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Pavement Preservation Compendium
A Call for Action: A National Initiative for Pavement Preservation
Proactive Asset Management, Lower Life Cycle Costs and Higher Quality Pavements
The investment in our nation's highway system is over one trillion dollars. As state, city and county departments of transportation are evaluating their road assets to comply with GASB 34 guidelines1, they are recognizing the need to manage that investment.2,3,4 Many agencies are realizing the cost benefits of a sound pavement preservation program which includes preventive and corrective maintenance practices. For example, Michigan DOT reports they are saving $10 in future rehabilitation and reconstruction costs for every $1 spent on preventive maintenance while improving the overall quality of their roads.5
ISTEA and TEA-21 facilitated the use of federal-aid highway funds for preventive maintenance activities, and many departments of transportation now have some type of pavement preservation program area. While in the past, most agencies had previously been reactive in their maintenance approach, they are now becoming increasingly proactive in preservation initiatives. The potential benefits are numerous, including improved pavement performance, safer roads, higher user satisfaction and reduced overall life-cycle costs. For example, Rhode Island calculates that if they had spent six to seven million dollars for preventive maintenance, they would not now be faced with a 30 million dollars rehabilitation need for Interstate 295.6
Further, sound pavement preservation programs facilitate decreasing congestion, increasing mobility and improving work zone safety because preventive maintenance treatments are quick and cost-effective.
Protocols for Performance
Materials, methods and specifications for new construction, reconstruction and rehabilitation of roads have been highly developed by years of peer-reviewed research and discussion by TRB, ASTM and AASHTO, including the Superpave specifications and test protocols developed by the Strategic Highway Research Program (SHRP). The primary goals of the SHRP asphalt research projects were to improve overall quality and prevent premature failures. Nationwide AASHTO standards recommended by the work done by SHRP are now in place. The AASHTO standards, guidelines and mix design methods generally have a proven record of performance and are readily available to all agencies.
The same is not true, however, of pavement preservation techniques, which include but are not limited to, crack and joint sealing; hot and cold preventive maintenance surface treatments such as chip seals, slurry seals, micro-surfacing and HMA overlays; hot and cold partial depth recycling; and minor rehabilitation of both flexible and rigid pavements by such methods as milling and filling, diamond grinding, and dowel bar retrofit. Here the research and experience on materials, performance and equipment seriously lags behind the demand for such knowledge.
There was some limited work during SHRP recognizing the importance of pavement preservation, and some preliminary research was done which documented the positive impact of thin surface treatments and their long-term performance. There is also much in the literature on various pavement preservation techniques and some agencies have developed their own local application standards. For example, Montana, Minnesota, California and other transportation departments have detailed design and testing procedures for chip seals, and New Mexico has detailed information on cold in-place recycling. However, there are no nationally recognized protocols for design, materials, selection, specifications and quality assurance or performance criteria for most preservation techniques.
The use of pavement preservation techniques varies throughout the U.S. In many cases some of the techniques were applied for years but are no longer used because of a history of poor performance caused by inadequate design, materials, specifications, construction, performance criteria or quality assurance/quality control. For example, while chip seals are used on Interstate highways in some states, they are not used on any type of road in other States. The recent International Scanning Tour on Pavement Preservation found that chip seals are routinely used on all types of pavements in Australia and South Africa, where there are highly developed protocols for design, materials, construction and acceptance. A survey of all states found that while 21 states routinely use cold in-place recycling, quality varies significantly, and one of the primary complaints is the lack of a national design procedure.
Addressing the Need
Developing national protocols and publishing them as AASHTO standards would improve overall quality and long-term performance. The availability of such standards would also help disseminate information enabling all agencies to use the most cost-effective treatments for their highways, roads and streets. Four areas of need are:
Short- and long-term programs are required to address these areas of need; the short-term program would consist of a 6-month project to define the scope and to prepare work plans. The long-term program would be a 5-year effort to research topic areas and write the protocols. A budget of $10 million per year for the 5 years is suggested.
The industry associations are enthusiastic about the potential benefits of this project in improving road quality while lowering costs, and the members of the Asphalt Emulsion Manufacturers Association, the Asphalt Recycling and Reclaiming Association and the International Slurry Surfacing Association, as well as the Foundation for Pavement Preservation, pledge our support and assistance in its successful implementation.
A literature search and analysis of current best practices should be an important part of the process. The Basic Asphalt Emulsion Manual (updated in 1996), the recently published Basic Asphalt Recycling Manual, other publications by industry associations, and the newly developed National Highway Institute training courses on pavement preservation are just a few of the available materials to facilitate the work.
The Foundation for Pavement Preservation, working closely with FHWA and Industry Associations has assembled toolboxes of information, which are distributed at workshops to improve overall pavement preservation practice. These toolboxes consist of materials on preservation practices, two award-winning videos on the benefits of preservation and project selection, and periodic newsletters. In addition, the Foundation supports a website (www.fp2.org) and booths at association annual conferences (including the National Association of County Engineers, American Public Works Association and AASHTO Subcommittee on Maintenance).
The Foundation has also developed a standard glossary of pavement preservation terms, National Highway Institute training classes, and a CD on pavement preservation state of practice. Support for research on topics from slurry seals and micro-surfacing to noise measurements are also an important part of the Foundation's vision. To provide incentives for preservation, the Foundation will be giving Excellence in Highway Preservation Awards. And to improve communication and knowledge sharing, the Foundation sponsors such opportunities as the Forum for Pavement Preservation II "Protecting Our Investment" conference and workshop in San Diego in November 2001, several state workshops, Spray Applied Binder Workshop scheduled for March 2002, and a demonstration of various preservation techniques at the next AASHTO maintenance meeting.
Similarly, AEMA has produced a CD of basic emulsion practices, AEMA, ISSA and ARRA have all expanded their newsletters, and all have recently sponsored international conferences bringing together experts from all over the world to share best practices as well as innovations in preservation techniques.
The Next Steps
Leadership and immediate action is needed to develop and implement a contract for the short-term program, which would scope the longer term R & D project, to write a work plan, develop a budget, obtain funding and execute the 5 year program. Immediate action appears necessary to input R & D needs into the reauthorization legislative process.