Uber launched its self-driving pilot program in Pittsburgh Wednesday. It's the first time self-driving cars have been freely available to the public. There will be only four self-driving vehicles available to passengers, to start, and two people will sit in the front to take over driving when the car cannot steer itself. Uber provided ride-alongs to reporters Tuesday. Vehicles stopped at red lights and accelerated at green lights, traveled over a bridge, moved around a mail truck and slowed for a driver opening a car door on a busy street.