Nissan Motor Co. is carrying out Japan’s largest demonstration to date of autonomous vehicles in Yokohama as the automaker moves toward rolling out a commercial automated service.

Although regulations and the need for further technology improvements mean a full-scale launch is still some years away, Nissan has been testing the self-driving taxi service in Yokohama, near its corporate headquarters. Passengers can book rides via a smartphone app that covers some 650 routes and embark and disembark from 23 points around the city.

For now, the autonomous taxis have operators sitting ready to take over in case the vehicles’ various sensors encounter a situation that requires human assistance. The goal is to eventually have such "safety drivers” monitor a fleet of such taxis remotely. In this way, savings on driver fees could lead to lower fares versus conventional taxis, according to Nissan.