Responding to the last part of your comment the sensors are there to cancel the crossing request if the pedestrian crosses early or wanders off elsewhere, to av

Responding to the last part of your comment the sensors are there to cancel the crossing request if the pedestrian crosses early or wanders off elsewhere, to avoid stopping traffic for no reason. The sensors pointed at oncoming traffic can be used to halt traffic if they detect it's moving too quickly for the area. Crossings with the sensors and the don't walk/walk lights on the side closest to you are puffin crossings. The other ones are the older pelican crossings. Infos from http://en.wikipedia.org/wiki/Puffin_crossing http://en.wikipedia.org/wiki/Puffin_crossing