USA Banner

Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Public Roads - Summer 1994

The Automated Highway System: An Idea Whose Time Has Come

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 without regard to weather and environmental conditions. Fog, haze, blowing dirt, low sun angle, rain, snow, darkness, and other conditions affecting driver visibility (and thus, safety and traffic flow) will no longer impede progress. (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.

"[Our] basic performance needs are increasingly beyond the performance capabilities of the existing system with its manual mode of vehicle operation."
--Lyle Saxton, "Automated Control--Cornerstone of Future Highway Systems"

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.

The 1997 Demonstration

"The goal of this program is to have the first fully automated roadway or an automated test track in operation by 1997."--Intermodal Surface Transportation Efficiency Act of 1991, Part B, Section 6054(b)

People have been talking seriously about an automated highway system of one type or another since the 1950s. Visionaries and utopians have been prophesying its development even longer. And now, after all that time and all those plans, it's finally going to happen. We will see a road, rather than a driver, guiding a car. And it will happen in this century.

In 1997, FHWA's Automated Highway System program will--as per its congressional mandate--provide proof of the technical feasibility of fully automated AHS concepts, designs, technologies, and functions. What is shown will not necessarily be the automated highway system of the future. But it will be practical, real-life applications of the latest technologies to the driving task. The demonstration will also give the world its first glimpse of what the automated highway system of the 21st century might look like and how it could perform.

What will be demonstrated in 1997? The specifics have not been set yet, but we'll see a car moving along the road by itself not controlled by its driver. This car will stay in its lane, merge and demerge, and maintain a safe distance from other cars. It will accelerate and decelerate. It will probably handle malfunctions, such as a flat tire.

The automated highway system is no longer a fantastic device for futurists, dreamers, and science fiction writers. The technology exists, and we'll see it in action in just three short years.

The AHS Program

The Automated Highway System program started up in 1992 as part of the Federal Highway Administration's (FHWA) large-scale Intelligent Vehicle-Highway Systems (IVHS) initiative. IVHS is a major government-industry-academia collaboration aimed at applying advanced technology to the U.S. highway system in order to improve mobility and transportation productivity, enhance safety, maximize the use of existing transportation facilities, conserve energy resources, and reduce adverse environmental effects. Five components make up the IVHS effort: Advanced Traffic Management Systems, Advanced Traveler Information Systems, Commercial Vehicle Operations, Advanced Public Transportation Systems, and Advanced Vehicle Control Systems (AVCS).

The AHS program falls within the AVCS area and is, in fact, its logical long-term goal. AVCS research and development is aimed at using advanced sensor and control technologies to help--or replace--the driver in responding to immediate roadway situations. (3) The AHS program is also closely tied to the National Highway Traffic Safety Administration (NHTSA), particularly its program to develop performance guidelines for collision avoidance systems. (5)

The AHS development program is organized into three phases. The first of these is now under way, and the second is about to begin.

"This overlap [in the precursor systems analysis contracts] will add value to the overall body of research in that each discrete effort will provide a different perspective and emphasis in identifying and analyzing issues and risks."

--"Precursor Systems Analyses of Automated Highway Systems"

  • Analysis Phase. This phase will provide the analytical foundation for AHS definition. During this phase, numerous in-depth research studies are being conducted so that all issues related to AHS design, development, and deployment are acknowledged and assessed. These studies fall into three groups: precursor systems analyses, human factors research, and NHTSA-sponsored collision-avoidance analyses, focusing on vehicle warning and control services. Much of the analysis phase should be completed by the end of calendar year 1994.
  • Systems Definition Phase. This multiyear phase has several outputs. It will establish AHS performance and design objectives; identify and evaluate alternative AHS concepts; conduct a full-scale demonstration in 1997 of AHS technical feasibility as required by ISTEA; select a preferred system approach; demonstrate, test, and evaluate a prototype of the preferred AHS approach; and prepare documentation for this configuration. This work will be conducted by a consortium of major stakeholders--state and local transportation agencies, the vehicle and highway industries, and other key private sector representatives--in partnership with the Department of Transportation (DOT). FHWA expects that the system definition phase will last through 2001 or 2002. At the conclusion of this phase, all specifications and documentation needed for product developers and transportation agencies to deploy automated highway systems will be available.
  • Operational Evaluation Phase. During this phase, one or more implementations of the preferred AHS approach will be evaluated at selected U.S. locations. This phase will take place in the early years of the next century. (5)

Program Progress

Precursor systems analysis contracts

Between July and September of 1993, 15 "precursor systems analysis" contracts totaling $14.1 million were let by FHWA to an array of impressive project teams. The purpose of the one-year contracts is to investigate the issues and risks related to AHS design, development, and implementation. Collectively, the contracts aim at surfacing, researching, analyzing, and debating a broad spectrum of AHS-related issues.

The structure of these precursor systems analysis contracts is innovative. Rather than assign a single topic to an individual contractor, the precursor systems analysis contracts comprise a matrix of 16 activity areas investigated by multidisciplinary, multi-organizational teams. Many teams are investigating one of more of these areas; two teams are addressing all 16 areas--one team from a broad systems analysis perspective and the other from the perspective of the vehicle industry.

The project teams individually and collectively represent a wide variety of perspectives, from state transportation departments (including New York, Massachusetts, and California), academia (including the Massachuetts Institute of Technology, Princeton, Tufts, and others), the aerospace and automotive industries (such as Hughes Aircraft, Daimler Benz, and Ford), and defense and high-tech research organizations (including Battelle, Honeywell, Martin Marietta, Rockwell, TRW, and Lawrence Livermore National Laboratory).

The specific AHS activity areas these contractors are investigating are: (5)

  • AHS in urban and rural operational environments.
  • Certification of proper vehicle functioning for automated operation (automated check-in).
  • Certification of proper vehicle and driver functioning for manual operation (automated check-out).
  • Lateral and longitudinal control of an automated vehicle.
  • Malfunction management.
  • Unique AHS-related needs of commercial and transit vehicles.
  • Lessons learned from deployment of comparable systems.
  • Deployment of possible AHS configurations within existing freeway networks.
  • Impact of AHS on nearby non-AHS roadways.
  • AHS entry/exit implementation.
  • Ongoing AHS operation.
  • AHS vehicle operation, including vehicle retrofitting.
  • Impact of alternative propulsion systems on AHS deployment and operation.
  • AHS safety issues.
  • Institutional and societal aspects of AHS deployment.
  • Assessment of AHS preliminary cost/benefit factors.

User Acceptance

"Change is inevitable. In a progressive country change is constant."--Benjamin Disraeli, 1867

The automated highway system will be a big change--a change on the scale of the transition from the horse and buggy to the automobile, from the adding machine to the calculator, from the pencil to the word processor. Like those changes, AHS represents automation of a task previously performed in a tedious, inefficient, and time-consuming manner. Like those changes, too, AHS does not preclude previous methods, but offers an improvement over them. But like those changes--like all changes--AHS will inspire resistance.

The AHS program recognizes that the issue of driver acceptance is a key one in ensuring the feasibility and usability of the automated highway. Focus groups are being conducted to determine potential user attitudes. Human factors studies will keep this issue to the forefront as AHS enters its system design phase. No findings are yet available on driver attitudes toward the AHS, but a few points can be made in this regard.

Full automation of the nation's roads cannot be achieved now and is not intended to be achieved for several decades. Driving as we know it today will not become obsolete either overnight or over the next generation. Just as the advent of computers didn't supplant the workforce, the automated highway system won't take the place of drivers. AHS will, in the beginning, be implemented only on certain high-grade, high-performance facilities. People will still need to drive on secondary roads to reach these facilities. Moreover, these facilities will probably not span a whole roadway, but rather they will comprise one or more lanes of a multilane expressway.

Also, for several years after AHS implementation, safety will require that the driver stay "in the loop." Even on an AHS facility, the user will need to stay on the alert in case manual control needs to be resumed. This is a situation similar to that of a pilot overseeing autopilot control of a plane.

Finally, slow, gradual implementation of AHS facilities will help build user acceptance. And as the many advantages of AHS--its reliability, efficiency, safety, timeliness--are demonstrated daily, user fears and distrust will be eliminated.

Three other efforts are also being undertaken by the contractors. One team is looking at the feasibility of integrating existing models in such areas as vehicle dynamics, sensor characteristics, traffic flow, and environmental factors into a coherent modeling framework so researchers can evaluate high-level AHS concept alternatives. A second team is investigating AHS applications of Global Positioning System Integrated Carrier Phase techniques. A third is looking at AHS applications of knowledge-based systems. (5)

"[The program] provides the opportunity for U.S. industry to stake out a dominant position internationally in the unique technologies that will comprise the future automated highway system."

-- Rodney Slater, FHWA Administrator

While it is premature at this early phase in the program to develop a definitive systems approach, some framework is important to support this research. In this respect, each contractor has defined a set of "representative system configurations," which are strawman, system approaches, spanning the range of possibilities. (See figures 1, 2, and 3.)


Figure 1 - One of the many plans being investigated features separate AHS lanes and "smart vehicle" control. It is for use by passenger cars and light trucks only. A wide variety of these "representative system configurations" (RSC) form the basis on which the precursor systems analysis research is conducted.

Photo courtesy of Parsons Brinckerhoff Quade & Douglas Inc.


Figure 2 - Another possibility is a dedicated AHS facility featuring "Smart roadway" control and is for use by passenger cars and light trucks only.

Photo courtesy of Parsons Brinckerhoff Quade & Douglas Inc.​​​​​


Figure 3 - This option accomodates passenger cars mixed with large trucks and buses and features separate AHS lanes and mixed controls

Photo courtesy of Parsons Brinckerhoff Quade & Douglas Inc.


Key to the success of these precursor systems analyses is communication. The 15 contractor teams are talking to each other, sharing findings, relating problems, seeking solutions, collaborating, and brainstorming. This innovative approach to contract conduct foreshadows and ensures the technological innovations to come in AHS. This synergy is being fostered through teleconferences and participation in an on-line bulletin board sponsored by IVHS AMERICA. Also, the contractors are meeting in April 1994 for an Interim Results Conference; they will meet again the following October to present their final results. This latter meeting will be open to the public.

Through matrix management and open communication, the precursor systems analysis contracts will yield both questions and answers as input for the AHS systems definition phase. Moreover, they will establish a core AHS community to serve as a fountainhead of AHS technical expertise.

Human factors research

All too often in large-scale system development, engineering for human factors is put in as an afterthought. Not so in the Automated Highway System program. "FHWA has recognized the importance of human-centered design in [AHS] system development." (3) Thus, at the AHS program's onset in 1992, a contract was let to Honeywell for human factors research. The contract focuses on determining what drivers and AHS can and cannot do well and on how drivers and automated driving should fit together. In addition, some research will be conducted on the issue of driver acceptance of the automated highway system. The project will result in specific guidelines and handbooks for AHS system developers to ensure that human needs and capabilities are met in system design.

The human factors questions surrounding AHS involve the transition from manual to automated driving and back again, normal automated driving, and handling of emergency events. The research is informed by comparable systems analyses--that is, looking at lessons learned from other automated roadway systems that have humans in the loop. These other systems are Germany's O-Bahn system (buses whose steering control is taken over by an automated system in narrow tunnels); the Chunnel repair vehicle (which operates on both normal and automated roadways); the Washington, D.C., Metro subway system (whose automated speed control feature must sometimes be controlled manually); and airplane autopilot systems.

The National AHS Consortium

One of the most intriguing aspects of the AHS program is that its management plan is as innovative as its technology. A prime, if not the prime, example of this is the consortium that will manage the AHS program's systems definition phase.

This consortium--which, as of this writing, has not yet been selected--"will provide leadership and focus to the nation's AHS effort." (2) A solicitation for consortium applicants was issued by the Department of Transportation this past December; these applications are currently under review. FHWA will execute a cooperative agreement with the successful applicant. Under this agreement, the consortium will manage the AHS definition phase; provide for national coordination, including outreach and public relations; and meet program milestones. In addition, consortium members will share in the project's cost, contributing time, materials, and/or funds equal to at least 20 percent of the costs of the activities conducted under the agreement.

But why a consortium? And who will comprise this consortium? FHWA Administrator Rodney Slater put it well:

"Throughout this endeavor, we will aggressively reach out to shareholders and to stakeholders to involve them in the decision-making process, beginning with the establishment of the National AHS Consortium. This consortium, in partnership with FHWA, with NHTSA, and with other members of the DOT family, will be the focal point for this nation's AHS program. And as such, we will be seeking to partner with a consortium which represents the key stakeholders--state and local transportation agencies, the vehicle industry, the highway design industry, and the electronics and communications industry. And, in order to tap their creativity, this program will provide significant opportunities for small businesses, disadvantaged businesses, as well as historically black colleges and universities." (4)

The National AHS Consortium will symbolize a "new partnership between the public and private sectors." (4) And it's a partnership that makes good sense. AHS will depend on cutting-edge technology. Success means tapping into the diverse experiences, knowledge, creativity, and expertise represented by the various consortium members. AHS is a radical departure from today's means and methods. Success means having the visible and unwavering support of the consortium membership and their constituents. Success means using consortium members' crucial financial and other resources. The consortium members will enjoy future payoffs in new business and enhanced services to their customers, and society as a whole will enjoy the broad benefits of highway automation.

In short, the AHS program's consortium management approach will help ensure that every intriguing idea is considered, every concerned voice is heard, and every stakeholder is a full partner in the effort.

A key component of the AHS human factors research is driving simulation using Iowa University's highly sophisticated, motion-based driving simulator. The simulator consists of a Ford Taurus with three seamless widescreen projection systems showing realistic computer-generated roadway scenes around the vehicle and a motion system that provides the sensations of braking and accelerating. Together, these components yield a very high-quality driving simulation.

Specific AHS issues and questions that are being, or will be, examined by the human factors researchers include the following:

  • What are the speeds and headway distances and the combinations of speed and headway distance that are too difficult for drivers to manage well?
  • How well can people get into and out of an automated lane under various speed and distance combinations?
  • What kinds of behaviors do drivers exhibit in automated lanes? Are they alert? How much attention do they need to pay to the driving task to ensure that they can take over in case of a malfunction? How can this attention be ensured? How can AHS keep a driver from becoming bored during automated vehicle control?
  • How do people react to the reduced intervals (between vehicles) that are possible in automated lanes? How do they react to the close proximity of the other cars and to the close merges of entering cars?
  • What are the potential carryover effects of automated control? How will drivers who have been going at high speeds at a very close interval react when they resume manual control of their vehicles as they exit from the AHS lane and turn onto secondary roads?

The human factors team will complete a preliminary handbook addressing these and other issues as they relate to AHS design by 1994; a second edition of these design guidelines should be ready by 1996. This research will provide essential guidance to the National AHS Consortium during the initial prototype system design.


Increasingly, we are applying automation to routine, repetitious tasks so that our minds and hands are free to pursue worthier objectives. Driving is a natural candidate for automation. Its automation will free people from performing an often frustratingly tedious, tremendously time-consuming chore. It will also ensure that the chore is performed more safely, quickly, reliably, and efficiently than people could ever do unassisted.

Although the various technologies exist to create and implement an automated highway system in this country, we cannot--nor would it be desirable to--move immediately to full-scale automation of the driving task. AHS development will be a long-term, multiphased project. This slow and steady approach will ensure that the work is done correctly, the right technologies are optimized, drivers can gradually become comfortable with increasing technology in their cars, driver and industry concerns are addressed, and concurrent upgrades in the driving experience--such as energy-efficient alternative propulsion methods--are incorporated. Moreover, long-term implementation will ensure that the exotic (read "expensive") technologies needed in AHS design will be significantly more cost-effective and accessible when they are used in volume.

As we move into a new century, AHS will usher in an era of rapid technological advancements that will improve the safety, efficiency, and convenience of highway transportation as much as the change from dirt to paved roads revolutionize travel at the beginning of this century.

Visions of the AHS Future

Your meeting downtown is in an hour, but you leave your house--which is some 100 miles away--knowing you'll make it in on time. In fact, you'll even have time to go over your notes on the way in. You get in your car, guide it to the AHS expressway, and then settle down with your cup of coffee and notebook computer on a tray in front of you.

* * *

It's the first weekend in June with the kids home from school. It seems that everybody's on their way to the area theme park. Traffic is, like it was in the 1990s, bumper to bumper. But the difference is that now everyone's going smoothly at full speed. All the cars around are filled with families reading, talking, and enjoying the natural scenery that's whizzing past on both sides of the narrow road.

* * *

Each compartment of the automated truck is loaded with goods. The driver verifies that the vehicle's automated systems are in perfect operating order; she then eases into the designated lane, turning control over to the "autopilot." She will continue to monitor progress, while checking her data sheet for the next delivery and overriding automatic control if necessary. All of the truck's stops have been timed practically to the second; this control lets stores buy more efficiently and better manage their inventories.

* * *

The roadway-powered electric vehicle picks are fueled through the electric strip laid in the AHS road. It runs cleanly, fast, and smoothly--emitting no pollutants. The balance between automation and conservation, between human needs and dwindling natural resources, has been successfully struck.


(1) Lyle Saxton. "Automated Control--Cornerstone of Future Highway Systems," IVHS Review, Summer 1993, pp. 1-16.

(2) "Request for Applications Number DTFH61-94-X-0001 to Establish a National Automated Highway System Consortium," Federal Highway Administration, Washington, D.C., December 1993.

(3) J. Richard Bishop Jr. and Elizabeth Alicandri. "Status Report on the Automated Highway System Program,"Presentation made at the Autonomous Unmanned Vehicle Society Annual Meeting, Washington, D.C., June 28-30, 1993.

(4) Rodney Slater. Speech to Automated Highway System Public Meeting, Oct. 21, 1993, Washington, D.C.

(5) "Precursor Systems Analyses of Automated Highway Systems," Federal Highway Administration, Washington, D.C., October 1993.

Nita Congress is a senior writer/editor with over a dozen years of experience in preparing a wide variety of informational and technical materials for the federal government. She has served as technical editor for Public Roads since 1985 and has frequently contributed articles to this publication. In addition, she has written several FHWA Research and Development annual reports, and she has documented numerous FHWA-sponsored conferences and workshops. Ms. Congress recently served as the senior editor to Vice President Al Gore's Reinventing Government task force. She is currently editing and revising a NAFTA-related manuscript on North American Transportation: Statistics on Canadian, Mexican, and U.S. Transportation for DOT's Bureau of Transportation Statistics.