Mr. Santamala said the project aimed to establish a real bus route — probably a seasonal one — in the next two years. And there’s no reason self-driving technology could not be applied to bigger buses eventually.

For now, the project is focusing on so-called last mile service — taking riders from a stop on a more conventional bus line to a point closer to their homes, shops, offices or schools. An autonomous bus, presumably going faster, could be useful, especially because of a quirk in Finland’s motor vehicle laws.

“It doesn’t state anywhere that we need to have a driver holding the steering wheel or even inside the vehicle,” Mr. Santamala said. “A legal driver can be observing the operation through a computer.”

That means a number of buses could run autonomously, with one operator in a central office intervening remotely as needed. Reducing the number of operators could make it financially feasible to run routes that serve only a few customers, or to vary routes throughout the day based on ridership.

Helsinki has already seen several efforts to use technology to change public transportation. One was an on-demand minibus service, Kutsuplus, that was operated by the regional transport agency for four years. Using a smartphone, customers could choose pickup and drop-off locations. The service’s software then combined requests from several customers and calculated an optimal route for one of its 15 minibuses.

“It was a good experiment,” said Sami Sahala, who advises the city on “intelligent transportation” issues. “But it was a little bit ahead of its time.” Kutsuplus was heavily subsidized by the city, and although the service was popular and gaining riders, it was doomed by budget cuts at the end of last year.