Transportation Research Record Journal of the Transportation Research Board · 2019 · 11 citations · 19 references
Public HealthTransportation PlanningUrban PlanningTransportTransportationVehicle Safety EngineeringPedestrian SafetyRoad SafetyTraffic EngineeringTraffic SafetyTraffic Signal ControlTransportation SafetyCase Study EvaluationIntersection Safety For CyclistsPedestrian Delay AnalysisPilot Study DesignProtected Turn PhasingSignal TimingTraffic Sensor Data AnalysisTraffic Signal Timing
Recent research has focused on the safety or mobility impacts of signal timing. Several studies have compared the choice between a protected-only left turn (PO) and a protected-permissive left turn (PPLT). However, few have compared both the safety and mobility impacts, and their tradeoffs. This study proposed data-driven methods to conduct a pilot study at an intersection in Tucson, Arizona. This study evaluated the impacts on vehicular mobility and multi-modal safety when changing from a PPLT to a PO. First, the daily and annual delay for the through and left-turn movements for the intersection was evaluated using a calibrated delay model and year-long 15-min traffic sensor data. Then, real-world near misses between cyclists, pedestrians, and vehicles were manually collected and analyzed using 48 h of videos. Last, both mobility and safety measures were converted into an annual cost to determine the trade-off between the before (PPLT) and the after (PO) situations. The results of this study demonstrate the feasibility of the proposed methods, providing practitioners with different options to evaluate left-turn phasing strategies effectively and efficiently.
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