Download - Moffatt and Nichol Engineers

Virginia Dare (Manteo Bypass) Bridge over Croatan Sound
Moffatt & Nichol served as subconsultant for a new $106 million, 8.4-km-long bridge crossing Croatan Sound, North
Carolina. Moffatt & Nichol performed a Vessel Impact Study and Hydraulic Analysis and Design that were used for
both the conventional and segmental bridge design alternatives. For the conventional alternative, Moffatt & Nichol
also provided Substructure and Foundation Design.
For the conventional bridge alternative, Moffatt & Nichol provided a substructure & foundation study; preliminary &
final design, and contract drawing preparation. The Bridge Type Study involved determination of the most economical
foundation types for each superstructure span alternative and determined a minimum pile size and number of piles
per bent required for three prestressed concrete pile alternatives. Bents were evaluated and designed for economy based
on AASHTO load group considerations, soil regions, probability of vessel impact, and variable scour depths based on
foundation type. Moffatt & Nichol then completed final design for both a conventional substructure alternative and a
prestressed cylinder pile alternative.
Additional structure design tasks included preparation of opinions of probable costs, evaluation of precast concrete substructure
elements, pier alignment study, and preparation of project special provisions for special foundation types.
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Owner: North Carolina
Department of Transportation
Location
Dare County, North Carolina