WHY AUTOMATED CARS need new traffic laws.

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.

True.