Salt Lake motorists forced to detour around the Fourth South viaduct will have to wait until the first week in October for the 16-year-old bridge to open following a $2.6 million repair job.
The bridge, spanning 26 railroad tracks in the west-downtown area of Salt Lake City, was closed to traffic July 11 so crews could begin reconstruction, said project manager Dan Noziska, a Salt Lake civil engineer.Only the city is funding the project, Noziska said. Federal funding for reconstructing the bridges is available, but a long waiting period made that option impractical.
Crews are working on the proj-ect with a sense of haste, Noziska said, noting that detours around the closed bridge cost the driving public about $2,500 daily.
The bridge is suffering from severe decay as a result of corrosion from salt spread over it in winter. Further deterioration could have led to a potentially dangerous situation, Noziska said.
"It wouldn't have been catastrophic, but it would have caused some problems," he said.
Salt, spread liberally over the bridge in winter months, actually soaked into the concrete and began corroding the steel reinforcement bars supporting the structure, Noziska said.
Crews are using a "cathartic" protection process to repair the bridge. Since April, workers have been stripping the bridge of deteriorated layers of concrete and then wrapping the exposed concrete with wire mesh.
The mesh will then be electrified, a process which will prevent the salt from corroding the re-bar, Noziska said.
"The interesting part about this project is that this is the biggest application of cathartic protection that we're aware of on the continent," he said.
Better Roads and Bridges magazine will feature the bridge in its November issue, and the American Public Works Association will tour the project during a conference Aug. 31.
Additionally, crews have repaired 16 of the 19 vertical supports holding up the bridge by installing jacks to lift 1,300 ton sections of the bridge. Crews then conduct cathartic protection on the supports.
Potholes and other deteriorated portions of the bridge's road surface are also being cleaned out and filled with special concrete that will fend off corrosion, Noziska said.