DETROIT -- While Uber and other ride-sharing services are evaluating self-driving cars, the biggest user of autonomous-vehicle fleets may turn out to be the U.S. Army.

The Army, which has hundreds of thousands of vehicles, has been testing convoys of driverless vehicles that follow a truck driven by a human.

Initial tests involved as many as 10 vehicles equipped with cameras, radar and onboard computers to identify potential road hazards.

The Army wants to learn whether such convoys can ease the workload of its drivers -- a major priority during wartime, when equipment is transported around the clock.

"One vehicle drives and a number of vehicles can follow," said Paul Rogers, director of the Army's Tank Automotive Research, Development and Engineering Center in Warren, Mich. "You won't need as many drivers. You see commercial truck operators trying similar platooning projects at highway speeds."