Three-tonne concrete panels fell from the roof of Boston’s Big Dig cross-city tunnel, killing a woman in a car and shutting down a section of the massive US building project.
The woman was a passenger in a car hit by debris from the roof late yesterday, authorities said.
A man believed to be the driver was able to squeeze out and was taken to a hospital with minor injuries, authorities said.
Authorities say safety has not been compromised by problems with the $14bn (€11bn) Big Dig highway project, which buried Interstate 93 beneath the centre of the city and extended the Massachusetts Turnpike to Logan Airport.
Massachusetts State Police said that stretch would be closed indefinitely while authorities cleaned up debris and inspected the area.
In a news conference early today, Massachusetts Turnpike Authority Chairman Matthew Amorello said the ceiling collapse was caused by a steel tieback giving way. The tieback held a 40-foot ceiling section in place over Interstate 90.
“There was a snapping sound heard,” Amorello said. “One of the tile panels from the roof released. It caused a series of panels to be released.”
Amorello said he’s confident there is only one 200-foot section of the Big Dig project where the type of tieback that failed were used. Those ceiling panels were erected in 1999.
“Any responsible party will be held accountable for what happened,” Amorello said. “This is an unacceptable, horrible tragedy.”
The accident happened about 200 feet from the end of the connector tunnel. The site is near the entrance to the TedWilliams Tunnel, which goes under Boston Harbour to Logan International Airport.
Shortly after the accident, at least three large pieces of debris, tilted slightly at one side, were lying across a lane of the roadway about 100 feet from the end of the connector tunnel.
There have been water leaks in parts of the tunnel system and at least one incident when smaller amounts of dirt and debris from an airshaft in another section of the tunnel system fell onto travel lanes, causing minor damage to cars.
In May, prosecutors charged six current and former employees of a concrete supplier with fraud for allegedly concealing that some concrete delivered to the Big Dig was not freshly mixed.
State and federal officials said any effects on maintenance would likely be long-term, and did not pose an immediate safety threat.
Amorello said preliminary investigation showed that the quality of the concrete was not to blame for the fatal accident.