Road Trains and Dynamically Reconfigurable Modular Vehicles

The EU is working on road trains, where cars have electronics to allow them to automatically follow lead vehicles driven by professional drivers.

A new EU project SARTRE is being launched to develop and test technology for vehicles that can drive themselves in long road trains on motorways. This technology has the potential to improve traffic flow and journey times, offer greater comfort to drivers, reduce accidents, and improve fuel consumption and hence lower CO2 emissions.

The first test cars equipped with this technology will roll on test tracks as early as 2011. The vehicles will be equipped with a navigation system and a transmitter/receiver unit that communicates with a lead vehicle. Since the system is built into the cars, there is no need to extend the infrastructure along the existing road network.

Lead vehicle

The idea is that each road train or platoon will have a lead vehicle that drives exactly as normal, with full control of all the various functions. This lead vehicle is driven by an experienced driver who is thoroughly familiar with the route. For instance, the lead may be taken by a taxi, a bus or a truck. Each such road train will consist of six to eight vehicles.

A driver approaching his destination takes over control of his own vehicle, leaves the convoy by exiting off to the side and then continues on his own to his destination. The other vehicles in the road train close the gap and continue on their way until the convoy splits up.

Many advantages

The advantage of such road trains is that all the other drivers in the convoy have time to get on with other business while on the road, for instance when driving to or from work. The road trains increase safety and reduce environmental impact thanks to lower fuel consumption compared with cars being driven individually. The reason is that the cars in the train are close to each other, exploiting the resultant lower air drag. The energy saving is expected to be in the region of 20 percent. Road capacity will also be able to be utilised more efficiently.

Dynamic Configuration of Light Car Modules
Another advantage is that it would enable smaller single person modular cars, that still allow more non-driver passengers or empty follow cars with cargo. Why would this be an advantage ? Couldn’t we just have a trailer hitch or a sidecar between your car and modules with another person or cargo ? There would be easier dynamic reconfiguration convenience and a module or pod could be dynamically handed off to follow a different vehicle with known destinations (such as buses or delivery trucks). You could start out from your home leading a car with driving controls disabled with a child and you can rendezvous with a school bus or a someone in your trusted network of friends who is communicating a path that will pass the child’s destination.

A dynamically configurable set of car modules allows easier usage of only the amount of vehicle that is needed for a trip. You do not have to drive a seven passenger SUV that only has one passenger and no cargo 90% of the time.

The car modules can be cheaper and lighter and more easily fully electrified.

You could also dynamically lend public charging modules, that can be paged for a rendezvous and docked to provide a charging boost.


I noticed that some people are concerned about safety if the people do not take back control of the vehicle. The robotic driving cars that exist now have:

1. Automated parking
2. Developing dynamic cruise control to automatically adjust speed based on location
3. Have been able to navigate urban traffic and rural courses for dozens of miles of driving (DARPA challenge vehicles)

A road train enabled vehicle that does not get the proper alert response from a person who is ready to take over driving again would be able to safely drive the vehicle to the nearest place for a safe park to wait until the person is ready. This capability would be less challenging than the tasks already performed by the DARPA grand challenge vehicles. The sensors and systems for the DARPA grand challenge vehicles are getting cheaper and more capable.