Representatives for Daimler and Bosch declined to say where in the San Francisco area the driverless taxis will be offered or how large a pilot they are planning, citing ongoing negotiations.

The firms said the service would be free and run on select routes, with taxis able to be summoned by app by passengers.

The taxis, which will have humans on board to monitor performance, are expected to be open to the public, but the number of users is likely to be limited, they said.

They will incorporate technology from US chipmaker Nvidia.

Bigger possibilities

Daimler announced a partnership with Uber last year, but the ride-hailing company scaled back its driverless car programme after a fatal accident earlier this year.

Other firms continue to move forward.

Waymo, which shares a parent company with Google, opened its driverless vans to a limited number of passengers in Arizona last year.

California also issued its first approval for driverless shuttles to travel on public roads in March.

Randell Iwasaki, executive director of the Contra Costa Transportation Authority, which worked on the plans, said multiple driverless car companies have approached the authority about getting in on the game, and he expects interest to grow.

The authority is not in discussions with Daimler and Bosch, he added.

"We think this has got some viability at least in suburban applications ... and if it works here, then most likely it will work in any suburban application in the United States," he said.

Two driverless buses, manufactured by the French firm Easymile, are expected to start taking passengers in the city of San Ramon later this year, Mr Isawaki said.

The vehicles, leased by the owner of the Bishop Ranch business park, are intended to help transfer employees at the site, reducing parking needs, he said.

Public transit agencies are also planning to offer a driverless Easymile bus in nearby Dublin in Alameda County, Mr Iwasaki said.

Source: BBC