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Vehicle platooning has been operated on a public motorway among other road users for the first time. The trial brings one step closer the concept of road trains, where cars travel nose-to-tail with other vehicles, led in a convoy by a trained driver.
The concept has the potential to deliver benefits in reduced congestion and better fuel economy. But it also faces stiff challenges, not just in terms of engineering, but also in persuading motorists to trust the technology and take their hands off the steering wheel.
The trial took place on a motorway outside Barcelona last month, and the partners behind the project said it proved “highly successful”. The road train comprised a Volvo XC60, a Volvo V60 and a Volvo S60 plus one truck automatically driving in convoy behind a lead vehicle. The convoy travelled at 85km/h and the gap between each vehicle was just 6m.
Tom Robinson at engineering consultancy Ricardo, which is leading the Safe Road Trains for the Environment (Sartre) project, said: “This is a very significant milestone in the development of safe road-train technology.
“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 motorway.
“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.”
Sartre is a pan-European joint venture between Ricardo UK, Applus+ Idiada of Spain, Tecnalia Research and Innovation of Spain, Institut für Kraftfahrzeuge Aachen of Germany, and Sweden’s SP Technical Research Institute, Volvo Technology and Volvo Car Corporation. The project builds on existing safety systems from Volvo, including features such as cameras, radar and laser sensors.
The vehicles monitor the lead vehicle and also other vehicles in their immediate vicinity. Using wireless communication, the vehicles in the platoon “mimic” the lead vehicle using Ricardo autonomous control – accelerating, braking and turning in exactly the same way as the leader.
The partners said that the project aimed to deliver improved comfort for motorists, who could spend their time doing other things while driving. They could work on their laptops, read a book or sit back and enjoy a relaxed lunch.
The project also aims to improve safety, reduce environmental impact and – thanks to smooth speed control – cut the risk of traffic tailbacks, said Ricardo.
Sitting in a car just 6m behind another one while travelling at 85km/h and relying totally on the technology may feel a bit scary, admitted Linda Wahlström, project manager at Volvo. But the experiences gained so far indicate that people acclimatise very quickly.
“We covered 200km in one day and the test turned out well,” she said. “During our trials on the test circuit we tried out gaps from 5m to 15m. We’ve learnt a whole lot during this period.
“People think that autonomous driving is science fiction, but the fact is that the technology is already here. From the purely conceptual viewpoint, it works fine, and road trains will be around in one form or another in the future.
“We’ve focused really hard on changing as little as possible in existing systems. Everything should function without any infrastructure changes to the roads or expensive additional components in the cars. Apart from the software developed as part of the project, it is really only the wireless network installed between the cars that sets them apart from other cars available in showrooms today.”
Ricardo’s Robinson said the partners would now assess the likely mechanisms for platoon technology to be operational on public highways, “at which point we believe there will be a really positive impact on highway utilisation”.