The Automated Highway System (AHS) concept defines a new relationship between vehicles and the highway infrastructure. AHS refers to a set of designated lanes on a limited access roadway where specially equipped vehicles are operated under completely automatic control. AHS uses vehicle and highway control technologies that shift driving functions from the driver/operator to the vehicle.
Throttle, steering, and braking are automatically controlled to provide safer and more convenient travel. AHS also uses communication, sensor and obstacle-detection technologies to recognize and react to external infrastructure conditions. The vehicles and highway cooperate to coordinate vehicle movement, avoid obstacles and improve traffic flow, improving safety and reducing congestion. In sum, the AHS concept combines on-board vehicle intelligence with a range of intelligent technologies installed onto existing highway infrastructure and communication technologies that connect vehicles to highway infrastructure.
The idea of automated driving dates back to almost 50 years ago when General Motors (GM) presented a vision of ―driverless‖ vehicles under automated control at the 1939 World fairs in New York. In the 1950’s research by industrial organizations conceptualized automated vehicles controlled by mechanical systems and radio controls. After the first appearance of the computers in the 1960’s, researchers began to consider the potential use of computers to provide lateral and longitudinal control and traffic management. The fully automated highway concept was initially examined by GM with sponsorship from the US department of Transportation (DOT) in the late1970’s. During these times, focus was laid on automated vehicles on a highway as computers were not powerful enough to consider a complete fully automated highway system.
Advances in the computing technologies, micro-electronics and sensors in the 1980’s provoked commercial interest in the technologies that might enhance driver capability and perception and both private and public researchers examined partially automated products and services. Among others, the University of California Partners in Advanced Transport and Highways (PATH) has carried out significant research and development in the field of highway automation since the 1980’s. As various transportation technologies emerged that could assist driving on one hand and also traffic efficiency on the other, interest in fully automated driving or integrated auto-highway technologies grew once again.
With the passage of the 1991 Intermodal Surface Transport Efficiency Act (ISTEA), efforts were on early prototype development and testing of fully automated vehicles and highways. This act prompted the US DOT to develop the National Automated Highway System Research Programme (NAHSRP), whose goal was to develop specifications for a fully automated highway system concept that would support and stimulate the improvement of vehicle and highway technologies.
In 1994, the US Department of Transportation launched the National Highway System Consortium (NAHSC). The consortium consisted of nine major categories of organization including academia, federal, state, regional and local government besides representatives from vehicle, highway, electronics and communications industries. The consortium believed in expanding the program’s expertise and resources, and maintained that the collaborative approach among the stakeholders would be critical in building the common interest that would be required in the early development and deployment of fully automated highway systems. Research continues to this day though it is largely sketchy owing to the withdrawal of the financial support for the National Automated Highway Systems Research Programme (NAHSRP) by the US Department of Transportation in the year 1997.
Many studies conducted by the National Automated Highway Systems Consortium (NAHSC) continue in partial way with a couple of federal programmes like the Intelligent Vehicle Initiative (IVI) with more focus on a nearer-term horizon.