- Pennsylvania Department of Transportation, District 6-0
- Montgomery County, Pennsylvania
- Our Role
- Geophysical Investigation.
- Identified the root cause of 44 of the 52 reported sinkholes along I-476
- Findings assisted engineers in selecting the best approach to remedial reconstruction.
The section of I-476, known as the Blue Route, is the primary north-south Interstate corridor through eastern Pennsylvania. The section between the Schuylkill Expressway (I-76) and the Mid-County Turnpike Interchange (I-276), in Montgomery County, Pennsylvania, was constructed in the 1970's and has a history of sinkhole activity. It comprises six lanes and carries approximately 100,000 vehicles daily.
The highway between mile markers 17 and 19 is underlain by karst terrain prone rock formations. Between 2005 and 2007, sinkholes were found in the north and southbound shoulders.
- MASW survey was conducted on a 3,500-foot-section of the southbound inside lane of the reinforced concrete roadway during the course of three nights
- Surveyors worked between 10:00 p.m. and 5:30 a.m., averaging approximately 800 linear feet of continuous data each night
- The MASW survey explored to a depth of approximately 80 feet below grade, a difficult or impossible task by other geophysical profiling methods.
- MASW is a non-invasive, non-destructive, continuous profiling method.