Cianbro replaced 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 was replaced on a new foundation, with a similar aesthetic and the same draw width as the existing bridge built in 1953. The project’s purpose was to ensure safe passage by providing a structurally stable roadway for the traveling public. Specifically, the project involved the replacement of the existing bridge along with associated roadway improvements and incidental items. Consistent with the existing bridge structure, the new bridge provides an 80+ foot wide navigation channel with 10 feet of clearance in the closed position (ordinary high water) and unlimited vertical clearance when open.

• Cianbro:
  • Designed/procured/erected a temporary movable bridge
  • Shifted traffic to the temporary bridge and demolished the existing double-leaf bascule bridge
  • Constructed two new bascule piers founded on bedrock within sheet pile cofferdams
  • Installed mechanical, electrical, and hydraulic bridge components for the movable spans
  • Erected the new double leaf bascule steel
  • Constructed micro pile supported abutments and barrier gates
  • Erected two approach spans
  • Erected a new operator's house with associated architectural elements
  • Started up and commissioned the new bridge
  • Switched traffic to the new bridge and removed the temporary bridge

Due to the excessive traffic detour distance, a temporary bridge was established during construction of the new bridge. The temporary bridge (single leaf bascule) provided two lanes of vehicular traffic and had a 40-foot wide navigation channel. In the closed position, the under clearance is 10 feet (ordinary high water).