Big Dig 1

[bioengr82]

If I were this engineer, I'd be making sure my professional liability is current.

What do you gents think: Engineer, Contractor, or Force Majeure?

 

[ctopher]

Seems to me the contractor.

Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-06)

 

[EddyC]

I'd go with the project manager. I've worked with the first half of their team for several years and I wouldn't want them involved in the construction of even an outhouse.

 

[JStephen]

Dunno. There's not anything that I've read so far that gives any reason to think one or the other party is responsible.

 

[Blackhorse007]

this havea similar case tt happened in singapore, the workers were working on a wall and the wall collapsed crushing some people below it, think it was a demolition job.

Well the verdict if i was not wrong was contractor. There was not enough training for the workers and the contractor did not reflect the potential problems on site.

 

[DonMcC]

This article looks at the suspension system used to hold up the concrete slabs.

http://news.bostonherald.com/localRegional/view.bg?articleid=147984&format=&page=1

 

[DonMcC]

...and a graphic from the Boston Globe:

http://www.boston.com/news/traffic/bigdig/articles/2006/07/12/Cutaway_view_of_tunnel_ceiling/

 

[analogkid2digitalman]

Are those concrete panels just for beauty or do they add any structural benefits? From the graphic it looks like theu are just there for appearance.

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"It's the questions that drive us"
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[bioengr82]

Looking more like the Contractor

 

[JStephen]

I'm glad I'm not the only one that wonders stuff like that, analogkid. If the rock above them is strong enough to support the bolts, why do they need concrete slabs there? And if it's just cosmetic, why not use something lighter? Seems an odd way to do it.

 

[analogkid2digitalman]

Turns out those heavy slabs were not needed, they just provided a means for air control. What a waste and now an unfortunate accident.

http://www.boston.com/news/traffic/bigdig/articles/2006/07/13/need_for_heavy_panels_was_debated/

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"It's the questions that drive us"
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[debodine]

Some political leader with a finacially generous constituent that also owned a concrete company needed a contract...

 

[vpl]

My first thought on it was: lack of maintenance. Just based on what I heard/read, that the bolts started vibrating loose. No one has mentioned that any one went back in and retightened them/verified torque after they had been in service for a while. Much less any program to go back in and periodically tighten them.

Patricia Lougheed

Please see FAQ731-376 for tips on how to make the best use of the Eng-Tips Forums.

 

[DonMcC]

The nuts weren't loose; it appears that the bolts were. From what I'm reading, epoxy is used to bond the bolt to the concrete. But to be effective, the hole must be clean, the bolt must not have any grease on it, the epoxy must be mixed in the correct ratio, moisture must be avoided, and it must be allowed to cure.

Some previous problems with the epoxy were caught in 1994, and 1999, but the bolts on this section were possibly either not pull tested, or the strength of the epoxy prematurely declined.

A rush to finish?

 

[ctopher]

I think it was a rush. It was such a big project, that cost would cause shortcuts.
For that design, I would have imbedded threaded bent rods into the supporting concrete to help hold the load.
Poor design from enginners, poor project management from contractor.
I think it's worth removing the concrete slabs and doing something better.

Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-06)