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

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.


  • English

Media Info

  • Media Type: Web
  • Edition: Final Report
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 120p

Subject/Index Terms

Filing Info

  • Accession Number: 01710897
  • Record Type: Publication
  • Contract Numbers: BDV24-977-21
  • Created Date: Jul 10 2019 7:46AM