The Marc Basnight Bridge in Dare County, North Carolina spans the Oregon Inlet, one of the most dangerous channels on the Atlantic Coast due to its treacherous currents, shifting depths, and high winds. Designers and architects turned to precast concrete to build a structure that will remain strong for decades to come while accelerating construction and mitigating disruption to the environment.
2,000 local, year-round residents of the Outer Banks attended a Community Day party to celebrate the new, $252-million Marc Basnight Bridge in February 2019 despite thirty-degree temperatures and thirty-mile-per-hour winds. In its completion, the replacement bridge won the 2020 Sustainable Design Award and 2020 Best Main Span Bridge More Than 150 Feet. See the team below:
- Owner: North Carolina Department Transportation, Raleigh, NC
- PCI-Certified Precast Concrete Producer:
- Engineer of Record: HDR, Raleigh, NC
- Precast Concrete Specialty Engineer: Eriksson Technologies, Tampa, FL
- Contractor: PCL Civil Constructors, Raleigh, NC
- Additional Team Member: Corven Engineering, Inc., Tallahassee FL
We’ll explore the durability and sustainability of precast concrete, so you can better determine if it’s right for your next project. To learn more about precast flexibility, watch the video below.
Long-Term Strength & Durability
The old bridge was a lifeline for residents of North Carolina’s barrier islands, but it was rapidly reaching its end of life. Located over the Oregon Inlet, the replacement bridge had to endure up to eighty-four feet of seafloor erosion, hurricane-level winds, and occasional impacts by the passing ship. The piles’ final depths are 140 feet below the seabed to provide sufficient embedment and accommodate anticipated scour.
The project team took advantage of precast concrete’s inherent durability, building a structure that can withstand inclement weather and the extremely harsh, saltwater environment. The Marc Basnight Bridge is a high-quality, resilient, and low-maintenance structure designed to maintain stability and strength for a 100-year service life.
Structural Versatility
The 2.8-mile-long bridge features the third-longest, continuous, segmental, box-girder superstructure in North America, with eleven spans at lengths up to 350 feet. The forty-four approach spans use virtually identical precast concrete bent caps and cylinder piles, and the bridge’s foundation consists of 669 precast concrete piles, totaling over twelve miles.
Precast offers the structural versatility needed to meet critical, high-performance measures while reducing the need for other materials and maximizing freedom for designers. The prefabrication of concrete in a factory-controlled environment guaranteed that every pour met the owner’s expectations, both aesthetically and structurally.
Minimal Site Disruption
The remote job site had limited access for material delivery and often faced inclement weather and high winds. By choosing precast concrete over fresh concrete, the precast producer delivered structural elements to the job site just in time. The team accelerated installation and minimized disruption to the vulnerable barrier islands, lessening the risk of impact on the area’s legally protected animals and plants.
Throughout construction, extensive measures were taken to conserve wildlife, such as using the minimum number of driven precast concrete cylinder piles in the approach structures to reduce the impact on submerged, aquatic vegetation beds. The original bridge was mostly precast concrete, and it was broken down and deposited at several offshore, artificial reefs to provide new habitats for fish.
Learn More About Precast, Prestressed Concrete
Learn why precast was chosen for the Marc Basnight Bridge in the video above and share it with your industry peers and clients to convey the strength and durability of precast concrete.
Interested in learning more about precast and how the precasters of the PCI Mid-Atlantic Chapter support projects of all kinds? Explore the PCI Mid-Atlantic Solutions Center for helpful resources and get in touch with PCI-MA for precast information, higher education partnerships, and more.
