Decision-Making Guide for Traffic Signal Phasing

The FHWA has identified intersections as one of four primary focus areas for improving safety and reducing crashes. In the United States, it is estimated that signalized intersections comprise less than 10 percent of the total number of intersections; but more than 30 percent of intersection fatalities occur at signalized intersections. One of the most important factors impacting both the safety and operations at a signalized intersection is signal phasing (the order and manner in which movements are served by a traffic signal). Little research has been done in recent years related to the safety and operational aspects of signal phasing. Although there is some guidance in national manuals (such as the FHWA Signal Timing Manual), much of the information is based on rules-of-thumb with limited empirical underpinning. Selection of an appropriate signal phasing, given the prevailing conditions, can have the benefits of improving safety, decreasing delay, reducing congestion, and reducing emissions. The objective of this research is to develop an engineering decision-making guide that incorporates both safety and operational impacts in evaluating traffic signal phasing alternatives for conventional intersections. Examples of Signal Phasing Alternatives that may be addressed: (1) Left Turns (Protected Only v. Protected/Permitted v. Permitted Only, Leading v. Lagging, Split Phasing, Changes in phasing based on time of day or traffic conditions, Treatment of multiple left-turn lanes); (2) Right Turns (Overlaps with complementary left turns, Treatment of dual right turn lanes); (3) Pedestrians (Concurrent v. Exclusive, Leading Pedestrian Indication); and (4) Interactions (Elimination of permitted left turns and right turns on a conflicting pedestrian actuation, Conflicts between U-Turns and Right Turns).

• Record URL:
  http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=3853

Language

• English

Project

• Status: Active
• Funding: $600000
• Contract Numbers:

  Project 03-118

• Sponsor Organizations:

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590

  American Association of State Highway & Transportation Officials (AASHTO)

  444 North Capitol Street, NW, Suite 225
  Washington, DC  United States  20001

  National Cooperative Highway Research Program

  Transportation Research Board
  500 Fifth Street, NW
  Washington, DC  United States  20001
• Project Managers:

  Derr, B

• Performing Organizations:

  VHB Engineering, NC, P.E.

  4000 WestChase Boulevard, Suite 530
  Raleigh, NC  United States  27607
• Principal Investigators:

  Daily, Christopher

• Start Date: 20150813
• Expected Completion Date: 20190212
• Actual Completion Date: 0
• Source Data: RiP Project 37563

Subject/Index Terms

• TRT Terms: Crashes; Decision making; Fatalities; Guidelines; Signalized intersections; Traffic safety; Traffic signal phases; Traffic signal timing
• Subject Areas: Highways; Operations and Traffic Management; Safety and Human Factors;

Filing Info

• Accession Number: 01543349
• Record Type: Research project
• Source Agency: Transportation Research Board
• Contract Numbers: Project 03-118
• Files: TRB, RiP
• Created Date: Nov 13 2014 1:01AM