidence. There was however some evidence, although not statisticallysignificant of improvement of driver safety due the presence of PCT. The trend was more pronounced at the intersection of17th and G (smaller intersection with less visual clutter) where we observed reduction in the percentage of red light runnersand some reduction of dilemma zone boundaries