Complex Design Choices Underpin the Marc Basnight Bridge’s Beauty
Designing a $252 million bridge to last 100 years in one of the harshest inlets on the eastern U.S. coast is no simple task. Planning for North Carolina’s Marc Basnight Bridge meant careful consideration about the inhospitable environment and the lifespan of the structure, as well as the aesthetics of such a monumental project.
Opened to traffic in February 2019, the bridge is capable of resisting wind, wave and vessel collision forces from the worst storms the Atlantic Ocean offers, all while subject to unprecedented scour depths.
To conquer the dangerous Oregon Inlet in the Outer Banks, our engineers separated the project into five regions based on inlet conditions and navigation requirements. Bridge sections were then designed to meet the unique challenges of each region. In the center navigation unit for instance, more than a dozen iterations of superstructure and substructure designs were performed to determine the optimal pier and foundation designs.
Senior HDR Bridge Engineers Domenic Coletti, Dominick Amico, Nick Burdette and Mohit Garg wrote about the planning process, the design choices and the methods chosen to complete the bridge in two articles in the Fall 2019 edition of Aspire, The Concrete Bridge Magazine from the Precast/Prestressed Concrete Institute. Find them on pages 18-22 and 28-30.
The bridge’s final design capitalizes on the extensive use of repetitive, precast concrete structural elements to improve constructability, quality and durability — key criteria in such a harsh marine environment. The result is a structure that is not only durable, but also lovely to look at, “a happy consequence,” according to a commentary by noted bridge architect Frederick Gottemoeller in the same issue of Aspire.
“The Marc Basnight Bridge impressively applies modern foundation technologies to the challenging conditions of the Oregon Inlet,” Gottemoeller said. “The aesthetic consequences of decisions made for technical reasons will make the Basnight Bridge a valued improvement to the Oregon Inlet seascape.”