For the first time, a road train has operated on a public motorway among other road users.

The historic test in motorway outside Barcelona, Spain, took place last week and was highly successful.

“This is a very significant milestone in the development of safe road train technology,” commented 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.”

The Sartre (Safe Road Trains for the Environment) project is a joint venture between Ricardo UK Ltd, Applus+ Idiada, Tecnalia Research & Innovation, Institut für Kraftfahrzeuge Aachen (IKA), SP Technical Research Institute, Volvo Technology and Volvo Car Corporation. A road train consists of a lead vehicle driven by a professional driver followed by a number of vehicles. Building on Volvo Car Corporation’s and Volvo Technology's already existing safety systems – including features such as cameras, radar and laser sensors – the vehicles monitor the lead vehicle and also other vehicles in their immediate vicinity. By adding in 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 project aims to deliver improved comfort for drivers, who can now spend their time doing other things while driving. They can work on their laptops, read a book or sit back and enjoy a relaxed lunch. The project also aims to improve traffic safety, reduce environmental impact and – thanks to smooth speed control – cut the risk of traffic tailbacks.

Sitting in a car just six metres behind another one while travelling at 85 km/h and relying totally on the technology may feel a bit scary. But the experiences gained so far indicate that people acclimatise very quickly.

The three-year SARTRE project has been under way since 2009. All told, the vehicles in the project have covered about 10,000 kilometres. After the test on the public roads in Spain, the project is now entering a new phase with the focus on analysis of fuel consumption.

Robinson concludes: “Once the fuel consumption measurements are completed we will be drawing on the learning we have gained developing the platoon system and understanding the various human factors, to assess the likely roadmap and mechanisms for platoons and platoon technology to be operational on public highways - at which point we believe there will be a really positive impact on highway utilization”.