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Big Dig tunnel collapse blamed on adhesive

Big Dig tunnel collapse blamed on adhesive

BOSTON—A fatal ceiling collapse in Boston's "Big Dig" tunnel a year ago stemmed from an epoxy adhesive used in the tunnel's construction, the National Transportation Safety Board concluded last week.

In July 2006, a Boston woman who was a passenger in a vehicle traveling through the Interstate 90 connector tunnel was crushed when a section of concrete panels weighing about 26 tons detached from the tunnel roof.

The NTSB, which laid blame on many fronts, said its full report on its investigation into the accident would be released in coming weeks.

In a synopsis released last week, though, the Washington-based agency stated the probable cause for the ceiling collapse was "an inappropriate use of an epoxy anchor adhesive," which over time deformed in a process called "creep" to the point where several of the tunnel's ceiling support anchors pulled free and caused a portion of the roof to collapse.

Following the accident, the Big Dig--widely regarded as the largest, most complex highway and tunnel project ever undertaken in the United States--underwent a complete safety review. The tunnel's last remaining section, which had been closed to the public, finally reopened last month.

According to the NTSB, blame for the accident rests with companies involved in the tunnel construction, including: Bechtel/Parsons Brinckerhoff, Gannett Fleming Inc., Modern Continental Construction Co. and Powers Fasteners Inc.

"The Massachusetts Turnpike Authority also contributed to the accident by failing to implement a timely tunnel inspection program that would likely have revealed the ongoing anchor creep in time to correct the deficiencies before an accident occurred," the NTSB said in a statement. The accident further stemmed from "a general lack of understanding and knowledge in the construction community about creep in adhesive anchoring systems."

The NTSB said Bechtel, Modern Continental and the Massachusetts Highway Department should have monitored performance of the anchors given that the "anchor creep" was noticed as early as 1999.

In a statement, San Francisco-based Bechtel said: "NTSB has performed a thorough and objective investigation of this tragic accident. We look forward to reviewing its final report."

However, Brewster, N.Y.-based Powers Fasteners said in a statement that while the ceiling panel collapse and death of Milena Del Valle "cry out for explanation and accountability," "it would be an untenable conclusion if the federal investigators were to consider Powers Fasteners in any way responsible, since there is overwhelming evidence that fault lies elsewhere."

Cambridge, Mass.-based Modern Continental declined comment, and Harrisburg, Pa.-based Gannett Fleming could not be reached.

The potential liability in the tunnel collapse and whether related losses will be covered by the parties' insurance coverage remain to be seen.

Shortly after the accident, the MTA said it had an all-risk property program with a $550 million limit over a $10.5 million retention that would cover a tunnel ceiling collapse (BI, Aug. 7, 2006). That program also covered lost toll revenue stemming from roadway closures. The MTA said it also had liability coverage with a $50 million per occurrence and policy-aggregate limit, along with a separate program with a $200 million limit covering construction that insures the MTA and several Big Dig contractors.

Last November, then-Massachusetts Attorney General Thomas F. Reilly filed a civil lawsuit against 15 companies involved in the management, design, oversight and construction of the tunnel. That suit names Bechtel/Parsons Brinckerhoff, Modern Continental, Gannett Fleming, Powers Fasteners and several epoxy distributors.

The suit also names Modern Continental's surety coverage providers: Fireman's Fund Insurance Co., United States Fidelity & Guaranty Co. and National Surety Corp.

Additionally, current Attorney General Martha Coakley is considering pursuing criminal charges, a spokesman said.

Furthermore, a wrongful death lawsuit on behalf of Ms. Del Valle's family is pending against companies involved in the tunnel construction.

Jeffrey A. Denner, an attorney with the Boston-based law firm of Denner Pellegrino L.L.P. and who represents the family, declined to comment on the status of the suit and whether a settlement is in the works.