CNN reports major bridge collapse in Minnesota

[gtalum]

That bridge should've been repaired or additional support should've been added after that engineering report.

It's far too early to be assessing blame. Nobody even knows why or where the bridge failed yet. Once that is found, it will have to be compared to the recent inspectiosn to determine what, if anything, was missed and how to prevent such an error in the future.

[JQ Public]

such a sad event. why weren't these issue being addressed...america is getting old and so is its infrastructure.

[Brent]

Missing toll lowered to 8...

I'm amazed that the death toll will be so low considering it was bumper-to-bumper traffic with 50+ cars, and a school bus with 60 kids!

[Dionne]

That bridge should've been repaired or additional support should've been added after that engineering report.

It's far too early to be assessing blame. Nobody even knows why or where the bridge failed yet. Once that is found, it will have to be compared to the recent inspectiosn to determine what, if anything, was missed and how to prevent such an error in the future.

An outside truss failed during the repair process. It's quite obvious in the CNN footage. Catastrophic failures like this are usually the result of a series of errors. A new layer of blacktop doesn't make an old bridge new. Somebody dropped the ball.

AP is now reporting that the bridge had "a two decade history of worrisome inspections"......

[gtalum]

An outside truss failed during the repair process. It's quite obvious in the CNN footage. Catastrophic failures like this are usually the result of a series of errors. A new layer of blacktop doesn't make an old bridge new. Somebody dropped the ball.

I'm not sure it's that obvious. Look at the "after" pictures that show the bridge piers. The one on the south end of the bridge is tilted almost 45 degrees towards the water. This pier was vertical. The pier should not have moved, even as the bridge collapsed around it. I'm wondering if there was a hidden erosion or foundation issue with that pier. If the pier moves, the span will come down. It might explain why the over-water span and south approach collapsed well before the northern approach.

[coriolis]

It looks like it was a continuous truss, as opposed to a series of simple spans? It's a design solution that provides material savings in construction but as you can see, one failure and the whole thing comes down. Unfotunately a truss design literally has hundreds or thousands of connections, each of which is a potential failure. Plus, continuous spans multiply the thermal movements.

If it is a continuous truss, the inner piers would not be designed for a lot of horizontal thrust. It is conceivable that the falling superstucture could have pulled that pier over.

I know that there's been discussion about two-girder continuous span bridges having low degrees of redundancy also. In this state, I've been seeing P/S concrete beams being used in longer and longer spans. Usually they're multiple girder, simple spans, which have a higher degree of redundancy and would contain a failure.

[gtalum]

It will be interesting to see the failure analysis. My only point is that assigning blame at this time is counterproductive. We need to figure out what happened and why, and we need to do it quickly to avoid another similar catastrophe. The political finger-pointing going on in congress and the media already is making me angry.

[coriolis]

For sure.

The politicians are always quick to start wringing their hands and pointing fingers. The local news had the DOT district bridge engineer on the program, giving assurances that they do everything they can. Maybe they felt that the public "needed to know" but to me it was a waste of airtime.

Budgets are always tight and the agencies are always trying to prioritize all the needed work. The public rightfully has high expectations for safety, but also has expectations for reasonable taxes. I'm sure that at the time it was built, it was considered "state of the art."

Sadly, bad things do happen, and all we can do is make our best effort. That doesn't help the victims, I know.

[RL3AO]

Amazingly, Minnesota is one of the best in the nation at taking care of infrastructure...so it makes you wonder about a lot of other areas.

[Miss Mary]

One theory or speculation keeps being mentioned on local and national news outlets - weather. We all know Minneapolis has harsh, severe winters. Does anyone here know if there's a strong indication this bridge might have failed, when others in warmer climates (the Indianapolis one for example) haven't failed, due to the fact that Minneapolis has extremely cold winters? One official mentioned the onslaught of de-icing fluids and compounds that would have been used on this bridge too. Winter after winter.

[RL3AO]

I've heard that a few times but not sure if it is responsible for that.

[P.K.]

One theory or speculation keeps being mentioned on local and national news outlets - weather. We all know Minneapolis has harsh, severe winters. Does anyone here know if there's a strong indication this bridge might have failed, when others in warmer climates (the Indianapolis one for example) haven't failed, due to the fact that Minneapolis has extremely cold winters?

That should have been covered in the structural steelwork specification when it was designed based on the relevant min and max temps in the highway bridges regulations for it to even get planning permission.

[gtalum]

With the information that's coming out into the open regarding our nation's infrastructure as a whole, it's becoming clear that we need a "Manhattan Project" type blitz to rehabilitate it completely and quickly!

[Stephanie]

It will be interesting to see the failure analysis. My only point is that assigning blame at this time is counterproductive. We need to figure out what happened and why, and we need to do it quickly to avoid another similar catastrophe. The political finger-pointing going on in congress and the media already is making me angry.

I agree. This may be a tough lesson to learn from regarding prioritizing the safety of our bridges and roadways. I know that the govenors of PA and NJ have ordered inspections on all of the bridges in the state.

There's a bridge that crosses the Delaware River to Northern East Philadelphia called the Tacony-Palmyra that has been deemed "structurally deficient". There's also an old, bridge in Philadelphia called the South Street bridge that has had it's share of concrete falling off as of late. There are weight restrictions on that bridge and it has been scheduled to be replaced next year. I hope that they move it up on the priority list - soon.

[angelwing]

Thanks for the tip on the Tacony Steph, sometimes I take that instead of the Burlington Bristol if I'm going straight from one job to the other and I can't stop home first. Ever since this happened, every single bridge I been riding on I've been worried, Scutter Falls, Trenton-Makes, the NJ-PA turnpike bridge, sigh. Oh and they are working on Rt 1 now at the PA/NJ border too.

They just redid the Tacony, it's only 3 lanes now, it's still deficient? Sheesh

[Stephanie]

Thanks for the tip on the Tacony Steph, sometimes I take that instead of the Burlington Bristol if I'm going straight from one job to the other and I can't stop home first. Ever since this happened, every single bridge I been riding on I've been worried, Scutter Falls, Trenton-Makes, the NJ-PA turnpike bridge, sigh. Oh and they are working on Rt 1 now at the PA/NJ border too.

They just redid the Tacony, it's only 3 lanes now, it's still deficient? Sheesh

I think that the only thing that they did on the Tacony was resurface it. I was confused when I heard that about the Tacony this evening on KYW because yesterday I heard that all of the Delaware River bridges under the DRPA were rated as "satisfactory" or "good".

I'm just glad that the govenors are ordering checks of all of the bridges in the states. This has been a big wake up call for the states.

[angelwing]

Yeah you're right, they went from 4 lanes to 3 and it was resurfaced, I forgot about that.

I found this link, looks like PA has the highest rate of bad bridges, I know Pittsburgh is a city of bridges, they probaly have a lot that need to be redone also:

http://www.cnn.com/2007/US/08/03/bridge ... nSTCOther1

[Stephanie]

I had heard that about PA. In contrast, look at MN's bridge rating and they are the ones with the bridge collapse.

[Opal storm]

Those images from the scene on TV run through my mind now during every bridge I cross. Being on a collasping bridge has got to be one of the most horrific situations anbody could ever experience. I'm shocked the death toll is so low though.

[HurricaneBill]

588 bridges here in Massachusetts have been rated as deficient.