A Field and Simulator Evaluation of All-Red Clearance Intervals for Use in Left-Turn Applications

As the implementation of the novel flashing yellow arrow (FYA) traffic control device advances throughout the country, agencies continually seek ways to improve intersection operations and safety, especially on left turns. For example, permissive left-turn intervals have been communicated to drivers using several traffic signal indications; however, most frequently these phases are represented using the circular green ball and, more recently, the FYA. Previous research in this area found that the FYA indication produced the most effective communication of permissive left-turns. As a result of the research findings, the FYA was included in the 2009 edition of the Manual on Uniform Traffic Control Devices. In recent years, agencies across the country have embraced the implementation of the FYA for permissive left-turns. However, a lack of national guidance remains on how to define the change and clearance intervals for transitioning between protected and permissive left turns. Complicating the matter is the connection between traditional signal phasing/design and human factors. Research on driver comprehension and real-world operations of the transition between protected and permissive left turns will allow evaluation not only of current conditions, but also of experimental and future conditions. This report presents findings from a static survey that studied the expectation of drivers after a signal indication is presented. This report also presents the results of a novel exploratory approach that allows the use of vehicle trajectory data to gain an insight into driver behavior during the transition between a protected left-turn movement and a permissive one. Research findings will provide a foundation for narrowing the scope and identifying elements that should be considered during a driving simulator evaluation.

• Record URL:
  • http://safersim.nads-sc.uiowa.edu/final_reports/UWI 1 Y3 report.pdf
• 
• Record URL:
  • https://rosap.ntl.bts.gov/view/dot/36047
• Supplemental Notes:
  • This document was sponsored by the U.S. Department of Transportation, University Transportation Centers Program.
• Corporate Authors:

  Safety Research Using Simulation University Transportation Center (SaferSim)

  University of Iowa
  Iowa City, IA  United States  52242

  University of Massachusetts, Amherst

  Department of Civil and Environmental Engineering
  130 Natural Resources Road
  Amherst, MA  United States  01003

  University of Wisconsin, Madison

  Department of Civil and Environmental Engineering
  1415 Engineering Drive
  Madison, WI  United States  53706

  Office of the Assistant Secretary for Research and Technology

  University Transportation Centers Program
  Department of Transportation
  Washington, DC  United States  20590
• Authors:
  • Knodler Jr, Michael A
  • Christofa, Eleni
  • Tainter, Francis
  • Santiago-Chaparro, Kelvin R
  • Bill, Andrea R
  • Noyce, David A
• Publication Date: 2018-3

Language

• English

Media Info

• Media Type: Digital/other
• Edition: Final Report
• Features: Appendices; Figures; Maps; Photos; References; Tables;
• Pagination: 47p

Subject/Index Terms

• TRT Terms: Arrows (Signals); Driving simulators; Exclusive permissive phasing; Exclusive phasing; Flashing traffic signals; Left turn phase; Left turns; Permissive phasing; Surveys; Yellow interval (Traffic signal cycle)
• Subject Areas: Highways; Operations and Traffic Management; Safety and Human Factors;

Filing Info

• Accession Number: 01673356
• Record Type: Publication
• Files: UTC, NTL, TRIS, ATRI, USDOT
• Created Date: Jun 25 2018 1:49PM