Convoys of wireless-linked semi-autonomous vehicles could soon be hitting our roads, giving drivers a chance to put their feet up on the morning commute.

Imagine cruising down a three-lane highway and rounding a bend to find four trucks rolling along in single-file. They are all traveling close together – perhaps too close – but otherwise everything seems normal.

Yet as you pass the trailing truck, you look up through the sun roof to see the driver on a mobile phone. He should know better, you think as you slide by. Passing the next one, the driver appears to be sipping a cup of coffee and you could swear that he’s watching TV. That can’t be right, but you power on regardless. Then, coming alongside the third, there seems to be no driver at all. You must be mistaken, you tell yourself, as the truck stays in lane and otherwise rides as per usual.

By the time you glance up at the lead truck, you glimpse a driver concentrating on the road. Perhaps your mind was playing tricks on you after all.

Or maybe not. In February this year, a similar line-up of four large trucks circled an oval test track in Tsukuba City, Japan to help get so-called “truck platooning” technology ready for real-world use.

This technology aims to create semi-autonomous road trains, where convoys of vehicles enter a snaking train of vehicles under the command of the lead vehicle. The drivers of the “drones” are then free to do whatever they like – read a book, take a nap or just sit. When they are ready to leave, the driver takes back control and exits the train. In theory the technology offers several benefits, such as cutting down on accidents and improving fuel efficiency.

“We think that this new technology can also lead to a reduction in the amount of road space used by vehicles, which would help to reduce traffic congestion,” says Nobuo Iwai, senior researcher on the project. In fact, some estimates suggest it could double the capacity of existing highways.  

Platoon prototype

The Japanese demonstration was the latest of a couple of projects set up to trial and develop the technology. A couple of years ago a project at RWTH Aachen University in Germany operated a platoon of four trucks spaced at 10m (33ft) intervals. In the US, research at the University of California, Berkeley put three-truck caravans on the road with spacing from 3 to 6m. And last year, the Scania Transport Laboratory in Sweden tested aspects of truck platooning on a 520km (325 miles) shipping route between the cities of Sodertalje and Helsingborg.

In addition, a recently completed European project led by Volvo called Safe Road Trains for the Environment (Sartre) has explored using cars and lorries simultaneously. Its platoons cruised at 85 km/h (50mph) with a gap between each vehicle of 6m. The study vehicles put in some 10,000 km (6,200 miles) of road, and – like the Japanese study – indicated that platooning could offer substantial benefits.

“Sartre showed that it is possible for vehicles – trucks and cars – to automatically follow a lead vehicle controlled by a trained driver,” says Carl Johan Alquist, traffic product safety manager at Volvo Trucks in Gothenberg, Sweden.  “Technically speaking, truck platooning is not that far away; it’s the other safety and functional issues that remain to be sorted out.”

The Japanese demonstration which was conducted by researchers from the semi-governmental New Energy and Industrial Technology Development Organization (Nedo), was intended to address some of the challenges in making the technology ready for public use by ensuring bulletproof safety and reliability. “Our target is to enable both large and small trucks to safely maintain a 4m distance between vehicles in single file while driving 80km/h,” says Iwai.

To do this, Iwai and his colleagues developed – or modified – a suite of technologies including an automated steering system, automatic vehicle-following system and cooperative adaptive cruise control.

In the trials, the lead vehicle – driven by a specially trained driver – took control of the caravan and led it round and round the test track issuing commands on the fly. For example, the speed of the leader was communicated wirelessly every 20 milliseconds to allow the train to make constant adjustments and to ensure that they were driving at both an optimum and safe distance.

But the second, third, and fourth vehicles are not dumb either – they were also equipped with millimeter-wave radar and infrared laser radars to detect obstacles and recognize lane markings, as well as a series of algorithms and fail-safe controls to better manage the vehicles.

Although the set-up sounds complex, Iwai believes that it would be a relatively simple task to upgrade modern trucks, many of which are already fitted with most elements of the technology. “We think that the eventual system/product would be sufficiently affordable for truck owners.”

Crucially, the demo also showed that the trucks’ fuel economy improved by 15% or more on average, by allowing the vehicles to slip stream each other like drafting Tour de France riders. It also showed that the lead truck can benefit from less drag at its rear as the ‘bow-wave’ of the tailing vehicle in-effect “pushes” the lead truck forward.

The tests were the first of a series for the organization. “Our next step is to obtain a permit and test this technology on public roads,” says Iwai. “In order to ensure safety and reliability of the system, we need to conduct many field demonstrations. In addition, we think it will be necessary to establish international technical standards.”

Obstacles ahead

In fact many questions remain before the system rolls out into common use. The biggest one of these is whether the public are ready for semi-autonomous vehicles to trundle alongside them. And then there is the question of whether truck drivers will put their faith in the technology.

At the same time several technical wrinkles need to be ironed out, such as automating the process of lane changing, or figuring out how drivers will merge with and leave the platoon. Ensuring that long road trains do not present a barrier to vehicles entering or exiting traffic flows will also have to be addressed.

Trials like the one in Japan also raise less obvious questions, such as how windscreens will deal with being pelted by grit and stones kicked up between vehicles or how the view-obscuring spray of rain water from long trains will affect other road users.

And if convoys go co-ed and mix cars and trucks, there are new road rules to think about, such as whether trucks only go at the front to accommodate to their longer stopping distance and therefore how new trucks insert themselves into the train.

But engineers and planners working on the technology believe none of these issues are insurmountable and that road trains could be cruising highways sometime in the next decade. Perhaps in the not-too-distant future, you yourself will commute to work on a robotic conga line, along with a line up of other drivers not paying attention to driving.

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