Boston, MA

Storrow Drive Tunnel Testing, Monitoring, and Rating


Constructed in the 1950s and carrying over 100,000 vehicles per day, the Storrow Drive Interchange is a major commuting route and link to Back Bay. The interchange includes two reinforced concrete tunnels with steel-framed and reinforced concrete roof sections, classified as bridges. The DCR was concerned about the weight of existing asphalt paving overburden on tunnel roofs. Through load testing, long-term monitoring, dead load reduction, and analysis, SGH helped the DCR safely and reliably extend the tunnels’ service life to approximately 10 yrs beyond completion of the Interim Repairs project.

Following our previous work for the Interim Repairs project, SGH assessed the tunnel roofs’ safe load-carrying capacity. We developed a Comprehensive Instrumentation Program, including long-term monitoring and load testing to observe the roof’s in situ behavior. SGH oversaw a team of subconsultants and highlights of our work include:

  • Performing proof-of-concept prototype instrumentation and initial load-testing
  • Installing strain/temperature gauges on steel roof beams in two areas of the main tunnel and one at the Berkeley Street Underpass
  • Monitoring roof-beam strains and collecting long-term data about temperature-induced stresses
  • Performing finite-element-analyses and calibrating the models with results from load tests on three instrumented areas of the roofs
  • Calculating a bridge-type rating of the various steel beams and reinforced concrete roof sections of the two tunnels
  • Redesigning roadway grading, drainage, etc., to reduce the overburden, mainly comprising asphalt pavement, on the roofs
  • Revising the bridge rating based on the reduced dead load
  • Installing a semi-automated, groundwater monitoring system in the vicinity of the tunnels that already use the existing array of DCR wells

Project Summary



Completion Date


Construction Value
Repair & Rehabilitation
Structures | Applied Science & Research | Advanced Analysis
Infrastructure & Transportation
Department of Conservation and Recreation (DCR)
Specialized Capabilities
Marine & Civil Works | Buried Infrastructure | Physical Testing

Key team members

Rosalind Imbaro
Rosalind Imbaro
Senior Project Manager