Engineers have been experimenting with autonomous vehicles for years, but last week Daimler Trucks North America LLC steered the challenge into the fast lane by unveiling the country's first licensed autonomous commercial truck.

Daimler's "Freightliner Inspiration Truck" is a self-steering 18-wheeler that earned its driver's license on May 5 from officials in Nevada. Introduced at a ceremony at the Hoover Dam, the truck took a joy ride down U.S. Highway 15 in Las Vegas, with Nevada Gov. Brian Sandoval and Daimler board member Wolfgang Bernhard along for the ride.

If widely adopted, the technology could help reduce accidents, improve fuel consumption, cut highway congestion, and safeguard the environment, Daimler said.

Officials emphasized that the robotic vehicle does not make human drivers obsolete. "It is not a driverless truck—the driver is a key part of a collaborative vehicle system," Richard Howard, senior vice president for sales and marketing at Portland, Ore.-based DTNA, said in a statement. "With the Freightliner Inspiration Truck, drivers can optimize their time on the road while also handling other important logistical tasks, from scheduling to routing. The autonomous vehicle technology not only contributes to improved safety and efficiency, but allows for improved communication through connectivity and integration."

The system works by using an array of camera and radar sensors to maintain the legal speed, stay in the selected lane, keep a safe braking distance from other vehicles, and slow or stop the vehicle based on traffic and road conditions. Operating together, those "highway pilot" capabilities have earned the truck a designation of Level 3 autonomous vehicle capabilities, as determined by the National Highway Traffic Safety Administration (NHTSA).

The designation requires drivers to take back control for such operations as exiting the highway, driving down local roads, and docking for deliveries, Daimler said. Human drivers only cede full control of safety-critical functions when cruising in ideal traffic and weather conditions on open highways, Daimler said.

While Daimler has built only two trucks with its full suite of Highway Pilot sensors and computer hardware, the company has also applied some of these technologies—known as "core autonomous vehicle systems"—in another model of commercial truck called the "Freightliner Cascadia Evolution."