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Bridge in Washington State collapses 6

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KIRO news from Seattle just had a Washington DOT representative state an over height vehicle struck the bridge and caused it to collapse. Well see if that story hold up.
 
any preliminary views as to what caused the collapse? span looks to have been simply supported. i'm not a bridge engineer but is that the norm for multi span bridges these days?

no fatalities it seems thankfully
 
Initial speculation is an overheight vehicle hitting the upper portion of the bridge. This was an older bridge with laess than optimal clearance for today's traffic. We'll see.

I also noticed some plants growing at the river pier by the rocker supports - not a good sign of proper maintenance in my opinion.

Mike McCann
MMC Engineering

 
Apparently an oversized load truck was heading southbound in the slow llane instead of the lane to the left where the clearance was greater, and hit one or more of the curved crossmembers above. The collapse followed VERY soon after that, apparently.

Mike McCann
MMC Engineering

 
thanks mike. looking at photos of the bridge it appears that the curved cross members are present on all of the spans. if so, i wonder did the driver move across to the middle land after crossing the first span or are the other spans in danger of collapse for the same reason?
 
Don't know yet...

Mike McCann
MMC Engineering

 
Buckled top chord compression member? It's hard to believe that a truck with an oversized load could hit the top (diaphragm) truss and buckle the whole thing. But there she lies in the water.
 
Facts:

1. Steel Warren truss with verticals, with steel and concrete deck structure, designed 1954 and constructed 1955.
2. Four 120' spans between concrete piers and abutments.
3. North 120'span failed.
4. Semi was hauling an oversized load and being proceeded with an escort vehicle used to verify the clearance height available.
5. Semi was traveling in the wrong lane - the slow lane, where the clearance was less.
6. The bridge had no height restriction signs posted.
7. In the State of Washington, for oversized loads, it is the responsibility of the transport company to get a state permit and verify all clearances along their proposed route.

Don't know of a Bailey bridge triple-triple will work for this span, but with load restrictions and special applications, it might work on a temporary basis, at least for emergency vehicles - the state does have a stockpile of BB parts.

Bridgebuster: Were you driving the semi? [rofl]

Seems like this is the perfect example of what results from a lack of redundancy, unless there is more to the problem than meets the eye here, which is very, very possible. Being such a critical bridge for commerce in the area, and since it is of older construction, designed and built in the early days of the Interstate Highway system under Eisenhower, it would have been prudent, if the bridge was not going to be updated, to do one or the other of the following two things:

1. Post the height restriction in an bodaceously visible spot, and/or
2. Construct a steel or concrete overhead warning barrier for over the height limit vehicles so that they are damaged and not the bridge. This could have been so easily prevented.

Too bad it's too late now. $15 million to replace at a minimum, and guess who pays for it....

Mike McCann
MMC Engineering

 
Height barriers? But you have so many more important things to deal with in WA...legal pot, gay marriage, etc.
 
Yea, and Ron told me that you were planning to relocate after you heard the news Hokie!

Mike McCann
MMC Engineering

 
15 million?

I'm not sure you could even get the enviro permits and the drawings for a government design decision nowadays for 15 million.

250 million minimum. Full rebuild and disposal of the old (laed-painted) steel and water/dredging/enviro permits for disposal of the submerged steel and new waterway dredging? 800 million more likely. Union state ya know.
 
Mike - I innocent (this time, stuck n traffic on I280 in New Jersey
 
I hit the send button by accident woofer correcting my errors. I reiterate my innocence.
 
I did it again.
 
I read an article where the State of Washington rates the bridges on a 0-100 scale (0 being the worst), and that any below 50 are slated for demolition... the collapsed bridge rated 47... so, just hastened the replacement...

Dik
 
I just passed over the Snohomish River Bridge on Highway 9 here, and it was posted at both ends at 14'8" in bright yellow signs. This bridge is of similar design and vintage and 0 to 100 rating - in the low 50's too I believe.

I just cannot fathom why this bridge, on a state highway, and of a higher clearance, is posted, but the interstate bridge over the Skagit River, a lower clearance, was not.

The only thing I can figure is that the State and Federal regs are not the same regarding posting of clearances.

Oh and the 15 million was the figure the Governor mentioned, and only for a replacement of the section that collapsed, not a complete replacement.

Anyone found where Mr. Bailey lives yet?

Bridgebuster: How much did you pay to have this done? :)

.

Mike McCann
MMC Engineering

 
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