North Hero – Grand Isle Drawbridge

North Hero & Grand Isle, VT

Scope of Work

Cianbro is replacing Bridge 8, a historic double leaf bascule bridge that carries U.S. Route 2 over Lake Champlain between the towns of North Hero and Grand Isle. Bridge 8 is the only vehicular movable bridge in the state of Vermont and will be replaced on a new foundation, with similar aesthetic and the same draw width as the 1953 bridge being replaced. The project’s purpose is to ensure safe passage by providing a structurally stable roadway for the traveling public. Specifically,the project involves the replacement of the existing bridge along with associated roadway improvements and incidental items. Consistent with the existing bridge structure, the new bridge will provide an 80+ ft wide navigation channel with 10 ft of clearance in the closed position (ordinary high water) and unlimited vertical clearance when open.

Project Details

  • Cianbro will:
    • Design/Procure/Erect a temporary movable bridge
    • Shift traffic to the temporary bridge and demolish the existing double leaf bascule bridge
    • Construct two new bascule piers founded on bedrock within sheet pile cofferdams
    • Install mechanical, electrical, and hydraulic bridge components for the movable spans
    • Erect the new double leaf bascule steel
    • Construct micro pile supported abutments and barrier gates
    • Erect two approach spans
    • Erect a new operator's house with associated architectural elements
    • Start up and commission the new bridge
    • Switch traffic to the new bridge and remove the temporary bridge

Lean, Innovative, and Unique Project Solutions

Due to the excessive traffic detour distance, it has been determined that a temporary bridge will be established during construction of the new bridge. The temporary bridge (single leaf bascule) will provide two lanes of vehicular traffic and will have a 40 ft wide navigation channel. In the closed position, the under clearance will be 10 ft (ordinary high water). In the open position, there will be unlimited vertical clearance.