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Big Dig - One of Engineering's Greatest Mistakes?
Enggirl1 writes "Design News discusses Boston's Big Dig and begs the question - is it one of engineering's greatest failures? The article reveals that forums and blogs are popping up all over the Internet as vehicles for engineers and contractors to discuss, under the guise of anonymity, their skepticism, thoughts and reactions to one of the biggest infrastructure failures in the news today." From the article: "One blogger, whose profile notes that he is an ICC Reinforced Concrete Special Inspector and an ICC Pre-stressed Concrete Special Inspector, among other specialties, says he has nearly 20 years of experience performing both placement and post-placement inspections of rebar, post-tensioning systems, concrete, masonry, etc. He says if structural engineers who specify epoxy for dowels and the like believe that the work is being done correctly then they live in a world unfamiliar to him."
Rock bolts are a staple in the mining industry. There are darn few failures. Of course the rock bolts are specified by engineers who work for the mining company and installed by miners whose safety depends on them. You tend to do things better if your life depends on it.
In the case of the big dig, you have contractors who are trying to make the maximum possible amount of money. I also bet that there weren't enough government inspectors or that they weren't properly qualified. Cutting costs is just as dangerous in the government as greed is in the private sector. The Canadian province of Ontario laid off all their government water inspectors and a bunch of people died in the town of Walkerton. If you don't give folks the tools they need to do a job then you shouldn't be surprised if the job doesn't get done.
The concrete ceiling tiles were used to create a separate space for supplying air to the tunnel. This is typically how you would do it in a building. In the case of the Chunnel between England and France, they dug a separate tunnel for that purpose. People have wondered why the panels had to be made of concrete. Something lighter would have worked just as well and might have been cheaper and safer.
"throws in numbers" and tosses together a design, then sends it out with the engineer's seal on it. Or when an engineer refuses to sign off on an incomplete or incorrect design, the manager brings in a new graduate because they're more "cooperative" (read: will sign anything to get a paycheck) and they go ahead and build it that way.
I'm not saying those things don't happen. I'm saying that they are highly illegal and not common place. Signing off on a design for an engineer is like preparing legal documents without being a lawyer or giving medical advice without being a doctor.
To sign off on any engineering or construction documents, an engineer must be licensed as a Professional Engineer (PE). The requirements vary by state but in most states new engineering graduates do not qualify to be PEs. The norm is an engineering student must pass an exam (FE) near graduation, then work under a licensed PE for several years, then pass the PE test. In most states like MA, it is 4 years minimum between passing the FE and even qualifying to take the PE test. Engineers who are not PEs can do some of the work in construction and design fields but are expressly forbidden to do certain things like sign off on plans.
I agree with you that management is most likely to blame but for another reason. As projects like this become complex, it requires very good management to ensure that the important details are not overlooked. With as many problems as the Big Dig seemed to have before completion, it would seem that the management was not up to the task.
In the case of the collapse, I think the most likely scenario is that the specifications were wrong or changed at a later date. The load required was specified to be 1/2 of what it needed to be. The engineer approved a wall thickness of so many feet that was later modified and built without approval. The specifications for the wall never included withstanding water (hydrostatic pressure), etc.
Well, there's spam egg sausage and spam, that's not got much spam in it.
As usual with engineering disasters of this sort, the failure seems to have been caused by a confluence of lesser mistakes that would not have been tragic in isolation. The root causes, however, seem to be:
Anyone who has lived in Boston can tell you that this is only the latest in a string of cost overruns and management failures. The actual mode of failure (i.e. the bolts) and the immediate causes of that failure should not overshadow the idea that the contractors who screwed this one up should be held responsible. The ongoing investigations should reveal whether the contractors were merely incompetent or whether they willfully ignored problems like these and crossed their fingers that nothing would happen.
Friends don't let friends misuse the subjunctive.
Posting anon here - I worked on the Big Dig (environmental) during peak construction (1997-2000) and I'm currently contracting with another MA state agency, and I don't want to ruffle any state feathers. I also want to write a book someday ;)
First a couple of general statements:
Now back to the facts - I have no knowledge of roof panel construction (I spent little time in that area), but I will note that working on the project during 1999 and 2000 was an interesting experience. Already at the point there was heavy pressure on project managers and contractors to reduce costs (this was before the national stories hit that led to the ouster of James Kerasiotes). It got to the point that office supplies were locked up - you had to get the office manager's permission to get a notebook or pens!
In any event, I wouldn't be surprised at all if cost pressures let to reduced safety factors, etc. The construction site was also the source of many stories about various screw-ups that I won't get into here (wait for my book!). There was of course several times that money was spent to shut people up (at least once against my direct recommendation), but the PTB felt it was needed for the project to move along smoothly. I suppose that it would have been better for B/PB to take the Vista approach, and wait for the tunnel to be "finished" but that wasn't going to happen because of the political pressures.
Now was the project a failure? I'll just say this - is used to take me 1.5 to 2 hours to drive from Braintree to Cambridge during midday traffic. I did the same trip a month or so ago during a Friday afternoon rush hour in abut 20-25 minutes.
One of the problems with the Big Dig ceilings is that some of the engineers that designed it have never actually built anything. These guys must not have ever gotten their hands dirty on an actual jobsite. Their the guys in ties, hard hats and a slight look of confusion on an actual site. The book says epoxy has the strength, it must, use it. When the accident occured and it first came out that the bolts were epoxied in place, my first thought was "what kind of idiot makes suspended ceilings out of concrete, then tries to epoxy them in place?" Epoxy is a wonder material, but this is just so obviously not a smart use for it. No, i'm not an engineer.
s /2006/07/28/bolt_system_graphic/
I've got a running bet with anyone that'll take it that the Big Dig is closed down in less time than it took to build the beast.
My wife is a news designer for the Boston Globe, she made this graphic to explain what happened, it's pretty cool. No complaints about it being in Flash, that's what she uses:
http://www.boston.com/news/traffic/bigdig/article
Enjoy,
Josh
gigantino.tv - Heavy but weighs nothing.
I'd trust a kid "off the farm" to be able to do construction work before about anyone else the same age. You grow up building and repairing big structures, welding, operating equipment that costs as much as most folks houses, etc you appreciate how to do things properly. Any random 20 year old kid off a farm might easily have ten years experience in what would be considered adult professional work in most of the trades. He's grown up wiring at high voltages, working on very large and complex plumbing installations, doing all sorts of carpentry, cement work, equipment maintenance, etc. It's a pretty thorough and complex process to keep a large farm operating. And today's farm kids are using automated and computerized devices, all the way to GPS enabled equipment that uses robotic steering. maybe it is past time to put that "country bumpkin" meme to rest, it no longer applies.
With that said,back on subject, that entire big dig project has a long history of controversy and accusations of weirdness around it. I am (somewhat) surprised it has taken this long to start to fall apart.
As to the illegals versus legals and so on, it's a crapshoot. I have worked on jobs with illegals that were a menace,totally incompetent and dangerous to be around, hired merely because it was a body to throw at a job for cheap pay obviously. A few have been quite good from recollection, most are pretty common, some skills, but a lot of enthusiasm. They come from a culture of lower resources, recycling old junk more, cob jobbing as normal, etc. I think it is just too large a variable to really be able to quantify it adequately. What can't be denied though, is that hiring illegals in a general sense is a cost cutting measure so the boss class can skim a few more bucks off the project, and when that becomes the primary focus on a job, the job suffers. Jobs should cost what they cost, not the lowest crap possible then cut corners from that point. You get your "problems" then. When you have something as important as a big dig styled project, you shouldn't screw up. If it is deemed to be unaffordable to do correctly, don't do it.
If your new garage roof sags and leaks after a few years because you hired the local cut rate guy with his "crew" of casual pickups from the home depot parking lot..well, it's no big deal to anyone but you and not a major threat. Something like the big dig is a totally different situation.