The Design-Build Institute of America (DBIA) recently gave the US 21 Harbor River Bridge Replacement a National Merit Award in the Transportation category. GeoEngineers provided comprehensive geotechnical services for this complex project, which replaced an outdated coastal bridge near Beaufort, South Carolina on an accelerated schedule. DBIA recognized the project team for its technical accomplishments and well-coordinated design-build approach.
For more than 80 years, the US 21 Harbor River Bridge was the only way to access a string of three barrier islands on the South Carolina coast. It was also the only hurricane evacuation route available to the several thousand people who call Fripp and Harbor Island home. Over the years the low swing-span bridge had become vulnerable to washouts and storm damage. A modern replacement was necessary.
In 2017, the South Carolina Department of Transportation (SCDOT) began planning to replace the aging swing-span structure with a higher fixed bridge, eventually awarding the project to the United Infrastructure Group (UIG) design-build team, which included Infrastructure Consulting & Engineering (ICE) and geotechnical subconsultant GeoEngineers. A national GeoEngineers team headed by the firm’s performance-based engineering specialists provided comprehensive geotechnical services including site exploration, soil characterization, geotechnical design, project management, scheduling and construction oversight.
Building a bridge in a tidal marsh brought its share of geotechnical challenges. Subsurface investigations revealed thick shallow layers of soft, highly compressible silt and clay as well as underlying layers of potentially liquefiable sand. In such complex conditions, the owner needed to carefully balance cost and risk to find a foundation design that is both safe and efficient. During the design-build process, GeoEngineers collaborated closely with partners and SCDOT to understand their goals, ultimately delivering a series of alternative technical concepts (ATCs) that satisfied the client helped our team earn the contract.
Thanks to the hard work and ingenuity of the project team, the new Harbor River Bridge was completed on budget and approximately five months ahead of schedule. DBIA’s recognition of the team’s work underlines GeoEngineers’ growing presence and portfolio in the southeast region. Check out our Project Page to see more of our work and read the full project profile on the US 21 Harbor Bridge Replacement Project.