Amy is the senior traffic manager for the Dallas–Fort Worth Metroplex area, the “Golden Triangle” that includes Denton to the north, Dallas to the southeast, and Fort Worth to the southwest. It is November 25, 2030, the Wednesday before Thanksgiving, and the American Automobile Association is predicting that 37 million people will be traveling 50 miles or more by car; of those, 750,000 are expected in the Dallas–Fort Worth area, and many have already begun to hit the roads. In her operations center Amy watches a late-season line of strong thunderstorms move through the area accompanied by lightning, heavy rain on the order of an inch per hour, and winds gusting to 40 mph. Her radar display indicates the heaviest precipitation has moved into the metro area. Amy consults her traffic simulation model that monitors traffic and weather in real-time and predicts congestion out to three hours; she sees that there should be no major delays for the millions of people trying to get to their friend’s or relative’s home to eat turkey and give thanks. Her suite of traffic cameras confirm the model; upon onset of the heavy rain, all vehicles have automatically slowed and reconfigured for optimal traction on wet roads, and the automatic spacing between the cars has increased. Although the line of storms is narrow, Amy thinks back to earlier in this century when a line of storms similar to this would have jammed the already busy freeways and caused accidents, further compounding the holiday congestion and creating ripple effects that would have lasted throughout the day. Thankful for the research and technology that now facilitate smooth traffic flow in inclement weather, Amy sits back and relaxes, unworried by the steady rhythm of rain on the roof of the building.
Now is the time for a focused research effort to be undertaken that will allow the road weather system of the future to be realized. An opportunity exists to leverage the knowledge from analogous programs, the efforts from existing projects (e.g., intelligent transportation systems, the Maintenance Decision Support System), and the expertise of the meteorological and transportation communities in order to improve the safety and efficiency of a transportation system that is used by millions of people every single day and is affected by weather every single day. Decision makers can help achieve the vision of the roadway system of the future portrayed above and in the earlier vignettes (see Chapter 2) by capitalizing on the framework provided in this report and bringing the road weather research program to fruition. Such a program would be the first of its kind; coming just over 100 years since the automobile was invented, it is a program that is long overdue.
The advances in knowledge and operational capabilities that could result from a comprehensive road weather research program such as that proposed in this report have the potential to improve public safety, economic efficiency, security, and environmental quality for the nation. Improved road weather information for the driving public should reduce the number of weather-related accidents, and the associated fatalities, injuries, and property damage. At the same time, individual drivers and commercial trucking operations would be able to find better routes that minimize exposure to weather threats, leading to less time spent on the road and more efficient shipping practices. Benefits also would be gained by developing weather information products and decision support tools that would enable a more cost-effective and optimized operation of the roadway system, from advanced winter maintenance practices to weather-responsive traffic management. Other advantages, such as the ability to better respond to chemical spills on the roadway or reduced environmental impacts from chemicals used to treat snow and ice on the road, are also likely (Ham and Lockwood, 2002). Although these benefits have not been quantified, they could be substantial if the proposed road weather research program were implemented to exploit the potential of current and new tools and technologies.
Beyond these direct benefits of improved road weather information and services, an enhanced understanding of how to address road weather problems will position the nation to better respond to many other large-scale socioeconomic and physical changes relevant to the roadway environment. Indeed, global trends in demographics, the environment, and technology will affect road transportation dramatically during the next decade. Thus,
any improvements and efficiencies to be gained in the surface transportation system, for example, from more strategic responses to inclement weather, are desirable.
Changes in the demographics of Western industrialized nations include increased life expectancy, leading to both an increasing and an aging population. These changes are compounded by the fact that relatively few new roadways are being built to accommodate the increasing volume of vehicles on the roadways, and the major road construction changes that are being undertaken often take on the order of 5 to 10 years to complete. An additional demographic change is the increase in the number of nonnative English speakers and non-English-speaking individuals. The proposed road weather research program will help alleviate some of the difficulties of these demographic changes with better traffic management, improved weather forecasting, human factors research, and vehicle telematics.
The population distribution is another demographic trend that will require attention over the next decades. Per capita vehicle ownership continues to increase while populations continue to disperse away from major urban centers. The result of these trends is ever greater volumes of vehicles to carry commuters to and from work. For example, from 1980 to 1990, 22 million drive-alone workers were added to the roads while car-pooling rates dropped sharply (NRC, 1998). The high speeds and close spacing of vehicles on the approaches to major urban centers provide the ingredients for accidents involving large numbers of vehicles as soon as conditions deteriorate. Indeed, the last decade has seen an increasing number of very large multivehicle accidents, sometimes involving on the order of a hundred vehicles, brought on by a sudden drop in visibility due to fog or in traction due to ice and snow. Integrated intelligent transportation systems solutions have been devised that can reduce these risks substantially, for instance, with on-vehicle safety applications that enable closer spacing and automated braking. However, mass production of affordable vehicles with this technology is some time away, and it will be longer still before a sufficient proportion of vehicles are equipped.
Environmental considerations have preoccupied the road transportation community for decades already, resulting in large reductions in vehicle emissions that cause air pollution. In response to global climate change, the transportation community is making additional technological changes in vehicles to reduce emissions of greenhouse gases, largely through the development of hybrid vehicles and hydrogen fuel cells. However, hydrogen fuel cells emit only water vapor, which could substantially impact the micrometeorology of the roadway environment with fog development or for-
mation of black ice on the roadway. The proposed road weather research program will facilitate the observation and modeling of the microscale roadway environment, which will improve understanding of fog and ice formation in the complex roadway environment, and it will help roadway operators and maintainers manage these conditions with improved forecasting and vehicle telematics.
Technological solutions from the intelligent transportation systems community will provide many of the required future solutions. Open systems and common standards for vehicle systems and the road infrastructure across the entire continentwide road system will help North America remain competitive in the global marketplace. But, technology alone will not be enough to attain the full benefits of improved road weather information and services. Transportation professionals will need to continue to move more aggressively from maintaining the system to managing it proactively, and using current and forecast weather data to anticipate the effects of weather on traffic flow is absolutely necessary to do that. Very careful planning and management will be required to ensure effective application of the intelligent transportation systems, sophisticated meteorological solutions, and other technologies. Part of that effort will have to go toward planning on a longer timescale to assess the potential impacts of these and other global trends. Longer-timescale problems require longer lead times to solve, making their early detection all the more crucial. Careful planning combined with focused road weather research will help the nation overcome the transportation challenges of the coming decades.