Why Automated Cars Need New Traffic Laws

They don't always need to come to a full stop, and they sometimes should exceed the speed limit

Photo: iStockphoto
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When Delphi took its prototype Audi robocar from San Francisco to New York in April, the car obeyed every traffic law, hewing to the speed limit even if that meant impeding the flow of traffic.

"You can imagine the reaction of the drivers around us,” Michael Pozsar, director of electronic controls at Delphi, said at a conference in Michigan last week, according to Automotive News.  “Oh, boy. It's a good thing engineers have thick skin. All kinds of indecent hand gestures were made to our drivers.”

And that indicates that a problem is brewing, argues Prof Alain Kornhauser, who directs the transportation program at Princeton University. “The shame of the driving laws is that they all sort of have a ‘wink’ associated with them,” he says. “It says 55 miles per hour, but everyone knows that you can do 9 over. If that’s the situation, why isn’t it written that way—with a speed limit at 64?”

People know when to disregard a law, but it isn’t easy to reduce such implicit knowledge to an algorithm. Even if you could, there are some laws that robots should never have to observe.

“A stop sign—rather than a ‘yield’ sign—is there to make sure people have the opportunity to look both ways and see nobody is coming,” Kornhauser says. “But with 360-degree camera coverage, lidars and radars, those automated cars know in a 20th of a second whether something is coming. Why should we require them to come to a complete stop?”

In fact, if all cars were autonomous and connected to each other wirelessly, they wouldn’t need stop signs even at the intersections of multilane highways, as shown in this video simulation by Kurt Dresner and Peter Stone of the University of Texas at Austin:

Like photons, the robot cars intersect without interference—so long as no human drivers are around.

“If you have one guy driving a ‘54 Chevy in the middle, the whole thing breaks down,” Kornhauser says with a laugh.

Pure robo-topias can occasionally become real. Automatic elevators and airport people movers work perfectly in their carefully isolated environments. But humans and robots will share the roads for a long time. That means the rules of the road will not be written afresh, but instead patched over again and again. They’ll make that sorry compromise with the past that computer scientists call a kludge.

“We’ve done it before,” Kornhauser says. “Somehow, horseless carriages had to be made so they didn’t scare the dickens out of horses; and horses had to learn to live with horseless carriages. And the traffic laws of the day had to change.”

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