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States Compare
SPS Report Cards
To learn how climate and cumulative traffic loading affect pavements
of different compositions and layer thicknesses, State highway agencies
across the country constructed specific pavement study (SPS) test
sections during the past decade as part of the long-term pavement
performance (LTPP) program. Eight of the 23 States with SPS-1 (flexible
pavement) and SPS-2 (rigid pavement) test sections gathered in Columbus,
Ohio, in November to exchange information on how the pavements are
performing to date and to discuss plans for using the data collected.
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| A rolling
wheel deflectometer is tested at one of Ohio's SPS sites. |
"This
was really the first time that States participating in the SPS-1
and SPS-2 experiments had an opportunity to come together and talk
about their data collection activities, uses of the data, and any
problems or issues," says Herman Rodrigo of the Federal Highway
Administration (FHWA). The nearly 70 attendees also included representatives
from industry associations, materials suppliers, academia, and consulting
firms. The conference was sponsored by the Ohio Department of Transportation
(DOT), Ohio University, and FHWA. States that attended included
Texas, North Carolina, Florida, Ohio, and North Dakota.
While some States, such as Florida, have only recently begun their
SPS experiments, others have 5 years or more of data collection.
North Carolina, for example, constructed 12 SPS-2 test sections
with varying base types in thickness, width, and concrete strength
in 1994. So far the pavements have performed well, with only minor
cracking in one test section. North Carolina has started analyzing
the data it has collected, says Shie-Shin Wu of North Carolina DOT,
"looking particularly at what type of base seems to produce
better performing pavements." Carlos Peralez of Texas DOT reported
on two SPS-1 sections in his State that were constructed in 1997.
The sections, which were designed to fail, are experiencing rutting
problems as expected. Engineers monitoring the pavement are learning
what level of traffic loading the pavement can handle before it
fails.
Although States generally report successful projects, they have
encountered problems--for example, the negative public reaction
toward test pavements that fail early by design. "A little
PR [public relations] would go a long way toward helping the public
understand that these are research sites," noted Rodrigo. The
conference participants also indicated that they would like to collaborate
more with FHWA on data analysis activities and would like FHWA to
provide more timely information on the results of the analysis.
The conference also featured an update on the development of the
American Association of State Highway and Transportation Officials
2002 Guide for the Design of New and Rehabilitated Pavement Structures
and a commemoration of a 1949 conference in Ohio that led to
the American Association of State Highway Officials Road Test in
Illinois, which was the first experiment to evaluate the effects
of heavy trucks on highway pavements.
FHWA will hold a follow-up SPS workshop on April 27-28, 2000, in
Newport, Rhode Island. This workshop will cover the SPS-1 (structural
factors for flexible pavements), SPS-2 (structural factors for rigid
pavements), SPS-5 (rehabilitation of asphalt concrete pavements),
and SPS-6 (rehabilitation of jointed portland cement concrete pavements)
experiments.
For more information on the November conference, contact Shad Sargand
at Ohio University, 740-593-2476 (fax: 740-593-0625; email: ssargand@bobcat.ent.ohiou.edu).
For more information on the upcoming SPS workshop, contact Bill
Bellinger at FHWA, 202-493-3156 (fax: 202-493-3161; email: william.bellinger@fhwa.dot.gov).
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