When it was originally built, they didn't expect it to last that long. Think they got a good return on their investment?
Always is amusing how the dime store lawyers can pass judgement on what engineers and surveyors do. The current generation of coddled buttonpushers (many are i-Zombies) is dumber than the previous group. (and a lot less reserved or understanding)
In structural design it common practice to design for 125-150% of the anticipated load. I guess in Edmonton the cat used up its nine lives after 100+ years.
Since the High Level bridge also carried road traffic, there may also be winter salt accelerating the rusting. Nothing lasts forever, which is why some of the large railway truss bridges have had quite a few components replaced over the years, especially the floor system. We are not told which specific members were of particular concern in the Edmonton article.
I agree that railway rust is mostly a purely cosmetic issue, but sometimes it grows into a bigger issue. The city of Edmonton is finding that out now, which is throwing a monkeywrench into some future light rail expansion plans:
http://edmontonjournal.com/news/local-news/rust-never-sleeps-high-level-bridge-too-weak-for-lrt-engineers-say
Makes one wonder about all the other large steel bridges of the same age that are still handling mainline tonnage, nothing lasts forever...
Greetings from Alberta
-an Articulate Malcontent
Every time we make something fool proof, they come up with a better class of fools.
Remove the old paint, rust etc down to "bright metal." Get your grabs on a product called Chlor Rid (might be clor rid) and apply that prior to priming. It is supposed to remove the chlorene iont that makes the rust.
We engineers put in a design safety factor to account for things we can't directly identify as loads. Of course there is no way to economically design for stupid. A dump truck driving down the roadway with the bed raised is a good example.
I was a mine construction manager in Western New York a number of years ago. We contractedwith a specialty heavy haul trucking company to deliver an over sized mine hoist drum through Hornell. The trucking company hired a pole car to ensure there was clearance for the many underpasses along the route. At the final underpass the pole driver alerted the truck driver there was insufficient clearance. What did the driver do? He put the pedal to the metal and the mine hoist hit the bridge damaging teo girders plus dropping about 50 tons of mine hoist onto New York route 36 causing traffic delays, damage to the mine hoist, bridge and roadway surface. And we got our names in the news paper.
There isa no cure for stupid.
BaltACD Warning systems don't penetrate the minds of idiots. http://11foot8.com/
Warning systems don't penetrate the minds of idiots.
http://11foot8.com/
Dang, beat me to it.
Modeling the Cleveland and Pittsburgh during the PennCentral era starting on the Cleveland lakefront and ending in Mingo junction
On King Street in Toronto between Dufferin street and Shaw street is a railroad overpass. There are electric eye warning lights for trucks on either side. On the west side between the sensor and the bridge is a side street called Atlantic Avenue. There are no sensors on Atlantic. A brewery was being dismantled at the foot of Atlantic. A truck hauling brewing kettles turned to go under the bridge. You can figure out the rest.
Interesting video on that "11foot8.com." I'll tell you, I held my breath when that bus went under the bridge, I'll bet the dust got brushed off the bus' roof!
So the driver went AWOL? Two things, either he went looking for a pay phone ( Good luck on that in this day and age!) or he panicked and ran. More than likely the second option.
Amazing what I see on the roads in my daily travels. I remember back in the 60's there were some road safety commercials on TV that ended with "Watch out for the other guy!"
Just as true now as then. Maybe more so.
Never too old to have a happy childhood!
There are warning systems in place for some of these low bridges. I believe most use lasers, or at least electric eyes. Ultrasonics might come into play as well.
Such a system might not have helped for the megabus that hit the railroad bridge just north of Syracuse a few years ago - The driver missed a turn and was busy fiddling with his GPS whilst trying to find his way back to the bus depot.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
Just require next vehicles that hit bridge to pay for the warning system.
BaltACDREMEMBER - every time you think you have made something idiot proof - along comes another idiot that defeats your protection - so who is the real idiot?
Isn't that obvious to anyone who has been reading many of these forum threads carefully?
But seriously: in many cases you don't need to completely idiot-proof things, you just provide better notice and let Talmudic kares do the rest. Here I thought the issue was just a little different: we need something that reliably indicates ONLY that a 'high-vehicle' condition has been detected and will result in immediate problems. It doesn't have to do that European thing where rising barriers plow through the truck's engine compartment to protect it from damage to the body from the overhead bridge. And if the truck driver in question doesn't stop ... well, from law enforcement's standpoint he's done the equivalent of running a different kind of red light.
I'm surprised we haven't heard from the coordinated-camera-and-satellite-radio people about doing machine vision on the overheight truck and sending a disabling signal to the FADEC or whatever to 'make it stop'. I am not that much of an idiot and hope no one else who posts will be. But there is a difference between putting explicit notes in your documentation that the lawn mower is not to be used as a hedge trimmer and putting an interlock on the mower that alerts any time there are fingers adjacent to a running blade.
And there's another issue: when you think you've made something idiot-proof and introduce new failure modes or opportunities for idiots to cause trouble ... you may not have thought you were an idiot, but reality begins to suggest otherwise.
OvermodWhat I suggested to one of my state representatives is an active telltale deployed from 'catenary cross-suspension' across each of the approach roads leading to a bridge, connected to a system of strobes and red 'truck traffic lights' ahead of and on the bridge structure itself. This would produce enough of a light show, enough ahead of even the dumbest truck driver, to give fair warning that something's not about to clear. I think there are ways to formalize this kind of alert system within, say, MUTCD as an active system of signage for fixed overhead obstacles. What kind of signage is desirable to 'instruct' drivers as to what to do if they see the lights is not yet determined, of course. As is who will be paying for the detectors and their maintenance, the fancy lights, and the power to run them. I of course argue that this is a road issue, not a bridge-owner issue. That's not the only potential answer.
I think there are ways to formalize this kind of alert system within, say, MUTCD as an active system of signage for fixed overhead obstacles. What kind of signage is desirable to 'instruct' drivers as to what to do if they see the lights is not yet determined, of course.
As is who will be paying for the detectors and their maintenance, the fancy lights, and the power to run them. I of course argue that this is a road issue, not a bridge-owner issue. That's not the only potential answer.
REMEMBER - every time you think you have made something idiot proof - along comes another idiot that defeats your protection - so who is the real idiot?
SealBook27Seem to remember back in the eighties, some steel manufacturer put out a product that would deliberately form a coat of rust that acted as a protective much like a coat of paint. Anyone else remember anything about that?
One of the local water agencies replaced a large standpipe with a new structure using that material a few years ago. As it went into its planned surface change, the local residents got up in arms about the "eyesore" and mounted a campaign to have the district paint the tower. The campaign fizzled when the district explained what would be involved and how often the repainting would occur and how much that would affect their water bills. I drive by it frequently these days and I bet neither I nor most of the complainers even notice it most of the time.
ChuckCobleighSomething similar might or might not help, but the rubber tire folks are not necessarily so aggressive in protecting low bridges, it would seem.
I think the situation is slightly different in that much of the railroad detector architecture is to catch things like shifted loads as opposed to the sort of mislined load that used to produce lots of tinfoil from auto racks 'back in the day'. Trucks that hit bridges are just plain where they shouldn't be, and it's difficult to figure out how to make an active 'nondestructive' detector or telltale that would reliably stop them short of many of these obstructions.
What I suggested to one of my state representatives is an active telltale deployed from 'catenary cross-suspension' across each of the approach roads leading to a bridge, connected to a system of strobes and red 'truck traffic lights' ahead of and on the bridge structure itself. This would produce enough of a light show, enough ahead of even the dumbest truck driver, to give fair warning that something's not about to clear.
Murphy Siding We have a bridge over the interstate here that has been hit hard at least 6 times. I recall 2 of those times they had to close lanes on the interstate to do repair work, once for several months. I believe the owners and insurance carriers of at least 6 trucking firms would have preferred a warning apparatus.
Interestingly, railroads employ wide-high detectors ahead of certain mischief-making features, like tunnels. About four miles east of Tehachapi, the new clearance detectors operate apparently to ensure no problems for the tunnels going down the hill. Maybe a similar distance west of Caliente on the same route there is another detector.
Something similar might or might not help, but the rubber tire folks are not necessarily so aggressive in protecting low bridges, it would seem.
Cor-Ten and other such steels (e.g. 'copper-bearing') are different: they are intentionally over-reactive to common environmental corrosion factors, and form a thick coat of oxide quickly that is supposed to be impervious enough to keep the corrosion factors from penetrating to the (reactive) metal surface itself. In this it is similar to many of the aluminum alloys, which almost immediately form an impervious oxide layer that is essentially self-healing in air. (This is not the 'chemical rust conversion', often a phosphating process, used in the 'rust converter' products)
Obviously the steel mill produces a plain steel shape from which some forms of mill scale have to be cleaned, and the steel is erected and welded essentially 'bare' (it may have to be spot-derusted in field weld locations). In the 'old days' there were enough atmospheric contaminants, particularly sulfur-related 'acid rain' related chemicals, to get a good quick and reasonably even oxide development within a few months of installation. Now that air is cleaner, some installations never quite get the right impervious-oxide composition, particularly as I recall in areas subject to chloride contamination, and there you get soluble oxide that forms mottled patching and continued runoff of stain. There is no magic in this kind of chemistry or this kind of protection, but sometimes it's not OK to be kind to Mother Nature when you expect her response to be stronger...
Sure do remember that stuff... a bank built a new building here with the siding made of it. It was not supposed to rust further and they said it would not stain the sidewalk. They kept advertising about the new building with: "Its big, its rusty and its yours!" I said, "If'n it were mine, I'd paint it."
It did stain the sidewalks and the city threatened to sue. I vaguely remember that the bank and architectural firm had to clean the sidewalks and maybe replace some parts to get rid of the very noticeable and ugly stains leading from the building across the sidewalks.
I think it took nearly a year before it stopped leaving rust streaks after a rain.
Semper Vaporo
Pkgs.
samfp1943 Speaking of Bridges vs, Trucks: As I recall, there was a bridge in the Greenville, High Point(?) areas of North Carolina. It seemed to be a'regular' subject photo in TRAINS(?) as the object of another 'hit' by an unobservant Trucker. The problem was that it was on a road directly off a major highway, and offered a way to get into town. It had been originally, a Sou Rwy Structure, and then if became a child of NS. As the weight of freight cars escalated, it was found that the bridge 'flexed' under the load of passing trains, that downward deflexion effected the passing of regular 13'6" height road equipment; ultimately, the bridge seemed to be 'hit' more times that most boxers. Repaving of roads is another reason that causes the passing truck traffic, to loose roof sheets, and other bits and pieces...MudChicken's " Highway Bubba's" can repave a road quickly, but replacing height signs, not so much. Contributing to the local economies, and truck repair shops. The Chicago area, also, being a prime example of that lack of any local jurisdictions ability's in adjusting bridges, roads and signs.
Speaking of Bridges vs, Trucks: As I recall, there was a bridge in the Greenville, High Point(?) areas of North Carolina. It seemed to be a'regular' subject photo in TRAINS(?) as the object of another 'hit' by an unobservant Trucker. The problem was that it was on a road directly off a major highway, and offered a way to get into town. It had been originally, a Sou Rwy Structure, and then if became a child of NS. As the weight of freight cars escalated, it was found that the bridge 'flexed' under the load of passing trains, that downward deflexion effected the passing of regular 13'6" height road equipment; ultimately, the bridge seemed to be 'hit' more times that most boxers.
Repaving of roads is another reason that causes the passing truck traffic, to loose roof sheets, and other bits and pieces...MudChicken's " Highway Bubba's" can repave a road quickly, but replacing height signs, not so much. Contributing to the local economies, and truck repair shops. The Chicago area, also, being a prime example of that lack of any local jurisdictions ability's in adjusting bridges, roads and signs.
Johnny
SealBook27 Anyone else remember anything about that?
Not only do I remember it, I used a similar product several weeks ago on my Jaguar. (It came from a little old man in Morristown, New Jersey, and he drove it in the winter ... not much, but enough for an English car!)
There are actually two versions of this: one does the full conversion to a 'paintlike coating' and the other needs to be covered by a proper primed topcoat for weather resistance. They work, and are nifty for 'completely rusty' items if you have the funds to acquire them.
The problem is that they don't penetrate well under adjacent areas of old paint or other contaminants, and it's expensive to use 'enough' of them to convert scaly and structurally-incompetent surface rusting above the metal surface itself. Therefore you really need to get out the needle gun, sander, etc. to get the surface prepared, and then you have to deal with the old paint, rust chips and dust, etc. as well as the labor and equipment and time. And you still may not get full coverage into the seams and cracks in the structure, or 'convert' problems with rivets or welded areas.
Cor-Ten? I think it may actually go back before that.
VOLKER LANDWEHRThe structural analysis of trusses is not sophisticated. The Cremona diagram or the method of sections are known since the 1860s and are exact for statically determined trusses.
What's gotten sophisticated is the determination of the materials needed. Nowadays, instead of just using, say, the next size larger beam, the computer determines that such and such a size will suffice, over a span of X, etc. The making of structural members (ie, the steel itself) has also gotten more sophisticated.
tree68 VOLKER LANDWEHR As someone said before many of the old bridges were overdesigned, if for rusting or looking forward to future higher loads or just so I can't say. But the effect is the same. I've always thought of the overengineered thing as a result of the lack of sophistication of their design computations. Rather than design specifically to use, as occurs today using computer modelling, they threw in a significant margin of safety.
VOLKER LANDWEHR As someone said before many of the old bridges were overdesigned, if for rusting or looking forward to future higher loads or just so I can't say. But the effect is the same.
I've always thought of the overengineered thing as a result of the lack of sophistication of their design computations. Rather than design specifically to use, as occurs today using computer modelling, they threw in a significant margin of safety.
The structural analysis of trusses is not sophisticated. The Cremona diagram or the method of sections are known since the 1860s and are exact for statically determined trusses.
That doesn't say that you are not right. I think we don't know the reasons. Therefore I added "or just so".Regards, Volker
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