A project examining the potential of ‘road trains’ where a platoon of cars autonomously follow a lead vehicle has completed its first test demonstrations.

In the test, a lead truck was followed by three Volvo cars driven entirely autonomously at speeds of up to 56mph with no more than six metres gap between the vehicles.

The SARTRE project (Safe Road Trains for the Environment) is being driven by seven European partners, including Volvo Cars and Ricardo, to develop technology that can be implemented on conventional roads in which platooned traffic operates in a mixed environment with other road users.

SARTRE also includes a major study to identify what infrastructure changes will be needed for vehicle platooning to become a reality, and is in discussions with technical experts, politicians, legislators and traffic safety researchers on a number of non-technical challenges for road trains, such as legal regulations, product liability and driver acceptance of automated vehicles.

Ricardo, which leads the project, said the main advantage of road trains is that the car driver has time over to do other things.

It added that road trains promote safer transport since the vehicle platoons are led by a professional driver, such as a truck and inter-vehicle reaction response times are much quicker.

Environmental impact is reduced since the cars follow close behind each other and benefit from the lower air drag.

The energy saving is expected to be in the region of up to 20%, it said, and road capacity will also be able to be utilised more efficiently.