By cooperative systems, we mean (definition adopted by the EC, unit C.5 – ICT for “ICT for Transport and the Environment”) :
“Road operators, infrastructure, vehicles, their drivers and other road users will co-operate to deliver the most efficient, safe, secure and comfortable journeys” The vehicle-vehicle and vehicle-infrastructure co-operative systems will contribute to these objectives beyond the improvements achievable with stand-alone systems.” In other words in cooperative systems, intelligence is shared between the vehicle and the infrastructure. Vehicles communicate with each other and with the infrastructure, opening up the possibility to considerably improve the quality and reliability of the information available on vehicles, their position and the road environment. This new information not only makes it possible to improve existing services but also to develop new services for road users.
In this cooperative vision, vehicles on the road permanently communicate with the infrastructure. They exchange data and relevant information regarding the section of road being used, in order to improve safety and implement cooperative traffic management. More precisely, a vehicle which detects a dangerous or critical situation, using integrated vehicle-infrastructure-vehicle communication protocols, will first use vehicle to vehicle communication (V2V) to warn other vehicles in the vicinity and to communicate this information to surrounding markers. If this information cannot be sent to other vehicles or the markers, the vehicle will use other communications channels to communicate with the management centre. The centre is responsible for transmitting the appropriate messages to other vehicles approaching the area concerned.
Cooperative system terminology refers to three levels of vehicle to infrastructure cooperation of increasing complexity: Autonomous, cooperative and interactive. This article details the main characteristics of these different types of systems.
- Autonomous system
On this first level, the vehicle is fitted with on-board sensors which provide information on the immediate surrounding environment. However, it does not interact directly with other vehicles. The vehicle is fitted with an Advanced Driver Assistance System (ADAS) which:
— measures distances in relation to the vehicle in front
— identifies obstacles,
— brakes in emergency situations (automatic braking one second before impact)
— detects deviations in trajectory in relation to road markings.
These functions use image sensors and laser ranging. The system may also include a location system associated with digital mapping.
- Cooperative System
On this second level, the driver is provided with enhanced information on the surrounding environment by communicating with the infrastructure (V2I) which informs them of traffic conditions, road grip and general information about the running lane. It also allows the driver to have an enhanced perception of surrounding vehicles on the section of road and in adjacent lanes.
- Interactive Systems
This final level is still a utopian concept. All vehicles exchange information with all other vehicles (V2V), and with the infrastructure (V2I) and (I2V) and operators. Probe vehicles feed back data which is analysed to assess the risk of accidents due either to the infrastructure or driver behaviour. At this level, the driver has real-time access to information on road characteristics and traffic conditions. Drivers’ perception of the environment is enhanced by a combination of different sources of information (autonomous sensors, cooperative systems, data exchange). As for the vehicle, it is able to detect real-time errors in terms of trajectory and dynamic behaviour.