Eventually he felt comfortable enough to take his eyes off the road to read and answer e-mail on his smartphone. "After a while you adapt to it and you feel like you're on an aircraft or a bus or something."

Reading e-mail while sitting in the driver's seat may be safe enough, said Ekmark, but sleeping is probably not a good option.

If something goes wonky during a Road Train trip, the system triggers a very loud alarm along with a "quite strong vibration" in the driver's seat. The driver then has about 10 seconds to take control of the vehicle and leave the Road Train.

Road Trains could be a safe stepping stone toward the day when all cars are autonomously self-driven and not reliant on a lead vehicle, Ekmark said.

Rail riders

Americans are increasingly embracing train travel. Need proof? More passengers rode Amtrak this year than ever before in its 41-year history, the train company said. And there's no reason to believe the trend won't continue, say experts.

Better rail service and increased funding offers America its best chance in generations to get off the highways and get on the rails, according to analysts.

Regional inter-city rail systems in California, Illinois, North Carolina, Virginia and elsewhere have been invigorated by 2009's federal stimulus legislation, said transportation expert Yonah Freemark, who runs TransportPolitic.com.

"Those investments are going to be built out and people are going to see better service on inter-city rail lines across the country," he said." And you'll see increasing ridership." That's good news for the nation's energy situation. Rail travel uses 20% less energy than traveling by car, according to the ASCE.

Still, U.S. train ridership ranks very low compared with other nations. The number of passengers on Amtrak and commuter rail total about 500 million a year, Freemark said. Compare that to the United Kingdom, a country five times smaller than the United States, which counted 1.35 billion rail riders last year. Other nations where railroads carry more than a billion passengers a year include Germany, India, China, France, Russia and South Korea, according to the International Union of Railways.