The Science of Bridge Collapse Prevention 276
toddatcw writes "In the wake of the Minneapolis Interstate 35W bridge collapse this week, Computerworld investigates ongoing research which could someday help to prevent future disasters. Acoustic emissions detection systems, which listen for the sounds of metal snapping on structures, are already sold and fitted. Likewise, a new generation of detector systems that monitor for tilting of bridge columns and piers are being designed, prototyped, and researched. 'Sound waves move more efficiently through solid objects than through air, making any sounds easier to listen out for, Tamutus said. "It's not amazing. It's simple. Doctors use stethoscopes all the time. If you put your ear on a train track, you can hear a train approaching from far away... The Sensor Highway II systems, which are portable and can be moved from bridge to bridge as needed, usually cost between $20,000 to several hundred thousand dollars each. Typically, evaluations take between one day and a week.'"
Barriers/Lights (Score:2, Insightful)
Re:Barriers/Lights (Score:4, Informative)
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alert officials about even the slightest tilting or swaying of critical piers supporting a bridge.
So was not this bridge already warned to politicians that it needed work? Do we need a 5000 DB whistle to make them wake up? The writing was on the wall.
We will as a human race either evolve to vote past voting for hype turkey ass kissing politicians or someday they will foobar us all real big. Fortunately it was less than 30. Could have been worse. Happens in Canada, or shall I say Quebec too: http://e [wikipedia.org]
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Re:Barriers/Lights (Score:4, Funny)
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Would this system also have a feature to alert the local road authority, or in a worst case scenario close the bridge?
It was already there, but no one was listening. How do you solve that?
Re:Barriers/Lights (Score:5, Insightful)
All that can be done is to have a flexible disaster prevention (eg. periodic bridge checks which actually were done) and a rescue program in place which from what I read about was quite good although to some who lost friends and relatives maybe not good enough. I would leave that to the investigation committee to comment on this.
The problem with any disaster is it normally happens with little or no warning and sometimes so quickly people just cannot get out of the way. The question of "it could have been prevented" is rather mute after it has happened.
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Political (Score:2)
At least from what I heared there are a lot of bridges in similar shape, but there's not much done about it.
-- Stephan
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Look at me, I'm cynical tonight.
Re:Political (Score:5, Insightful)
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It's called a traditional Democrat. They exist. Find one and vote for them, if that's what you prefer.
The bigger problem (Score:5, Insightful)
Re:The bigger problem (Score:5, Informative)
The classification of structurally deficient means that either the surface, the superstructure, or the substructure was rated poor. In this case it was the superstructure which for this particular bridge did not provide support. A little bit of repairs to the superstructure and this bridge would have been cleared of its structurally deficient rating.
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This bridge was designed with a pair of steel arches which balanced on slender concrete piers on either side of the river. The load from the deck was transferred to the arches by a truss system: a network of triangles that reinforce each other. The problem with this design is that the failure of a single e
Re:The bigger problem (Score:5, Insightful)
Re:The bigger problem (Score:5, Insightful)
Get elected, then just try raising taxes to pay for something that might happen someday.
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Which... actually HAS happened. Just like bridge collapses have happened. The difference is that there isn't so much malice involved in structural failure by way of aging infrastructure (as opposed to, say, flying airplanes into buildings or driving truck bombs up to otherwise perfectly fine structures).
Bridges don't routinely pronouce their desire to alter your culture and spread Bridgelam by way of killing themselves. I think what we really need here is a sense of specifically which of the
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Reminds me of a lecture I once heard... (Score:5, Interesting)
Discussing the politics of funding, he pointed out that it was easy - very, very easy - to get funding for new photo and signals intelligence sattelites, listening equipment, spy planes, and toys. He noted that, yes, some lobbying went on for these projects, but the lobbying isn't what swayed Congress - it was the new and shiny. They could all go home and say to themselves "wow, I put up a massive spy sattelite that can photograph buttons on Russian officers!"
However, when it came to support for this equipment - analysts to look at the data they gathered, technicians to keep them running, maintenance facilities, etc. - they always came up short. In some instances, multi-million dollar pieces of equipment were purchased and deployed only to have the data they gathered analyzed only long after it was too old to be useful, assuming it was ever analyzed at all.
I realize that this post is a bit off topic, but the problem of not supporting what is already there exists all through government. In the case of this bridge, shutting it down would have met with massive protest from all involved. Projects would have caused inconvenience, just as increased personnel staffing creates great cost for the government in many areas. People do the same thing all the time - buy new cars and toys, but never spend the money on maintenance, it all went to the toy. But if we build it or buy it we better be able to keep it in good shape.
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I realize that this post is a bit off topic, but the problem of not supporting what is already there exists all through government. In the case of this bridge, shutting it down would have met with massive protest from all involved. Projects would have caused inconvenience, just as increased personnel staffing creates great cost for the government in many areas. People do the same thing all the time - buy new cars and toys, but never spend the money on maintenance, it all went to the toy. But if we build it
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The media likes the hype of saying 'it was under repair at the time'.
Re:The bigger problem (Score:5, Insightful)
No it isn't...
This may seem callous and cold in the wake of this incident but in fact it is cheaper (hence "better") for the state to react sometimes than to mitigate a hazard. It is simple economics. The federal cost share is 75% federal, 25% state. In catastrophic events, that split drops to 90 / 10, or at the discretion of Congress, 100% federal (Katrina is 100% federal). If the hazard you are attempting to mitigate would cost more than if it fails, then it is cheaper to let it fail. Of course, you run the risk to life and property when you do this so it is a huge gamble.
States are cash strapped with the thousands of "unfunded mandates" the federal government places on them. Everybody want services but don't want to pay for them in higher taxes. Then you get pandering politicians running on "lower taxes" campaigns further reducing a states ability to operate properly. It is a wonder it took this long for something to happen.
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1. Its every elected and non-elected public service employee understanding that you NEVER want anything to make the news in a negative way, regardless how correct the information is. This goes for dog-leash laws to fire services. Preventing this from happening is almost their number 1 job.
2. Regardless of what your perception is, there are some serious employees at any government. How many profession
Wireless Sensor Networks (Score:2, Interesting)
How about this? (Score:4, Insightful)
Step 2: Start nation bulding OUR COUNTRY
Step 3: No step 3. It doesn't have to be so complicated.
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Each American who thinks the invasion Iraq is "saving" the middle east is an active contributor of why the US has had a sharp decline in buying power and the general decline in common sense and intelligence. If the
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That title will be lost fast the way we are tossing money around.
Um, let me see. We are borrowing about $3 billion dollars a day, mostly from Chinese and Japanese investors, to do this nation building. Also, we are robbing our citizens to give to their citizens for some unfathomable reason. They hate us more and more every passing day. Our troops are getting killed. The longer we stay, the more entrenched Al-Queda becomes in Ira
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Some of the locals seemed to know... (Score:5, Interesting)
This smacks of criminal negligence - complete catastrophic failure in 4 seconds could not have been an undetectable condition.
Re:Some of the locals seemed to know... (Score:4, Informative)
Re:Some of the locals seemed to know... (Score:5, Informative)
Personally, I sort of doubt that this could have been prevented. It's one of those one-in-a-billion sort of odds that unfortunately caught up with us...
I'm more than a bit irked at the media for taking the "structurally deficient" term, and plastering it all over the news without a very clear understanding of what it means. There's no cause for a panic or a rucus -- our bridges are no more dangerous today than they were last week. Hell, we don't even know what caused the bridge to collapse, and ordering all sorts of emergency inspections (which has been done in many many states so far) is pointless considering that the bridge that collapsed was previously deemed to be safe on multiple occasions.
Of course, other recent incidents such as the con edison steam explosion in NYC reek of criminal negligence.
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Here in WA, the WA DOT has essentially admitted that "structurally deficient" [kitsapsun.com] is a scare word used to boost priority in asking for federal funding.
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In fact, spending money to upgrade them to two-lane bridges would be stupid.
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He literally referred to them as being "largely" up to date. As in, not "fully" up to date. Nor even "mostly" up to date. But, at least "some," and possibly as many as "many" though not necessarily more than half, have up-to-date inspections. Don't even ask about the actual maintenance.
And the great irony is that w
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Personally, I sort of doubt that this could have been prevented. It's one of those one-in-a-billion sort of odds that unfortunately caught up with us...
I'm more than a bit irked at the media for taking the "structurally deficient" term, and plastering it all over the news without a very clear understanding of what it means. There's no cause for
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It's more like one-in-a-few-thousand odds. We don't have a billion bridges in this country, and a collapse seems to happen every couple years or so. And like it or not, it is a political calculation regarding how much we are willing to spend to prevent such things. Thus far the answer is that we are willing to spend enough that we don't have a collapse
Re:Some of the locals seemed to know... (Score:5, Insightful)
This smacks of criminal negligence - complete catastrophic failure in 4 seconds could not have been an undetectable condition.
You have way to much confidence in science and technology. I think it's certainly possible that the inspections done didn't detect the problem with the bridge. Science isn't perfect, and there's always assumptions and things no one knows.
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I also doubt that the proper engineering was done - and I suspect that this was not due to lack of recommendations, but more likely due to "fiscally conservative" minded legislature that was ultimately only penny-wise.
The bridge was inspected in 2005 and 2006, so there was quite a lot of inspection of the bridge occouring. If they had reason to believe the bridge was going to collapse, it would have been shut down right away. The major bridges across the country are inspected every 2 years.
Anyway, it's wa
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I also doubt that the proper engineering was done - and I suspect that this was not due to lack of recommendations, but more likely due to "fiscally conservative" minded legislature that was ultimately only penny-wise.
Ahh, here we go. It's the GOPs fault. If only we'd spent federal money used for the Iraq war to fix this bridge. This was the first comment on Kos about this tragedy and it was echoed verbatim by several reporters in the mainstream media. I don't mean they just had the same thought, I mean they used the same damn words.
Then there's the other one.. if only they'd instituted a 5 cent/gallon gas tax that was proposed. That's a more simple "pay as you go" (e.g. tax and spend) approach instead of the "
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1) The spindly structure makes it apparent that the whole thing will come down even with one minor structural stress problem.
2) The surprisingly small size of the bridge supports.
I personally expect the replacement bridge to be a writ large size version of 10th Avenue Bridge nearby with its thick, concrete structures.
Re:Some of the locals seemed to know... (Score:4, Informative)
The bridge is a truss arch bridge [wikipedia.org] built in 1967. The design doesn't interfere with river traffic (well, up until two days ago anyways) - but I did hear an interview with a Berkeley professor describe how such bridges are no longer built due to their lack of redundancy in case of span failure.
Won't fix apathy and greed (Score:3, Insightful)
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How about just using existing know-how... (Score:2)
Re:How about just using existing know-how... (Score:5, Interesting)
There's a lot of good info there, but here are the cliff notes:
A University of Minnesota Civil Engineer in a report to MN-DOT recently noted that this bridge is considered to be a non-redundant structure. That is, if any one member fails, the entire bridge can collapse. A key factor is that there are only four pylons holding up the arch. Any damage to any one pylon would be catastrophic. The textbook example of a non-redundant bridge is the Silver Bridge over the Ohio River. It failed shortly before Christmas in 1967 resulting in 46 deaths. A single piece of hardware failed due to a tiny manufacturing defect. But that piece was non-redundant, and the entire bridge collapsed into the icy river. Today, bridge engineers design bridges so that any single piece of the bridge can fail without causing the entire bridge to collapse. It is tragic that the I-35W bridge was built a few years too early to benefit from that lesson.
Hmmm, 1967 (Score:2)
A similar thing happened in California wrt the 1971 Sylmar earthquake. Several bridges of the newly completed I-5 came down, the cause was found to be lack of hoop strength in the re-bar inside the column. Columns built after that used helically wound rebar to keep the column intact under seismic loading. The need for retrofitting was dri
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Seriously? The Titanic? You realize the Titanic was considered unsinkable precisely BECAUSE it had redundancy (double bottom), other 'state of the art' technology, and went beyond the standard for lifeboats. (Even though there were not enough, yes, it was more than the standards called for.)
The ONLY lesson that could be learned from the titanic is that NOTHING is invincible/unsinkable/indestructible.
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Also that steel gets brittle when cold. See Liberty Ships.
ironic (Score:2, Informative)
what's ironic is that moder
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Also, some of the other "value" decisions made during WTC 1 & 2 construction are laughable b
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Re:ironic (Score:4, Insightful)
He says look at the WTC, it collapsed because of the lack of redundancy.
What?
Seriously, the building was hit by 150,000 lb aircraft carrying 20,000 gallons of flammable liquid. It was obviously never designed to withstand that kind of structural complication.
However, for a minute lets say someone had enough foresight to add "resistance to impact from commercial aircraft" into the structural requirements. Why stop there? What about earthquakes, hurricanes, tornados, tsunamis, or meteorites?
Where do you draw line? How much cost can you tolerate?
It is not engineering that is overly concerned with cost to benefit ratios, that responsibility falls on management and/or accounting. If engineering comes up with two designs for a bridge, where one is under budget and lacks redundancy and the other is over budget and but incorporates redundancy, it is management or the customer that must decide what is most important.
Now some people may say that engineering has an ethical responsibility to build the best product, which may be true. But how does one do that, by quitting their job every time that don't get their way? Or by building the better a better product with the lesser budget, that is working for free?
While I agree that modern engineering has a lot less design tolerance. I think this is thanks to a better understanding of physics as well as better tools. So it is now possible to safely design bridge with a poor failure mode because we 'better' understand what drives the failure (I am not saying that poor failure modes are better).
In this case I think the inspection process is more suspect than actual design. I think everyone would agree that the design had areas of concern. But no design is perfect and all bridges will eventually fail. That is why they are inspected on regular bases. How is it that this bridge was inspected in the last few year and no critical issues were found? Doesn't that mean that a better inspection process is needed?
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I suck at math, so I'm sure that I'm expressing this wrong. But I'll try to answer your question anyway:
B / (W + F + H + P) = T
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That's thing - they did, which both you and the 'old engineer' seem to be unaware of. (However the commercial aircraft of the era were much lighter - and the analysis only took into acount impact damage, not the subsequent fire.)
Almost certainly the WTC desig
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What most likely caused, according to experts, the 1 and 2 towers to collapse was structure failure of the connections of floor struts due to the heat of furnishings, etc burning (note again, the jet fuel rapidly burned off in the first few moments) and heating the steel, which was poorly insulated...
The floor struts warped, floor connections to the curtain wall failed, causing floors to fall onto the floor below them - now that a
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Until someone
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I bet the average Roman bridge that existed during the height of the empire isn't as good as what examples are still standing for us to look at.
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You did not mention slaves and that is good since most of the Roman roads and bridge
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Re:ironic (Score:5, Insightful)
A disaster? WTF do you have to do to be considered a success for this guy?
A fuel-laden commercial jet slams into a 110 story building (x2) and a little less than 3,000 people died.
The buildings could have collapsed immediately and killed, what, about 20,000 people? But both stood long enough (56 minutes and 102 minutes) to evacuate most of the occupants. Sounds like a pretty damn successful building design to me.
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---snip
Wow. This really stands out to me for some reason; the one fatality on the Bay Bridge wouldn't have changed had she "waited for help".
A quick google:
http://www.sfmuseum.org/hist2/presidio.html [sfmuseum.org]
(ctrl-f for "Moal
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Bridges in the western world already have an extremely low failure rate. Reducing it further would require an enormous investment for almost no gain. There are much better ways that we can spend that money.
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Bridges in the western world already have an extremely low failure rate. Reducing it further would require an enormous investment for almost no gain. There are much better ways that we can spend that money.
Take money from various projects like the multi billion dollar war, or various graft projects awarded to Lockhe
In other words:The Science of Bridge Construction (Score:4, Insightful)
So it looks like were all in agreement... (Score:3, Insightful)
It's a hard question, so I think I'll just ignore it, in light of the sad truth that a month from now, no one (who doesn't have a personal connection to the tragedy) will care. To hell with "doomed to repeat it."
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My technique (Score:5, Interesting)
On the other hand, perhaps it isn't necessary to piss off all the Minnesota sports geeks (read: voters) and instead utilize the $2 billion dollar state surplus [publicradio.org] to deal with the states bridges. But alas, there are voters to buy [ncsl.org] with that money.
This is about the priorities of the citizens of a staggeringly wealthy nation being focused on everything but the infrastructure.
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Look at the benefits New Orleans got by attracting the Saints instead of spending that money on tacky flood control...
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Bridge collapse prevention "someday" (Score:3, Insightful)
Maybe if we stop worrying about falsely exaggerated threats like terrorism and manufactured problems like the war on in Iraq, we'll have more than adequate resources to build a really damn good infrastructure, and then things like the bridge collapse in Minneapolis and the steam main explosion in NYC wouldn't ever happen.
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and i'm sure many of them haven't
sure if you build a stone arch accross a narrow vally in an area with no sismic problems then it will stay up for a very long time, especially if the area is too dry for much plant life. However it will be very expensive for the ammount of utility it gives.
but of course we want more, we want our longest bridges longer, we want all our bridges able to stand being p
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We just have to pay attention and maintain what we build. It's not THAT hard.
I used to work for the state highway authority, working on traffic signals. When I was there the entire bridge department were made redundant and replaced by contractors. No matter how much you document these things, you still need continuity from one generation to the next. The old guys have to be around to tell the young guys to look out for this and that, or it may cause problems.
But it is cheaper to outsource.
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But it is cheaper to outsource.
I find the notion of contractors comical. basically you pay 3 times the amount to them so that i
Here's an easy way (Score:2)
Bridge Engineering Isn't What It Used To Be... (Score:2, Insightful)
Take a look at the famed Rialto Bridge in Venice, Italy. This bridge was built almost 500 years ago and still stands even after numerous earthquakes in the region.
Then there is the stone bridge in the Czech Repub
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Maybe you should learn a little bit about bridges - over 80% of the major ones are at least forty years old, and a good number are getting pretty close to the century mark. A handful are well past the century mark.
Equally, there are more than a few stone bridges in Europe that have collapsed (some within decades of construction - at least one in mid construction).
A collapsing bridge is terrifying (Score:2)
A massive bridge collapsing underneath you is terrifying, e.g. a source of terror. We could close the thousands of bridges in the US that, like the 35W bridge, are rated "structurally deficient", in the name of preventing "another 8-1". This might help expedite funding to rehab these bridges, and fighting the "terror" of unsafe bridges would fit with our current national priorities.
Boring (Score:2)
Yes, a little testy. From the Cities and watched it from first rumor until dark on the MythTV box. Burned a DVD of the lot. Used to work at U of M and commuted from near South Minneapolis. Remember the bridge well.
Dumb bitch of the Transportation Commissioner was on the news 10 minutes ago. I just looooved her line about, "Don't any of you accuse me of
Myth and Rice Crispies (Score:2)
Has anyone done this before? The bumper sticker on a train reads If you can hear me, your head will be cut off.
Feel a rail on a track. Long after a train has passed, the track is still hot. I put my ear to the track, but could not hear the train through the rail. This was a rail that has its segments bolted for high speed trains. However, I did hear the train in the air, ear not on rail. The train was a high speed train with
How acoustics helped parking garage problem (Score:2)
About five years ago, a chunk of cement about the size of a football fell on a buddy's car in the parking garage. At that time, the garage was a few years old.
Engineers were called in and placed acoustic monitors all over the place on many of the beams. Then drove vehicles over them on a couple of weekends.
Evidently acoustics found anomalies. They determined that the interior cabling was insufficient.
After a couple of different fix attempts engineers decided on the following.
A
Bureaucracy will kill the efforts (Score:2)
Coupled with my government's incompetence, bigotry and history of wasting money (read Iraq), it will surely be a wonder if this setup ever works. God help us!
Say what??? (Score:2)
Metal snapping? Why not just listen for motorists screaming? I assume these actually listen for some kind of metal stress sound, rather than actual failure? No, I didn't read TFA, so feel free to ignore me.
The data was already there (Score:3, Informative)
For more info, see today's Minneapolis Star Tribune article [startribune.com].
benefit analysis (Score:3, Insightful)
Perhaps if this accident killed hundreds of people, and resulted in a settlement of tens of billion of dollars, then the landscape might shift. Or, if like automobile manufacturers of past, we find that the accountants are making fundamental compromises of safety merely because the cost of a human life is less than the cost of implementing the features.
About the only thing that does not fall under this risk analysis is the military. This is why they can get away with spending 100 billion dollars a year with only a discrediting italian letter to substantiate the claim, a letter not even endorsed by the US government, but by the british. Otherwise we have to use the imperfect system of where to spend our money and where not to. I don't suppose that we are going to see an increase in taxes, or the removal of the new corporate welfare incorporated a few years ago, or a reduction in say in money spent on standardized test for kids. i think we can have anything we want if it is really worth sacrificing.
My 2 step plan for avoiding bridge collapse (Score:2)
2. Politician tells engineer "Ok, fix it".
Sadly, the more common scenario is...
1. Engineer tells politician bridge needs fixed.
2. Politician is too busy bragging about his "low tax government" to listen.
3. Bridge falls over.
4. Politician calls an official enquiry, staffed by his cronies, which blames the engineer.
When I think of civil engineering... (Score:2)
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Or if he tried a shotgun lawsuit against the Catholics, Baptists, Unitarians, Muslims, etc? In that case none of the defendants would risk trying to get out of the case, because whoever's god was responsible is the true religion.
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