Getting your car in line

The SARTRE (Safe Road Trains for the Environment) project involved seven European partners, whose prototypes made use of state-of-the-art technology to link vehicles into ‘road trains’ – or ‘platoons’ – that can travel as semi-autonomous convoys.

This unique, EU-funded project highlights the potential for eventually implementing road trains on conventional motorways, with platooned traffic operating in a mixed environment with other road users.

Safer and more convenient

Platoons of vehicles would be under the control of a professional lead driver in a lorry or coach. Each participating car in the platoon is fitted with equipment such as cameras, radar and laser sensors, allowing the vehicle to monitor the distance, speed and direction of the vehicle in front and the other vehicles in their immediate vicinity. Using wireless communication, the vehicles in the platoon ‘mimic’ the lead vehicle autonomously – shadowing the car in front of them.

All drivers are able to join or leave the convoy at any time, making use of a touch screen interface. But once a vehicle joins the road train, its steering, acceleration and braking is automated as the vehicle smoothly follows the one in front towards its destination. During a journey, participating drivers are able to communicate with each other using vehicle-to-vehicle communication, or perhaps just relax, drink a coffee, or read a newspaper.

Dr Erik Coelingh, Technical Specialist at Volvo Car Corporation, one of the project partners, is enthusiastic: ‘The road train is the best of two worlds. You can enjoy all the multi-tasking possibilities of public transportation behind the wheel of your own car.’

But despite a successful demonstration with five platoon vehicles at the Hällered test track near Borås, Sweden in September 2012, the project’s partners recognise that the challenge of implementing road train technology on Europe’s motorways is not solely a technical matter.

‘There are several issues to solve before road trains become a reality on European roads. However, we are convinced that road trains have great potential,’ says Dr Coelingh.

Advantages aplenty

Platooning offers several other advantages, not least improved road safety, as the human factor – the cause of an estimated 80 % of road accidents – is minimised. It will reduce fuel consumption by 10-20 % thanks to constant speeds and lower air drag, thus cutting CO₂ emissions. It will also relieve traffic congestion, as vehicles will travel with only a few metres gap between them. Requiring no changes to current road infrastructure, current plans are for 90 km/hour speeds with a six-metre separation between vehicles. This distance could be reduced still further, however, now that tests have been successfully performed with four-metre gaps.

‘There have been several different projects on platooning before – with or without drivers,’ explains Dr Daniel Skarin, a researcher at project partner SP – Technical Research Institute of Sweden. According to Dr Skarin, the technology developments required are already well underway, with production possible within a few years. However, what might take substantially longer, he says, is public acceptance of road trains and passing the necessary legislation in EU Member States that wish to use the technology.

Off-the-shelf components

‘Technically, platooning is feasible using off-the-shelf components,’ says Dr Skarin, highlighting the widespread use of parking aid cameras, blind spot warning systems and cruise control technology in many of today’s cars. ‘The real problems are non-technical. It will require new laws and human acceptance. Would you like to be in a vehicle where you’re so close to the vehicle in front that you can’t see the road?’

Legal acceptability is another potential barrier – although this has not stopped the Google driverless car, which is now licensed for use on roads in Nevada, Florida and California in the USA. Incentives are also being investigated to encourage use of platooning – such as road authorities offering discounts, drivers paying freight companies, or freight operators offering piloting services.

Ensuring platoon safety

Safety too is an important element, with SARTRE focused on ensuring that platoon safety is greater than for individual vehicles. ‘We have a standard for functional safety – ISO 26262 – which is good enough for one vehicle controlled individually, but not good enough for several vehicles subject to external influences,’ says Dr Skarin.

Whether or not the concept materialises in the short term remains to be seen. What is certain, however, is that it offers a fascinating glimpse into the future of motoring in Europe.