The old Van Buren Bridge carried two lanes of eastbound traffic through Corvallis, Ore., for many decades.

But the bridge, which was built in 1913, was under weight restriction and couldn't safely support a firetruck.

In response, the Oregon Department of Transportation (ODOT) is working closely with local firm Hamilton Construction to build a new bridge designed by DOWL Engineering.

Corvallis is a bustling city that is home to approximately 38,000 students at Oregon State University. Students and locals use the Willamette River flowing under the bridge for kayaking, boating, fishing and other recreational activities. The university's rowing team also glides through these waters.

The project is about 90 percent complete; the construction team plans to finish it this year. The job will cost about $85 million, with the bridge serving as a welcoming landmark to the city.

In addition to the two traffic lanes carrying cars and freight, the bridge will have a bike lane and shared-use path for walkers who prefer a more leisurely pace to absorb the scenic views from above.

"Our contractor had to build three bridges during the project: one temporary construction bridge used to build the new Van Buren Bridge, one temporary bridge to carry one lane of vehicle traffic and the final new bridge itself," Mindy McCartt, an ODOT spokesperson told Construction Equipment Guide. "The two temporary bridges had to be very sturdy. They carried all types of vehicular traffic with no weight restrictions, and the construction bridge also had to support several heavy cranes during construction.

"The temporary bridges flanked the new bridge with a bridge carrying the westbound traffic for OR 34, located a few yards away. The construction team operated under a time restriction, with in-water work only allowed from June to October. The bridge also was designed according to the latest seismic guidelines. The temporary bridges enabled workers to keep traffic flowing along this city's crucial bridge."

The new structure is a five-span bridge with steel haunch girders on drilled shaft interior bents. Workers will remove the old steel bridge once the new bridge is completed.

Drilling

One of the most challenging aspects of the bridge was the workers finding a solid foundation to build upon.

The construction team drilled through many feet of clay and sandstone. The holes were drilled more than 200 ft. deep in many places. The drilled shafts, 8 ft. in diameter, were constructed using rebar cages installed in sections.

Because of crane height limitations, crews could only install the rebar cages in sections. They would lower a roughly 45-ft. section into the shaft, then position another section above it and tie the two together before continuing to lower the cage into place. Once the full cage was assembled in the shaft, it was filled with concrete. The rebar cages were fabricated on site.

"The noise of the construction was loud," McCartt said. "I was impressed by the crane operators from their chairs using the pile drivers for precision strikes to drive the pilings into the river bottom. It requires great skill to deliver those blows accurately on the pilings."

Workers used 2,500 cu. yds. of concrete for the drill shafts, 1,250 cu. yds. for the bridge deck and nearly 1,000 cu. yds. in other parts of the project. The team used 423,000 lbs. of steel for the rebar.

Workers were careful while operating near the river, as the project included environmental protection measures.

Crews installed water quality swales to treat roadway runoff, and containment systems were used during over-water work to prevent debris from entering the river. The construction activity required five large cranes, including some capable of handling a 250-ton lift.

Workers are being meticulous in protecting trees and planting vegetation as the project nears completion.

The area under the bridge also will see foot and bicycle traffic as the ground is graded, and workers create a natural greenway and access to the parks nearby.

In addition to the bridge work, the construction team will make improvements to the intersection of Van Buren Avenue and NW First Street, installing a new signal to replace the flashing yellow pedestrian crossing light.

"It was an impressive sight to watch the bridge taking shape over the last three years," McCartt said. "The contractor has done an excellent job in building a bridge that is already becoming a shining star for the community. The crews have taken a lot of pride in building something they can show their friends and family for years to come." ♣

(All ph