As part of the new North Carolina State Veterans Home in Black Mountain, Big R Bridge was selected to design and supply a 56′-5″ span Super•Cor box culvert, considered to be the largest corrugated steel box culvert in North America. The structure’s installed cost was also 40 percent lower than a similar rigid bridge – due to the elimination of expensive H-pile deep foundations.
A tight vertical rise constraint, from creek invert to road elevation, was a major factor in this project. Plus, hydraulic requirements called for a minimum 48′ clear span at 6′ above the invert. The creek bed soils were also sensitive to scour.
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The Big R Engineering Team designed a long span and low rise box culvert geometry with reinforcing ribs that worked perfectly within the site constraints. Shallow foundations became an option because of the settlement tolerances for the buried flexible structure. Big R’s Galvanized Steel Sheet Pile cut-off walls were added to provide additional scour protection.
By working in close collaboration with the consultant and the contractors, we developed a value-engineered solution prior to project award. As a result, we were able to move into final design and submittals immediately after receiving notice to proceed.
This project was recently featured in a case study at a workshop on use of buried bridges as an alternative for traditional bridges at the Transportation Research Board’s 92nd Annual Meeting in Washington, DC.