UBER

But cars that can reliably and safely navigate urban areas on their own is thought to be years away. The technology also suffered a significant setback only recently, when the driver of a semiautomated Tesla got into a fatal crash.

Even experts in automated driving were therefore surprised by Uber’s move, which will mark the first time everyday commuters will be able to hail a ride in a driverless car.

“They’re bringing their customers into the development process,” said Pete Koomen, founder and president of Optimizely, a startup that tests alternatives for websites.

To help allay concerns and to comply to with state law, which requires a driver behind the wheel, Uber will have two trained safety drivers on each ride. Uber officials said the Otto acquisition gives it “one of the strongest autonomous engineering groups in the world.”

Even with safety drivers, Uber’s wager is risky because the project will allow vastly more people to see the technology’s flaws, said Bryant Walker Smith, a law professor at the University of South Carolina who researches self-driving cars.

“This is going to expose the technology to the public but also will give them a much more intimate view of its mistakes,” he said. “They’ll see in a very direct sense that these are technologies in progress.”

He said he expects that the program will engender trust and that riders who experience the beta test are likely to walk away with a positive idea of automation. “The astounding thing is that people think that these are terrifying until they get into a vehicle,” Walker Smith said. “Then, a mile later, they have total and complete confidence in these systems.”

But for regulators to truly know whether a selfdriving car is safe, they will need reams of data that come from hundreds of millions of miles of testing, he said.

By that all-important metric, self-driving cars are a long way off. As of June, Google’s fleet of roughly 50 autonomous vehicles had driven 1.7 million miles without a fatal accident, the company said. According to the Rand Corp. and other experts, self-driving cars need to be tested in real-world conditions for hundreds of millions more miles — at least — to be considered safe.

These test trips enable the automation software to acquire the huge amount of data necessary to detect the difference between a puddle and pothole — something that today is still challenging, experts said. Uber declined to share how many miles its self-driving program had logged.