Heading_1-RtCol
Past, present, and future of pavement preservation
Rubberized slurry seal in Los Angeles
Minisink Township polymer-modified fiber membrane
If you haven’t checked out Tom Kuennen’s Web site— expresswaysonline.com—you’re missing an opportunity. Kuennen provides one-stop shopping for all kinds of information about surface transportation including history, research, current practice, the latest equipment, and politics. With all that experience behind him, Kuennen’s presentation at the 11th annual Minnesota Pavement Conference, titled “Hot Button Issues in Pavement Preservation,” was like a state-of-the-union address on pavement preservation (PP).
Defining PP
Kuennen defined PP as a group of methods “intended to prolong pavement life, avoiding high future costs…through the expenditure of much lower amounts of money at critical points in a pavement’s life.” He listed crack sealing; fog, chip, and thin cold-mix seals; surface recycling; and thin hot-mix asphalt overlays as the most common PP methods. He also claimed that spending a dollar on PP “can eliminate or delay spending six to ten dollars on future rehabilitation or construction costs.”
History of PP
On one hand, Kuennen explained, PP was simply the next obvious step after most interstate highway construction was completed in the 1980s. On the other hand, he pointed to the 1990 European Asphalt Study Tour as the single event that most forcefully propelled PP into the consciousness of U.S. pavement professionals. He quoted the tour’s report: “By far the study team’s most striking observation was that the pavements on European motorways and trunk routes are in superior condition. The extreme forms of distress that are evident in many parts of the United States…were, simply, rarely seen. Even pavements that were being rehabilitated or resurfaced were in fairly good condition by United States standards.”
As a result, several organizations and programs were formed to promote PP in the United States:
- The Foundation for Pavement Preservation (formed in 1992)
- FHWA’s Office of Asset Management (OAM, created in 1999)
- The Governmental Accounting Standards Board (GASB, which in 1999 issued Statement 34 requiring state and local governments to include long-lived infrastructure assets in their annual financial statements)
- The National Center for Pavement Preservation (opened in 2003)
Leaving ‘worst-first’ behind
Kuennen said that, despite all of this activity, PP continues to face a stubborn obstacle: the view held by many politicians and citizens that money should be spent on the worst pavements first. His suggested solution to this problem is hard data in the form of pavement inventories created via pavement management systems (PMSs).
Exemplary practices, new and old
Kuennen showcased two agencies—one large and one small—that have embraced PP practices. Necessitated by the tax cuts mandated in California’s famous Proposition 13, the Los Angeles Public Works Department began a PP program, using PMS data and a proprietary rubberized slurry surfacing process. At the other end of the map, the town of Minisink, New York, has had excellent results with a proprietary surface treatment called FiberMat, in which short fibers are laid down with a polymer-modified emulsion and then covered with a sealer. Minisink claims the process has reduced reflective cracking by almost 90 percent over four years. But, citing NCHRP Synthesis Report 35-02 titled Chip Seal Best Practices, Kuennen also showed that the tried-and-true chip seal is still a useful PP option.
The road ahead
Kuennen closed his presentation with a view to the future. He praised agencies that have compiled and issued PP reference material, including Mn/DOT’s Minnesota Seal Coat Handbook. He also showed that, despite tight budgets that force agencies to direct funds toward road building, agencies are making PP progress. He cited a recent NCHRP study showing that state, county, and local agencies across the country are using hard PMS data to win dollars for pavement preservation.
—Richard Kronick, LTAP freelancer