Carolina Crossroads

Geotechnical design for the largest transportation project in South Carolina’s history.


Columbia, South Carolina

In 2019 the South Carolina Department of Transportation (SCDOT) received federal approval to move forward with the Carolina Crossroads project, an ambitious plan to redesign 14 miles of I-20, I-26, and I-126 through the central part of the state—an area popularly known as Malfunction Junction. Frequent traffic slowdowns over the years gave the corridor its well-deserved nickname. The Carolina Crossroads project aims to improve safety, increase traffic capacity, and modernize the corridor thanks to new ramps, interchanges, and widened roads.

To date, GeoEngineers has delivered geotechnical design services for the first two phases of Carolina Crossroads, which involved building new bridges near the busy I-20, I-26, and I-126 interchanges near Columbia, South Carolina. Our services included soil characterization, geotechnical designs, and construction recommendations.


Geotechnical Design
GeoEngineers provided preliminary and final geotechnical designs and analyses for Bridge 34 in Phase 1 and Bridge 44 in Phase 2 of the project. Bridge 34 was a 387-foot, three-span, bridge connecting Bush River Road to I-26 and I-126 over Arrowood Drive and a flyover ramp to I-126. Bridge 44 was a 142-foot, single-span, bridge connecting Broad River Road to I-20 over the I-20 ramp to I-26. Both bridges included multiple pile bents to support the structures and two earthen embankments with large Mechanically Stabilized Earth (MSE) retaining walls, as much as 27 feet tall at Bridge 34 and 33 feet tall at Bridge 44, at the bridge abutments. The geotechnical team evaluated the geotechnical conditions at each bridge location and performed static settlement, liquefaction susceptibility, global stability, MSE wall, and pile capacity analyses before delivering final geotechnical recommendations for the bridge structures.

Construction Support
The GeoEngineers team also provided recommendations for construction sequencing along with pile drivability analysis for the project team prior to construction. During construction they also evaluated Pile Driving Analyzer (PDA) and Case Pile Wave Analysis Program (CAPWAP) testing results to verify the estimated foundation capacities and provide driving criteria for the contractor.


Construction on the entire Carolina Crossroads project is expected to last until at least 2029, with a total of 43 new bridges and ramps, 7 completely redesigned interchanges, and 132 miles of new travel lanes. GeoEngineers hopes to continue providing geotechnical design services as this important transportation project continues.

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