Nathan Bomey

USA TODAY

PITTSBURGH — In this city, the age of the self-driving car has arrived.

Uber’s partially self-driving car will begin accepting passengers here Wednesday, a critical test for the ride-hailing service as it seeks to develop a fleet of autonomous vehicles that could someday ferry passengers around crowded cities.

The company on Tuesday gave journalists test drives in about two dozen Ford Fusion sedans that engineers bought off dealership lots and retrofitted with light-mapping systems, radar, sensors and cameras. For now, a Uber employee stays behind the steering wheel to intercede if the car's self-driving system makes a mistake.

“I really believe that the most important thing that computers are going to do in the next 10 years is drive cars,” said Anthony Levandowski, leader of Uber’s self-driving car effort.

Specially trained Uber employees will pick up Pittsburgh passengers who agree to the possibility that they could be randomly assigned a self-driving car when they request an UberX ride through the app. Rides will be free for now.

In a USA TODAY test drive, the Fusion smoothly navigated many of the bustling urban streets of Pittsburgh, breezing over the Three Sisters bridges above the Allegheny River and safely avoiding bicyclists and walkers on vibrant Penn Avenue. On several occasions, the car handed control back to the driver when a situation was too complex for the car's algorithms, such as when a construction vehicle was parked backward in the right lane.

Behind the wheel of Uber's self-driving car: 'Frightening and exhilarating'

Operators are instructed to loosely grip the steering wheel at all times and must be ready to take over immediately at any time, with beeps and color indicators on the dashboard providing notice. A touch-screen in the backseat shows ride info to passengers.

Pittsburgh is home to Uber's new Advanced Technologies Center, which is staffed by many former Carnegie Mellon University researchers whom Uber recruited. But it's also a good town to test self-driving cars, with its combination of bridges, pedestrians, bicyclists, urban driving, railroads and bad weather, which has historically bedeviled self-driving vehicles.

"We like to call Pittsburgh the double-black-diamond of driving," said Raffi Krikorian, leader of Uber’s Advanced Technologies Center, using a term for an extremely difficult ski slope. "If we really can master driving in Pittsburgh, then we feel strongly that we have a good chance of mastering it in most other cities around the world."

In recent weeks, the road to self-driving cars has developed potholes.

According to recent reports, Google’s self-driving car project is losing ground to rivals, and Apple is recalibrating its secret car project and conducting layoffs. Meanwhile, Tesla Motors is introducing an upgraded Autopilot software system after a deadly crash raised questions about the company’s self-driving strategy. All the major automakers are proceeding with various versions of autonomy.

The biggest hurdle to achieving total autonomy: handling a small percentage of scenarios that a human understands and a car does not. What's more, with little infrastructure installed to foster communication between vehicles and road infrastructure, most cars are unaware of each other on the roadway.

Recent hiccups for Google, Apple and Tesla represent a “reality check” for near-term hopes of self-driving cars, said Columbia Business School professor Evan Rawley, who has researched ride-sharing.

“The idea of self-driving needs to be heavily put in quotation marks," Rawley said. "Nevertheless I think it is a pretty impressive technological breakthrough" for Uber.

Follow USA TODAY reporter Nathan Bomey on Twitter @NathanBomey.