U.S. 70 Bridge Over Gallants Channel

Beaufort, North Carolina

The U.S. 70 Bridge over Gallants Channel replaces the structurally deficient Grayden Paul bascule bridge . The North Carolina Department of Transportation (NCDOT) engaged Michael Baker to design the replacement structure. Our team designed a 3,400-foot-long fixed-span bridge to carry the four-lane divided highway over the channel. The project significantly reduces travel delays and increases capacity of U.S. 70 through the town of Beaufort.

The design of the new Gallants Channel Bridge posed several challenges, requiring the analysis of multiple substructure and foundation configurations to best accommodate vessel traffic on the channel, meet external loading conditions and provide the most cost-efficient span arrangement.

To meet these challenges, our team designed a post-tensioned, spliced Bulb-Tree main span configuration of five pre-stressed concrete-girders. The structure was designed with a 65-foot vertical clearance to eliminate the need to raise and lower a drawbridge, providing a continuous flow of traffic on U.S. 70 and its feeder roads and significantly reducing the potential for vessel collisions on the channel below. To provide additional corrosion protection, we detailed the use additional clear-cover, epoxy-coated reinforcing steel and concrete additives/corrosion inhibitors in concurrence with NCDOT standards.

The design of the new bridge also reflects a commitment to minimizing impacts to the sensitive environmental areas within the project footprint. This commitment is reflected in a complex closed-drainage system, which includes multiple longitudinal and transverse trunk lines that collect drainage spread and prevent direct discharge into the waterway. Because the median barrier and super‐elevated cross-section change directions over the length of the bridge, we designed downspouts and trunk lines in multiple locations to collect the water.