Waymo will start offering robotaxi rides to people in its "Waymo One" early rider program in Mountain View, Los Altos, Palo Alto, and "parts of Sunnyvale" starting Wednesday, an expansion that will bring its footprint in Silicon Valley to 27 square miles.

Waymo vehicles will be available around the clock, and the new territories add to the 55 square miles of coverage already offered in the San Francisco Bay Area, the Mountain View-based company said Tuesday.

Last week, Uber users in Austin, Texas could start getting matched to Waymo vehicles on the ride-hailing app. Uber and Waymo plan to bring the same service to Atlanta later this year. Waymo is also launching in Miami in partnership with African mobility startup Moove.

Waymo plans to test in as many as 10 new U.S. cities this year, including Las Vegas and San Diego after a 5.6- billion-U.S.-dollar funding round, which helped value the robotaxi company at 45 billion dollars late last year.