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Scanning the Globe for Pavement Preservation
Innovations
In recent years, an increasing number
of highway agencies have discovered the benefits of low-cost pavement
preservation treatments that can extend the service life of pavements.
To learn more about pavement preservation innovations worldwide, the
Federal Highway Administration (FHWA), American Association of State
Highway and Transportation Officials (AASHTO), and industry sponsored
a Pavement Preservation International Scanning Tour in July 2001.
The scanning tour team, which included representatives from FHWA, State
departments of transportation, and other public and private organizations,
identified France, South Africa, and Australia as countries using innovative
techniques, materials, procedures, and equipment in their pavement preservation
programs. Team member Duane Blanck, a Highway Engineer with the Crow
Wing County Highway Department in Minnesota, says, "It was an excellent
opportunity to observe and learn from the rest of the world." Blanck
represented the National Association of County Engineers on the tour.
The host countries shared with the team their experiences and expertise
with pavement preservation. The team's findings were divided into four
categories:
- Management Perspective and Policies;
- Resource Commitment and Cost-Effectiveness;
- Treatments, Techniques, and Performance; and
- Innovative Methods, Practices, and Procedures.
The countries visited are committed to designing and building long lasting
structural pavements for their roadway networks. Such policies mean
that these countries have focused their maintenance activities on preserving
surface courses with low-cost seals and thin overlays to protect the
large investment in the roadway. These design techniques postpone more
costly methods of rehabilitation.
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| A
preventive maintenance approach has helped to ensure the excellent
condition of this primary highway in Perth, Australia. |
France and South Africa share similar management philosophies that help
them effectively appropriate resources. France develops a comprehensive
road investment plan every 5 years, and South Africa uses a rolling
5-year improvement plan, which is developed annually using Pavement
Management System (PMS) data and funding optimization strategies. Australia
takes a different approach to management by implementing long-term maintenance
contracts (10 years) that give control and responsibility for roadway
system maintenance, rehabilitation, and capital improvements to private
contractors.
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| A surface treatment
has been applied to this highway near Johannesburg, South Africa. |
The team discovered in the three countries a general acceptance of and
commitment to using effective pavement management systems and techniques
to protect structural investments. In South Africa, 80 to 90 percent
of the needed maintenance projects identified using PMS data are scheduled
for implementation. Nearly 90 percent of the annual maintenance budget
in various regions of Australia is committed to maintenance, with the
other 10 percent going towards rehabilitation. And France conscientiously
implements protective measures by using low-cost seals on a 7- to 10-year
cycle.
Each of the countries uses only high quality materials for bitumen and
aggregates, which is ensured through the implementation of rigorous
specifications. Using high quality materials results in longer lasting
products that respond well to their environment. "We were amazed
that they would haul high quality aggregate 250 to 700 km," says
Blanck, "We use what's available locally."
Such high quality materials are more costly, which makes preservation
all the more important. South Africa and Australia make extensive use
of chip seals, with Australia improving performance by pre-coating the
aggregates. Australia also widely uses polymerized asphalts to ensure
a quality seal. The polymers were generally being applied at twice the
rate used in the United States. Because hot-mix asphalt is not always
available, France has found success in using cold asphalt concrete as
a riding surface for low-volume roads.
Innovative methods, practices, and procedures were observed in all three
countries. France has developed the "Charter of Innovation"
system, for example, through which the government and industry share
the risks and rewards of developing new products and applications. A
crack activity meter was designed in South Africa to measure surface
cracking and the need to repair a road surface before applying a traditional
overlay. And in Australia, the use of sandwich seals with a two-coat
geotextile reinforced treatment has resulted in surfaces with 11-year
acceptable performance ratings.
Following the tour, the team reviewed their observations from the countries
visited and came up with a number of pavement preservation recommendations,
such as applying thin seals earlier in the distress cycle and developing
mechanisms to evaluate and implement new and innovative pavement preservation
processes. The team's ultimate conclusion: Apply the right treatment
to the right pavement at the right time.
A report detailing the findings and recommendation from the scanning
tour is due out in early 2002. A technical working group comprised of
representatives from the team, the AASHTO Subcommittee on Maintenance,
FHWA, and a consulting firm are developing a Scan Technology Implementation
Plan (STIP) that will demonstrate to transportation agencies and industry
the observed innovative pavement preservation techniques and facilitate
the implementation of the team's recommendations. Overall, the team
found that the direction that the United States is taking in pavement
preservation is in alignment with some of the best practices in the
world.
For more information on the scanning tour or STIP, contact Luis Rodriguez
at the FHWA Southern Resource Center, 404-562-3681 (email: luis.rodriguez@fhwa.dot.gov).
For more information on pavement preservation treatments and techniques,
contact Julie Trunk of the FHWA Office of Asset Management's Construction
and System Preservation Team, 202-366-1557 (fax: 202-366-9981;
email: julie.trunk@fhwa.dot.gov;
Web: http://www.fhwa.dot.gov/infrastructure/asstmgmt/preserv.htm).
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..................................................
Articles
in this issue:
In brief...
Managing DC's assets: partnership produces
better tunnels
QuickZone
1.0: A better approach to work zone planning
Scanning
the globe for pavement preservation innovations
FHWA
structures lab investigates Milwaukee bridge collapse
Highway
technology calendar
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