PITTSBURGH — Anthony Levandowski, head of Uber's self-driving car team, folds his 6-foot-7-inch-frame into one of Uber’s new self-driving Ford Fusion hybrids for another ride-along through downtown Pittsburgh, Pennsylvania. He's just finished up a trip with city Mayor Bill Peduto, and he's visibly tired. Settling himself in the car's backseat, he jokes that he's looking forward to the rollout of Uber's autonomous Volvo XC90 SUVs: Soon, he’ll actually fit comfortably inside one of the cars in his fleet.

Last week, Uber became the first technology company in the US to let people hail rides in self-driving cars. That's quite a feat, considering Uber only opened the Pittsburgh Advanced Technologies Center that birthed the project about 18 months ago.

For Levandowski, the transition has been even quicker. He officially joined Uber last month, when the company acquired his autonomous truck startup, Otto. In a past life, Levandowski was the guy who built Google's very first self-driving car. Now he's quarterbacking Uber’s bet on autonomous vehicles.

It's a big bet. But there's still a lot of work to be done. Each self-driving car in Uber's Pittsburgh pilot is manned by a safety driver (ready to take the wheel or hit the brakes during emergencies) and a co-pilot (to monitor the car and its route on a laptop).

“We still have a long way to go before the technology’s truly ready to take over, before there's no driver in the car,” Levandowski says.

Uber is looking at two core metrics to evaluate its self-driving cars’ performance: how long they can go before a human driver intervenes for any reason, and how long they can go without a “critical intervention” — basically, without having an accident.

“You have a number for both of those before you feel like the product is ready for launch without a safety driver,” Levandowski explains. “I’m not going to tell you where we’re at on those metrics or what the goals are, but that’s how we think about it.”

Regardless of where Uber currently stands on those goals, it’s clear that a fully autonomous future — or even a more autonomous one — is quite a ways off. Indeed, Levandowski says human drivers and human Uber drivers will be around for a long time.

“In a world where car ownership kind of goes away and you use Uber for all your transportation needs, you’re going to need more drivers than you have today on the Uber platform,” he explains. “The fraction of drivers might change over time, but we anticipate having a huge need as far as maintaining and servicing the vehicles, as well as driving vehicles.”