A new study out of Toronto found that the installation of Pedestrian Countdown Timers (PCT) has led to an increase in crashes. The idea is some drivers will see the countdown approaching zero and speed up to beat the light (driving more aggressively than they otherwise would have if there was no PCT) while others will slow down knowing the light is about to change (driving slower than they otherwise would have if there was no PCT). This mix of driving behavior may lead to an increase in rear-end crashes.
Of course, there's a lot of contradicting studies out there. Studies performed in other cities suggest PCTs are safer for drivers and pedestrians alike. Here's an article that summarizes the issue (and has links to multiple studies):
http://www.fastcodesign.com/3032651/slicker-city/the-hidden-dangers-of-crosswalk-timers
In my personal experience, I'd say the opposite is true. A lot of Chicago drivers will use them to figure out when the signal will change to yellow and avoid Rahm's Revenue Machines..er..the red light cameras.
I don't know of any studies of any product where the results swung 100% one way or another. Even within a single city, you're going to find intersections where crashes have gone down, and intersections where crashes have gone up. Conflicting studies and results would be typical.
I try to use them to determine when I'll get a green so I can shift into gear and be moving immediately. Doesn't work at all lights, but it does at many.
I'd be lying if I said I didn't accelerate to beat the timer, or at least be tempted to.
Here are a few requirements that were introduced in the 2009 edition of the MUTCD that may be relevant to this conversation:
Section 4E.07.01 All pedestrian signal heads used at crosswalks where the pedestrian change interval is more than 7 seconds shall include a pedestrian change interval countdown display in order to inform pedestrians of the number of seconds remaining in the pedestrian change interval.
Section 4E.06.04 A pedestrian change interval consisting of a flashing UPRAISED HAND (symbolizing DONT WALK) signal indication shall begin immediately following the WALKING PERSON (symbolizing WALK) signal indication. Following the pedestrian change interval, a buffer interval consisting of a steady UPRAISED HAND (symbolizing DONT WALK) signal indication shall be displayed for at least 3 seconds prior to the release of any conflicting vehicular movement. The sum of the time of the pedestrian change interval and the buffer interval shall not be less than the calculated pedestrian clearance time (see Paragraphs 7 through 16). The buffer interval shall not begin later than the beginning of the red clearance interval, if used.
The required 3 second buffer impacts the termination point of the Flashing Don't Walk (FDW). Before this requirement, agencies would often end the FDW at the end of all red (IE. the FDW would end simultaneously with a conflicting vehicle movement release). This is no longer allowed since it doesn't provide the necessary 3 second buffer. The question is what is the preferred termination point for the FDW?
Quote from: tradephoric on July 17, 2015, 03:14:23 PMThe question is what is the preferred termination point for the FDW?
This chart details all the different ways the pedestrian change interval (a.k.a. Flashing Don't Walk) can terminate. I personally don't like it when the countdown timer extends past a yellow light. The idea is to clear all pedestrians from the intersection before the yellow light. Do you really want pedestrians still in the crosswalks when critical decisions are being made by drivers when the light changes to yellow (should i floor it, should i stop, should i try to squeeze in this gap and complete my left turn and risk getting t-boned, etc.)?
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi478.photobucket.com%2Falbums%2Frr144%2Ftradephoric%2FTransportation%2520Pictures%2FRandom%2FPedIntervals_zpsbhrodwmm.png&hash=b52bafa0937757dbaf978fb0d345a66712aa35de)
I agree tradephoric. Of the choices in the chart, I prefer the second choice: yellow change interval + red clearance interval = buffer interval. What this means is that there is a short vehicular all-red and the countdown timer will come to 0 at the point when the yellow light comes on.