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
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