INTRODUCTION

The Nation's transportation system has supported the economy for decades, but it has come under increasing pressure due to limited capacity, poor connections between different transportation modes, and the rapid travel growth that accompanies a robust economy. In the 1950's, with automobile use and traffic increasing rapidly as a result of the post-war boom, we initiated construction of the Interstate Highway system—the largest public works project ever, and one which linked the United States from coast to coast.

That same approach to accommodating increasing travel and traffic in the 1990's is not feasible or acceptable; we continue to experience long-term traffic increases beyond our capabilities to serve them because of our continuing growth and increasing reliance on the automobile as our primary source of mobility. Although we are still building new highways and expanding existing ones, we no longer can afford to build all the roads we might need—and even if we could afford it financially, we cannot afford the other impacts of such an expansion.

So we are striving to manage the transportation system more effectively and efficiently through strategies which include an increased emphasis on Integrated Transportation Management Systems (ITMS) approaches as well as advanced technology applications such as Intelligent Transportation Systems (ITS). And, while the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA) directly authorized more than $660 Million through Title VI for Intelligent Transportation Systems (ITS), with the likelihood of very substantial expenditures of funds through other program categories, the full potential of the more sophisticated of these systems will not be realized for many years. Moreover, many of the ITS applications depend heavily on the successful implementation of ITMS, including many first generation ITS applications, which are in place or being implemented in many locations throughout the United States.

For example, tracking and transaction systems for commercial vehicles fitted with sensors and Global Positioning Systems, fully automated collection of tolls, automatic clearance of trucks at state borders, enhanced vehicles with collision avoidance systems and other safety features, and automated highway systems such as the recently announced consortium led by General Motors will not be fully operational for quite some time. Yet, integration of the various components of existing systems and modes (the underpinning of ITMS) through applications such as smart traffic signals, synchronized signal systems in major travel corridors, and traveler information systems providing real time information offers immediate and short term opportunities for ITMS to play a critical role in our ability to address congestion and environmental concerns in our urban areas. The potential of ITMS to fully integrate transit systems into traffic and highway systems is especially promising.

The results of the 1990 National Personal Transportation Survey (NPTS) ¹ are revealing with respect to our increasing reliance on the automobile and the opportunities for ITMS to play a critical role in our transportation systems of the future. According to NPTS, household vehicles available from 1969 to 1990 increased 53% and the total number of household vehicles increased at a rate of 4% per year or 128% over the 21 year period.

The number of households which had more than one vehicle available grew from 26.4% in 1969 to 38.4% in 1990, a 117% increase or 3.8% per year compounded annually. Similarly, the number of households with three or more vehicles available increased from 4.6% of households in 1969 to 19.5% in 1990, an increase of 535%, a 9.2% compounded annual rate of percentage change.

Over the 1969 to 1990 period, the total number of households increased by 49% while the number of household vehicles increased by 128%. Further, from 1983 to 1990, steady decreases in household size brought more daily trips and longer trip lengths resulting in a 29% increase (3.6% compounded annually) in daily household vehicle miles travelled from 1983 to 1990.

Concurrently, the number of daily person trips increased 58% from 1969 to 1990 with the number of person trips by auto, van, and truck increasing 64% over the same time period. Alternative mode use for commuting such as transit, bicycling, walking, decreased during this same time period while an increase in driving alone for commute trips occurred.

Demographic trends also affected increased travel. For example, people over 65 drove more often and for longer trip lengths than ever before according to NPTS, resulting in an increase of 26% in average annual person miles of travel by individuals 65 years of age or older. These trends combined with established land use patterns will lead to even more travel in coming years.

On a parallel track with these growth trends, we are realizing more and more that for a variety of reasons, we simply cannot continue to add capacity in traditional ways to our transportation system. Reasons for this include: cost and availability of land in our most congested areas, environmental concerns including noise, water, and air quality; and, importantly, a growing realization among transportation professionals and policy makers at all levels of government that building more and more lanes of capacity will never satisfy our collective desire for greater mobility. The more we build, the more we need to build. Finally, the cost of construction is prohibitive in an era when government finances are increasingly scarce and the existing maintenance and operations needs of the system cannot be met. Enormous backlogs in the maintenance and rehabilitation of our roads, bridges, and highways are commonplace in many areas in the country.

All these factors combined lead transportation professionals to the conclusion that we must concentrate our collective energies on identifying ways to better manage, maintain, and operate what we have in the most efficient manner. This challenge is a central theme of the ISTEA and is fundamental to implementing ITMS.

The need for solutions to the complex array of problems which all point to more congestion also point to tremendous opportunities for the development and implementation of ITMS. Yet, the delivery of such programs, from the policy, political, institutional, technical, and operational perspectives, is an enormous undertaking. And doing so in an environmentally sensitive manner is an integral part of the challenge. The tools available to assist us in this endeavor are truly extraordinary, however. Specifically, the advances in technologies available to the transportation sector to address these problems coupled with the federal governments' willingness to invest heavily in technological applications to ITMS provide a critical catalyst to bringing new technologies to market to help address truly enormous congestion and environmental problems.

How do transportation professionals meet the dual challenges to deliver ITMS programs which address the full array of environmental and congestion concerns in a cost effective manner in both the short-and-long term? This paper will discuss environmental issues related to developing and implementing ITMS for maximum efficiency and benefit of the customers.

Upon reflecting on events of the past few years in the transportation industry, it is clear that air quality issues have served as a catalyst to changes in the methods and analysis techniques transportation professionals use to advise public policy decisions on investments. Air quality issues and immediate concerns about compliance with transportation conformity requirements and other Clean Air Act mandates such as implementation of Transportation Control Measures (TCMs) have tended to take precedence over much larger environmental issues and challenges to successfully implementing ITMS in an environmentally sound manner. In addition to the important objective of meeting the federal standards for various air borne pollutants caused by mobile sources, other environmental concerns which need to be considered include:

In discussing environmental considerations, a broad view of environmental issues should be taken: one which recognizes the broad array of environmental issues with which we should be concerned. Concurrently, we must take into account the realities of widespread congestion, the development patterns which have resulted in part due to our extensive highway network, and the fact that automobiles are, for the foreseeable future, going to be the primary source of mobility in this country. For even if the air quality problem can be addressed in large part through the application of various technologies (e.g., electrically heated catalysts, reformulated gasoline requirements, enhanced inspection and maintenance programs, the introduction of alternatively fueled vehicles), transportation professionals must address the irrefutable fact that ever increasing numbers of vehicles are filling up limited road space resulting in congestion levels that denigrate overall system performance. It is the concern with system performance embodied in ITMS that helps us sharpen our focus.

ISTEA requires that state and metropolitan area transportation professionals develop six Management Systems and explicitly consider twenty-three and fifteen planning factors respectively. These requirements have, as the ISTEA intended, prompted transportation professionals and policy makers to recognize the broad implications of investment decisions. These provisions have also caused us to think differently than in the past about how we design, construct and maintain efficient and environmentally friendly transportation systems. The new orientation brought about by ISTEA is that the transportation system should serve the customers needs, not that the customers should be placed at the mercy of the system. The question transportation professionals need to ask themselves on a regular basis is: are we serving the public's needs and desires by providing an efficient, well-integrated, and environmentally friendly transportation system?

ITMS approaches can be helpful to us in achieving our broad environmental objectives. The key to balancing our transportation needs and environmental goals through ITMS lies in the design for and application of ITMS concepts and practices. To succeed in this endeavor, environmental issues need to be carefully considered in two interrelated but distinct phases of ITMS implementation. These are the planning, project selection, and design phase on the one hand; and, on the other hand, the implementation, maintenance and operating phases.

The planning, project selection, and design phases of ITMS is the time to fully integrate all modal considerations into projects and programs. For example, the needs of existing or future High Occupancy Vehicle (HOV) lane access and egress need to be considered throughout these phases. Existing or future transit needs on the arterial or highway system should be addressed. Priority treatments for transit have proven, in the U.S. and abroad, to be very successful to encouraging transit use and can be effectively designed into ITMS. True multi-modal planning should consider all modes which will be or could be operating on the same or adjacent Right-of-Way (or in the same corridor) such as light rail, bicycling, rail or truck freight, and pedestrian movements.

Below are some specific suggestions for integrating ITMS into the overall transportation planning process which are in part based on the results and recommendations of a recent study by the State and Local Policy Program of the University of Minnesota's Hubert H. Humphrey Institute ².

These are all examples of how fully integrated ITS depends on ITMS being implemented with an eye toward the future. All parties involved with the design and selection of projects need to consult a broad array of modal interests on their plans if the ITMS system is going to properly address both current and future transportation needs and environmental considerations.

The implementation, operating and maintenance requirements of the systems must be identified in order to ensure proper consideration of environmental impacts. The implementation of complex computer systems and equipment will not allow, in and of itself, the transportation sector to realize its full range of objectives in implementing ITMS. For example, if the objective of a system is traffic flow uninterrupted at 30 miles per hour, the system needs to be continually monitored, maintained, and properly operated to achieve that objective. The difference from an air quality perspective, of free flow vs. stop and go congestion can be significant and implementers and maintainers of the system need common agreement on their operational objectives vis. a vis project and program delivery. This points to the need for sufficient training and anticipation of operating requirements, on-going operations monitoring, and consensus among policy makers and transportation professionals on the objectives of ITMS implementation.

One example of the complex policy trade-offs which need to be addressed relates to the recent emergence of information concerning the relationships between emissions of Nitrogen Oxides (NOx) and highway speeds. This case also illustrates the complexities of air quality chemistry and interactions among pollutant types as well as the lack of good tools for credible analysis of these interactions. Nevertheless, until better tools are available and understanding of these relationships advanced, the following issues should be considered in planning for the implementation and operations of ITMS.

NOx emissions vary considerably with speed and heavy duty trucks are a much larger source of NOx than any other type of on-road vehicles. With respect to cars, emission factors (based on EPA MOBILE5 model) decrease with increasing average speed in the range of 0-15 miles per hour. Thus, at constant VMT, speed improvement strategies in extremely congested areas may yield NOx emission decreases. Emission factors gradually increase, however, with increasing average speed in the mid-speed range of 15-45 miles per hour. For constant VMT in this range, speed flow improvements generally reduce VOC emissions but may increase NOx emissions. According to the MOBILE5 model, NOx emissions increase sharply with increase average speeds in the high speed range (greater than 45-50 miles per hour).

The overall impact of transportation projects on NOx emissions will depend on the project-induced changes in the VMT distribution among the various speed improvements. In order to minimize increased NOx emissions due to speed flow improvements (many of the first generation of ITMS applications) and reduce VOC emissions, one could strive to increase speeds beyond the 15 miles per hour range but attempt to hold speeds on average at no greater the 45 miles per hour. Thus, the desire to improve traffic flow through ITMS applications while reducing or having a neutral effect on emissions presents difficult trade-offs. The political and institutional will to make these trade-offs can only be decided at the local level where all variables can be taken into account. This example also illustrates that transportation professionals must be able to explain these trade-offs to decision makers when advising them on ITMS investments.

With respect to on-going maintenance and operations efforts to date, a March, 1994 GAO ³ report on the use of traffic control systems to reduce congestion revealed that in a review of 24 signal systems nationwide, the FHWA found that 21 systems (88%) did not meet the minimum standards of performance and that some localities were designing systems that were outdated or did not meet their needs. In addition, the Institute of Transportation Engineers (ITE) estimated in 1989 that 74% of the 240,000 signalized intersections in the nation's urban areas needed upgraded physical equipment or improved signal timing. These problems are currently preventing regions from achieving the optimum results; the implications for the future may be even greater because of the reliance on these systems of the emerging ITS technologies. Interestingly, an increasing amount of federal funding is being used for traffic control systems (1991-$221 Million, 1992-$289 Million, and 1993-$503 Million) and hopefully some of these funds are being used to address problems identified in the GAO report. Since the Congestion Mitigation and Air Quality Program (CMAQ) program funding began in 1992, a considerable proportion of CMAQ funds have been used for ITMS investments.

The GAO report also confirmed that properly designed, operated, and maintained traffic control signal systems can yield significant benefits both along the corridors in which they operate and along adjacent corridors. These benefits include congestion mitigation, reductions in air pollution, reductions in accidents, fuel consumption, and travel time.

One illustration of benefits is Automated Traffic Surveillance and Control (ATSAC) System in Los Angeles where the City of Los Angeles reports that the system reduced travel time (in the areas covered by the system) by 18%, signal delays by 44%, vehicle stops by 41%, fuel consumption by 13%, and air pollutants by 14%. During the aftermath of the earthquake in Los Angeles in Spring, 1994, the benefits of the system were apparent from the first day when the City and Caltrans immediately used the ability to dynamically control and synchronize signals in the Santa Monica Freeway (I-10) corridor to manage more than 434,000 person trips per day affected by the collapsed segment of the Santa Monica Freeway.

According to the GAO report, in Orlando, Florida, an analysis of a new signal system implemented in 365 intersections showed $2.2 million in fuel savings per year, a 56% drop in both vehicle stops and delays, and a 9 to 14% reduction in air pollutants. The State of Washington analyzed the benefits of upgrading and coordinating signal control equipment and re-timing existing signals for six signal systems. These studies showed annual fuel reductions of 295,500 gallons and annual reductions in vehicle delays of 145,000 hours. In Virginia, a recent study showed that re-timing several signal systems reduced delays by 25.2%, stops by 25.5%, travel time by 10.2%, fuel consumption by 3.7%, and air pollutants by 16 to 19%.

These cases demonstrate that the environmental impacts of ITMS can be beneficial: however, our data collection and analysis tools are weak and we need to better monitor, evaluate, document, and understand the impacts during implementation as well as consider the potential impacts during the planning, project selection, and concept design.

Many opportunities exist for ITMS to play a critical role in both short-and-long term solutions to transportation and environmental problems. Practitioners and policy makers alike must work toward a more inclusive transportation investment decision-making process however; a process which allows all parties to provide input and consider trade-offs where they exist. These enhanced interactions will allow for environmentally sound ITMS applications and new investments to be made, and for ITMS to successfully open the policy and funding doors to the more sophisticated ITS applications which are increasingly available to the transportation community. The realization of the benefits that ITMS offer as critical elements of solutions to transportation and environmental problems is dependent on the community of transportation and environmental professionals working together to provide the leadership necessary to change the old way of doing business and move on to a more environmentally proactive posture when considering transportation investments. Efforts to foster good working relationships have been initiated in many forums since the adoption of the Clean Air Act and the ISTEA. The importance of creating opportunities for transportation and environmental professionals to interact on an ongoing basis cannot be overstated. In the final analysis, successfully meeting the challenges of the ISTEA to maximize system efficiency and address environmental issues in an open decision-making process rests upon people making the commitment to work together toward these dual objectives.