One aspect of Scott Allen and Sean Murphy’s Big Dig story in today’s Globe strikes me as a significant advance in our understanding of what went wrong. They write:
In the end, the connector tunnel got a ceiling like few others in the United States, counting on bolts that essentially have been super-glued into the roof to each suspend 2,600 pounds of concrete. [University of Texas professor David] Fowler and other outside experts could name only one other tunnel, in Virginia, that used a similar bolt system for such a heavy ceiling, and they say few are likely to be built in the future because of the Big Dig’s problems.
Haven’t we been told from the beginning that the epoxy-and-bolt system of connecting those concrete panels was actually a tried-and-true technique used in many projects around the country? Indeed, at one point the Big Dig accident raised the specter of massive, nationwide inspections.
The Globe story casts serious doubt on that assertion, and raises the distinct possibility that the fatal accident of July 10 wasn’t just the result of incompetent workmanship but also of a deeply flawed design.
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alkali
The Globe story casts serious doubt on that assertion, and raises the distinct possibility that the fatal accident of July 10 wasn’t just the result of incompetent workmanship but also of a deeply flawed design.Indeed, query whether “incompetent workmanship” deserves blame at all. If a building will fall down if every single nail used in its construction isn’t driven precisely correctly, the problem is not with the contractor but with the architect.
Steve
What Alkali said.How many bolt assemblies in the connector tunnel roof were found to be defective? Over 1000? This is not a case of workmanship – this is an engineering design failure.
Anonymous
not sure how you come to that conclusion based on the words in the story. could be that the design was ok, but only if the work were carried out perfectly. could it be that the reason the design was bad was that it assumed the workmanship would be top notch? the union that did this work was the laborers, at a time of more than full-employment. these weren’t all jouneymen up there doing the drilling…
Anonymous
Dan: You’re missing some nuance here. I think what the Globe story is saying is that what’s unique about this tunnel ceiling is the weight of the panels, not how they’re anchored to the ceiling. My understanding is that the epoxy bolt system IS quite common throughout the country, but everywhere it’s used you have much lighter ceiling panels [like in the Ted Williams Tunnel].