DFI ACTIVITIES 2019 Outstanding Project Award Winner: Marc Basnight Bridge This year’s DFI Outstanding Project Award (OPA) is being bestowed to the team of HDR (engineer), PCL Civil Constructors (general and foundation contractor) and North Carolina Department of Transportation (owner) for the 2.8 mi (4.5 km) long Marc Basnight Bridge in the Outer Banks, N.C. The new bridge replaces the Herbert C. Bonner Bridge and was designed to provide a 100-year service life, resist unprecedented scour depths and minimize environmental impacts while offering a reliable, safe passageway. The award is at the DFI 44 Annual Conference on Deep Foundations in Chicago, Ill. Using first-of-their-kind design and being presented on Thursday, October 17, th transition spans, and provided the required strength and durability. To address the concern of how to drive large displacement piles through dense sand, the team developed innovative jetting installation methods. The need to optimize the design led to the extensive use of refined soil-structure interaction analyses. The approach spans, with significantly less scour and ship construction methods, the new bridge conquers the Oregon Inlet, offers a lifeline to Hatteras Island and was built with minimal environmental impacts in a sensitive ecosystem. The bridge is capable of resisting wind, wave and vessel collision forces from the worst storms the Atlantic Ocean offers, all while subject to unpre- cedented scour depths. The new bridge is subject to 12 ft/s (8 mph or 13 kmh) currents, winds up to 105 mph (170 kmh) and vessel impacts up to 2,151 kips (9.6 MN). The foundations for the new bridge were designed to resist scour as deep as 84 ft (25.6 m) below sea level. The bridge foundation design was key to project success, but The 2019 Outstanding Project Award (OPA) is being awarded to the team of HDR, PCL Civil Constructors and North Carolina DOT for the Marc Basnight Bridge. impact loads, are supported by highly-efficient foundations with three or four 54 in (1,372 mm) diameter vertical concrete cylinder piles. The transition spans and the high-level, long- navigational spans use a combination of cast-in-place reinforced concrete pile caps with six to thirty, 36 in (914 mm) square concrete piles in a battered configuration to provide greater lateral resistance against wind and ship impact loads under deeper scour conditions. In total, there are 690 piles measuring more than 15 mi (24.1 km) in total length of piles installed. In 1997, DFI established the Out- standing Project Award (OPA) to recognize the superior work performed by its members on geotechnical, deep excavation and deep foundations related projects. During the evaluation process, consideration is given to the ingenuity of the design, the construction techniques used, how the design achieved the owner’s requirements, and how the project-specific geotech- nical conditions and challenges were met. also posed the greatest challenges. Driven, prestressed concrete piles were selected for the long spans as well as the approach and This project is being featured as the cover story in the next issue of this magazine. DEEP FOUNDATIONS • JULY/AUG 2019 • 23
