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Publication Number: FHWA-SA-96-022
Date: November 1996
The Ohio Department of Transportation's (DOT) new test road opened to traffic in August. The project includes five long-term pavement performance (LTPP) experiments, which will provide important clues in the search for more durable portland cement concrete (PCC) and asphalt concrete pavements.
The Ohio Test Road is a 5.3-km (3.3-mi) section of U.S. Route 23 in Delaware County, 40 km (25 mi) north of Columbus. Its flat topography and uniform soil conditions and weather make the site ideal for pavement experiments.
Three of the five LTPP experiments on the test road are located on new traffic lanes built in the median of U.S. 23. The new northbound lane contains an LTPP specific pavement studies (SPS-2) experiment, which compares the performance of different structural designs for PCC pavements. The new southbound lane contains an SPS-1 experiment, which compares different structural designs for asphalt concrete pavements. The southbound lane also includes an SPS-9A experiment to validate the Superpave binder specification and to evaluate the performance of Superpave mixes relative to the DOT's own asphalt mix. These pavements carry an average annual daily traffic of 26,000 vehicles, 20 percent of which are trucks. The old lanes of U.S. 23 are now serving as low-volume frontage roads.
The test road's two other LTPP experiments are intended to isolate the effects of weather on PCC and asphalt concrete pavements. These two SPS-8 experiments are located on a southbound on-ramp to what is now a frontage road.
By constructing the SPS experiments at a single site, Ohio DOT will be able to collect more meaningful data than if the experiments were scattered across the State. Soil, weather, and topographic conditions are the same for all five experiments, and Ohio DOT used identical aggregates and other materials in all test sections wherever appropriate. "These uniform conditions will make it much easier to compare the performance of different pavement designs," says Roger Green, physical research engineer with Ohio DOT. "We've eliminated a lot of the variables that can affect performance."
Placing all five experiments at one site had other benefits. "It was much easier to build at one site, and it reduced the cost," Green notes.
Conditions and performance at the Ohio Test Road are being monitored by several thousand sensors. Pavement sensors measure horizontal strain, vertical displacement, vertical pressure, pavement temperature, frost depth, and moisture. Weigh-in-motion sensors in the northbound and southbound lanes of U.S. 23 measure the dynamic force generated by passing vehicles. A weather station measures air temperature, precipitation, wind, relative humidity, and solar radiation.
The instrumentation system was designed and installed by six Ohio universities-University of Akron, Case Western Reserve University, University of Cincinnati, University of Toledo, Ohio State University, and Ohio University. The universities are responsible for collecting data at the test road.
To make the most of the test road, the universities installed far more sensors, will monitor more sections, and will take readings more frequently than required by the LTPP protocols. As a result, says Shad Sargand, a professor of civil engineering at Ohio University who is coordinating the data collection, the experiment "will provide us with much more information. We can look at how the pavement, particularly rigid pavement, performs under different environmental conditions."
The data will add up quickly. In two tests in August, Sargand reports, researchers collected 2.1 gigabytes of data-enough to fill nearly 1,500 floppy disks.
The Ohio Test Road is a complex project that would not have been possible without strong communication and cooperation between the participating agencies and universities. To bring all the parties involved in the project together, Ohio DOT held a series of conferences. Participants in the first conference included Ohio DOT pavement designers, university researchers, staffers from FHWA's Ohio Division office, and representatives of other State DOTs who had been involved with the design and construction of test roads. FHWA's Bob McQuiston says other States' experiences-good and bad-helped Ohio DOT prepare for the project. At a second conference, participants focused on instrumentation.
To ensure that contractors were fully informed about the job's requirements, Ohio DOT also held a prebid conference featuring presentations by the DOT, universities, and FHWA.
"Contractors had lots of questions on what they could and couldn't do. By answering those questions before the bidding process, we saved some headaches down the road," says Green. "I'd recommend that anyone considering doing an SPS project hold a prebid conference."
Now that the Ohio Test Road is complete, data from the site are being added to the LTPP database, which will eventually be used to develop new pavement design models and procedures. But Ohio DOT expects the data to yield some near-term benefits as well.
"We have two goals," says Sargand. "The long-term goal is to make the data available to the LTPP studies, for the development of mechanistic design procedures. We also have a short-term goal to use the data to draw some conclusions on how these pavements perform. These conclusions could be used to improve our pavement design within 1 year."
Charlie Churilla, chief of FHWA's Pavement Performance Division, says "The Ohio Test Road is unique in terms of the LTPP program. I don't believe there is another place in North America with that many SPS experiments in one location. The test road is not only going to be useful to the State of Ohio, but also to the Nation as a whole."
For more information on the Ohio Test Road, contact Bill Edwards (telephone: 614-752-5272; fax: 614-752-4835) or Roger Green (telephone: 614-752-5277; fax: 614-752-4835).
For more information on the LTPP program, contact FHWA's Pavement Performance Division (telephone: 703-285-2355; fax: 703-285-2767; email: email@example.com).
The Ohio Test Road includes five LTPP experiments and an extensive array of monitoring devices.
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