Jason Sandefur

Application error on the bolt-and-epoxy system of Boston’s Big Dig tunnels likely contributed to the ceiling collapse that killed a woman in 2006, investigators learned.
“Contractors apparently used the wrong adhesive to install at least some of the bolts in a Big Dig tunnel ceiling that partially collapsed last summer, project records show, prompting criminal investigators to focus on whether the mix-up was a significant factor in the accident,” wrote Scott Allen of the Boston Globe.
A public firestorm has put fasteners in the spotlight following the July 10, 2006, collapse of 4,600-pound ceiling panels that crushed a 39-year-old woman as she was riding in a car.
Construction crews reportedly used at least one case of “quick-drying epoxy” to install the bolts, contrary to design specifications.
“The distinction was crucial to the safety of the ceiling: The ‘fast-set’ epoxy holds 25% less weight than standard epoxy and is not recommended for suspending heavy objects overhead,” Allen reported.
State criminal investigators are examining the possibility that the weaker epoxy was used in the ceiling section that collapsed when 20 bolts popped out, according to the Globe. Investigators have collected more bolts for analysis.
“If [workers] used the wrong stuff, which appears to be the case, the issue is who knew about this or were they reckless about letting the project go forward with the wrong stuff?” said a consultant to one of the firms involved in the ceiling project.
To save time, Big Dig managers and designers eliminated half the ceiling bolts specified in the original ceiling design; likewise, bolts were safety-tested with a weight now regarded as too low, potentially allowing defective bolts to pass.
“If the bolts were held in place by fast-set epoxy, the ceiling would have had little, if any, margin of safety left,” Allen reported. “Bolts secured with fast-set epoxy could safely carry 4,285 pounds each, rather than the 6,350 pounds the designers had planned on, based on their final report to Big Dig managers on the ceiling.”
The woman’s family has filed a multi-million lawsuit against the main tunnel contractors, along with the fastening system’s distributor, wholesaler and manufacturer.
A review of records by the Associated Press determined that the bolts, about 5/8 of an inch in diameter and 6″ to 8″ long, had pulled out of drilled holes. Some of the bolts had no epoxy on them, while others had an uneven distribution of epoxy or epoxy that was discolored, according to AP.
Complicating the issue is a debate over design specs.
“All of the safety calculations are based on bolts secured by standard epoxy, but the design specifications don’t explicitly forbid fast-set, and the fact that fast-set can support less weight than standard epoxy is contained only in a footnote,” Allen wrote. �2007 FastenerNews.com