Ayear after shifting bridge bents halted work on the $217-million U.S. Route 20 project near Oregon’s coast, engineers are hoping for rain and a solution.
While over 50% of the new 6.5-mile bypass is complete, four bridges up to 1,100 ft long sit partially constructed. Lateral load from adjacent fill and subsurface ground pressure may have caused two of the 20 bents on the 10-bridge project to shift as much as two inches. Since that discovery in February 2010, crews have been collecting data.
Joe Squire, Oregon Dept. of Transportation project manager, says that, while the bents haven’t moved much farther, more data is needed. A rainy season will allow crews to monitor effects of elevated groundwater levels. “The geotechnical models become better calibrated with a season’s worth of winter data varied back into them,” says Squire.
The project has been plagued since 2007, when discovery of an ancient landslide halted work and changed the scope. Work resumed in 2008 after a change order mitigated risky sections with buttresses and shear keys. The design-build team Yaquina River Constructors, led by Watsonville, Calif.-based Granite Construction Co., is working with ODOT on potential solutions, including reinforcing the buttresses. Chris Burke, the team’s deputy project manager, hopes for a “true fix” by spring and says only “minor work” will remain. Who will pay for the cost of the fix is still a question.