Sabo Bridge failure due to dramatic cable vibrations unaccounted for by engineers [VIDEO]

The city and county are pinning blame for Sabo's failure on URS Corp.
The city and county are pinning blame for Sabo's failure on URS Corp.

In March, we brought you video of the Martin Olav Sabo Bridge cables playing "The Wind Cries Mary," and wondered if the cable's ability to play air guitar could've had anything to do with them giving way weeks earlier.

It seems pretty obvious that if you're going to build a bridge with loose cables that vibrate like guitar strings, you'd account for that in your design calculations, right? Well, if you're San Francisco-based URS Corp. -- the same engineering consultant that worked on the Interstate 35W bridge before it collapsed in 2007 -- apparently not.

Today, in a press release reporting the preliminary findings of an investigation into the Sabo Bridge's February failure, Hennepin County and the city of Minneapolis wrote that "wind-induced cable vibrations caused fatigue cracking in the diaphragm plates resulting in two cable connections fracturing." The release also notes that "cable vibrations were not included in the original design calculations package." Doh!

The Star Tribune reports that URS Corp. is seeking an engineering contract related to the Southwest Corridor Light Rail line, but officials with the Metropolitan Council said earlier this week they wanted to examine the Sabo Bridge report before making a decision on the bid. A word of unsolicited advice -- after the 35W and Sabo Bridge debacles, perhaps it'd be wise to try another firm for a change?

The Sabo Bridge is now reopened, though permanent repairs to the cracked plates have yet to be made. Be sure to wear your helmets, ya'll!

If you missed it a few months ago, here's the video of the Sabo Bridge's cables vibrating like they were just plucked by Jimi himself -- vibrations that the renown engineers at URS apparently overlooked when designing the bridge.

Related coverage:
-- Video: Sabo Bridge cables vibrate like guitar strings, July 2011
-- Balky Sabo bridge consultant same firm that consulted on I-35W bridge before it collapsed

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