CHAPTER 4—CONCLUSIONS AND SUGGESTED RESEARCH

CONCLUSIONS

NCHRP Project 01-54 developed a suite of products to assist highway agencies in determining the need for drainage and recommended approaches to address or minimize the effects of excess moisture in asphalt or composite pavements. The primary products include the following:

• Guidelines document. This stand-alone report addresses available features, practices, and procedures for minimizing damage in asphalt and composite pavements due to the presence of water; in essence, it is a single resource that provides best practices for minimizing pavement damage due to the presence of water.
• Webinar. PowerPoint presentation materials to support a 90-minute webinar on limiting moisture damage in asphalt and composite pavement structures was developed to help promote and advance the use of the Guidelines document.
• Training course. A 1-day training course was developed to provide practicing engineers with a detailed introduction to the Guidelines document. The course materials include PowerPoint slides, an Instructor Guide, and a Participant Workbook.
• Web-based application. The companion web-based application (DRAIN) provides easy access to the technical content presented in the Guidelines document, providing additional resources to support the practice of designing, building, maintaining, and rehabilitating asphalt and composite pavements so they are less susceptible to moisture damage.

Much of the value of these products is that they are based on successful practices that have been used by highway agencies nationwide. Taken together, these products should go a long way towards reducing the potential for moisture-related damage on asphalt and composite pavements and thereby lead to improved performance, increased pavement life, and reduced costs.

BENEFITS OF IMPLEMENTATION

The Guidelines document provides a standard, uniform body of information that will help highway engineers and designers develop a better understanding of all the factors that contribute to moisture damage within a pavement; as such, they provide best practice recommendations for addressing potential moisture problems in new design as well as in maintenance and preservation. By implementing these best practice recommendations into everyday practice, highway agencies will experience fewer problems with moisture damage, obtain improved performance, and realize lower long-term costs. The Guidelines document will be especially beneficial for the engineers and designers new to pavement engineering.

POTENTIAL BARRIERS AND IMPLEMENTATION RECOMMENDATIONS

None of the best practices recommended in the Guidelines document are new or unique. Accordingly, the only real barriers to use throughout the country are informing highway agencies about the availability of the information and providing training/education in a manner that demonstrates that moisture damage is a major problem and advises areas where highway agency personnel could improve their practices. The webinar, the training course, and the DRAIN web application tool were all developed to support that implementation process.

The Guidelines document must be widely promoted in order for agencies to become aware of them and then work to integrate them into their projects. There are a number of ways that this could be done, including:

• Webinars. These webinars could be presented through TRB in cooperation with relevant committees or could be presented in conjunction with other pavement organizations (e.g., National Center for Pavement Preservation, National Center for Asphalt Technology) or industries.
• Local or regional workshops. These could be targeted to a single highway agency (state or local) or to a regional grouping of interested states.
• Conference presentations. A presentation could be made as part of major conferences (such as TRB, regional pavement preservation conferences, etc.) to help publicize the products.
• Federal Highway Administration (FHWA) resource centers. The FHWA could consider enlisting the services of its technical resource centers to help disseminate the materials and schedule appropriate outreach events.
• NHI training course. The existing course materials could be converted into a formal NHI training course, thereby leveraging that organization’s reach and influence within the pavement community.
• Pooled-fund project. A pooled-fund project could be initiated by interested highway agencies to evaluate the impact of the drainage guidelines on the performance of their asphalt and composite pavements.
• Case studies. Short case studies (2 to 4 pages) could be prepared that highlight an agency’s experiences in adopting information contained within the Guidelines document.
• Dedicated web page. A dedicated web page could be developed where the major products are hosted along with links to many of the key references.

SUGGESTED RESEARCH

As indicated in the title, the Guidelines document was developed for use on asphalt and composite pavements. As such, there is a need for additional research to extend the applicability of the document to include concrete pavements. That work should include appropriate revisions to the DRAIN tool and the training course materials.

Follow-up studies of agencies that have implemented information from the Guidelines document are recommended to quantify the benefits that are being achieved. This would require an agency commitment to the long-term monitoring of the projects over various seasons and ideally would be done in different parts of the country with different climatic conditions. New pavement construction projects, maintenance and preservation projects, and rehabilitation projects would all be of interest.

With the changing climate patterns, it may also be useful to examine the impacts of future climatic impacts on the performance of current and future pavement infrastructure. There are potentially two aspects to this: 1) increased flooding as the result of sea level rise, storm surge, or riverine flooding, and 2) reduced moisture levels due to changing precipitation patterns and extended droughts. Both could have a significant impact on an agency’s need for improved drainage capabilities of their pavements (as well as on the type of drainage improvements that may be needed).