WASHINGTON (AP) – Federal investigators are examining a wide variety of possible causes of the deadly Big Dig tunnel ceiling collapse, including whether nearby construction could have shaken loose the panel bolts, and the state’s criminal probe is honing in on the project’s manager.
The National Transportation Safety Board is looking into whether vibrations from nearby construction projects – from activities such as blasting, movement of heavy equipment or the pounding of metal beams – could have contributed to the ceiling panel collapse, lawmakers who were briefed on the probes said Thursday.
U.S. Rep. Michael Capuano, D-Mass., said federal officials sounded skeptical that nearby construction could have caused the July 10 accident, but he said they were not ruling it out until they had more evidence.
“They said, We don’t think it’s the cause, but we are going to check it,”‘ Capuano said. “They are looking at every single step and every aspect at this point.”
Federal officials have issued 12 subpoenas to Big Dig contractors, subcontractors and others, according to U.S. Rep. Stephen Lynch, D-Mass. The subpoenas closely mirror ones that state Attorney General Tom Reilly has issued in his criminal probe that he said could result in involuntary manslaughter charges.
Much of the focus of the investigations has been on epoxy-bolt fasteners that anchored the ceiling panels in some of the tunnels. More than 1,300 of those fasteners failed “pull tests” in the past two weeks.
Reilly said Thursday he was focusing on the work of project manager Bechtel/Parsons-Brinckerhoff, and its limited liability contracts with the state, though he emphasized no one involved was “off the hook.”
“The relationship between Bechtel and the Commonwealth of Massachusetts will not shield Bechtel or anybody or anyone who has been involved we find they disregarded obvious, obvious risks,” he said.
Reilly said some of the 40,000 documents gathered so far in his probe make it clear project officials were concerned as far back as 1999 about whether the epoxy anchor bolt system could support the three ton ceiling panels.
“Now we have to find out, what did they do about it?” he said.
A spokesman for the company did not immediately return a call for comment.
Gov. Mitt Romney said Thursday that crews tested two bolts Wednesday night in the Ted Williams tunnel. The bolts, which were rated by their manufacturer to withstand 5,600 pounds of pressure, were pulled at 8,400 pounds of pressure and held at that 150 percent rating level.
He said if the testing pattern continues, it would suggest individual bolt failures, but not a system failure.
“That would mean a need for ongoing inspections at a very high level and a frequent level, but it would not mean a requirement to completely reconstruct the ceiling structure in the Ted Williams tunnel,” Romney said.
Members of the Massachusetts congressional delegation were briefed behind closed doors on Capitol Hill on Wednesday about the probes by the NTSB and the U.S. Department of Transportation Office of Inspector General.
NTSB officials stressed they were simply outlining a range of possible causes and that they were at an early stage in their investigation.
“I just don’t believe vibration from other construction projects had anything to do with it,” said Rep. Stephen Lynch, D-Mass. “I tend to think there might be something more fundamental that was wrong. We’re just surmising at this point.”
The NTSB also is investigating whether the bonding strength of the epoxy used to secure the ceiling panel bolts could have been weakened by freezing temperatures, faulty installation or other factors. The falling panels crushed a passing car, killing Milena Del Valle, 39, of Boston.
One such factor cited by the NTSB was whether the diamond-tipped bits used to drill holes for the bolts may have created a smooth surface that did not allow the epoxy to bond properly. Carbide bits create a rougher surface that enhances the epoxy’s adhesive strength, Lynch said.
A team of experts is being assembled by the NTSB to analyze the chemical composition of the epoxy, he added.
Lawmakers said officials told them concrete was probably not an accident cause.
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Associated Press reporters Denise Lavoie and Jay Lindsay in Boston contributed to this report.
AP-ES-07-27-06 1620EDT
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