NCDOT requested A&O to design for top-down construction methods. However, since the main spans of each bridge exceeded the standard span length for top-down construction, A&O evaluated the structure spans for various cranes – up to a 150-ton HSL Crawler Crane – and provided calculations to NCDOT for review and approval.

Bridge 121 was designed with three spans of cored slabs for a total length of 147.5 feet, end bents on piles, 90-degree skew, and roadway clearance of 30’-10” superelevated.

Bridge 123 was designed with three spans of cored slabs for a total length of 132.5 feet, end bents on piles, 90-degree skew, and roadway clearance of 30’-10” superelevated.

Bridge 80 was designed with three spans of cored slabs for a total length of 162.5 feet, end bents on piles, 90-degree skew, and roadway clearance of 30’-10” normal crown. Additionally, 21-inch thick cored slabs were used at the end spans, while 24-inch thick cored slabs were used for the main span. The bents accommodated the three-inch thickness difference.