ON A WINDING stretch of motorway just outside Barcelona, a lorry chugs along the inside lane at a cruise-controlled 85km/h. Behind it, in tailgating close attendance, are three cars, matching its speed perfectly. Nothing unusual to see here: please keep moving, folks.

But there is something unusual. For a start, all three cars are Volvos. Odd coincidence? No: look closer. None of the drivers of the three cars is actually holding on the steering wheel, and, if you could peer down into the footwells, you would see that none is pressing the accelerator. This is road-train technology getting its public-road debut. This is, apparently, the future.

Sartre (safe road trains for the environment) is the slightly torturous acronym for a high-tech project involving Ricardo UK, Applus+ Idiada, Tecnalia Research Innovation, Institut für Kraftfahrzeuge Aachen (IKA), SP Technical Research Institute, Volvo Technology and Volvo Car Corporation.

It’s a surprisingly simple system that is intended to dramatically improve driver comfort, safety and the environmental performance of our motorways.

Essentially, a road train is radio-controlled cars on a grand, automated scale. The idea is that a lead vehicle, a lorry packed with high-tech telematics systems, rolls along the motorway at a steady 85km/h.

A car fitted with the appropriate electronic steering, braking and acceleration controls can hook up electronically to the back of the lead vehicle and then play follow-my-leader as far along the motorway as its driver desires.

Press a button, sit back and your car will follow the lorry perfectly as it steers, speeds up and slows down. Then disengage the system as you come up to your exit and take control again. In the meantime, you could sit back, relax, listen to the radio, make a phone call, read the paper, even have a snooze. Let the (highly trained, one hopes) driver of the lead lorry take the strain.

There is an obvious potential safety benefit in terms of keeping driver fatigue at bay on a long journey, as well as simply turning over control to a computer that can make decisions faster and better than you can for the length of the journey.

The environment benefits too, as cars running at a constant 85km/h are emitting very low levels of C02 and other pollutants, as well as a consequent improvement in fuel economy, while congestion on motorways at busy times could be virtually done away with if mass acceptance of road trains were ever to dawn.

“This is a very significant milestone in the development of safe road-train technology,” says Sartre project director Tom Robinson of Ricardo. “For the very first time we have been able to demonstrate a convoy of autonomously driven vehicles following a lead vehicle with its professional driver, in a mixed traffic environment on a European motorway. The success of this test is a reflection of the hard work, dedication and innovative skills of the Sartre project team and its contributing companies. While there remain many challenges to full-scale implementation, the Sartre project has demonstrated a very practical approach to the implementation of safe road-train technology that is capable of delivering an improved driving experience, better road-space utilisation and reduced carbon- dioxide emissions.”

But is turning over control of our cars to machines a good idea? Clearly, any red-blooded car enthusiast will blanche at the thought, and there’s always the worry that computers are only as infallible as the people who programme them, not to mind the people who bolt them together. But, in a bigger sense, are drivers ready to make this kind of leap?

“A long convoy travelling six-metres apart at 85km/h would be very disconcerting to other drivers and under current legislation would actually be deemed as careless driving,” Tony Toner, training director of the Institute of Advanced Motorists of Ireland, says.

“It is a massive step to remove driver intervention and overall control of a vehicle used in a public place and legally place it under the control of a computer chip. Currently the driver is responsible for the vehicle they are driving – it is they who will be answerable to the courts for how the vehicle is used in a public place. Should the system become lawful to use, it will certainly follow that all users should have to receive specific training, testing and follow-on assessment, say every three years.”

We are, for the moment at least, some time away from this being an Irish problem, but the Sartre team is trying to take as much notice of how drivers will react to the system as to the system itself, according to Volvo Car Ireland’s David Baddeley: “The original Sartre project was for three years from 2009. Once the technology is proved there is still a lot to be resolved particularly in terms of user (and other road users’) acceptance. I am not aware that a time frame for market roll-out has been established at this stage.

“Driver reaction is a concern with all active safety systems, from cruise control upwards. The research focuses as much on psychology as technology, as it is important to understand the way drivers will react.”

The cars, it seems, are more ready for the switch to road trains than any of us. At an engineering level, it’s simplicity itself to have a straightforward radio link from a convoy of cars to a lead vehicle – modern cars are as much about binary code as they are about steering dynamics. But will drivers ever really be able to put their total trust in such systems?