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Unintended Consequences For Traffic Safety Feature
An anonymous reader writes: Traffic engineers had a problem to solve: too many pedestrians were getting hit by cars while using the crosswalks at intersections because they didn't know when the 'WALK' sign would change. Their solution was simple: implement a countdown timer. Countless cities have now adopted these timers, but it turns out to have an undesired consequence: motor vehicle crashes are actually increasing at intersections where the countdown timer is used. Researchers think this is because pedestrians aren't the only ones who see the timers. Drivers see them too, and it provides them with information on when the light will change. Then they anticipate the change by either speeding up to beat a change to red light, or anticipating a green light in order to get through before the pedestrians can move into the road. The researchers suggest finding some way to hide the countdown from the drivers, perhaps through the use of an audio countdown that would be difficult to hear from inside a car.
Computers will fix this kind of thing by default.
The dangers of knowledge trigger emotional distress in human beings.
In Ca, it's a ticket if a car enters a crosswalk while a pedestrian is using it, no matter if they're on the other side of the intersection or not. And the new walk signals have a visor around them so unless you're almost directly in front of it, you can't read it. They also started using audio signals, which beep and talk, for the blind.
...is they try to fix human behavior via engineering, but people can't really be engineered.
For example, in my home town we had a roundabout from hell. Five highways came into a loop via offramps. Literally once a week there would be an accident and once a month it was a fatal one.
So some brilliant traffic engineers tried to solve the problem by creating off ramps for each other highway. At highway A you could choose to offramp to highway B, C, or D. But the "offramps" used the roundabout, which now had concrete dividers about curb height. The mayor, the local press, and local government kept trumpeting how many lives this would save.
Well, turns out the only thing more dangerous then five highways going into a giant roundabout is five highways going into a roundabout with concrete dividers to slalom around. Accidents became a daily occurrence and fatalities went up.
As it turns out, people are stupid. Sure, if you are new to town and take the time to slow down to read the sign, and drive carefully, you can figure out where you're going. But people zip in at highway speeds, apply the brakes quickly, and try to swerve over.
The problem is not one of engineering, but one of behavior. Modifying the behavior (via police enforcement) would be more effective then a fancy solution.
A better solution might be to remove the signals altogether. Several European towns have tried shared-space experiments where there are no signals or markings and the pedestrians and vehicle drivers have to actually watch out for each other. In all such experiments so far, traffic fatalities have dropped significantly.