Apparently an Interstate Highway bridge collapse in Washington on I-5 across the Skagit River. No word on injuries.
I-5 Bridge Collapses
The Interstate 5 bridge over the Skagit River in Mt. Vernon, Washington has collapsed.
I-5 Bridge Collapses
I would normally be spending the night right there tonight in Mt. Vernon if my truck didn't just start having mechanical problems. Perhaps tomorrow...hope people are okay...
I-5 Bridge Collapses
WSDOT: "This won't be fixed by Monday."
High Wide Load Takes Out Poorly Designed Bridge
Reports say that the load was 12' wide and 14' high. In addition a second tractor trailer was passing said truck, forcing it to the outside where the load struck an intermediate vertical member. There is evidence that this has repeatedly occured on this bridge. Photos show damage to a vertical and horizontal top bracing member on the adjacent still standing span.
Once the vertical member was damaged the top compression truss buckled and then the main diagonal load members snapped in brittle fracture.
I say poorly designed based on casual observations. The bridge spans are Subdivided Warren Truss style, however the geometry is wrong. Warren Truss diagonals should form an equilateral triangle. A Neville Truss would be a more appropriate name. The flatter diagonals of the I-5 bridge have considerably higher loads. In addition there is wasted useless vertical and top chord members at the ends of the trusses that carry no loads. That steel could have been used in the load carrying members increasing strength. In addition because that useless vertical had top portal bracing they failed to add top portal bracing to the adjacent main sloped end members. The outer end of the collapsed section did not have the useless verticals and was portal braced. The portal bracing at the ends was not a factor in this particular collapse, however it indicates that the designer was more concerned with esthetics than strength.
Ultimately they will want to place blame on this one particular truck driver, who was not the person to increase load weights and sizes beyond initial design parameters. I believe the failure was really caused by believing that initial factors of safety can be encroached upon on an every day basis. Because I see unrepaired damage on other bridge components one can readily assume that the failed member was already severely damaged prior to this incident. That is a failure to "inspect and repair" and is a state responsibility.
I await release of the bridge monitoring videos that should show the bridge strike clearly.
Paul in PA, PE, PLS
The designer of the bridge
The designer of the bridge is probably spending all of his time in a cemetery somewhere. The report says the bridge was built in 1955. That suggests the actual design would date to 1953 or earlier. Such an important bridge would have surely been assigned to a senior designer. Add 60 or more years to the senior designer's age and you probably get a number greater than 100.
High Wide Load Takes Out Poorly Designed Bridge
I would think that the age of the materials alone (unless it's had a retrofit) and the almost 80k ADT played a factor in the failure.
I'm interested to see how a longitudinal impact actually contributed to the collapse. One of those "sequence of events" I'm sure.
Let's see how long it takes for the NTSB to publish some findings.
no deaths reported
news this morning said 3 people rode the bridge down and all were rescues w/ only minor injuries.
Great news, but ....
I am certain that would be a "Why I am late for work excuse" that you never heard before.
Texas Bridge Collapse
[flash width=560 height=315] http://www.youtube.com/v/LLVKb1HxhAY?version=3&hl=en_US [/flash]
Texas Bridge Collapse
A RR trestle like that burned a few years ago here in an apparent arson fire. Creosote burns really well.
High Wide Load Takes Out Poorly Designed Bridge
If one oversize truck can bring a major interstate bridge down then something is wrong with the bridge.
High Wide Load Takes Out Poorly Designed Bridge
:good:
High Wide Load Takes Out Poorly Designed Bridge
In 55 we were still making our own steel and Engineers were building large safety factors into all structures. What loads the bridge was originally designed for was probably thrown out, justified by the built in safety factors by the Hwy. Dept.. That bridge must have been part of the first structures for the Military Road System promoted by Eisenhower. Was 12-13 when that bridge was built and still was able to serve under Eisenhower as President.
jud
Like a mortgage survey being used as a boundary survey.
The 1955 build date precedes Interstate 5 by a few years. The first pieces of I-5 in Washington opened in 1960 and it wasn't considered complete until 1969.
I suspect that this bridge was built on a piece of State Hwy which was later incorporated into the Interstate System. What was sufficient for a state highway was undersized for an Interstate freeway. So not really a poor design but rather a design pressed into unintended use.
I've traveled over it many times. It did have a noticeably low overhead.
Like a mortgage survey being used as a boundary survey.
They've had ODOT down to fix the one over the Mary's river in Corvallis twice within a couple of years.... from the same "oversize" load problem.
It's still up and running, and yes, it is a state highway bridge as well.
Bridges do take a beating that most people don't realize.
Another bit of bad news - Hopefully Now..
> Apparently an Interstate Highway bridge collapse in Washington on I-5 across the Skagit River. No word on injuries.
>
Hopefully now, The washington state legislature will get off their hinny and pass through the Columbia River Crossing legislation and funding package that they are sitting on to get that I-5 bridge done. I commute over the current I-5 columbia river bridge daily, and Im a huge proponent for its replacement. I'm a huge fan of most infrastructure improvements really.
Skagit Bridge Report
http://nationalbridges.com/index.php?task=showResults&query=8&lqm_id=679300
I-5 SB Bridge - (Right side in photo)
http://nationalbridges.com/index.php?task=showResults&query=8&lqm_id=678741
"Sufficiency Rating (%):18.3"
I-5 NB Bridge - (Left side in photo)
http://nationalbridges.com/index.php?task=showResults&query=8&lqm_id=679359
Looking South
Interstate 5 connects Canada to Mexico; billions of dollars worth of commerce travel along this route every day.....
This will not be something that will be fixed in the next few days, weeks, or even months.....This will be a huge impact on the region for quite some time.
How many bridges, across the country, are older than 58 years?
From infrastructurereportcard.com
> Over two hundred million trips are taken daily across deficient bridges in the nation’s 102 largest metropolitan regions. In total, one in nine of the nation’s bridges are rated as structurally deficient, while the average age of the nation’s 607,380 bridges is currently 42 years. The Federal Highway Administration (FHWA) estimates that to eliminate the nation’s bridge deficient backlog by 2028, we would need to invest $20.5 billion annually, while only $12.8 billion is being spent currently. The challenge for federal, state, and local governments is to increase bridge investments by $8 billion annually to address the identified $76 billion in needs for deficient bridges across the United States.
Get out your check book.....:-(
Great news, but ....
> I am certain that would be a "Why I am late for work excuse" that you never heard before.
I'm certain a lot of Memorial Day weekend plans have been impacted.
