Recommended Practice

Flashing Yellow Arrow (FYA) is an option for protected-permissive left-turn phasing. Careful consideration is needed in deciding where to install the FYA.
Some areas have existing FYA installations, while others have no experience with the display. Generally, implementation should consist of an initial pilot or demonstration project consisting of a few isolated intersections or a small section of corridor. The district should obtain local buy-in and approval, and provide press releases and information explaining where the FYA is being installed, what the FYA indications mean, how the motorists should interpret the indications, and why we are changing the existing set-up (the benefits).
Locations to consider for the pilot project installation of FYA protected-permissive left turns are typically sections of corridors with signalized intersections with the following characteristics:
  • Low speeds
  • 1 left-turn bay per approach
  • 3 or less through lanes
  • Low number of left-turn related crashes
  • Adequate driver sight distance to oncoming vehicles
  • Low left-turn volume during peak periods
  • Low traffic volume
  • Signal coordination plans indicate operational improvement with the FYA protected-permissive operation.
Locations with the following characteristics are discouraged for use in the pilot project installation of FYA protected-permissive left turns:
  • Corridors with multiple signalized intersections in view using solid green ball for permissive phase
  • High speeds
  • Dual left-turn lanes
  • 4 or more through lanes
  • High left-turn crash history
  • Poor sight distance to oncoming vehicles
  • High left-turn volumes during peak periods, and/or
  • High traffic volumes.
It is better to be consistent in the application of left-turn treatment along a corridor for driver expectation. That said, it may not be practical to install FYA left turns consistently along a corridor. FYA left-turn operation requires a separate left-turn signal face. If a corridor is equipped with shared signal faces it may need new signal poles installed with longer mast-arms to cover the left-turn lane. Thus, it may be cost prohibitive to convert to FYA left-turn operation.
Installing FYA protected-permissive mode at a location that previously operated in protected-only mode should be considered only after careful study of the intersection. One research study of locations that were converted from protected-only mode to FYA protected-permissive mode saw an increase in the crash frequency. Do not remove protected-only left-turn phasing if opposing sight distance is inadequate for permissive left turns, operating speed is too great, roadway geometry is complicated, or there are too many opposing through lanes. If the protected-only left turn was installed for other safety reasons (crash prevention when under less restrictive phasing), care should be used in operating a possible FYA protected-permissive installation.