Bridge in Washington State collapses
Bridge in Washington State collapses
(OP)
Near Mt. Vernon: http://abclocal.go.com/ktrk/story?section=news/nat...
No real info yet.
No real info yet.
Brian C Potter, PE
http://simplesupports.wordpress.com






RE: Bridge in Washington State collapses
RE: Bridge in Washington State collapses
This cuts I-5 southbound at the Skagit River. Great, just great.
Mike McCann
MMC Engineering
RE: Bridge in Washington State collapses
no fatalities it seems thankfully
RE: Bridge in Washington State collapses
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
RE: Bridge in Washington State collapses
Mike McCann
MMC Engineering
RE: Bridge in Washington State collapses
RE: Bridge in Washington State collapses
Mike McCann
MMC Engineering
RE: Bridge in Washington State collapses
RE: Bridge in Washington State collapses
RE: Bridge in Washington State collapses
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?
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
RE: Bridge in Washington State collapses
RE: Bridge in Washington State collapses
Mike McCann
MMC Engineering
RE: Bridge in Washington State collapses
Shown most clearly in this pic: http://media.king5.com/images/600*338/052413-Mount...
Brian C Potter, PE
http://simplesupports.wordpress.com
RE: Bridge in Washington State collapses
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.
RE: Bridge in Washington State collapses
RE: Bridge in Washington State collapses
RE: Bridge in Washington State collapses
RE: Bridge in Washington State collapses
Dik
RE: Bridge in Washington State collapses
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
RE: Bridge in Washington State collapses
RE: Bridge in Washington State collapses
SEATTLE - The chairman of the National Transportation Safety Board said Saturday the bridge collapse in Washington state is a wake-up call for the nation.
"This is a really significant event and we need to learn from it, not just in Washington but around the country," Debbie Hersman said after taking a boat ride on the Skagit River below the dramatic scene where a truck bumped against the steel framework, collapsing the bridge and sending two vehicles and three people falling into the chilly water.
Investigators need to find out what happened in Washington and if it could be repeated at similar bridges around the country, Hersman said.
RE: Bridge in Washington State collapses
RE: Bridge in Washington State collapses
And yes, I agree with the NTSB that this design could be a major flaw in the Interstate Highway System, a trigger just waiting to be pulled. Moreover, how much weakening to the structure had been done with earlier hits? The one that I am aware of was on the south side of the bridge, not the north, but I imagine there were many others, some documented, some not. The "straw that broke the camel's back" scenario here could be playing out too.
Mike McCann
MMC Engineering
RE: Bridge in Washington State collapses
"State officials approved Mullen Trucking in Alberta to carry a load as high as 15 feet, 9 inches, according to the permit released by the state. However, the southbound vertical clearance on the Skagit River bridge is as little as 14 feet, 5 inches, state records show. That lowest clearance is outside of the bridge's vehicle traveling lanes, Transportation Department communications director Lars Erickson said Friday. The bridge's curved overhead girders are higher in the center of the bridge but sweep lower toward a driver's right side.
The bridge has a maximum clearance of about 17 feet, but there is no signage to indicate how to safely navigate the bridge with a tall load.
At a news conference later Saturday, Hersman said Washington state does not require signage unless the clearance is 14 feet, 4 inches or less.
The permit specifically describes the route the truck would take, though it includes a qualification that the state "Does Not Guarantee Height Clearance.""
So, I am not really sure what the height clearance is or was as I have heard many different values here. In my opinion, but what do I know, what should be posted, or recorded. is the minimum height to the underside of the superstructure in the traveled roadway, whatever that was. The trucker must have moved to the left after he hit the initial portion of the bridge, as none of the other curved members, that all appear to be of the same geometry as the first from a Google Maps roadway view, appear to have been hit. Time will tell...
Mike McCann
MMC Engineering
RE: Bridge in Washington State collapses
http://www.komonews.com/news/local/NTSB-Bridge-col...
Mike McCann
MMC Engineering
RE: Bridge in Washington State collapses
RE: Bridge in Washington State collapses
RE: Bridge in Washington State collapses
Mike McCann
MMC Engineering
RE: Bridge in Washington State collapses
Brian C Potter, PE
http://simplesupports.wordpress.com
RE: Bridge in Washington State collapses
RE: Bridge in Washington State collapses
Mike McCann
MMC Engineering
RE: Bridge in Washington State collapses
Mike McCann
MMC Engineering
RE: Bridge in Washington State collapses
Dik
RE: Bridge in Washington State collapses
Dik
RE: Bridge in Washington State collapses
The likelihood of the collision/derailment right under a highway bridge, as happened in MO, is really pretty slim when you consider ton/miles or track miles of railroad transport activity. This isn’t something we can practically or economically design against, we can’t afford to do that. We haul HW&H (high, wide and heavy) loads over the highways every day. It takes some clearance, structure load cap’y, and actual movement planning and study to do it right. Not just a car with blinking lights in front of the truck. Railroads and highway depts. have people who do this on a regular basis. If the state gave the trucking company a permit for 15.75', they would normally give some advice about critical clearance locations below that elev., but with no guarantees. That trucker should have had a route/trip plan which said stay in the middle lane at the Skagit River bridge, 17' clr. for a 15.75' load, is no biggy, and he should not have been going 40-60mph crossing the bridge either. That wasn’t even a particularly high or heavy load, was it? Someplace, I thought I saw a video, maybe only a recreation, showing the truck hitting the bridge, and continuing on, and the bridge falling seconds later. It seems that we would be wise to let these things develop a bit, before we pass final judgement. As knowledgeable engineers, we might do what we can to prevent (or correct) the talking heads from pushing the negative and spectacular for the sake of air time. And, we should use a bit of common sense about how we approach and analyze these situations, to help minimize the hysteria. And, I certainly don’t mean to downplay our need for infrastructure spending. ASCE has been harping on this for years to essentially no avail. But, we may need more spending on bridges, sewers and water mains, etc., not very glamorous, but essential to our economy and well being, and less on new stadiums and the like.
RE: Bridge in Washington State collapses
RE: Bridge in Washington State collapses
RE: Bridge in Washington State collapses
"We shape our buildings, thereafter they shape us." -WSC
RE: Bridge in Washington State collapses
One quick point: of course ASCE is going to rate our infrastructure deficient; they are hardly a disinterested third party, it is in their interests to do so. That doesn't mean it couldn't be the case, but, rather, simply that they are not in a position to objectively grade such a thing. It's no different than an insurance salesman telling you you need additional insurance or a shoe salesman telling you you need new shoes. Or, to state it in the inverse, it would be akin to a fox rating the hen house security system overdone.
As for the fracture-critical issue, my understanding is that that was brought up by Berkeley professor Abolhassan Astaneh. Per his post on another site he described how this issue was brought up in the mid-1800's and at that time they decided to recommend that bridges be designed using pure trusses, which are statically determinate, but which therefore have no redundancy. This is what he referred to as fracture-critical. According to him the decision was made at that time so that the structure could be properly analyzed and it therefore be known whether the chords were in tension or compression -- and to what degree -- so that they could be properly designed. His argument is that since we now have modern computer techniques this no longer applies and the structures should be designed with some degree of redundancy. I guess that's analogous to the movement towards progressive collapse resistant designs. That is my understanding, at least, and any mistake in conveying his views in this paragraph are mine, not his.
RE: Bridge in Washington State collapses
Mike McCann
MMC Engineering
RE: Bridge in Washington State collapses
Mike McCann
MMC Engineering
RE: Bridge in Washington State collapses
Mike McCann
MMC Engineering