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Cities are more and more doing this (what you specified for pedestrian lights outside the US). My problem: there's a very large intersection that I walk throug

by dkl 14y ago

Cities are more and more doing this (what you specified for pedestrian lights outside the US). My problem: there's a very large intersection that I walk through daily that changed to "only allow walk when the button is pushed" and 9 times out of 10 when I walk up to it and push the button when it normally would have been set to "walk", nothing happens. Then, the next traffic cycle I get the "walk" light. However, I've also noticed that from the time I push the button until when the cross traffic starts, 90% of the time I would have had time to walk across the street. So, I've started ignoring the button and just walking when "the time is right." In this case, it has made me less safe. Twice in a few months I've been caught in the middle of the street when the light turns. I realize that in this case, the walk portion is probably just not tuned properly, but I wonder how often that happens.

masenf 14y ago
I am not a traffic flow engineer, but I have experienced what you describe in regard to the walk button behavior in many places in western Washington, US. I always reckoned that they were using a simple model in which a button press would cause the "WALK" signal to always be fired at the corresponding light configuration at the _next_ cycle start. This is most likely a safety consideration because, as you noted, there may not be enough time to safely cross. In some complex intersections I've noticed that the 'cycle start' doesn't necessarily line up with the corresponding configuration for the walk button which was pressed. This may result in having to wait nearly two complete cycles for the walk signal in the worst case (pressing the last configuration's walk button immediately after the cycle start). The resulting behavior could be considered a bug, or perhaps just more consideration payed to vehicle traffic. But it is certainly frustrating as the pedestrian. At many intersections I cross now the signals are automatic with the traffic flow. Most of them also contain a countdown timer indicating the number of seconds until the light changes. It seems that this behavior would be a good tradeoff for pedestrian efficiency and safety. However it comes with a bit of trust from the gov, that you know you can't walk across 5 lanes in 2 seconds.

by dkl 14y ago

masenf 14y ago

I am not a traffic flow engineer, but I have experienced what you describe in regard to the walk button behavior in many places in western Washington, US. I always reckoned that they were using a simple model in which a button press would cause the "WALK" signal to always be fired at the corresponding light configuration at the _next_ cycle start. This is most likely a safety consideration because, as you noted, there may not be enough time to safely cross. In some complex intersections I've noticed that the 'cycle start' doesn't necessarily line up with the corresponding configuration for the walk button which was pressed. This may result in having to wait nearly two complete cycles for the walk signal in the worst case (pressing the last configuration's walk button immediately after the cycle start). The resulting behavior could be considered a bug, or perhaps just more consideration payed to vehicle traffic. But it is certainly frustrating as the pedestrian. At many intersections I cross now the signals are automatic with the traffic flow. Most of them also contain a countdown timer indicating the number of seconds until the light changes. It seems that this behavior would be a good tradeoff for pedestrian efficiency and safety. However it comes with a bit of trust from the gov, that you know you can't walk across 5 lanes in 2 seconds.