Uber users in Pittsburgh, Pennsylvania have awoken this morning with the chance that when they hail a cab using the mobile service, it will show up without a driver inside.

The company has launched the first public pilot for its self-driving car program, unveiling its autonomous vehicle system for the first time.

While only four of the self-driving vehicles have been deployed in Pittsburgh, it still represents the first time autonomous vehicles have been so freely available to the public in the US.

Uber established its Advanced Technologies Centre in Pittsburgh around 18 months ago, having announced its intention (like many other automotive and technology firms) to invest in autonomous vehicles. This real-world test represents a big leap forward for both the company and self-driving technology as a whole.

While the cars are thoroughly tested, an Uber driver and engineer will be present in the car at all times to take over in the case of emergencies or situations like bad weather when the autonomous technology may struggle, as well as monitor how the cars cope with real-world situations.

Local journalists were given rides by Uber in the cars earlier today, and reported generally smooth journeys with the vehicles able to manoeuver around parked vehicles and slow down for drivers exiting other vehicles.

“We cant predict exactly what the future will hold,” said Travis Kalanick, CEO and co-founder of Uber. “But we know that self-driving Ubers have enormous potential to further our mission and improve society: reducing the number of traffic accidents, which today kill 1.3m people a year; freeing up the 20 per cent of space in cities currently used to park the worlds 1bn+ cars; and cutting congestion, which wastes trillions of hours every year.”