Imagine joining the motorway in your car, nose-to-tail with other vehicles. You settle down for the journey ahead, but instead of worrying about keeping your distance as you whizz along you take your eyes off the road, reach for a book, and settle down for a good read. Or perhaps you might like to open your laptop and send a few emails as you speed along the outside lane in close proximity to other vehicles.
That, on the face of it, sounds like a preposterous scenario. It would certainly seem dangerous. But if a €6.4 million pan-European project into “platooning” delivers on its promises, convoys of cars travelling close together might just emerge as the future of travelling on motorways.
The concept has the potential to deliver benefits in terms of congestion and fuel economy. But it also faces some 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.
“Platooning is essentially a means of creating a road train, where the cars autonomously follow a lead vehicle, manually driven by a professional driver,” explains Tom Robinson at engineering consultancy Ricardo, which is leading the Safe Road Trains for the Environment (Sartre) project.
“In theory it could offer significant aerodynamic benefits in terms of reduced drag as the vehicles travel closely together. There could also be safety benefits as we are talking about taking the driver out of the equation. And it could also cut congestion as platooning could increase the stability of the traffic itself, resulting in less oscillation of traffic flow. Potentially it’s a way of using our roads more effectively.”
The Sartre project started 18 months ago and will deliver its findings in the middle of next year. Although the concept of platooning might sound far-fetched, the research involves some respected organisations in the automotive and academic sectors. Alongside Ricardo in the UK is Volvo Technology and Volvo Cars and several other research outfits from Sweden, Germany and Spain.
The concept relies on vehicle-to-vehicle communication, based on the IEEE 802.11P standard. Each convoy would be led by a professionally driven vehicle such as a coach or a truck which would monitor and control the behaviour of the cars behind it. A combination of sensors such as radar, camera and laser would keep the cars spaced around 5m apart from each other, while helping the convoy to follow the movement of the lead vehicle.
The cars in the convoy would need some additional hardware such as steering actuators to allow steer-by-wire and some form of autonomous control module. The lead vehicle is likely to be fitted with additional safety systems such as driver alert and lane-keeping support.
The lead driver would ultimately have full control over the convoy, deciding for instance if and when the platoon needs to change lane. The aim is to allow the drivers behind to relax, only needing to take control of their own vehicle when they leave the platoon.
So far, Sartre has delivered the first successful demonstration of the technology at the Volvo Proving Ground close to Gothenburg, Sweden. The tests carried out included a lead vehicle and single following car at 30mph. The steering wheel of the following car was controlled by the lead vehicle, moving by itself as the car followed the truck around the test track. The driver behind was able to drink coffee and read a paper, using neither hand nor foot to operate his vehicle. Sartre expects to extend this test to five cars by the end of 2011. “It’s a three-year project and we have been going around 18 months,” says Robinson. “A large part of the early work was about understanding the concept and agreeing on some of the safety issues. The second phase is the development of a prototype with five vehicles in the platoon. We have now started testing with more than two vehicles and hope to extend it to comprise five vehicles by the end of the year.”
Robinson says that, in terms of technology, there appear to be “no show-stoppers” that would make the concept of platooning impossible to implement. “Much of the sensor technology already exists – we are trying to develop the system so that it needs as little new hardware as possible,” he says.
“But I would say that we have still got quite a bit of work to do in terms of speeding the platoon up. And we are looking at platoon management activities around issues such as joining manoeuvres. It’s easy to do a joining manoeuvre with two vehicles but when you start considering how other vehicles might interact, and you start to test how those systems respond to other vehicles trying to squeeze into your platoon, then it all starts to become a bit more difficult. We also have a workshop planned where we will hold wider discussion on how legislation might need to change in the future.”
The specifics of how platooning might work in the real world still have to be agreed upon. The partners haven’t, for instance, settled on a means of stopping other cars barging into the platoon. It is also not certain how a car would legitimately join or leave a platoon. There might be some form of online brokering system, whereby a driver can identify a platoon and its destination, book a slot in the convoy and pay the necessary charge, and then navigate to join up at an agreed point, automatically linking to the lead vehicle when in range.
There is also still some debate over distance between the cars and the length of platoons. Robinson says that the partners would like to get the cars to travel around a half-vehicle length between each other, or possibly even closer in order to achieve a maximum reduction in fuel consumption. But he admits that drivers might feel nervous about travelling at high speed with such a small gap between them and the cars in front and behind. However, Robinson says that safety is one of the guiding principles of the Sartre project and that the vehicle-to-vehicle connection would mean that cars travelling in a platoon would be capable of quicker reactions than their manually driven counterparts.
One key factor is that the platoon needs to be able to interact with other road users, who for example need to be able to conveniently leave the motorway without being disturbed by the convoy of cars. Computer simulation is being used to study how platoons will affect and be affected by surrounding traffic. Human factors research studies have shown that drivers would accept platoons of up to 17 cars, but very long road trains could potentially block exits to slipways for other vehicles, and so that is something that is still being discussed.
There is also the problem of public resistance to such a radically different means of road transport. Robinson argues that platooning would merely complement individually operated cars, and that no one would be compelled to use it.
“Platooning presents people with an option so that when they are in traffic they can use their time more effectively,” he says. “However, there is bound to be some resistance from people who see it as an attack on their right to drive. But this would likely be an optional system – you would have a choice. I don’t like driving on the M25 – so I would pay to use it. I have cruise control on my latest car and I find that a little bit frustrating because I am still having to be in control. I’d like to see things move a step forward so I could use my time more beneficially.“
There is also a need for it from an environmental perspective. If we can get a 10% fuel saving, that’s a significant impact on the environment and on people’s pockets.”
Ultimately Robinson sees Sartre as a step towards a fresh approach for road transport. He says that, with traffic congestion likely to get worse in coming years, new thinking is needed to help cut jams and reduce accidents. Eventually he sees a place for fully autonomous vehicles that can navigate from one point to another without any driver control.
But that’s for some time in the distant future. For now he wants to see the Sartre project through to its fruition, and acting as a prover for new technologies that the partners might exploit commercially. He says: “One of our goals is to introduce technology that will lead to a step change in the way we go about transport. And the Sartre project will lead to a lot of technical knowledge that will go towards that. Each partner has their own way of thinking how they might get their own return on involvement in the project.”
