The Big Dig is a restructuring of roads and tunnels in Boston, Mass. In July 2006 about 26 tons of concrete ceiling panels fell on a car in a tunnel, killing a passenger. The panels were secured to the ceiling by steel bolts. Epoxy resin was used to prevent the bolts from loosening. Unfortunately, the grade used was not appropriate for the application. This paper is based on the 2007 report of the National Transportation Safety Board.
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