Dynamic Flashing Yellow Arrow (FYA) A Study on Variable Left Turn Mode Operational and Safety Impacts Phase III

US Transportation Collection2019PDFTech ReportAbou-Senna, HatemRadwan, EssamEldeeb, HeshamUniversity of Central Florida. Department of Civil, Environmental and Construction EngineeringUniversity of Central Florida. Center for Advanced Transportation Systems SimulationFlorida. Department of Transportation. Research CenterUniversity of Central Florida. Center for Advanced Transportation Systems SimulationFloridaUnited StatesDecision support systemsFlashing traffic signalsHighway operationsHighway safetyIntersectionsLeft turnsPeriods of the dayFlashing Yellow Arrow (FYA)Four-Section HeadDecision Support System (DSS)Left Turn ModeTime of DayPeer-o-Peer LogicBDV24-977-21Final Report, (Mar 2017 \u2013 Mar 2019)The four-section head Flashing Yellow Arrow (FYA) provided an opportunity to advance the operation of the left turn mode at intersections. In phase III of the project, the UCF team further enhanced the decision support system (DSS) by developing an exclusive hardware platform. The hardware platform was developed for two main objectives: first, to provide a generic device compatible with the different controller types used by different jurisdictions within the FDOT Districts and, second, to automate selection of the FYA left-turn modes based on available gaps in the opposing traffic at intersections acquired in real time from existing sensors in the field. Phase III provided conclusive offline testing using a peer-to-peer logic environment as well as online and field testing of the DSS. Peer-to-peer-logic offers the advantage of acquiring and analyzing real-time traffic data coupled with video feed, with the benefit of a safe environment. The testing verified that the system was able to accurately acquire real-time traffic conditions and react by switching between red and FYA modes in a rational manner consistent with driver expectations and left-turning gap acceptance thresholds. It was also concluded that coordinated signals with very long cycle lengths, 3 minutes and longer, help in providing adequate gaps even in heavy traffic patterns since most of the vehicle arrivals are in platoons and at the beginning of the cycle. However, short cycle lengths eliminate sufficient gap times even with coordination. Two methods were used to calculate the minimum gap: discrete and average approach. Although the average method provides a more conservative approach, the discrete approach was more accurate. The developed platform is applicable at any four-section head configuration to alter the left turn restriction throughout the day to maximize safety and efficiency of the intersections.99