DETROIT (AP) — General Motors’ troubled Cruise autonomous vehicle unit said Monday it will start testing robotaxis in Arizona this week with human safety drivers on board.

Cruise said that during the testing, it will check the vehicles’ performance against the company’s “rigorous” safety and autonomous vehicle performance requirements.

Testing will start in Phoenix and gradually expand to Scottsdale, Tempe, Mesa, Gilbert, Chandler and Paradise Valley, the company said. The vehicles will operate in autonomous mode, but the human drivers will be ready to take over if needed as the company takes a step toward resuming driverless operations.

Human drivers are important in testing the vehicles’ performance “and the continuous improvement of our technology,” Cruise said.

Cruise suspended operations in October when one of its Chevrolet Bolt autonomous electric vehicles dragged a San Francisco pedestrian roughly 20 feet (6 meters) to the curb at roughly 7 miles per hour (11 kilometers per hour), after the pedestrian was hit by a human-driven vehicle.