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Traffic signal inequality


David Levinson, who is based Sydney and authors the Transportist – a blog you should follow if you don’t – has a recent post up about signalling inequity and “how traffic signals distribute time to favour the car and delay the pedestrian.” In it he provides some background into traffic signal coordination (introduced in New York City in 1922), as well some some suggestions for how we could and should be prioritizing pedestrians.

Here is an excerpt from the article:

There is a reason that traffic engineers don’t automatically allocate pedestrian phases. Suppose the car only warrants a six second phase but a pedestrian requires 18 seconds to cross the street at a 1 meter/second walking speed. Giving an automatic pedestrian phase will delay cars, even if the pedestrian is not there. And there is no sin worse than delaying a car.  But it also guarantees a pedestrian who arrives just after the window to push the actuator passes will wait a full cycle.

Sometimes pressing the walk button appears to do nothing. I suppose that’s why some cities call it the “placebo button.” And in other cases if you don’t press the walk button you’ll never get a walk sign. That’s usually a strong indicator that you are located in an environment not intended for pedestrians. David’s article also has me curious about the relationship between traffic signals/pedestrian phases and urban form. I bet you could tell a lot about the latter simply by understanding the former.

Image: Transportist

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