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Re: What Really Causes Traffic Congestion

Posted by Stephen Bauman on Sun Jul 14 22:42:39 2013, in response to Re: What Really Causes Traffic Congestion, posted by BrooklynBus on Sun Jul 14 22:04:06 2013.

What I meant was too many pedestrians for the amount of time for the green cycle.

Consider midtown crosstown streets. There's 1 travel lane and 2 parking lanes. Turning speed for cars is approximately 5 mph. A single turning car slows down all the cars behind it.

Let's assume a car travels 3 car lengths (45 ft) @ 5mph (7.5 ft/;sec) for a turn. Each car will take 6 seconds per turn. This means the turning capacity for the 35 second green cycle is 6 cars without any pedestrians in the traffic mix.

The only way to guarantee no automobile congestion (cars waiting more than a single green cycle to cross a street) is to limit car volumes to 6 cars per cycle. That's 6 cars per 90 second cycle or 240 vechiles/hr. That's village volumes not city volumes.


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