Troubled Big Dig tunnel scheduled to reopen

| Wednesday, November 01, 2006

One of the key tunnels in Boston's Big Dig will open as soon as next week, according to the Boston Globe.

The Interstate 93 tunnel, which connects the Massachusetts Turnpike with Logan International Airport, was one of several closed for inspection and repairs after a concrete ceiling panel collapsed and killed a motorist.

Meanwhile, according to the Globe, inspectors with the National Transportation Safety Board have found that the panel that collapsed was designed with a smaller margin of safety than most tunnel ceilings in the U.S.

Specifically, there were no beams attaching the panel to the walls, and only half as many bolts were used to attach the panel to the ceiling as were called for in the original design.

"No redundancy was built into the ceiling in the event the hangers failed," according to a preliminary report by the National Transportation Safety Board obtained by the Globe.

"The NTSB has researched other tunnels throughout the country and has found that significant redundancy is built into the ceiling design" so that the ceilings would not collapse when bolts fall out, the report said.

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