A major long-term element of Intelligent Transportation Systems research and development is Automated highway Systems (AHS). The AHS program is a broad international effort “to provide the basis for, and transition to, the next major performance upgrade of the vehicle/highway system through the use of automated vehicle control technology” . The detailed definition of the Automated Highway System is as follows
The term “fully automated intelligent vehicle-highway system” is interpreted to mean a system that:
- Evolves from today’s roads (beginning in selected corridors);
- Provides fully automated “hands-off” operation at better levels of performance than today’s roadways in terms of safety, efficiency, and operator comfort; and,
- Allows equipped vehicles to operate in both urban and rural areas on highways that are both instrumented, and not instrumented.
Applications in advanced traffic management, traveler information and public transportation systems (ATMS) will require more sophisticated vehicle location capabilities. In addition, the number of uses for vehicle-to-roadside communications will eventually increase. services, fleet tracking and automatic vehicle location (AVL) applications will use radio-location beacons as well as more sophisticated transceivers. As a result of AVL and AVI, processing real-time information on vehicle locations will be possible. Although the number of vehicles equipped with AVI/AVL technologies will initially be small, traffic management centers can effectively use a small percentage of vehicles as “probes.”
Roadside-to-vehicle and vehicle-to-vehicle communications are also important for the future of AHS. Automatic braking systems may be activated by decelerating vehicles in front, or by the infrastructure sending a deceleration request to the headway control system. The vehicle must be very sure about the imminent danger, and knowledge of following vehicles and their speeds is an important factor to be considered. Inter-vehicle communications and rear sensing both would help in automatic braking.
Evolution of the automated highway solution system will continue with lane departure warning. It will be the first system to control lateral movement of vehicles. The lane holding feature will consequently be added to the adaptive cruise control, shortly after the lane departure warning feature. Automatic lane holding will provide a "hands off/feet off" driving situation where the driver is still responsible for all command decisions in the vehicle and must be aware at all times of his surroundings. If the infrastructure knows the location of each vehicle, possesses the information about its current path, and is communicating with the vehicle, then the lateral control can be coordinated from the infrastructure.