Alphabet’s Waymo unit announced this week that it will begin test drives of its robotaxis in Denver and Seattle, with human drivers behind the wheel. The company plans to first drive manually before fully validating its technology and operations for autonomous services in the future.

This comes as Waymo looks to expand its driverless, ride-hailing service across the U.S. after already launching in cities such as Austin, Atlanta, San Francisco, Phoenix, and Los Angeles.

The company will have safety drivers manning the steering and braking behind the test vehicles in Denver and Seattle, with a fleet including fully electric Jaguar iPace and Geely Zeekr AVs. Additionally, Waymo is also running similar tests in New York, its latest market entry.