Now the company is shifting gear by moving into cargo hauling.

After road-testing its self-driving trucks in California and Arizona over the past 12 months, Waymo's fleet of autonomous big rigs is due to start hauling cargo to Google's data centers in Atlanta, Georgia, from next week.

Partnering with Google's logistics team, the pilot trucks will make use of the same kind of custom sensors used in Waymo's autonomous Pacifica minivan, and leverage the same software. But since controlling a truck is quite different from driving a car, the Waymo fleet will have trained human drivers in the cabs to monitor the technology and take over if needed.