How does it work?

How do the vehicles communicate with each other?
Wireless through a technique which will be standardized on an EU-level (based on 802.11p). However we are still exploring which communication systems that will be used.
How long will a platoon be?
The human factors work has indicated that up to 15 cars would be acceptable. In the SARTRE prototype we will implement a platoon of 5 vehicles. 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 access or leave the motorway without being disturbed by the platoon. Computer simulation is being used to study how platoons will affect and be affected by surrounding traffic.
What will be the distance between the vehicles?
In the initial tests, the inter-vehicle gap was around 10m. We’re aiming to minimize the distance in order to achieve reduced fuel consumption.  The actual distance we achieve will depend on safety, human factors and environmental benefits.
What technology will be used?
A combination of sensors (such as radar, camera and laser), as well as communication between the vehicles will help the vehicles to follow the movement of the lead vehicle.  For administration of the platoon, a software client will be used that for example will guide the driver to a suitable platoon and perform other platoon organizing related tasks.
How will an existing vehicle create the necessary gap to pull off?
The current intention is that the lead vehicle will control the following vehicles and create the gap.
What happens if the lead vehicle drives off the road?
We strive for preventing this from happening, and believe that the safety systems in the lead vehicle are an important factor for helping the vehicles to stay on the road (e.g. Volvo’s ESP, Driver Alert Support, Lane Keeping Support…). There could however be situations where the lead vehicle (by intention or not), drives off road, and we are evaluating different solutions for handling these situations.
Can any driver with a drivers licence drive the lead vehicle?
No. Our view is that the lead vehicle should be driven by a professional driver, with high likelihood of additional training to ensure they understand particular issues with road trains. In the project, we therefore let professional truck drivers lead (as the likely first adopters). Coaches would also be an alternative. Cars could also lead but this is not the focus of SARTRE.
Isn’t there a risk that the drivers in the following vehicles become too passive and inattentive if the driving is autonomous?
The driver should be able to relax, that is an important part of the project. However, we are also looking at supportive systems that will help the driver to take control of the vehicle again, when, for example, it’s time to leave the platoon.
How will a potential joiner know if he or she can join?
The information about access will be communicated by the lead vehicle. A web based client can support the planning.
How will you handle a lane change?
The lead vehicle driver decides if the platoon needs to change lane. To achieve this the driver needs a good “view” of the surrounding traffic.
To support this we will be transmitting the sensor information from all vehicles to the lead vehicle.
Will a platoon crash be more damaging than a normal motorway crash due to the shorter distance?
Not necessarily. The platoon vehicles are being driven automatically and as such we are benefiting from the faster reaction times of the platoon system, in addition the relative speed between vehicles in the platoon is less thus damage is likely to be less. One of our guiding principles is to ensure we do develop a system that is safer than existing systems.
Why not use a train instead?
We believe in using the most appropriate transport mode and the train provides an important transport alternative, however this is not always the most efficient or convenient alternative. The road train provides a good complement, since it combines the flexibility and benefits of a car with the benefits of a train.
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