TuSimple claims it successfully completed an 80-mile nighttime run on Interstate 10 in Arizona with no driver in the cab — the first to reach the goal in the U.S. among many competitors working on robot-driven trucks.

San Diego-based TuSimple (NASDAQ: TSP) kept secret the timing of the first driverless pilot, announcing Wednesday that the upfitted Class 8 truck left a large rail yard in Tucson, Arizona, on Dec. 22 and covered surface streets and highways for an hour and 20 minutes before safely arriving at a high-volume distribution center in the Phoenix metro area.

The autonomous driving system navigated surface streets, traffic signals, on-ramps, off-ramps, emergency lane vehicles and highway lane changes in open traffic while naturally interacting with other motorists, TuSimple said in a press release.

The Arizona Department of Transportation and law enforcement collaborated on the initial run, which had no remote control or traffic intervention. But it wasn’t without precautions.