Uber has officially put its self-driving semi-trailer trucks into operation under the new service Uber Freight. In fact, Uber has had the self-driving trucks in service for a few months in the state of Arizona, The New York Times reported last week.

It comes after the startup Otto, which Uber has since acquired, sent a self-driving semi on its maiden voyage across 120 miles of Colorado freeway in 2016.

Uber's semi trucks have a licensed truck driver behind the wheel at all times in case any system fails. Obviously, the goal is to remove the human from the driver's seat in time, and Uber doesn't believe it will put truck drivers out of work by doing so.

Wait,  what?

The ride-sharing company focuses solely on highway driving for its autonomous technologies and doesn't envision its self-driving semis taking to local roads for quite some time. Thus, companies will still need humans to handle local deliveries and take over from the truck in many situations.

Uber envisions transfer hubs where self-driving semis will pick up and drop off trailers. At these hubs, human drivers would pilot semis destined for local deliveries, while the self-driving trucks shove off to trek across freeways. Uber's backend systems would calculate demand for self-driving trucks and human drivers.

The hope is to make trucking a safer industry since many drivers are prone to drowsiness behind the wheel, which can cause crashes. Eventually, analysts believe self-driving trucks will be less expensive than employing humans since the high-tech semis won't need to stop for breaks or catch some rest.

Uber and its Otto subsidiary won't be alone in the race to automate the trucking industry. Mercedes-Benz parent company Daimler is eying self-driving trucks, as is Tesla with its battery-electric Semi.