Uber’s self-driving trucks are now cruising and shuttling cargo through Arizona state highways.

Integrating with its shipment-booking Uber Freight app, which connects drivers with commercial shippers, the ride-hailing brand is working alongside trucking companies to haul cargo using its fleet of self-driving Volvos.

In the process, a human-driven truck passes through weight station hubs, which then passes its load to Uber’s autonomous vehicles. Once deployed on the road, it reaches its second transfer hub, where non-autonomous trucks carry the load off to transport on a short-haul to its final destination.

At the moment, Uber is not operating a “dock-to-dock” service, with truck drivers continuing to serve as intermediaries. A human safety driver is behind the wheel at all times in case of emergencies.

As of this writing, no word has been given on which companies are involved, the number of trucks, nor the number of miles driven or which goods Uber is helping to transport.

This event comes after Uber’s inaugural self-driving milestone, an Oct. 2016 commercial delivery of 2,000 cases of Budweiser beer on a 120-mile trip from Fort Collins, Colo., to Colorado Springs. In May 2017, it launched the Uber Freight app. Like the traditional Uber rider and driver service, all drivers are thoroughly vetted with comparable in-app ride data, payment processing, and navigational capabilities.

An increasing number of players have entered the autonomous trucking-as-a-service business, such as San Mateo, Calif. based startup Embark, which recently completed a coast-to-coast self-drive from Los Angeles, Calif. to Jacksonville, Fla. in five days with a driver at the helm. At the moment, it features Level 2 autonomy with a goal to reach Level 4 within the next few years, whilst achieving a two-day run on the same route.