Storrow Drive Tunnel Testing, Monitoring, and Rating

Boston, MA

Completion

2013
Storrow Drive Tunnel Testing, Monitoring, and Rating Boston
Storrow Drive Tunnel Testing, Monitoring, and Rating Boston
Storrow Drive Tunnel Testing, Monitoring, and Rating Boston

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 date of the Interim Repairs project.

 

Scope | Solutions

 

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

  • Performed a proof-of-concept prototype instrumentation and initial load-testing program

  • Installed strain/temperature gauges on steel roof beams in two areas of the main tunnel and one area at the Berkeley Street Underpass

  • Monitored roof-beam strains and collected long-term data about temperature-induced stresses

  • Performed finite-element-analyses (FEA) and calibrated the FEA model with results from load tests on three instrumented areas of the roofs

  • Computed a bridge-type rating of the various steel beams and reinforced concrete roof sections of the two tunnels

  • Revised the design of roadway grading, drainage, etc., to reduce the overburden, mainly comprising asphalt pavement, on the roofs

  • Revised the bridge rating based on the reduced dead load

  • Installed a semi-automated, groundwater monitoring system in the vicinity of the tunnels that already use the existing array of DCR wells

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