Tuesday, January 23, 2018


Scope of Work
Cianbro constructed a new 426 ft 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 ft of Route 9
  • Blasted 8,500 cy of rock to construct the west (VT) abutment and wingwalls
  • Constructed a 61 ft by 73 ft 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 ft 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 eighteen 43 to 57 ft 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

Unique Challenge

The Cianbro team designed an innovative, overhead, cable-stay temporary support structure to help erect the 43 to 57 ft 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.

Project Information

State of New Hampshire Department of Transportation

Type of Project:

Construction Schedule:
Completed October 2003

Chesterfield, NH & Brattleboro, VT
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