Experts Say Design Defect Caused Minn. Bridge Collapse

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Updated: Federal investigators are expected to announce today that a design defect caused the collapse of a Minneapolis bridge last summer, killing 13 and injuring more than 100 in a horrific accident that focused attention on bridge safety nationwide.

As an ABAJournal.com post soon after the accident details, steel gusset plates used in the construction of the bridge were immediately suspected as a possible cause. And, unnamed sources tell the Washington Post, National Transportation Safety Board investigators are expected to confirm today that some of the hundreds of gusset plates connecting the bridge’s angled steel beams did indeed fail, causing the collapse.

The gusset plates used to construct the 40-year-old Interstate 35 bridge were, as the Post puts it, neither “thick nor strong enough to meet safety margins of the era” in which the bridge was built, according to the newspaper’s sources. As additional weight was added to the bridge with subsequent renovation work, it eventually failed. (At the time of the Aug. 1 accident, a renovation project was under way that added heavy construction equipment to the usual bridge traffic.)

Failed gusset plates are not identifiable during ordinary bridge inspections, according to the newspaper. Hence, the Post reports, the NTSB “is expected to recommend at a news conference today that federal and state authorities conduct more rigorous engineering studies of gusset plates before beginning renovation projects on bridges in the future.”

As discussed in other ABAJournal.com posts, litigation is under way over the accident, with at least some law firms reportedly representing clients on a pro bono basis, and victims are seeking the creation of a 9/11-style compensation fund.

Associated Press: “NTSB says design flaw caused Minneapolis bridge collapse”

Los Angeles Times: “Minneapolis bridge part designed too thin”

Updated at 11:06 a.m., CST, on Jan. 16, 2008.

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