Pile Driving on MN bridge per MNDOT

[NMDemDist2]

per Keith Olbermann

link....

http://www.dot.state.mn.us/projects/crosstown/pdfs/Weekly%20Update%20July%2030,%202007%20Approved.pdf

Weekly Update
For the week of July 30, 2007
General Updates
I-35W Bridge Work at Minnehaha Parkway
Work on the I-35W bridge over Minnehaha Creek and Minnehaha Parkway continues; weather
permitting. Daytime pile driving will occur for temporary widening of the existing northbound I-
35W bridge; excess noise may be associated with the activities. Starting Monday, August 6,
2007, Minnehaha Parkway will be closed for three weeks. (see Neighborhood Updates for more
information).

[NMDemDist2]

1. kick for new info n/t

[HysteryDiagnosis]

2. I wouldn't be surprised if they find that many of the bolts/rivets that

held the structure together just "popped", possibly rusted and or neglected. Every so often a crane has to have a tremendous load applied to it, up to and possibly exceeding its rated capacity. Perhaps the same should be done with bridges with robotic vehicles heavily laden. One wouldn't need to destroy the bridge, strain gauges could be attached to members to see if there is excessive flex or give and to flag needed reinforcement/repair.

[Junkdrawer]

3. Picture: (note the rust)...

[TheMadMonk]

5. That rust looks faily superficial to me.

Admittedly a well read layman's opinion.

My first suspects would be those spindly pylons. Concrete has enormous compressive strength, but that presupposes an intact matrix. The slightest amount of corrosion in the reinforcing can cause cracks to begin to form in the concrete.

Pile driving on the bridge, would be the ideal energy source to cause any such cracks to grow over quite a short period of time.


They (or the "feet" between the bridge and pylons) would also be the logical "linchpins" for any deliberate attempt to bring the bridge down. However appearances can be deceiving. Guestimating off surrounding feattures Those "tiny" pylons are still a good 4 m (fifteen feet) through and the "ankles" two feet thick and something like 30 ft (9m) off the ground. It would take some decent and well placed (and very very noisy) charges to make a dent.

My bet is on sudden catastrophic failure of one or more pylons. Most probably caused by corrosion, exacerbated by heavy vibrations.

[NMDemDist2]

6. that sounds as logical an explaination as I've heard

:hi:

[KharmaTrain]

4. Unique Bridge Design...

I'm hearing the History Channel's "Modern Marvel's Guy" in my head reading this one:

http://en.wikipedia.org/wiki/I-35W_Bridge

Damn...they're fast on Wiki:

The I-35W Bridge was a deck-arch truss bridge that spanned the Mississippi River in Minneapolis, Minnesota. It was built in 1967 by the Minnesota Department of Transportation.

The bridge was notable for not having any piers in the water. Instead, the main support piers were located on the banks of the river, and were built of tubular-shaped concrete pillars. This allowed for a wide, clear span across the river, making river navigation easier. Although not very decorative, the bridge was one of the widest bridges in the Twin Cities area and provided an important link for Interstate 35W traffic. According to the Minnesota Department of Transportation, 200,000 cars used the bridge per day before its collapse.<1>

Could be the design enabled the span to fall in one flat pancake that could have saved lives.

[Horseradish]

7. wrong bridge

pile-driving for a new overpass about 3 or 4 miles away

[ender]

8. and it doesn't start until next week.

[Horseradish]

9. HA

How much pile-driving do they do on existing bridges with rush-hour traffic on them these days?

[ConsAreLiars]

10. It is nice that most speculative nonsense on DU gets quickly de-bunked.

I think by now most who read this thread will understand that pile driving on a bridge some miles away that will begin a few days from now is a rather unlikely cause.