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Just How Does an Officer Pull Over a Self-Driving Car, Anyway?

Somebody call Robocop!


Now that Google's driverless cars have logged 1.2 million miles on the road and inspired countless think pieces about how autonomous vehicles will reshape cities, something totally commonplace for a human motorist finally happened to one in Google's fleet: One of the vehicles got pulled over yesterday by a Mountain View cop. Not for speeding, but for backing up traffic while going just 24 miles per hour in a 35 zone on El Camino Real. To the Internet’s delight, the Mountain View Police Department recapped the incident on its blog, and Google chimed in with a Google Plus post and a priceless photo of an officer at the window of the driverless car.

Amid all the bad cop humor, robot quips, and dad jokes (“Please step out of the car…”), one question kept cropping up: How does a cop pull over a self-driving car? Can it even recognize flashing lights, using the robotic equivalent of a paranoid glance in the rearview mirror? 

In the case of yesterday’s scofflaw vehicle, there were people on board, and they saw the lights and manually directed the car to pull over. And that’s how it will stay for the foreseeable future, says Saul Jaeger, a traffic sargeant with the Mountain View Police Department. Right now, per California’s vehicle code, “there are no autonomous vehicles operating without a driver inside,” he tells San Francisco. “They have to have someone inside who can take control if something was to happen.”

If Uber has its way, though, that could change in years to come. The ride-hailing platform has already vowed to convert its fleets over to autonomous vehicles, and even poached dozens of robotics experts from Carnegie Mellon to make this driverless future a reality. So what happens when totally empty cars get pulled over? How would that even work?

The cameras on Google’s self-driving cars are already good enough to recognize hand signals by cyclists—though fixies are still confusing!—so you’d think they’d be able to pick up the flash of red and blue lights, right? When we put the question to Google, a representative referred us only to the same Google Plus post about yesterday’s stop, which answered none of our questions and was about as satisfying as, well, flipping off a driverless car.

Jaeger was more willing to entertain the thought. Even though driverless-driverless cars (someone’s got to think of a better name) are a long way off, Google's fleet of comically small motorized gumdrops may already be on the way to having the ability to pull over for a traffic stop, based on what Jaeger has seen. “[Google] did some testing with our emergency equipment, because they need to have the cars understand how to pull over to the right when there’s an emergency vehicle behind them, like an ambulance or fire truck,” he says. 

OK, so it’s possible. But how would the cars know the flashing lights are meant for them? Google’s autonomous cars may not need much help to catch up to human drivers on that score, at least from one cop’s perspective. “As soon as the lights turn on on a police car, people lose their mind, and they think it’s them,” says Jaeger. “A lot of times the police are just trying to get around you.”


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