Tuesday, August 9, 2011

Pedestrian Countdown Timers and End of Green

An example where the pedestrian
countdown doesn't agree with the
vehicle signal indication.

I had a request inquiring about why the pedestrian countdown timer can't be used to give information to bus drivers, people riding their bikes, or people in their cars. I have had to give the response a few times, so I figured it was worth posting so I can refer back to it later.  

The pedestrian countdown timers are the new standard for indication of the amount of time that people crossing the street have to clear the intersection. There are many cases when the pedestrian logic in the traffic signal controller does not match the green time for the vehicles (people on cars and bicycles or transit vehicles) and for this reason we can not always end the green at the same time as the end of the countdown timer for the pedestrian indication (the time that we must make the decision to go from Walk to Flashing Don't Walk is obviously earlier than the time we decide to go to yellow).  
I use the countdown timer as an indication of how much time is left in the green at the intersection when I am on the street. That being said, it has to be used in context and I don't recommend that practice, especially if you're approaching an intersection at a high rate of speed. In that case, you should pay attention to the vehicle indications (green, yellow, and red) as this presents the information that is presented for you as a vehicle to obey. 

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