Road Trains—Not Driverless Cars—Are The Future Of Hands-Free Driving

Before we get cars driven fully by computers, we'll have platoons of vehicles lead by a professional driver that let you take your eyes off the road and save fuel. They'll be on the road in Europe by 2020.

road trains

Google may be grabbing headlines for its experiments with driverless cars, but fully robotic vehicles probably aren't the next step in our automotive future—think about how long it will take for governments to approve the technology and for auto companies to manufacture driverless cars en masse. Instead, we may soon see vehicle platoons (aka "road trains") that allow software-equipped cars to automatically follow a professional driver in a "lead car". It's a technology that could reduce congestion and increase both speed and fuel economy—and according to Volvo, it may be on European roads by 2020.

"This is easier than what Google is trying to do," Erik Coelingh, a technical specialist at Volvo, tells Fast Company. "What we are trying to do is take a step in the middle between the adaptive cruise control cars that we have today and the Google car that we have in the future."

When road train technology is commercialized, a driver equipped with platooning software could use an in-vehicle navigation screen to find the nearest platoon and drive to the end of it. At that point, the car could wirelessly connect to the platoon and take over braking, acceleration, and steering—and drivers could safety start texting or watching a movie.

Volvo imagines that professional drivers would lead each platoon, though there is no technical reason why regular drivers couldn't take over. But just as bus drivers are required to have special licenses, Coelingh believes that road train lead drivers should probably have special qualifications for the job. Employing professional drivers would also remove a lot of legal hurdles, since each road train would be led by a real, live human.

Beyond giving drivers the opportunity to relax on the highway, road trains have a number of advantages over today's cars: They're ostensibly safer, and they save fuel (driving close to the car in front of you reduces aerodynamic drag forces, which are a major contributor to fuel consumption).

So far, Volvo has successfully completed tests on a closed track in Sweden with one lead vehicle and one following car. Next up: driving in platoon formation with several vehicles at the same time on a closed track, and then moving into the real world.

Volvo is working on road platooning as part of the EU's Safe Road Trains for the Environment (SARTRE) Project, an (apparently existential) initiative that aims to put road trains on unmodified highways—no embedded magnets under the road, for example—where they can safely interact with traffic.

"What we want to try to do is take cars that we have in production today and modify them as little as possible in order to allow them to drive on the road-train platoon project," says Coelingh.

Major auto companies are already working on a common communication standard for intelligent vehicles. This will allow platoon-ready cars from a variety of automakers to communicate with each other.

There are still kinks to work out, of course. What happens if the software malfunctions while a car is in a platoon? How many auto companies need to be involved to make this viable on a large scale? And who will pay the professional drivers?

"We're in the research stage, so we cannot solve all the problems," says Coelingh. "The most important thing is that we have the cars communicating with each other."

Reach Ariel Schwartz via Twitter or email.

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  • Steve Moore

    Why is a truck driver a safe driver?
    I would hate to be stuck behind one of those things.
    We have all been stuck behind an elephant race between 2 selfish truckers.

    I can just imagine trying to exit the motorway in my classic car built in say 2010, only to find the exit blocked by a mile long roadtrain. Much as trucks do today.
    I guess the benefit of the roadtrain is that you will be able to see the signs of the exit as you miss it where the trucks obscure them (here in the UK at least) today.

    The trains need to have a maximum length & some car drivers are just as qualified as a polish trucker to be the lead vehicle.


  • James E

    Great idea for long haul trucking and military convoying. I'm sure the railroads would hate it.
    I think a DARPA competition with competitors racing a platoon of five cars against other platoons would be pretty fun.

  • jtsee2

    To add to the previous comment... I second the vote for keeping this one on the drawing board.  This will not lower vehicle emissions.  How is this better than a bus system in any major city?  Now I'm not saying that bus systems are the answer, but a vehicle convoy that will take up more space on our roads and carry LESS people than a bus -  is definitely not the answer.

    Other thoughts...When a 30 car platoon enters an intersection, I'm sure the light will change from green to red before the platoon is completely through the intersection.  There are many problems that vehicle platoons do not solve; moreover, there are many problems the vehicle platoons will create.

    I think about being at the supermarket and waiting inline, even though there are 4 other lanes open.  This is not efficient.  This will create more engine idling for followers (non-drivers in a vehicle platoon) waiting at lights, lead platoon drivers will drive slower, etc.  How do they expect to get a long platoon onto a major highway?  The platoon will be longer than most entrance ramps.  I guess each vehicle platoon will be assigned a police officer escort, similar to a funeral.  

    Autonomous cars are not the immediate answer, so I appreciate the attempt by Volvo suggesting an alternative.  However, there are a plethora of questions that need to be addressed while brainstorming any idea.  

  • Stuart Bogue

    This is for use on restricted access highways ie; Interstates,Autoroutes,AutoBahns. Traffic lights and intersections will not be a concern. Click in the intention to exit and away you go. Same for entering a highway.Searching for and finding closest group and linking....

  • Don Jarrell

    Very interesting to think about.  OK, now I've thought about it and see many problems.  Just to begin:

    How many professional, equipped platoon leaders will be expected (1) on a given section of a given road, (2) with a given destination, (3) at the time needed ?

    The above factors, especially if it means "platoon hopping" to get to a desired location, plus disagreements about driving style, restroom stops and other discontinuities will mean a LOT of time and attention is spent on managing one's participation in road trains.

    Even professional drivers crash, so this means in those instances they will probably take several people with them.

    As cars continue to add autonomous driving safety controls, what is the likelihood they will conflict in a heterogeneous group of vehicles ?  How will that be resolved ?  Will a very safe car and its driver surrender to a relatively unknown combination of platoon leader driver and set of technologies ?

    Do we create a whole new legal defense, and irresponsible attitude, that "the platoon made me do it" ?

    I'm sure there are more.  Let's keep this one on the drawing board a while longer.