Tesla. Google. Delphi. Nissan. They're all racing to make self-driving cars that are both efficient and (most importantly) safe. But as Larry Greenemeier reports in Scientific American, the real vehicle companies should be accelerating research and production for is autonomous big rigs.

How big the big rig industry really is

To understand the potential effect of self-driving trucks, take a look at some of these facts from the American Trucking Industry:

  • Trucks move 70 percent (10.49 billion tons) of the nation's freight by weight.
  • Commercial trucks make up 12.1 percent of registered vehicles, with 31.4 million trucks registered and used for business purposes. 3.63 million Class 8 trucks operated in 2015.
  • In 2014, all registered trucks traveled 279.1 billion miles. Combination trucks traveled 169.8 billion miles.
  • The number of for-hire carriers on file with the Federal Motor Carrier Safety Administration was 586,014 in May 2015.
  • Excluding self-employed individuals, 7.3 million people were working in jobs related to the trucking industry as of 2014. The number of drivers employed in 2015 was 3.5 million, up from 3.4 million in 2014.

The Bureau of Labor Statistics adds that demand for truckers is good, with employment projected to grow 5 percent through 2024 (about as fast as other industries) as the economy strengthens and more products come on the market.

Widespread problems self-driving semi-trucks could fix

The Federal Motor Carrier Safety Administration (FMCSA) regulates how long drivers can work at a time. Drivers can't work more than 14 hours straight (11 driving), and they have to have at least 10 hours between shifts. They also are prohibited from working 60 hours in 7 days or 70 hours within 8 days. Even so, because most heavy truck and tractor-trailer drivers are paid according to the miles they have driven, they're under personal pressure to stay on the road as long as regulations allow to maximize their pay. Fatigue is a common problem among drivers as a result.

At the very least, being tired poses general (but not insignificant) health risks to the driver, such as increased chance of obesity and high blood pressure. But according to FMCSA, trucks are at fault for nearly one out of every 10 driving fatalities (9.5 percent). There's a very real safety concern not just for the truckers, but also to others on the road that could be involved in truck-related crashes.

Then there's pure efficiency to consider. Drivers typically travel in convoys, relatively close together, because doing so allows them to eliminate some of the wind drag that ends up eating up the trucks' fuel. Self-driving trucks, in theory, could be programmed to travel safely even closer together. They'd also allow truckers to stay on the road longer and, subsequently, get products to stores and consumers faster. That can make a big difference for all retailers, but it could be particularly important for companies working with perishable items, such as produce. Lastly, in the "down time" created by the autonomous truck, truckers could complete other tasks for their companies, using the truck as a mobile office.

But for those behind the wheel...

Despite the potential benefits that companies looking into driverless trucks see, not all truckers are convinced that self-driving rigs will become the standard, or that autonomous trucks will be any safer.

"Maybe [self-driving rigs could work] down long stretches of highway, but there's always gonna be a human needed to take over to drive in the city," says Zac Cunningham, a Mt. Pleasant, Michigan driver with a decade of experience. "I go around corners, back in docks, adjust for road conditions."

Cunningham also feels that problems would come from traditional drivers, too. "Four-wheelers don't give room to trucks, so accidents will rise significantly, because computers can't foresee some things that humans anticipate sometimes. People's selfishness and [their] 'me first, I'm in a hurry' mentality has got to go away first. A lot of truckers don't feel [self-driving rigs are] gonna happen for a long, long time. There's just too many variables...a truck is not a four-wheeler."

For now, self-driving cars still have the limelight, and drivers like Cunningham recognize there's more involved to making autonomous semis work than the truck itself. Consider, too, that 78 percent of people still are afraid of driverless cars, which don't have nearly the weight or size of rigs. But with companies like Uber and Mercedes already investing in the technology, a shift to autonomy still could happen relatively fast, especially since the greater simplicity of the open highways translates to easier programming for big rigs than for other vehicles. Don't be surprised if, the next time you're traveling and you want a driver to blow their truck's horn for fun, you look over and there's nobody there.