Project Detail

Mystic River Bascule Bridge Rehabilitation

Stonington & Groton, CT

This project has received ABC, ENR, ACEC, and SSPC Awards.

Scope of Work

Cianbro rehabilitated the structural steel, mechanical and electrical systems, replaced the control house, and performed realignment of the Historical Mystic River Bascule Bridge, which was originally built in 1922.

Project Details

  • Jacked the counterweights to realign the counterweight truss
  • Replaced the counterweight trunnion bearings
  • Replaced the balance links and associated bearings
  • Replaced the electrical systems including the main drive motors, braking systems, controls, lighting, traffic signals, gates, and the closed circuit television monitoring system, then installed a stand-by generator
  • Replaced the drive machinery and realigned the main pinion and bull wheel bearings
  • Replaced the control house and support steel; then removed the existing motor houses and relocated the motors to their original location with the drive machinery
  • Performed a detailed rebalancing using strain-gauge analysis of the moveable bridge structure and mechanical components after all mechanical and structural upgrades were completed
  • Blasted, cleaned, repaired and painted the structural steel
  • Installed a hydraulically operated vehicle barrier gate at the east approach
  • Removed and replaced 320 linear feet of submarine cable
  • Repaired the fender system and installed scour monitor devices
  • Replaced the bridge railing on the east span and extended it to the approaches on the north and south sides of the road
  • Removed and replaced concrete counterweight protective coating
  • Repaired the stone wall and east abutment

Lean, Innovative, and Unique Project Solutions

Located in Mystic’s downtown tourist district, the bridge rehabilitation was phased over the course of three winters in an effort to minimize disruption to the community and local businesses. It was also completed concurrently with, and adjacent to a major streetscape expansion project.


ABC National Excellence in Construction Eagle & Productivity Awards
ABC Connecticut Excellence in Construction Award
ENR New York Best Project Award
ACEC Connecticut Engineering Excellence Award
SSPC George Campbell Award