Uber has started testing self-driving functions on roads in San Francisco after a few months of testing its sensor suite and hardware on the streets of Pittsburgh.

The ride-hailing company has three Volvo XC90s, each equipped with Uber’s hardware and software. (Although Volvo has made strides in self-driving functions, Uber is using its own system.) When a passenger requests a ride, Uber lets the passenger know a car with self-driving functions will be picking them up, and the passenger can accept or decline the ride. An Uber engineer rides in the front seat at all times.