Walt Martin is kneeling, legs folded behind him, butt resting on his heels. "I've got to practice my yoga," he says, clearly joking. Never mind that we're in the cab of an 18-wheeler cruising through Colorado at 55 mph and Martin was, until a moment ago, the guy at the wheel.

Maybe he was feeling cocky. After all the truck, outfitted with $30,000 worth of hardware and software from San Francisco startup Otto, had just hours before made the world's first autonomous truck delivery. You'd think so momentous an occasion would have involved something more glamorous than 50,000 cans of Budweiser, but there it is.

The drive was as mundane as the beer in the trailer. At 12:30 am, after leaving the brewery in Fort Collins and merging onto Interstate 25, an Otto driver punched a switch labeled "engage," and, once sure autonomous mode had, in fact, engaged, climbed out of his seat. He buckled the safety belt behind him, to keep the warning chime from driving him crazy as the truck trundled 120 miles south to Colorado Springs.

Don't worry. Otto, which Uber bought last summer for roughly $680 million, doesn't want to put Martin or anyone else out of work.

Its technology works only on the highway, where it doesn't have to deal with tricky variables like jaywalking pedestrians, four-way stops, or kids on bicycles. It maintains a safe following distance, and changes lanes only when absolutely necessary.

And unlike Tesla's Autopilot, Otto's system offers true 'Level 4' autonomy. Once the rig hits the interstate, it is entirely capable of the job at hand, letting the human deal with paperwork, thumb her phone, or even catch a few Z's.

"The technology is ready to start doing these commercial pilots," says Otto co-founder Lior Ron. "Over the next couple of years, we'll continue to develop the tech, so it’s actually ready to encounter every condition on the road."

If he can nail that, Ron says he can make trucking a local profession. "You can imagine a future where those trucks are essentially a virtual train on a software rail, on the highway," he says. He sees a day when trucks do their thing on the interstate, then stop at designated depots where humans drive the last few miles into town. Drivers, in effect, become harbor pilots, bringing the ship to port.

Otto

Otto's hardware works on any truck with an automatic transmission, and the retrofit doesn't look like much. Three LIDAR laser detection units dot the cab and trailer, a radar bolts to the bumper, and a high-precision camera sits above the windshield.

Inside, the few hints of a human-free future include the two red, half dollar-sized buttons that shut off the autonomous system (one near the steering wheel, the other in the sleeper cab behind the seats) and the on/off switch, labelled "Engage." A bank of computers turns all that data into driving directions, and an Uber engineer keeps tabs on it all.

Autonomous cars are sexy, but trucks are more practical. And they'll almost certainly be here sooner than cars, because the industry desperately needs them. The trucking industry hauls 70 percent of the nation's freight—about 10.5 billion tons annually—and simply doesn't have enough drivers. The American Trucking Association pegs the shortfall at 48,000 drivers, and says it could hit 175,000 by 2024.

Beyond eliminating the need for a hiring spree, autonomous technology will make the roads safer. Some 400,0000 trucks crash each year, according to federal statistics, killing about 4,000 people. In almost every case, human error is to blame. "We think that self-driving technologies can improve safety, reduce emissions, and improve operational efficiencies of our shipments," says James Sembrot, who handles logistics for Anheuser-Busch and worked with Otto on the October test run.

Sean McNally, a spokesman for the American Trucking Association, concedes autonomous technology can improve safety and efficiency, but he questions the wisdom of turning a 40-ton rig over to a computer. And the federal government has yet to weigh in on the idea.

You can imagine a future where trucks are essentially a virtual train on a software rail. Otto Co-Founder Lior Ron

Still, Otto is moving quickly. The company launched in January, and quickly bought its first truck. By May, it had a working prototype. A fleet of six trucks roams interstates 101 and 280 in the San Francisco Bay Area. Engineers push software tweaks weekly, and major updates every month or so.

Right now, they're focusing on the basics—smoothing out the acceleration and braking, improving lane control, that sort of thing. Longer-term goals include predicting how other drivers are likely to behave, navigating construction zones, and dealing with hazards like sudden bad weather.

Go-anywhere, do-anything autonomy is the ultimate goal, but that requires tackling far more complicated city environments, along with things like parking. "That's a pretty big leap," Ron says.

For the foreseeable future, the driver will remain an essential part of the system. But with Otto, they can can do something other than deal with the stress of driving. Like practice yoga.