The Automated Highway System: an idea whose time has come

Public Roads, Summer, 1994 by Nita Congress

The Automated Highway System--An Overview

The demand on our overburdened highway system is increasing every day. Traffic is snarled, drivers are snarling. What should be a routine 20-minute trip can take hours, as traffic congestion multiplies the effects of individual variations in driving performance "as determined by physical abilities, knowledge, experience and, indeed, personality." (1) We lose control over our plans and schedules; we rush because we're late; we cause accidents and create ill will through recklessness and bad temper. This, in turn, makes the highway system even more sluggish, unpredictable, and nonresponsive to driver needs.

A solution is waiting in the wings. The Automated Highway System (AHS) program, stepped up in response to the mandate of the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA) to "develop an automated highway and vehicle prototype from which future fully automated intelligent vehicle-highway systems can be developed," will provide the vision and technology to make highway driving efficient, safe, and predictable.

In an automated highway system, the car will be guided by the road rather than by the driver. Sensors and communication devices will link the road and the vehicle to maximize driving performance. Driver error will be reduced and ultimately, with full implementation, eliminated.

"This high-performance highway system, seen as the next major evolutionary stage of surface transportation, is expected to be the focus of major U.S. implementation efforts early in the next century, much like the Interstate Highway System program was the focus of the last half of this century." (2)

Although AHS represents a long-term effort, perhaps the most exciting aspect of it is that the technology is ready now. The technology to automate routine driving functions exists and will be demonstrated in 1997.

AHS Benefits

Research has proven that the benefits of AHS on the performance of the existing U.S. transportation system will, over time, be enormous and far-reaching. Over the long term, traffic congestion will be reduced; safety will be enhanced to produce a virtually collision-free environment; driving will be predictable and reliable. More specifically, the advantages of AHS implementation include the following:

* More vehicles can be accommodated on the highway. The number of vehicles per hour per lane can be significantly increased as traffic speeds are standardized and increased and headway distances are decreased.

* Driving safety will be significantly greater than at present The human error factor will be removed.

* High-performance driving can be conducted in adverse weather and environmental conditions. The effects of fog, haze, blowing dirt, low sun angle, rain, snow, darkness, and other conditions affecting driver visibility (and thus, safety and traffic flow) will be mitigated. (1)

* All drivers using AHS can be safe efficient drivers. AHS offers enhanced mobility for people with disabilities, the elderly, and less experienced drivers. (1)

* Fuel consumption and emissions can be reduced. In the short term, these reductions will be accomplished because start-and-stop driving will be minimized and because on-board sensors will be monitored to ensure that the vehicle is operating at top performance. (1) In the long term, the AHS can support future vehicle propulsion/fuel designs. (2)

* Land can be used more efficiently. Roads will not need to take up as much room, since AHS facilities should allow for more effective use of the right of way. (1)

* More efficient commercial operations. Commercial trucking can realize better trip reliability to support "just-in-time" delivery.

* More efficient transit operations. Transit operations can be automated, extending the flexibility and convenience of the transit option to increase ridership and service.

AHS Technologies

What will the automated highway system actually be? Will it be very different from what we have now? Will our roads hover in mid-air as futuristic cars whiz along?

Not really-or at least not yet. An AHS facility will probably be a normal lane or two on an existing freeway.

Initially, AHS will probably be deployed and operated on high-priority routes in high-demand major urban and intercity freeway corridors. (2) And an AHS car will look like a normal car. But both facility and road will be outfitted with sophisticated control and communication devices that will essentially put the vehicle in communication with the roadside. The car will "know" what roadway conditions are like. The road will "offer" each vehicle options, navigation, and advisories based on its conditions. While on the AHS facility, the vehicle will be operated under automated control-similar to the autopilot control in aircraft. (2)

The products, technologies, and concepts underlying AHS do, for the most part, currently exist. For example, products now on the market or under development include sensors that detect obstacles in vehicle blind spots, collision warning systems, and infrared vision enhancement systems. Also, intelligent cruise control systems (systems that accelerate and decelerate in response to the speed of the vehicle immediately ahead) are under development by automobile manufacturers. (3) In addition, concepts and products from the defense industry--advanced computing systems, sensors, advanced command and control, etc.--are being applied. "The automated highway program is perfectly positioned to harness these military technologies and convert them for civilian use." (4) Thus, over the next few years, an integrated system that uses all these existing or developing technologies will be developed, and that system will be tested in more realistic environments.