bwrts Posted July 25, 2006 Posted July 25, 2006 Engineering Quiz A backhoe weighing 8 tons is on top of a flatbed trailer and heading east on Interstate 70 near Hays, Kansas . The extended shovel arm is made of hardened refined steel and the approaching overpass is made of commercial-grade concrete, reinforced with 1 1/2 inch steel rebar spaced at 6 inch intervals in a crisscross pattern layered at 1 foot vertical spacing. Solve: When the shovel arm hits the overpass, how fast do you have to be going to slice the bridge in half? ( Assume no effect for headwind and no braking by the driver...) Extra Credit: Solve for the time and distance required for the entire rig to come to a complete stop after hitting the overpass at the speed calculated above. Check all three photos below. Answer - Who cares, the trucking company just bought themselves a bridge. Quote
olyclimber Posted July 25, 2006 Posted July 25, 2006 This was obviously an act of domestic terrorism. Quote
foraker Posted July 25, 2006 Posted July 25, 2006 Hey! Peterbilts are the trucks of peace! WHo says math isn't useful in real life? Quote
underworld Posted July 25, 2006 Posted July 25, 2006 the truck driver's cell phone told him to do it! Quote
olyclimber Posted July 25, 2006 Posted July 25, 2006 using Google's revolutionary new calculator, i determined that you'd need to be going 94.15467564 miles per hour. teh calculator of teh internets Quote
snoboy Posted July 26, 2006 Posted July 26, 2006 WTF is that in the second picture? I think pic 1 and 3 are real, but 2 looks photoshopped or unrelated. Quote
fern Posted July 26, 2006 Posted July 26, 2006 it's the elbow of the big digger arm sticking through the deck of the bridge. Quote
sobo Posted July 26, 2006 Posted July 26, 2006 Pic 2 is indeed NOT PhotoShopped, nor is it unrelated. These pictures (and many many more) made the rounds several months ago in many of the trade magazines that come through my engineering consulting office. It's not a joke. Nobody got hurt, but I think the driver went looking for a new line of work... Quote
Alpinfox Posted July 26, 2006 Posted July 26, 2006 Why isn't the bridge cut all the way through on the right side in this picture? Quote
jmace Posted July 26, 2006 Posted July 26, 2006 k this is so bull..look carefully yup alpinfox beat me to it Quote
Alpinfox Posted July 26, 2006 Posted July 26, 2006 I'm thinking maybe the whole backhoe (or whatever that thing is) rocked to the right upon impact and then when it righted itself, it poked up through the bridge leaving the right side intact? This would also explain the damage on the underside of the bridge above the cab of the digger. Quote
dt_3pin Posted July 26, 2006 Posted July 26, 2006 (edited) Snopes sez its true, so it must be Edited July 26, 2006 by dt_3pin Quote
lI1|1! Posted July 26, 2006 Posted July 26, 2006 Scopes sez its true, so it must be unless snopes is doing hoaxes now... i'm guessing the arm angled up into the bridge when it hit, basically penetrating the bridge from beneith rather than slicing it. Quote
jmace Posted July 26, 2006 Posted July 26, 2006 nah..the arm hits first then forces the cab and front to hit the bottom of the bridge, damage, then the arm drops lower than the railing moves under the bridge then slices through the deck and pokes through the top of the bridge.. Quote
sobo Posted July 26, 2006 Posted July 26, 2006 (edited) During transit, the boom and arm are typically lowered in the forward position. That is, the excavator is loaded in the same orientation as the transporting vehicle with the "elbow" in the most forward position on the excavator. Therefore, the elbow (or more likely the back (top) side of the boom) would be the first thing to hit the underside of the overpass. Immediately upon impact, the arm/boom combo would attempt to reverse upon itself (think inverted cam, hyper-extended knee, etc.) as friction grabs a hold of it, and also because it can't deflect downward because of the excavator body and the low-boy trailer upon which the excavator sits. With no place else to go, the arm/boom combo begins to hyper-extend and lifts to a higher elevation as the transporting vehicle combination slows to a stop, and thereby continues to slice through the bridge deck and ultimately appears as it does in Pic #2. I've got about a half-dozen more pics of this if anybody's interested is seeing them. Edited July 27, 2006 by sobo Quote
Alpinfox Posted July 27, 2006 Posted July 27, 2006 OK. Well here's a photo of the aftermath of an even more incredible event. Meteorite comes through roof/ceiling and destroys printer: Quote
sobo Posted July 27, 2006 Posted July 27, 2006 Yeah, that shit only happens about every 100,000,000 years or so. A lot less often than trucks hitting bridges on the highway. About five or six years ago in Yakima, a Waste Management driver was hauling one of those huge, trailer-sized dumpsters through town on Nob Hill Boulevard at some ungodly hour of the morning. Apparently, he'd forgotten to lower the dumpster completely onto the trailer bed, and headed for Yakima Valley Community College. Welllllllllll, five or six years ago at YVCC on Nob Hill Boulevard, there used to be this overhead pedestrian bridge... It was finally replaced about two years ago. Quote
snoboy Posted July 28, 2006 Posted July 28, 2006 it's the elbow of the big digger arm sticking through the deck of the bridge. It's got an awfully long boom then. I guess it's one of those extra long reach ones. Quote
MisterMo Posted July 28, 2006 Posted July 28, 2006 Engineering Quiz A backhoe weighing 8 tons is on top of a flatbed trailer and heading east on Interstate 70 near Hays, Kansas . The extended shovel arm is made of hardened refined steel and the approaching overpass is made of commercial-grade concrete, reinforced with 1 1/2 inch steel rebar spaced at 6 inch intervals in a crisscross pattern layered at 1 foot vertical spacing. First off that's no 8 ton excavator. I can't make out the model number but just looking it appears to be closer a 315-320 Cat sized machine. Second, the visible rebar doesn't look like inch and a half to me. Since I call BS on the word problem part I guess I call BS on the photos as well. Quote
catbirdseat Posted July 28, 2006 Posted July 28, 2006 What would have really been awesome would have been a stop frame movie of the actual collision. I imagine that upon impact, the trailer busted loose from the tractor instantly. The driver would look in his rear view mirror and mutter something like, "oops", "oh, no!", or perhaps, "Doh!", as he continued down the highway, sans load. Quote
crackers Posted July 28, 2006 Posted July 28, 2006 First off that's no 8 ton excavator. I can't make out the model number but just looking it appears to be closer a 315-320 Cat sized machine. R290LC-7A I think the snopes picture is the best one...it looks nice at night. Quote
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