There has been quite a bit of discussion lately about Flashing Yellow Arrows. It's actually died down quite a bit, but I found this National Cooperative Highway Research Program (NCHRP) study that summed up one of the thoughts that colleagues of mine have had for awhile: "It was clear from the results that converting from protected phasing to FYA operation (third scenario) leads to a dramatic increase in left-turn crashes" - NCHRP 705 - Summary Page 4.
Now, I think there's a place for Flashing Yellow Arrows in signal timing, it just appears that there needs to be some pretty careful thought on when and where they are applied. I think it is a bit telling when the report summarizes the results and puts that sort of language in the Summary of the paper.
Given this, there has been some good work on applying Flashing Yellow Arrows creatively based on a gap seeking criteria in traffic signal controllers. What this means is that the FYA only is shown when it is likely that a driver would find an acceptable gap and the pedestrian intervals are complete at an intersection. One last piece of the puzzle is the occasional person on a bicycle that is using the facility that perhaps isn't visible due to an adjacent automobile blocking the view of the person trying to complete the left turn at the intersection.
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