Does the MUTCD permit agencies to provide a flashing amber indication for a left-turn movement for the permissive left-turn phase?
This display is not allowed by the 2003 MUTCD. Section 4D.06 requires the display applicable to a left turn lane that is allowed to turn permissively to be a CIRCULAR GREEN. However, NCHRP Report 493 describes the results of a comprehensive research project to evaluate the use of different permissive displays for protected-permissive mode left turns (PPLT), including the flashing yellow arrow (FYA). The research found that the most easily understood and most effective permissive display is the FYA in an all-arrows separate turn signal face for the left turn. As a part of the NCHRP research project and as follow-up to it, several dozen jurisdictions have been experimenting with the FYA for PPLT. Based on experience to date, FHWA anticipates proposing for the next edition of the MUTCD that the FYA display be added to Section 4D.06 as an optional alternative for PPLT mode. In March 2006, the FHWA issued an Interim Approval for the use of FYA as an optional alternative display for PPLT or