Medford, MA

Auburn Street Bridge, Mystic Valley Parkway


The Auburn Street Bridge spans the Mystic River. Constructed in 1906, the single-span concrete arch bridge has abutments that act as large-spread footings. Undermining of the abutments and wing walls caused by scour, raised concerns that the bridge would not be able to survive a 500-year flood. As part of an on-call engineering services contract with the Commonwealth of Massachusetts Department of Conservation and Recreation, SGH evaluated potential scour effects and designed countermeasures to protect the bridge foundation during extreme floods.

SGH investigated the potential for foundation scour and determined that a 500-year flood could severely compromise the bridge abutments. We recommended and designed river bed armoring with an articulated concrete mat that extended approximately 25 ft upstream and downstream of the bridge. As part of the rehabilitation project, SGH performed the following services:

  • Prepared all required permitting documents
  • Attended meetings with appropriate agencies
  • Designed the restoration and reattachment of missing cast-stone parapet capstones salvaged from the river
  • Oversaw landscaping subconsultant’s design, which completely restored the construction area in the parkland adjacent to the bridge
  • Provided engineering consultation during construction of the scour protection system
  • Resolved issues that arose when contractors discovered a 2 ft deep by 30 ft long scour hole that threatened to undermine one of the abutments

Project Summary



Completion Date
Repair & Rehabilitation
Infrastructure & Transportation
Massachusetts Department of Conservation and Recreation
Specialized Capabilities
Marine & Civil Works | Geotechnical

Key team members

Paul Kelley
Paul Kelley
Senior Principal