Looking over the news footage, I have noticed several things:

1) All of the bridge beams look great, no signs of rust, evenly applied protective coatings.

2) This Collapse (domino) Pattern reminds me of either an Earthquake Effect (per the USGS website, no current activity) or a militarily applied solution to a crucial bridge target.

a) Notice that the ramp on one side of the river is still standing while the river span and the entire ramp on the opposite river bank has all collapsed.

b) This collapse has negated the use of a railroad track, the Upper Mississippi River above (6 miles of navigable waterway???)the collapse. It has restricted the use of (created a chokepoint) of an Interstate Highway (I-35). It has negated the use of a USA COE Lock, as well.

c) Could this have been a better soft target for domestic or imported terrorist???? It would provide a lot of bang for the buck!!!!

3) I find it interesting that a train was passing underneath the bridge at, what appears to me, to be the point of initial piling failure/collapse.

a) Most of that long train had already passed under the bridge and there were 6-7 cars left to pass when the bridge collapsed on top of it.

b) I am wondering about the associated vibrations of a long train moving at slow speeds.

4) My initial conclusion is that the train passing underneath what appears, to me, the collapse point, has to have a connection to the collapse of the bridge, based on what I observed via CNN's coverage.

5) No, I am NOT an ENGINEER!!!!

6) What do the Engineers on ETS think???

I think that, according to the news I just saw, there is still a truck burning and possibly people in the water. Second and first priorities. Figuring out what broke can wait a bit.

Here is a link to a page with good side view pictures for you wildman800

http://www.visi.com/~jweeks/bridges/pages/ms16.html

I can't see any of the photos, just the red X in a box.

Sue

Try again. It's up.

I can only say what I can based on the limited knowledge I glean from news reports, but if this wasn't deliberate (and right now I don't have an opinion one way or another), it points to some kind of really basic & previously unknown engineering or manufacturing flaw that could not be detected by normal inspection techniques.
At this point, it's too soon to give up ALL hope for anyone in a vehicle that went down, but it's not looking good.
Oh, and just to put some perspective on this - there's almost nothing you can do to be "equipped" for something like this, with, perhaps, the exception of having a window punch and a seatbelt cutter nearby, and those are only good if you a)can get to them and b)know how to use them correctly.

Otherwise, this is one of those times where physical fitness can mean literally life or death, because if you're fat and out of shape, you won't have the strength you might need to survive the fall, get out, and swim. Forget helping someone else if you can't help yourself.

I was reminded of this fact the other night as we did a water rescue drill, in which I was in the Delaware River, fully clothed, with shoes on, and wearing a PFD while strapping a "victim" (another firefighter) to a backboard and lifting them to a rescue boat 8 times while we were in 14' deep water. It was exhausting and I had a PFD on. Without a PFD I probably would have been able to swim to shore and that's about it.

Ultimately, it's not gear that saves your ass, it's your well-maintained body & brain that does.

My parents live in the suburbs of Minn/St Paul and tell me that the bridge has been under construction/renovation for a while. Turns out my Brother had decided not to go home that way last night and went a different route instead. It does look like it will be a long term recovery op.

Physical conditioning should be a key element in any survival "kit". I've gone through both the Navy's old Dilbert Dunker and the newer Helo Dunker. Both of those devices are relatively gentle water entries compared to a car falling into the water during a bridge collapse. Add parts of the bridge and moving water, and IMO getting out of the car at all will be a major challenge.

The last time I did the helo dunker I did a lot of swimming underwater conditioning myself. For someone to survive this in cold river water never having thought about the procedures (let alone actually practiced in a trainer) would be a miracle.

Mine said that Internet Explorer can not display the page...

Ok, I am an engineer...

(Disclaimer: I work for a transportation agency in another state and am very familiar with the National Bridge Inspection Standards. I am giving my personal opinions and observations and not stating any official position or anything else but my opinions. Now, back to the discussion.)

So here goes...

1. Looks ARE deceiving, especially from the distances we are seeing things. The only way to really tell is "up close and personal".

2. The main cross channel span was over 460 feet. The "domino pattern" (progressive collapse) as seen in the video is caused by the span failing at one end and pulling the rest of the span down.

a) The approach spans might have collapsed due the the shifting of the main span as it failed (on the side it failed).

b) I am not familiar with the area, except what I have seen on the news, but I would expect that the railroad and the roads on either side of the river would be back in operation by late next week. The river channel will probably take a couple of weeks to clear once the NTSB has finished their high-resolution surveys.

c) No argument here. I was not pleased that it seemed that even before the dust had settled, Homeland Security had declared that the collapse was not terrorist related. The eyewitness reports that I have heard (again from the media) tend to support that conclusion, but I would appreciate a more measured approach.

3) That a train was passing under the bridge at the time is, initially to me, just as coincidental as there only being 50 vehicles on the bridge (4 lanes being closed). Also, the photos I have seen show no damage to the piers (piling), so I would look elsewhere for the cause of the collapse such as the truss ends that were atop the pier.

a) Yes, and apparently the train was pulling empty cars, as no HazMat situation was noted.

b) The vibrations from an unloaded train are much less that those of a loaded train (F=Ma). Additionally, the speed of the train also is a factor, faster trains produce stronger vibrations than slower ones. A long, loaded, fast moving train would cause considerable vibration than a slow unloaded one, and could theoretically, add to fatigue inducing stresses.

4) I wouldn't initially think so - I would tend to see it more as coincidence. Prudence dictates though, that every possibility
be throughly investigated.

5) I have a BS in Mechanical Engineering. I am not a licensed Professional Engineer.

6) You got it.