12. The “Big Dig Ceiling Collapse” of 2006 saw 26 tons of debris crush a car traveling through the Fort Point Channel Tunnel in Boston
On July 10, 2006, a concrete ceiling panel along with debris weighing 26 tons suddenly collapsed and fell into the Fort Point Channel Tunnel, in Boston, Massachusetts. Crashing onto a two-lane exit ramp connecting the major freeways I-93 and I-90, the falling debris crushed an unfortunate car situated below, killing a passenger and injuring the driver. The Big Dig project throughout Boston was delayed by a year as a result of the incident, with a total of $28 million paid out to date in compensation by the construction companies responsible.
A product of fundamental architectural faults, the ends of the main tunnel were built earlier than the east ends of the connector tunnels to enable the bridge atop to be constructed sooner. As a result, these end sections were never designed to accommodate the ceiling that was ultimately used. Each panel consisted of bolts anchoring the concrete to the roof; as one failed, more followed suit in a chain reaction that triggered the fatal collapse. This system had been used in the Ted Williams Tunnel and identified as early as 1998 as retaining significant problems, but countermeasures including epoxy glue proved ineffective due to sub-standard adhesives used by constructors.