Boston "big dig" collapse

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yellow1995Cobra

New Member
Dec 23, 2002
2,959
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Massachusetts
#1
Im sure this has gotten nationwide news... Our 14.6 BILLION tunnel/highway project is falling apart. A 3 ton piece of the ceiling in one of the tunnels calapsed on a couples car killing a woman, but her husband luckily survived with minor injuries.

If any of you guys wanna read about it, check it out - link

What a joke this project has been. It started with leaks, and now is falling apart. There are 60, yes 60 other spots which are unsafe now as well and need to fixed. Causing major traffic issues to boot.

Keep in mind this porject started over 10 years ago with a price of i believe 2.5 billion, and the cost kept rising, to the 14.6 billion we are at now.

I go through these tunnels alot for work, and they have really made commuting alot better then it used to be, but people shouldnt have to cross there fingers before going in lol.
 

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#3
Being, an engineer myself, I've been thinking that there may have been some kind of unforseen problem like dynamic fatigue or seismic activity to cause those panels to fall. It's extremely difficult to design for some things like that but one would think that they would (should) have designed it with enough safety factor and at least some redundancy to keep something like that from happening.

The other problem is that when a project gets rushed, contractors tend to do whatever the hell they want out in the field and it's hard for the inspectors to control them. So in this case, it could have been any number of things between the geotech engineers, structural engineers, concrete contractor, steel fabricators etc etc.

Honestly, if I were in that car, I would probably wish I hadn't survived once I know my wife has been crushed. I feel terrible for the husband.
 
#5
Zero Signal said:
Being, an engineer myself, I've been thinking that there may have been some kind of unforseen problem like dynamic fatigue or seismic activity to cause those panels to fall. It's extremely difficult to design for some things like that but one would think that they would (should) have designed it with enough safety factor and at least some redundancy to keep something like that from happening.

The other problem is that when a project gets rushed, contractors tend to do whatever the hell they want out in the field and it's hard for the inspectors to control them. So in this case, it could have been any number of things between the geotech engineers, structural engineers, concrete contractor, steel fabricators etc etc.

Honestly, if I were in that car, I would probably wish I hadn't survived once I know my wife has been crushed. I feel terrible for the husband.
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Well the project overall has been going on for about 20 years i believe, maybe even more. That particular section of the tunnel system was completed 10 years ago. They are now saying that the method used to hang the ceiling tiles is obsolete now, good to hear right.

Also, one company that was supplying concrete was accused of suppling substandard concrete.

Theres a TON of issues with this project.. You would think with 15billion you could do almost anything, and do it prefectly.
 
#8
No project is perfect, and the bigger they get, the worse the problems. The probability of error is so high it's scary. Don't get me started on hot headed contractors, they have a habit of doing things their own way for their own befit regardless of our drawings. :nonono:
 
#9
Zero Signal said:
No project is perfect, and the bigger they get, the worse the problems. The probability of error is so high it's scary. Don't get me started on hot headed contractors, they have a habit of doing things their own way for their own befit regardless of our drawings. :nonono:
Click to expand...

yup, money money money!!!!!
 
#12
I still wanna know who even thought that hanging a 6000 lb piece of concrete over a road was the right thing to do. These could have / should have been part of the structure OR supported by columns of some kind...

Also being an engineer I know that the only reason you bolt stuff together is when you want to take it apart later...
 
#13
94-302-vert said:
Also being an engineer I know that the only reason you bolt stuff together is when you want to take it apart later...
Click to expand...

That's why the bolts are fixed into place with epoxy.

Hanging concrete slabs like that is an accepted and proven method of tunnel construction. The procedure for using said epoxy is exact, and if used correctly, is literally stronger then the concrete its injected into. With the proper epoxy, the system can support over 100K pounds. If, however, it is applied incorrectly, like here, then its compromised.

I mean, imagine this: certified union workers slacked off on a job site? No way! That would never happen! Union workers are the best around! That's why they get paid so much! And why it takes 3 guys to operate a front end loader, 4 guys to clean up around the hole, and 5 guys to manage those 7 guys. Safety first.

For everyone that lives in Mass, I guess this puts into perspective all those pictures in the Globe of workers asleep in trucks or at the bar for 3 hour lunches, on our dime. Making 35 bucks an hour. Or that time they put a GPS tracking device on a Big Dig pickup truck and tracked the guy going to the ATM, grocery store, and getting a hair cut during business hours.

Adam
 
#14
You use bolts becuase field welding is expensive and when it comes to concrete, it's very difficult to coordinate cast-in-place embed plates designed to be welded. Bolted connections are just as strong and are much easier to construct. And of course it can be fixed since it can be taken apart.

Another thing to note, a 5/8" bolt embeded 5" into a regular ol' concrete hole and epoxied can take close to 15,000 lbs of tension if done correctly. With safety factors, we only assume it can take around 6,000 lbs.

Most of the buildings being built today (if built exactly to code) are actually way over-designed. The idea is that there is roughly a 1/100,000 chance of some kind of failure. When we do our designs, we always consider failure modes and design a strength path into the system to provide warning and prevent sudden failures.

With that said, when I design connections, I almost always design them stronger than the members they support (like beam ties and bolted connections). This way a beam will sag and start falling apart long before the column or support gives way.
 
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