Review of Related Work and Analysis of Research Gaps
The committee’s review of existing highway research programs with regard to the potential research topics identified in preparation for the June and October 2000 committee meetings is summarized in this appendix.
Strategic Focus Area 1: Accelerate the Renewal of America’s Highways
After soliciting research needs from numerous stakeholders and highway research experts, the committee identified four promising research approaches within this strategic focus area. The first was to develop tools for asset management to help managers of transportation agencies, who face countless needs and limited resources, decide which investments will yield the best return in their state or locality. The second was to focus on methods and technologies for performing highway reconstruction and rehabilitation quickly, with minimal disruption to operations and minimal need for future reconstruction and rehabilitation. The third was to focus specifically on the renewal needs of city street networks. The fourth was to develop infrastructure preservation strategies for preserving the system, retarding deterioration, and reducing the need for major renewal in the future.
The committee reviewed existing highway infrastructure research and technology programs to assess the state of the art in each of these areas and identify research needs. The main programs reviewed were those of the Federal Highway Administration (FHWA), the National Cooperative Highway Research Program (NCHRP), the Transportation Research Board, and industry associations. In addition, a search of the Transportation Research Information Services (TRIS) database, including the TRIS Research in Progress database, revealed work being conducted in state departments of transportation (DOTs), universities, and other countries. Summaries of the results of these analyses are provided in the following subsections.
FHWA is developing a number of analysis tools, such as life-cycle cost analysis and the Highway Economic Requirements System. FHWA, NCHRP, and state DOTs have developed many management systems for specific assets (for example, pavements, bridges, signs, and real estate). University research is focused on analytical frameworks and tools. Currently, many research papers and projects appear to focus on data collection, integration, and management, especially using newer technologies, such as the Global Positioning System, geographic information systems, and visualization techniques. The American Association of State Highway and Transportation Officials has a detailed Asset Management Strategic Plan covering the period 2000 to 2005, and work has already begun on the plan’s initial tasks. In particular, an NCHRP report due in 2002 will address asset management using a top-down, holistic approach. The report will provide a synthesis of knowledge and tools, identify a recommended applications framework, and set forth research needs.
The F-SHRP committee identified research gaps in three areas related to asset management: (a) data and data management (methods and tools to make data gathering and database updating cheaper, easier, more reliable, and more accurate, and systems for integrating data from various sources); (b) analysis and decision making (performance measures, performance and prediction models, analytical methods that can be used across assets, tools for developing and presenting options at the highest management levels); and (c) institutional issues (how to organize to implement asset management, human resource needs, and methods to achieve stable funding of asset management support work).
Rapid Renewal of Interstates and Freeways
FHWA currently has several research projects under way on materials that are lighter and more durable and that facilitate faster construction. The agency also runs a nondestructive evaluation research program for bridges. Several smaller-scale programs under way or completed encompass the faster fabrication
and reconstruction of bridges and various state demonstration projects for the accelerated reconstruction of segments of roadway. FHWA is also continuing its development of a freeway simulation model for traffic operations and analysis tools for work zones. An agencywide team is developing an integrated approach to work zones (including infrastructure, safety, and operations considerations). NCHRP projects completed or under way include project-level reconstruction and contracting methods, mitigation of delays in the construction process, materials for early opening to traffic, and rapid rehabilitation of high-volume roads and replacement of bridge decks.
Gaps were identified in four areas related to rapid renewal: (a) performance measurement (for work zone performance, delay, user costs, methods to measure quality in the construction/maintenance phase, and monitoring of traffic composition and behavior); (b) methods and operations [rapid replacement/ repair systems, construction for confined spaces, methods to address work zone operations during planning and design (including consideration of corridor and systemwide impacts), effective work zone traffic information systems and traffic management systems]; (c) materials and equipment (life-cycle cost optimization of materials for early opening to traffic, long-term performance of high-performance materials, mechanisms to foster development of innovative pavement construction equipment); and (d) designs that take advantage of renewal efforts to improve safety, environmental, aesthetic, and congestion mitigation aspects of the facility.
Renewal of Urban Street Networks
There is very little research focused specifically on the renewal of urban street networks, although some of the current and recent work described under the previous topic of Interstate and freeway renewal could also potentially apply to this area. FHWA is performing some work directly related to urban areas that deals primarily with computer simulations of surface street operations and design considerations for bicycles and pedestrians.
Research gaps related specifically to urban street networks include noise mitigation, construction techniques in urban residential areas, construction techniques for confined spaces in urban commercial areas, storm water models, aesthetic design issues, better and less disruptive urban lighting, access and mobility issues related to urban work zones and construction management, urban utilities, and freight movement and delivery of goods in urban centers.
FHWA is currently funding several materials technology research projects, addressing such topics as predictors for the performance of jointed plain concrete pavements, mix designs for micro surfacing, and corrosion control research for reinforced concrete structures. NCHRP and other research programs have completed or are currently conducting research in the management and decision-making processes and preservation strategies. Several states perform research on preservation strategies for pavement, bridges, and other infrastructure elements.
Gaps were identified in the following areas related to infrastructure preservation: performance-related specifications for construction and maintenance activities, performance and prediction models, integration of pavement preservation strategies into pavement management systems, quality control/quality assurance criteria for pavement preservation data collection, and field testing of performance models.
Strategic Focus Area 2: Make a Quantum Leap in Highway Safety
After soliciting research needs from numerous stakeholders and highway research experts, the committee identified two promising research approaches within the strategic focus area of making a quantum leap in highway safety. The first was to devote significant effort and resources to addressing one or more common crash types, such as run-off-the-road crashes (which account for about one-third of highway fatalities) or intersection crashes (which account for almost one-quarter of highway fatalities). The second reflects a research gap mentioned frequently during the outreach process: the conduct of a comprehensive, in-depth study of what really causes crashes.
The committee reviewed existing highway safety research and technology programs to assess the state of the art in each of these areas and identify research needs. The main programs reviewed were those of FHWA, the National Highway Traffic Safety Administration (NHTSA), and NCHRP. In addition, a search of the TRIS database, including the TRIS Research in Progress database, revealed work being conducted in state DOTs, universities, and other countries. Summaries of the results of these analyses are provided in the following subsections.
The two major areas of research related to run-off-the-road crashes are the Intelligent Vehicle Initiative (IVI) and more traditional roadside safety research. The IVI program is run by the Intelligent Transportation Systems Joint Program Office at FHWA and focuses on the use of ITS technologies (particularly in-vehicle) to increase highway safety. In the road departure area, this means systems to warn the driver that the vehicle is likely to leave the lane. Adaptive cruise control (to adjust vehicle speed on the basis of road geometry) is a potential technology as well. This work is being done in cooperation with vehicle manufacturers and suppliers, who are doing much of the research and development for in-vehicle systems. DOT efforts are focused on defining performance requirements, identifying locations for application, developing standards, supporting operational test and evaluation, and performing human factors research to ensure the safety of IVI systems. Traditional roadside safety research is carried out by FHWA, NCHRP, and state DOTs. This research addresses such topics as roadway geometry; lane delineation; and roadside features and obstacles, including terrain features, barriers, guardrail, trees, and utility poles. This research usually results in design standards aimed at reducing the likelihood and severity of run-off-the-road crashes. In addition, FHWA is developing the Interactive Highway Safety Design Model (IHSDM), which integrates safety considerations into roadway design. Additional run-off-the-road research is needed to address the issue of lower-speed roads and to integrate cooperative infrastructure systems into the IVI program. Some plans already exist to extend work into these areas if the necessary resources are made available to these programs.
The IVI program has an intersection collision avoidance segment under which systems to warn drivers about possible dangers at intersections will be developed. IHSDM is used to analyze safety at intersections on two-lane rural highways. Other intersection-related work addresses red light running (including the use of automated enforcement), traffic calming, and pedestrian and bicycle safety. FHWA is conducting some human factors research in support of IVI to better understand precrash behavior at intersections, as well as human factors research related to traffic calming and CORSIM (a traffic simulation model).
The intersection safety problem is highly complex, involving vehicles; infrastructure; operations; and all road users, including pedestrians and bicyclists.
As a result of this complexity, the IVI Business Plan indicates that cooperative vehicle–infrastructure solutions are necessary and suggests that operational testing will not take place before 2006, with deployment closer to 2014. FHWA’s Infrastructure Plan for IVI acknowledges the need for more research and development in this area. Also, IHSDM has focused on rural two-lane roads but needs to be expanded to address larger roads with more complex intersections. Driver simulation models for signalized and unsignalized intersections were identified as a specific research gap, needed to study new geometric design and control approaches for intersections. Two populations of drivers are especially at risk for intersection crashes: teens and the elderly. Intersections are particularly complex situations to negotiate, requiring attention to several things simultaneously. Both teens and the elderly have difficulty multitasking while driving. Since both the teen and elderly populations are growing more rapidly than those of other age groups, these demographic facts add urgency to the intersection crash problem.
Various efforts have been made to improve the understanding of highway crashes and the factors that appear to cause them. Crash causality has been analyzed by the ITS program, through IVI, and the General Accounting Office, as well as some state DOTs and a pooled-fund study being conducted by the southeastern states. The analysis element of FHWA’s safety research program, the Highway Safety Information System, performs studies based on data provided by eight state DOTs. NHTSA also performs crash analysis. The agency’s Fatality Analysis Reporting System uses state DOT, police, and other data to study fatal crashes; while its National Automotive Sampling System looks at various types of crashes using two systems—the General Estimates System, which examines a nationally representative sample of crashes using information from police reports, and the Crashworthiness Data System, which performs detailed analyses of 5,000 crashes a year, supplementing police reports with on-site investigation and other data. NHTSA is also conducting a special study to investigate the use of event data recorders in gathering crash data. FHWA is performing research on human factors aspects of precrash events and funded the development of the ALERT vehicle, a law enforcement vehicle equipped with advanced communications technology to aid police officers in collecting more accurate data at crash scenes. Finally, the Federal Motor Carrier Safety Administration is conducting a congressionally mandated $15 million to $20 million truck crash causation study.
All these studies have significant limitations. For instance, all are based on crash events only; none use noncrash situations as an experimental control. Very few precrash data are employed. The availability and accuracy of certain types of data—such as crash location, roadway geometry, roadside features, and other road characteristics—are inadequate for performing the types of research that would help in understanding the contribution of these factors to safety and in designing better countermeasures. (The Highway Safety Information System collects some of these data, but from very few states.) NHTSA’s use of event data recorders is promising but limited at this time.
Strategic Focus Area 3: Provide a Reliable Highway System
The emphasis of this strategic focus area and the associated research topics considered by the committee underwent a number of transformations in the course of the outreach process. As a result, the review of existing research efforts and depth of analysis of gaps were somewhat less extensive than for the other strategic focus areas, which were more clearly defined earlier in the process. Two potential research areas were considered: providing real-time information to customers and reducing congestion from nonrecurring incidents. These evolved to the focus on travel time reliability discussed in the report.
Strategic Focus Area 4: Provide Highway Capacity in Support of the Nation’s Economic and Social Goals
Much work has been and continues to be done in the area of air quality modeling, including an approximately $5 million program of NCHRP research. The water quality area appears to be dominated by highway runoff studies. Several studies examine wetland impacts and assessment of the functional values of wetlands. There are several small studies of social and economic impacts of highways and a number of projects addressing data and systems for environmental decision making, including more than $2 million in NCHRP projects. NCHRP is also conducting a study of technologies to improve the consideration of environmental concerns in transportation decisions. This study involves a review of nearly 20 technologies in 5 categories to ascertain their usefulness with regard to environmental considerations in
transportation.2 A few studies can be found in areas related to noise, environmental justice, archeology, wildlife, and context-sensitive design. The Transit Cooperative Research Program has performed relevant studies of land use, sprawl, livable communities, planning, and the impact of demographic and social trends on travel. There are probably hundreds of studies being done by government agencies and universities on more scientific aspects of the environment; however, the F-SHRP literature search focused on research oriented mainly toward information and tools that would be useful for transportation agencies.
Three major gap areas were identified. The first relates to air quality issues that are expected to intensify in the future but have not been adequately researched, including greenhouse gases, air toxics, and particulate matter (PM) 2.5 (or even PM 1.0). The second is the need for tools focused on nonurban and small urban areas. The third pertains to the need for more systemwide data, analysis, and decision support tools, including analysis of secondary and cumulative impacts of new highway capacity (for example, issues of land use and sprawl and areawide assessment of environmental impacts as opposed to site-specific assessments); linking environmental data and analysis with asset management; integration of analysis across various areas (air, water, habitat, noise, community, economics) by developing a common rationale and framework that can link the various performance measures used in each of these areas; and integration of these analyses earlier in the planning and design processes (including the development of tools for improving public involvement and communicating information about impacts and alternatives).