Maine Department of Transportation

Coos Bridge Fracture Critical Member Inspection

Byron, ME

Project Summary

Inspection of the Coos Bridge utilizing traditional inspection access such as under-bridge inspection vehicles or ladders was not possible due a 5-ton live load posting of the bridge and location in a deep valley. We utilized rope access techniques to provide the required NBIS Routine and Fracture Critical hands-on inspection. 

The Coos Bridge is a 50’ long single span through girder structure built in 1919 consisting of two rolled shape girders, four rolled shape floor beams and timber stringers and deck. To provide access for our inspectors, we retained a subconsultant to provide rigging of the bridge for rope access and completed the NBIS Routine and Fracture Critical inspection during the month of February. The rope access allowed for close up and hands-on inspection of the fracture critical bridge in accordance with NBIS criteria while not impacting traffic across the bridge. 


  • NBIS Bridge Inspection 
  • Report Preparation 

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