Executive Summary

BACKGROUND

Traditionally, highway agencies have allowed the ride quality and structural condition of their pavements to deteriorate to fair or poor condition before taking steps to rehabilitate them. The aim of rehabilitation is to repair structural damage and restore measurable pavement conditions such as ride, rutting, and cracking. This is a costly and time-consuming activity with associated traffic disruptions and inconvenience to adjacent businesses and residences.

In recent years, increasing numbers of highway agencies have found that applying a series of low-cost pavement preservation treatments can extend the service life of pavement. This translates into a better investment and increased customer satisfaction and support. France, South Africa, and Australia are recognized as nations with innovative programs and new treatments for pavement preservation.

OBJECTIVE AND PANEL COMPOSITION

The objective of the scanning study was to review and document innovative techniques, materials, procedures, and equipment used in the host countries for pavement preservation and to evaluate these elements for potential application in the United States. To this end, the scanning team met with government agencies and private-sector organizations involved with pavement preservation, and visited sites to observe the results of pavement preservation techniques and strategies.

The Federal Highway Administration (FHWA), an agency of the U.S. Department of Transportation, the American Association of State Highway and Transportation Officials (AASHTO), and the National Cooperative Highway Research Program (NCHRP) jointly sponsored the Pavement Preservation International Scanning Study. The delegation included members representing State departments of transportation in Georgia, Michigan, Pennsylvania, and Texas; National Association of County Engineers; FHWA; National Park Service; American Public Works Association; and from the private sector, Koch Materials Company and Kristen Betty and Associates.

KEY FINDINGS

The team noted several key findings or actions taken in the host countries that have had a marked impact on pavement preservation activities and program success:

• All the countries visited have made a commitment to designing and building long-lasting structural pavement sections on their national roadway networks. This decision has caused these nations to focus maintenance activities on surface courses to preserve the large investment in underlying layers. This, in turn, promotes the use of relatively low-cost seals and thin overlays as the primary maintenance techniques, instead of more costly types of rehabilitation.
  
  
• Providing initially high structural capacity enables highway agencies to use relatively low-cost seals and thin overlays on set, repeatable cycles. For the most part, rehabilitation is a minor part of agencies' maintenance programs. Consequently, agencies emphasize pavement preservation techniques.
  
  
• All three countries use only quality materials for both bitumen and aggregate. Generally, crushed aggregate and proven polymer-modified asphalt binders are used. This is ensured through the use of rigorous specifications. Materials sources are specified and there is no inhibition to using sources a great distance away from the project site.
  
• Warranties, usually four years in duration, are used in contracts when applying preventive maintenance techniques. The functional properties warranted are friction, rutting, and smoothness. The responsibility of the contractor for the repair of non-compliant sections reduces with time and traffic. A secondary effect of the application of warranties has been the innovation of materials and mixtures by contractors and material suppliers.
  
  
• France uses a system called the Charter of Innovation, through which the government and industry share in the risk of experiments to develop new and innovative products. Requests for proposals are issued annually for new products and test sections are constructed. Surveys are conducted with the company and government sharing in the cost. Successful products are then accepted nationally for inclusion in the preventive maintenance program.
  

RECOMMENDATIONS

After discussing and evaluating what they had observed in the three countries, the team developed the following recommendations with potential for implementation in the United States. The findings, observations, and recommendations are those of the scanning team and not of FHWA.

1. Initiate demonstration projects with deep subbase and deep base designs in different regions of the country to determine the effectiveness of this design strategy.
   
   
2. Encourage highway agencies to include pre-coating of chips in their chip seal specifications.
   
   
3. Test and evaluate geotextile-reinforced chip seals in both freeze and no-freeze environments.
   
   
4. Encourage agencies that do not use modified binders for chip seals to do so.
   
   
5. Encourage agencies to review their specifications and upgrade them where appropriate so that superior aggregates are used and improved service life is achieved.
   
   
6. Encourage agencies to review their design practices for chip seals and consider placing them on base or subbase courses to prevent moisture infiltration.
   
   
7. Encourage agencies to apply chip seals earlier in the distress cycle.
   
   
8. Investigate the practice in New South Wales of placing thin (40-to-60-millimeter) asphalt overlays on portland cement concrete pavement.
   
   
9. Encourage AASHTO and FHWA to develop a mechanism to evaluate and implement new and innovative products and processes.
   
   
10. Encourage AASHTO and/or FHWA to conduct a seminar to share best practices and investigate the possibility of demonstration projects in the United States using long-term maintenance contracts.
    
    
11. Conduct studies of Road Crackä, a pavement condition survey vehicle, and similar vehicles to evaluate the potential for use by transportation agencies. If warranted, develop a pilot program for a side-by-side field evaluation of these vehicles.
    

IMPLEMENTATION

A small group of scanning team members has developed a technology implementation plan that outlines a series of activities to document, showcase, apply, and evaluate the innovative pavement preservation techniques, processes, materials, and equipment used in the nations visited. These activities will be directed at educating the U.S. highway community about the effectiveness and value of these innovative technologies.