Wednesday, October 8, 2008

How Smarter Traffic Lights Could Save The World

Following on from that previous post , about free electric vehicles:  If you're a mayor of a large city and want to reduce the pollution, the waste of fuel, the extra thousands of litres of fuel your citizens use every week, you may well want to commission someone to help you with a few road changes...

I've long maintained that a leading cause of speed and alcohol related accidents in cities occur at intersections.  You can agree with me or disagree, I just think back to how much detritus I see from accidents at intersections versus the rather smaller amount of broken glass at points along lesser roads.

Speeding to a light to catch the amber would have to rank really high on the list of intersection accidents, is what I would say, judging from the number times a day I see cars flashing across intersections just as my light is turning green.

So - given that computer power is dirt cheap these days, and software exists to examine an image for known outlines such as "car" or "motorcycle" or "truck" - why aren't there four or eight computers in that big ugly traffic light controller box at intersections, and at least two cameras pointing at oncoming traffic in each direction?

The average traffic light set is an embarassingly stupid pile of relays, and in the case of Perth, most of them worked on high voltage AC current until recently, and still had filament light bulbs.  Only recently have they changed to LED bulbs, which has no doubt increased reliability, but I'd say they are still on mains AC voltage...

Back to my point:  If a computer can compare the length of the traffic tails in each direction, it can adjust the green and red times of the lights to suit traffic conditions.  This would reduce the amount of time that cars spend standing still at lights, idling, wasting fuel, and creating an emissions congestion, a "stink spot."  Any easing in traffic flows has to save fuel and pollution, right?  In periods of low traffic, it can even make it possible for vehicles to flow straight through, using its control to cycle the lights more rapidly than it would during a congested period.

But the most important benefit is a hidden one:  You can see the speed of each individual vehicle by comparing subsequent frames of video.  That means that, even in the case where traffic is light, you would give a red light automatically to a single speeding vehicle, or a column of vehicles the majority of which are speeding.  You standardise the speed of traffic and make it easier to adjust the flows between lights, and you discourage speeding drivers who soon perceive speeding as being non-productive.

And because you have those cameras, if a speeder does run a red light, you have a nice pretty picture of them for their court case...

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