Cabin John Bridge

Client

Department of Army Corps Of Engineers

Location

Washington, D.C.

Key Challenges & Project Details

  • The Cabin John Bridge (Union Arch Bridge), completed in 1864, is designated as a Historic National Civil Engineering Landmark by the ASCE, and is listed in National Register of Historic Places
  • Until 1903, it was the longest, single span, masonry arch in the world
  • The Cabin John Bridge, by original design not a bridge at all, carries an 8’ diameter aqueduct over Cabin John Creek and Cabin John Parkway, as well as roadway
  • Still used today to convey drinking water from Great Falls, Maryland, over Cabin John Creek and Cabin John Parkway, to Washington, DC.
  • All work conducted under the intense scrutiny of local residents, the local historical society and the US Army Corps of Engineers
  • Contract involved replacement of the bridge deck and large-cut stone parapet elements
  • The aqueduct, the main water supply for Washington, DC, had to remain operational during construction
  • Bridge access was extremely limited due to the road’s 15-ton maximum weight capacity
  • Demolition work took place from 9pm – 5am to minimize hazards to motorists on roadway below bridge
  • Bridge work was elevated 100’ over Cabin John Parkway and included specialty items such as an in-house designed swing scaffolding system, cast-in-place concrete, stone masonry, and architectural ornamental detailing iron
  • The project required complete closure of a major artery between Bethesda, MD, and Georgetown, in Washington, D.C., dictating a tight rebuild schedule
  • Corman completed the project 5 days ahead of schedule in only 101 days