| OTIA III State Bridge Delivery Program |
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| Web Brief (Feb 04) |
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Delivering new approaches in bridge construction
BURNS, Ore.—The Central Oregon Highway (U.S. 20) is a major corridor connecting western and eastern Oregon and the main road between Bend and Ontario.
Along this often lonely highway, the Oregon Department of Transportation (ODOT) is practicing new management approaches and applying new technologies that may well become the standard for highway and bridge construction across the state and throughout the region.
ODOT is repairing or replacing 16 bridges on U.S. 20 between Riley and Vale as part of the OTIA III State Bridge Delivery Program. OTIA III is the third phase of the state’s 10-year, $3 billion Oregon Transportation Investment Act (OTIA) program. During the next decade, OTIA funds will repair or replace hundreds of bridges, pave and maintain city and county roads, improve and expand interchanges, add new capacity to Oregon’s highway system, and remove freight bottlenecks statewide. U.S. 20 has become a testing ground for innovations that are delivering bridge construction efficiency.
“The application of new, innovative technologies has helped make this the smoothest running program I’ve ever been associated with,” said James Farrens, the ODOT construction project manager and a 15-year veteran of highway construction.
Massive concrete beams, some of the largest ever used in bridge construction in Oregon, are being used to span creek beds without concrete piers and footings. That allows quicker construction times with minimal disturbance to the natural landscape.
Elsewhere, ODOT is using high-performance steel to span greater lengths as well, and the “metalizing” of steel extends the structure’s life and reduces a need for painting, which reduces maintenance costs. Rapid construction techniques, such as pre-assembling a bridge and sliding it into place, allow ODOT to replace bridges more quickly. The new technologies allow the agency to save time and money.
“Taxpayers are truly receiving value for their investment,” Farrens said. “These technologies are protecting the taxpayer investment by delivering more efficiency during construction.”
Begun in March 2004, construction work on the U.S. 20 bridges will be finished by September 2005. U.S. 20 gets its heaviest use during the summer months, and it serves year-round as a truck route and for tourist travel. But because the highway has relatively low traffic volumes even in peak-use times, it isn’t cost-effective to use flaggers to move traffic through construction zones.
Instead, ODOT is using automatic dynamic directional signage on this project to control traffic through work sites. When construction narrows the highway to one lane, automated traffic signs cycle traffic through at two-minute intervals. Drivers see a green, yellow, and red signal that tells them when to proceed.
Using these signs means more manpower can be used in actual construction. About 18 family-wage jobs are sustained for every $1 million spent on transportation construction in Oregon. Each year during the OTIA program, construction projects will sustain about 5,000 family-wage jobs. The automated signs also have helped keep traffic moving over the length of the roadway and have increased worker safety, particularly at night.
Another technology that is increasing efficiency for ODOT is the use of large, prestressed concrete beams for the bridge work on U.S. 20. These beams, some of the largest ever built in Oregon, make it easier to span waterways. The great length and strength of the beams allows bridges to span creek beds without using extra footings that would disturb the surrounding ecosystem.
Made by Morse Bros. Inc. in Harrisburg, Ore., the beams also allow construction to move more quickly without sacrificing safety or sturdiness.
“You don’t have to extensively prep the site with footings or other concrete structures,” Farrens said. “You just place the beams and you are ready to pave the deck.”
When it comes to paving the bridges, ODOT is using still another innovation: high-performance concrete.
While people may not normally think of concrete in terms of technological evolution, new mixtures of concrete are continually advancing toward an optimum blend. ODOT is at the forefront of these advancements in its bridge program. The result is concrete bridge decks that are denser; more resistant to the corrosive effects of water, ice, and anti-icing chemicals; and strong enough to support heavy truck traffic.
“The whole thrust of our development of high-performance concrete is to improve and extend the life cycle of our highway and bridge surfaces,” said Randy Kessler, ODOT’s concrete quality coordinator. “The use of these new, stronger blends of concrete means the roads and bridge decks will last longer.”
The Works Progress Administration (WPA) built the Central Oregon Highway in the 1930s, and stretches of the highway, including bridge approaches, still have WPA pavement. Other sections have concrete from highway improvements done in the 1950s. That concrete has lasted more than 50 years, but Kessler believes high-performance concrete will last nearly twice as long.
One interesting aspect of the concrete blends that Kessler has developed is the use of industrial byproducts to improve strength and decrease permeability. On U.S. 20, ODOT is using a blend of Portland cement, micro-silica, and fly ash in the dry mix. Micro-silica comes from the smoke generated during the production of silicon computer chips. Fly ash is a byproduct of the coal industry. It is made by collecting the smoke from burning coal.
These byproducts—when added to the traditional Portland cement, water, and sand mix—help to create an extremely hard, abrasion-resistant driving surface. This is especially important on U.S. 20, where more vehicles are equipped with road-damaging tire studs or chains in the winter.
Another critical reason the U.S. 20 projects have run so smoothly is ODOT’s application of a different philosophy in bridge construction management. This is a “design-build” project, meaning ODOT awarded the job to a single contractor who both designs then builds the bridges. This allows ODOT to focus on managing the design and construction work without hiring more staff engineers.
“This is the cutting edge in managing bridge construction,” Farrens said. He and his assistant constitute 100 percent of the ODOT manpower contributing to this project. “It is an innovative way to get a project of this size done, and I have seen on this project that it is the most efficient way.”
According to Farrens, the combination of design-build management and new technologies is helping to deliver ODOT’s bridge program on time and on budget. For him, the true benefit is to Oregon’s taxpayers.
“We are using our resources effectively and efficiently,” Farrens said. “The result is a safer, stronger route in central Oregon, and one that will endure for many years to come.”
Farrens notes with pride that other state transportation departments are closely watching developments on the Central Oregon Highway. Out on this two-lane road, ODOT is demonstrating new approaches in rebuilding and repairing the state highway system. Its success will translate directly to other projects in the state and throughout the region.
“I really couldn’t feel better about this project,” Farrens said. “It’s an honor to be associated with it.”
# ODOT #
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