In This Issue
Transportation Infrastructure
June 1, 2008 Volume 38 Issue 2
Transportation Infrastructure issue of The Bridge, Volume 38, Number 2, Summer 2008

Intelligent Transportation Systems in a Real-Time, Customer-Oriented Society

Wednesday, December 3, 2008

Author: Joseph M. Sussman

Intelligent transportation systems will change the way we think about surface transportation.

We live in a “real-time, customer-oriented” society. Since the advent of the Internet and the availability of computational and communications capabilities to large segments of the population, we have become accustomed to responsiveness—for example, buying a book from home with the click of a mouse—in real time. In addition, we have become used to a dynamic market for services and goods, that is, choices that allow us to make trade-offs between price and quality, often measured on multiple dimensions. Surface transportation must also perform in this real-time, customer-oriented environment. Thus the transportation system must meet 21st-century imperatives.

Intelligent transportation systems (ITS) can be defined as systems in which advanced technology operates the surface transportation system by electronically linking vehicles to one another and to infrastructure. But ITS represents not only the innovative use of advanced technology, but also a change in the way we think about surface transportation.

In this article, I describe the potential benefits of ITS for the surface transportation system and how it can serve as an agent of change for that complex system. In addition, I identify organizational and institutional changes that will be necessary for the full benefits of ITS to be realized.

ITS is based on technology that can sense individual vehicles and their characteristics (e.g., speed and location) on the transportation network (Chowdhury and Sadek, 2003). Various technologies are available for doing this, including devices that can sense vehicles using specialized roadside infrastructure (e.g., dedicated short-range communication beacons) or the Global Positioning System or the cellular telephone network. For this information to be of value to more than the drivers of individual vehicles, however, it must be communicated, either from the vehicle to some infrastructure or between vehicles to enable the gathering of data about the overall status of the network.

Collecting these massive amounts of data and reducing them to a form in which they can be used either to provide traveler information to individual drivers or to manage the transportation network as a whole requires computational capabilities and advanced mathematical algorithms to solve complex network problems. So ITS requires sensing, communicating, computing, and advanced mathematical techniques.

The availability of new technologies alone cannot drive the research, development, and deployment of ITS. Work on ITS is also motivated by shortfalls in the performance of the current surface transportation system on several dimensions. Congestion, which reflects insufficient capacity on our highways, is a major issue that affects the movement of both travelers and goods. The costs—both financial and environmental—of addressing capacity issues by building or expanding traditional infrastructure can be prohibitive, especially in urban areas where land-use constraints apply. ITS-based concepts can help combat congestion directly in two ways, through (1) information and (2) pricing. In combination with traditional infrastructure, ITS can also directly address the need for more capacity.

In the face of pressures on the highway trust fund, serious concerns have arisen, not only about congestion but also about the financing of surface transportation in the future. Another major concern is safety, particularly on highways. A fourth, continuing public policy issue is the environmental impact of transportation. ITS, as a technology-centric approach, can help address all of these issues (Sussman, 2005).

Congestion and Insufficient Capacity
The Use of Information
Real-time vehicle tracking and knowledge of the state of the transportation network as a whole would benefit both the traveling public and system operators. Many examples of advanced traveler information systems (ATIS) are either available or in development. ATIS provide drivers with real-time advice on navigating the dynamic transportation network, which can change rapidly many times in the course of a typical day. A system that “knows” where you are and where you want to go (because you have told it) and “knows” the conditions of the network can provide routing assistance that can make your trip faster and more reliable (Box 1).

    BOX 1 Privacy Issues
    Concerns have been raised about the Big Brother aspects inherent in
    the real-time tracking of vehicles. Privacy has been an issue since
    the beginnings of ITS, and research is ongoing to ameliorate some of
    those concerns. However, in our real-time, customer-oriented society,
    we have all given up some of our privacy for improved efficiency in
    many areas. For example, think of the privacy issues inherent in
    carrying a cell phone, which is in effect a tracking device. ITS is
    the mobility analog of a cell phone that would make individualized
    traveler information available, if the individual is willing to give
    up some personal privacy.

    But safeguarding privacy is a legitimate goal. The question is
    whether people will be willing to forego the convenience and
    efficiency ITS can provide to protect their privacy. The author
    suggests the answer is probably not.

The information gathered by sensing vehicles on the network in real time can be used by transportation system operators to improve network performance via advanced transportation management systems (ATMS). This information can be used to monitor the network for incidents such as breakdowns or crashes that can cause congestion and to dispatch emergency equipment to remove the disruptions and restore traffic flow.

More generally, operators can integrate current information about the network with historical data, then test a variety of operating alternatives (e.g., adjusting traffic-light cycles or ramp metering rates and changing the information on variable-message signs), predict which alternative will work best for, say, the next 15 minutes, and implement that alternative. Every three minutes or so a new set of alternatives can be considered as network conditions change. Unlike ATIS, which benefit only individual drivers, ATMS takes actions that benefit all drivers.

The relationship between ATMS and ATIS is complex. Because ATIS services would probably not be free, some concerns have been raised about creating two classes of users—those who can afford to pay for ATIS and those who cannot—with deleterious effects for drivers who cannot pay. This concern about equity has some merit and must be addressed. One can imagine, for example, the “haves” receiving information and traveling more quickly and reliably than the “have-nots,” who do not have access to that information.

It is generally true that people who buy tailored traveler information will have shorter and more reliable travel times. But some research shows that travel times for most drivers—those who receive information and those who do not—will be reduced as a result of ATIS routing (some) drivers away from points of congestion. Indeed, some experts believe that the best strategy for managing the transportation network is directing individual cars away from congested areas. This strategy, they say, would improve travel for most drivers throughout the network.

Clearly, ATMS and ATIS are linked systems, and this linkage raises the specter of drivers being given information for optimizing the system as a whole that might not be optimal for them in particular. This concern, too, may have some validity and should be addressed. However, it can be argued that this problem would be self-limiting, because if people are given bad advice, they will soon stop accepting it. Thus it would be in the interest of system managers to provide the best information they can. Research on linkages between ATMS and ATIS is ongoing.

Dynamic Pricing of Highways
Another way of dealing with congestion would be through sophisticated pricing. Available technologies, both in the vehicle and on the infrastructure, make it possible to dynamically price transportation services in a way that people willing to pay for a better level of service (e.g., shorter travel times, more reliable trips) will have the opportunity to do so, and will, in fact, receive a better level of service (Pickford and Blythe, 2006).

A straightforward example is high-occupancy toll lanes (HOT lanes), an extension of high-occupancy vehicle lanes (HOV lanes), which have been in operation for decades. HOV lanes are available only to vehicles carrying several people (usually two or three). The idea is that by giving people driving multiple-occupancy cars access to lanes that are less congested than traffic lanes used by people driving single-occupancy vehicles (SOVs), everyone will have an incentive to carpool, thereby reducing traffic.

HOT lanes provide another—and vital—degree of freedom, because a driver of an SOV willing to pay a fee for the privilege will be able to use the HOT lane. Vehicles with multiple occupants (including, for instance, express buses) would continue to use the lane for free. This would give SOV drivers an opportunity to trade off price for quality of service.

To ensure a good level of service, the price could be dynamic, that is, changed by the system operator as traffic conditions changed. If congestion increased in the HOT lanes, the price would be raised, so fewer drivers would be likely to pay to use them. This seemingly simple change is emblematic of how surface transportation could become part of our real-time, customer-oriented society, in which choices for consumers—both travelers and freight carriers—would be front and center.

Sophisticated, dynamic
pricing schemes could be
used to help address the
problem of congestion.

Dynamic pricing is a new concept in surface transportation. Typically, during rush-hour congestion, the highway system currently allocates its limited capacity by requiring people to queue for service, which creates a dead-weight loss because there is no market-clearing mechanism. Everybody queues, even those who would be willing to pay a price to avoid congestion.

Once price enters into the equation, customers can be sorted by their willingness to pay, which could lead to other possibilities. Our highway systems are plagued by recurring congestion during rush hour. Everyone knows that at 8 a.m. on weekdays, when people are traveling to work, which begins at approximately the same time for all of them, certain points in the highway system will be congested.

If operators of highway systems could price their facilities, they could, for example, charge people more for driving during rush hour. This could have the effect of “shaving the peak” by giving people an incentive to travel before or after the peak travel time, if they had that flexibility—a big if, of course. If enough people took that option, however, it would “clear the market,” thus creating a more uniform demand for limited highway capacity.

This demand-side approach would count on travelers to change their behavior. A similar incentive is used by energy providers who have implemented time-of-day pricing for energy in an attempt to lower their capital investment costs and entice people, through differential pricing, to use less energy during peak hours.

The extension of this idea, universal road pricing, is now a subject of discussion. We might sense all vehicles on the infrastructure everywhere at all times and charge for the use of the roadway as a function of location, time of day, and other parameters, such as congestion level, environmental conditions, and the characteristics of the vehicle (e.g., weight). In some situations, there might be a minimal charge or even no charge at all.

“Road charges” could partly
replace the traditional gas tax.

Financing of Surface Transportation
Based on the pricing concept described above, we can rethink how we finance surface transportation. Presumably, “road charges” would replace, at least in part, the traditional gas tax, through which people pay at the pump for access to the highway system.

There are several problems with the gas tax. First, it is a blunt instrument for managing the transportation network. Everyone pays the same gas tax, regardless of when or where he or she uses the system. Second, transportation officials are increasingly concerned about whether the gas tax can provide enough revenue for the continued building and maintenance of our highways and for advanced technologies to implement the improvements described above.

Third, raising the gas tax has been politically problematic for some time; see, for example, the recent high-level report by the National Surface Transportation Policy and Revenue Commission (2007), in which the commissioners were split on this very question. Fourth, rapidly advancing new technologies (e.g., hybrids) are making vehicles more fuel efficient. Finally, we must take into account the geopolitical situation surrounding oil.

Road charges would not only provide an alternative revenue stream, but would also be a more sensitive instrument for managing the transportation network strategically. Of course, there would be substantial political barriers to overcome. There was, and is, political opposition to simple congestion charging, and even to simpler cordon-pricing schemes, like the one recently tabled in New York City. Nevertheless, the author believes that, in our real-time, customer-oriented society, road charging is the wave of the future for surface transportation.

Pricing is a good example of how ITS and technologies can not only improve the operation of the transportation system, but can also be a fundamental force for change in the transportation field. Pricing would allow surface transportation to operate as a market, at least partly, and allow the pricing of heretofore un-priced externalities, such as congestion and environmental impacts.

Safety of Surface Transportation
Improving safety is an imperative for the transportation system in the United States. Although fatalities per vehicle-mile traveled (VMT) have decreased continuously over the last several decades, the overall number of VMTs has increased over that period. Thus we have reached a plateau at a still-unacceptable 40,000+ people killed per year on the nation’s highways.

Improving safety has long been a primary goal of ITS, which offers a new approach to safety problems. For many years, the watchword of safety programs was crashworthiness, that is, building vehicles that would increase the chances of survival in a variety of crash environments. Of course, we must continue to make vehicles safer, but with ITS, we can also emphasize crash avoidance.

Much recent attention has been focused on an initiative called vehicle-infrastructure integration (VII), the creation of linkages between vehicles and from vehicles to the infrastructure. I have already described how such linkages can provide traveler information and improve network operations, thereby improving mobility. However, the primary goal of VII is to improve safety.

Suppose two vehicles are approaching an intersection, one traveling in the north/south direction, and one in the east/west direction. Suppose also that they are electronically “aware” of each other, either via a vehicle-to-vehicle link or via the linkage of both vehicles to the infrastructure. Given this awareness, there is a smaller probability of a crash at that intersection, even if, for example, one of the drivers runs a red light.

Various ITS technologies, including VII, freeway-management systems (Olmstead, 2001), and in-vehicle autonomous driver aids (e.g., collision-warning sensors, lane-departure warning systems, and electronic braking) are important mechanisms for improving safety.

Environmental Impacts of
Surface Transportation
The relationship between transportation (i.e., mobile sources) and air quality, as well as emissions of greenhouse gases related to global climate change, have been understood for decades, and one of the benefits of sensing technologies might be to locate high emitters of pollutants. The more general question, however, is whether ITS would be a plus or a minus for the environment. Here are the competing points of view (in headline form):
    ITS can smooth traffic flow, thereby reducing stop-and-go driving, which has a deleterious effect on air quality.

    By adding capacity to the transportation network, ITS will induce demand and therefore “add tailpipes” to the traffic stream.
In fact, the issue is more nuanced than that. Dodder (2006) notes that investment in ITS has rarely been made strictly for environmental (specifically improving air quality) reasons. She suggests, therefore, that we look for opportunities (as many cities have) to invest in ITS alternatives that deal with congestion (which are relatively easy to fund) and that also have a positive environmental effect. She argues that cities should look beyond the issue of congestion relief and try to leverage a portfolio of ITS investments that would improve mobility for different modes of transportation, including public transportation, in ways that would move us closer to meeting air-quality goals:
    ITS seems to represent a case of potential synergies—or so-called “win-win” outcomes—that could be realized for the dual policy goals of air quality and mobility. If the various public sector organizations responsible for air quality and transportation could cooperate in deploying, assessing and further adapting these new (ITS) technologies to take advantage of these synergies, they could achieve a “sustainable use” of ITS (Dodder, 2006).
She goes on to develop a framework called “Integrated Innovation Deployment and Adaptation of Public Technologies (IIDAPT),” which she applies to Los Angeles, Houston, Boston, Orlando, Tulsa, and Mexico City as case studies of using ITS to address air quality.

Considering that not only technologies, but also institutional issues that influence how those technologies are deployed and adapted must be taken into consideration, the question of whether ITS is good or bad for the environment must be studied at a much more sophisticated level.

Experts disagree about
the effects of ITS on
the environment.

A Balanced Approach
Because of the need for a customer and market focus in providing surface transportation and because of constraints on building conventional infrastructure, especially highways, the emphasis in modern surface transportation systems must be balanced between infrastructure (which we will continue to build) and operations, using pricing to manage the network. This approach is possible with ITS technologies that can help us manage congestion and improve safety and, perhaps, the environment as well.

ITS requires that we approach surface transportation as a regional system as well as a multimodal/intermodal system, because customers (i.e., travelers and movers of freight) consider their trips not as separate links but as integrated origin-to-destination trips on a large geographic scale that often require several modes of transportation. Communications can be thought of as a “mode” that can make travel more efficient, and sometimes even a substitute for it.

Organizational and Institutional Change
The ambitious change to an operations and customer focus will not be easy to achieve. The focus on operations on a regional scale, along with new technologies and multimodal/intermodal systems, will require changes in transportation organizations, many of which will have to embrace new missions that include information-sharing and responsibility-sharing

(Box 2). These changes, together with new funding patterns that reflect a shift from capital to operations expenditures, will require fundamental changes in the relationships among these organizations.

Institutional changes will be necessary at all levels of government—federal, state, regional, and local, as well as in the private sector—that are involved in operating infrastructure (e.g., through concessions). The organizational and institutional changes, although difficult, will be necessary for the full potential of ITS to be realized (Sussman, 2001).

    BOX 2 Flexible Design
    Dealing with uncertainty is a fundamental concern in the design of
    complex, sociotechnical systems. Simply put, it is imprudent, not to
    mention ineffective and costly, to think of the future as a deterministic
    point estimate. One of the benefits of ITS is that it provides flexibility
    in the face of inevitable uncertainties about the future.

    Even when we must make an “inflexible” decision, such as having to
    commit to a large capital investment before we know what the
    demand will be, ITS can provide flexibility by enabling us to retain
    “options” to change the design as future conditions become clearer.1

    For example, ITS provides a mechanism for deferring conventional
    capital investment in highway infrastructure until we have a better
    idea of future demand. In addition, ITS can make investments in
    conventional infrastructure more flexible by allowing operators to
    change lane use, say, from HOV to HOT/bus to freight only or to
    conventional use. These flexible design decisions create an
    additional value stream over and above the inherent value of ITS technologies.

    However, “flexibility” is not cost free. We must develop a method of
    valuing it so we can compare value with costs. “Real options,”
    analogous to financial options, applied to real systems can be
    used to compute the value stream that results from flexible design.2

    1 In a companion article in this issue, de Neufville describes flexibility in designing airports (see p. 41).
    2 For a study of flexible transportation systems enabled by ITS technologies in Houston, see McConnell, 2007. For a study of ITS as an alternative investment to major infrastructure improvements in Finland, see Levi?kangas and L?hesmaa, 2002. For a study of flexibility-based value streams in VII, see de Neufville et al., 2008.

In this article, I have identified opportunities for improving—and even fundamentally changing—surface transportation in the United States through ITS technology. In the process, I have also uncovered emerging issues that must be addressed, including concerns about equity, privacy, and ambiguities in the impact of ITS on the environment. All in all, I believe that the opportunities for positive change in the transportation system substantially outweigh these concerns.

Nevertheless, we will continue to work on addressing those concerns. In truth, we must address them if we expect to build enough support for the full deployment of ITS technologies. Public acceptance, commercial acceptance, and political acceptance are all preconditions for the widespread deployment of ITS.

Space does not permit a discussion of all of the important aspects of ITS, such as privacy (Kokotovich and Munnich, 2007) and applications of ITS to public transportation (FTA, 2006), commercial vehicle operations (RITA, 2008a,b), homeland security (ITS-America and DOT, 2002; TRB, 2008), and automated highway systems (Bishop, 2005; PATH, 2007).

Success for ITS will be achieved when the new system is so well integrated in transportation decision making that it is routinely considered part of the overall transportation solution.

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Chowdhury, M., and A. Sadek. 2003. Fundamentals of Intelligent Transportation Systems Planning. Boston, Mass.: Artech House.
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Dodder, R. 2006. Air Quality and Intelligent Transportation Systems: Understanding Integrated Innovation, Deployment, and Adaptation of Public Technologies. Ph.D. dissertation, MIT, 2006.
FTA (Federal Transit Administration). 2006. Advanced Public Transportation Systems: State of the Art Update. Available online at pdf.
ITS-America and DOT. 2002. Homeland Security and ITS. Available online at 20Supplement.pdf.
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Sussman, J.M. 2001. Transportation Operations: An Organizational and Institutional Perspective. FHWA-OP-02-039. Report for National Special Steering Committee for Transportation Operations and FHWA, U.S. Department of Transportation. Available online at
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TRB (Transportation Research Board). 2008. Transportation Security: Emergency Response and Recovery. Transportation Research Record 2022.
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About the Author:Joseph M. Sussman is JR East Professor, Department of Civil and Environmental Engineering and the Engineering Systems Division, Massachusetts Institute of Technology, and chair of the Intelligent Transportation Systems Advisory Committee of the U.S. Department of Transportation.