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November/December 1999· Vol. 63· No. 3

TRB Superpave Committee: Keeping Superpave^TMImplementation on the Road
by Neil F. Hawks

TEA-21 and Superpave ™

The Transportation Equity Act for the 21st Century (TEA-21), signed into law in June 1998, radically redefined the traditional arrangements for surface transportation research funding and management. Far less highway research and development (R&D) will be centrally directed from Washington, D.C., and more will be managed and performed at the state and local level. It is far too early to assess the long-term merits of this redefinition, but for some major R&D programs caught in the transition, the short-term impacts have been traumatic.

Some programs have been lost. Some have survived only through creation of new, dramatically different, state-federal partnerships. The program to implement the Superpave system of asphalt pavement materials selection and mixture design was the beneficiary of one of these partnerships.

Superpave, one of the major outcomes of the Strategic Highway Research Program (SHRP), was at the midpoint of an extensive implementation campaign when TEA-21 was enacted. Unfortunately, neither TEA-21 nor the transportation appropriations acts for fiscal years 1998 and 1999 provided any funds to complete the implementation program. If left uncorrected, this oversight would forever limit the full realization of the public benefits of Superpave.

Consequently, the individual state departments of transportation, acting through the American Association of State Highway and Transportation Officials (AASHTO), have assumed the financial burden for completing this work through the National Cooperative Highway Research Program (NCHRP) in cooperation with the Federal Highway Administration (FHWA). FHWA will continue to use previously appropriated funds to support the Superpave implementation program to the extent possible.

Beginning with fiscal year 1999, some of the research, development, and technology tasks associated with Superpave implementation were carried out by AASHTO through NCHRP, and others remain under the direction of FHWA. In addition, AASHTO continues to directly support the valuable work of the Superpave Lead-State Team.

Because of the complex, programmatic nature of the Superpave implementation efforts and the need to keep all of the players in step, AASHTO and FHWA specifically asked the Transportation Research Board (TRB) to organize and staff a Superpave oversight committee. The governing board of the National Research Council created the TRB Superpave Committee on Dec. 8, 1998. TRB is part of the National Research Council, the operating arm of the National Academy of Sciences and the National Academy of Engineering. The committee held its initial meeting in March 1999.

TRB Superpave Committee

The TRB Superpave Committee. s mission is to review the Superpave-related work plans and component tasks of AASHTO and FHWA. The committee provides advice on the suitability of overall objectives, missing components in the plans, the appropriateness of the research tasks in the plan, the likelihood of success of the research tasks, and the coordination of activities among all parties engaged in Superpave implementation. In addition, the committee conducts regular program reviews, provides an accounting of progress, regularly reviews the financial needs for work remaining to be done, and offers advice regarding course corrections, promising opportunities, and significant findings.

Committee membership is drawn from the executive and professional levels of state departments of transportation and the asphalt-paving industry and also includes knowledgeable academicians. Members were selected with consideration of the needs for geographic balance; balance between large and small states; and expertise in asphaltic materials, materials science, mineral aggregate production, and highway construction engineering. Joseph A. Mickes, the recently retired director of the Missouri Department of Transportation, chairs the committee.

Because the program involves a broad spectrum of scientific and engineering disciplines (from basic chemistry to construction management and facilities maintenance), no single advisory group is likely to have all the necessary expertise on its roster. Consequently, from time to time, the committee designates and solicits assistance from ad hoc subcommittees or task groups with more focused expertise. The use of such expert task groups (ETGs) continues a practice developed under SHRP and further used by FHWA. The committee has designated two ETGs to date. These are the Asphalt Binder ETG and the Asphalt Mixtures and Aggregates ETG.

The committee will generally convene two or three times a year. It will regularly invite to its meetings the members of relevant AASHTO committees; AASHTO staff; NCHRP and FHWA research program managers; and potential users of anticipated research findings, including industry groups and associations such as the Asphalt Institute, National Asphalt Pavement Association, National Stone Association, and National Aggregate Association.

The findings and recommendations of the committee will be conveyed to AASHTO and FHWA via . letter reports.. After these letter reports have been reviewed by the National Research Council and transmitted to AASHTO and FHWA, they will be posted on the TRB Web site (http://gulliver.trb.org/). Committee meetings are open to the public, and agendas are posted in the Current Projects. database of the National Academies Web site (http://www.national-academies.org/).

Initially, the committee is advising AASHTO and FHWA on realistic objectives for continuing planned Superpave implementation activities and associated research. Even with the supplemental funds provided by the state departments of transportation, there is not enough money to continue the program as originally designed. The committee. s first task was to recommend a scaled-back plan that will still yield substantial progress.

Reaching consensus on this new plan has not been easy, but the committee delivered its first letter report to AASHTO and FHWA in March 1999. This letter provided recommendations for activities to be included in the fiscal year 2000 work program of NCHRP. With a few exceptions, this program was adopted by AASHTO. Table 1 shows the projects recommended by the Superpave Committee and adopted by AASHTO. With this immediate need behind them, the committee is now working on a longer range plan to meet the expectations that the highway community holds for Superpave.

Keeping the Promise of Superpave
The expectations for Superpave are great. The Superpave system was one of the principal outcomes of the Strategic Highway Research Program that ran from 1987 to 1993. The Superpave system is a comprehensive set of materials standards, test methods, and mixture-design procedures. The new system is much more performance-oriented than the empirically based systems traditionally used by highway agencies.

Over time, asphalt pavements often succumb to thermal cracking, as seen here. The Superpave system promises longer life asphalt pavements . pavements that can withstand time and weather better than ordinary asphalt.

The promise of Superpave is predictable, reliable asphalt pavements. However, this promise will be realized only if the SHRP research results are fully developed into standards and commercially available test equipment that are widely implemented among highway agencies, asphalt materials suppliers, and paving contractors.

During the 1990s, a partnership emerged among AASHTO, FHWA, TRB, and the highway industry to ensure the expeditious implementation of the most significant SHRP research products, including Superpave. The TRB-SHRP Committee provided a forum in which government and industry leaders and experts advised on the implementation process. The existence of this partnership prior to the passage of TEA-21 undoubtedly eased the transition to the new arrangements. The TRB-SHRP Committee served as the model for the new Superpave Committee, and the shared goals and experiences of the AASHTO member agencies and FHWA built bonds that withstood the stress of transition.

In the public works arena, where implementation of even simple technologies can take a decade or more, the rapid adoption of the complex Superpave system by many agencies is truly remarkable. Both the AASHTO Superpave Lead-State Team and the National Asphalt Pavement Association conducted recent surveys that indicated most states and their industry partners have adopted the Superpave standards for asphalt-binder selection, and many are moving toward full adoption of the mixture-design standards as well.

The Superpave Lead-State Team
The Superpave Lead-State Team was created in 1996 by the AASHTO Task Force on SHRP Implementation. Member states include Florida, Indiana, Maryland, New York, Texas, and Utah. The team has made significant contributions in support of system implementation and improvement. Its mere existence . and the publicity attached to its formation . provides focus and encouragement for the states to look seriously at implementing the system.

Many team members hold multiple memberships on key committees. They are members of the TRB Superpave Committee, the expert task groups, the AASHTO Subcommittee on Materials (SOM), NCHRP Superpave research panels, national forum steering committees, and others.

Being expert practitioners and true to their mission statement, they prepared "Implementation Guidance" in 1997 and 1998. These were widely published and distributed documents that helped other implementing states on the steep learning curve.

Ultimately, several members of the team served on an AASHTO SOM-sponsored task force to recommend significant changes to four mix standards based on both NCHRP research and the guidance statements. SOM adopted the recommended improvements, and they were published in the May 1999 interim edition of the AASHTO Provisional Standards.

Early in its history, the Lead-State Team developed and widely published a list of experts in Superpave and its component systems. States were encouraged to contact the experts for advice in the application of the technology. States were encouraged to develop formal implementation plans, and sample plans were sent to all of the states.

The Superpave system provides the highway agency and the construction contractor the information needed to knowledgeably select materials and control construction to help ensure a durable, reliable finished product.

The team participates in many national, state, and regional forums centered on the technology. It also conducts annual benchmarking surveys of all the states that measure the progress of implementation and the probable direction. The annual survey results are widely published in general media and are used in presentations by the lead states and FHWA; printed copies of the survey results are sent to state decision-makers each year. This benchmarking effort has done much to encourage states to adopt the system and to convince our industry partners of the national commitment to its adoption.

FHWA has provided a great deal of support to the lead-state program, expert task groups, and the overall Superpave implementation effort.

As a result, about 3,200 Superpave projects will be awarded by the states in 1999 as compared to a mere 95 projects in 1996. Superpave currently accounts for 46 percent of all hot-mix asphalt tonnage awarded by the states, and its market share is expected to grow to 80 percent by 2001.

– Paul J. Mack, NYSDOT Team Leader, Superpave Lead-State Team

Table 1 . Approved FY 2000 Superpave Projects

The Lead-State Team estimated that in the 1999 construction season, 41 percent of the state highway asphalt-paving projects will employ asphalt aggregate mixtures designed using the Superpave standards. Much remains to be done, however. Superpave is not yet generally applied, and early applications have revealed gaps and weaknesses in the specifications and problems related to construction and quality control. The TRB Superpave Committee will continue to work with the state departments of transportation, FHWA, and the asphalt-paving industry to ensure that these issues are addressed, the innovative Superpave system is fully implemented, and the promise of predictable, reliable asphalt pavements is kept.

Note: Superpave is a registered trademark of the National Academy of Sciences.

Neil F. Hawks is the director of special programs at the Transportation Research Board at the National Research Council. Programs under his direction include the Innovations Deserving Exploratory Analysis (IDEA) programs and a number of research program advisory committees, such as the TRB Superpave Committee. Formerly, he was director of the Long Term Pavement Performance Studies of the Strategic Highway Research Program and engineer of geology, soils, and foundations at TRB. He joined the National Research Council after 14 years with the Pennsylvania Department of Transportation. He is a graduate of Columbia University and a registered professional engineer.

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