Route 9 Bridge Over the Connecticut River

Chesterfield, NH &Brattleboro, VT

Scope of Work

Cianbro constructed a new 426 feet steel arch bridge.

Project Details

  • Constructed the project adjacent to the existing historic steel truss bridge that will remain in place for pedestrian use
  • Realigned 4,200 feet of Route 9
  • Blasted 8,500 cubic yards of rock to construct the west (VT) abutment and wingwalls
  • Constructed a 61 foot by 73-foot sheet pile cofferdam with a soil-anchored tie-back system to construct the east (NH) abutment and wingwalls
  • Drove 132 pipe pile and placed a concrete mat footing to construct the NH abutment
  • Constructed a temporary support structure by erecting two 110 foot temporary steel towers at each abutment—using wire ropes and an anchoring system to tie back the towers—to erect the steel arch ribs
  • Erected 1,100 tons of structural steel including 18 ea. 43 to 57-foot sections of steel arch ribs weighing up to 35 tons each
  • Installed 28 hangar assemblies—four wire ropes each—to suspend the roadway superstructure from the steel arch ribs

Lean, Innovative, and Unique Project Solutions

The Cianbro team designed an innovative, overhead, cable-stay temporary support structure to help erect the 43 to 57 foot sections of arch ribs weighing up to 35 tons each. Erecting the steel arch ribs from barge-mounted cranes, this unique overhead system avoided impacting the waterway.