Potential Application of Flashing Yellow Arrow Permissive Indication in Separated Left-Turn Lanes

Abstract

The consideration being given to the adoption of the flashing yellow arrow (FYA) permissive indication has led to a number of additional studies evaluating potential scenarios in which FYA may be effectively used. One potential scenario is in intersections with wide medians where the left-turn lane and the corresponding signals are separated from the adjacent through and right-turn lanes. Left-turn maneuvers at locations with wide medians typically operate with protected-only left-turn phasing and separate signal displays, as drivers cannot see the adjacent through movement signals; however, some transportation professionals have implemented a flashing red arrow (FRA) that requires drivers to first stop before accepting a gap in the opposing traffic stream. This research quantified driver comprehension of the FYA permissive indications compared with that of the FRA indication for use at locations with wide medians. The research used both driving simulator and static experiments with 264 drivers responding to 1,260 experimental scenarios. The results found that drivers understood the meaning of the FYA indication. Nevertheless, FYA was associated with fail–critical response errors in the driver's first exposure to the FYA indication. The large number of drivers who interpreted the FRA as a yield condition was consistent with that from previous evaluations and indicated an incorrect comprehension of the indication. At locations with wide medians where the use of protected-only left-turn phasing may not be desirable, the use of the FYA or FRA permissive indications should be used only after consideration of the safety and operational issues common to the initial implementation.