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. Good luck
You're really up to speed, so to speak, priusguy04. That happened a year ago. The haul driver had been given a specific route, but he knew better...
That could have been ten years ago and it's still impressive. Nice find PG04, notice that the boom did not cut through the leading edge of the bridge. That's weird! I would think that the weight of the package would play a big part in how fast they would have to be going to cause that much damage. Wildkow
When I was living in Ireland, they showed me footage of lauries intentionally driven into bridges and other overpasses. The government did this to remind the drivers what will happen if they do it themselves.
If you like those kinds of pictures, look at these: http://www.micom.net/oops/ The backhoe was going from right to left in that picture, and the boom was pointed towards the front (left). That's why the railing wasn't hit, but as the boom was pushed upright, it extended until it was higher than the railing (after punching a hole through the overpass).
From the above list: Titled "African Preflight." There's not a lot of shade in some parts of Africa, and in the hottest part of the day, the kitty cats like to rest in the shade. I was in planes that size and smaller in Kenya, but I never saw lions at the airport. [attachmentid=6536]
Not as impressive damage-wise this did create one of Oahu's worst traffic jams ever. Hard to believe the overpasses get hit. Doesn't anyone think to measure? http://starbulletin.com/2006/09/06/news/story01.html
As someone eluded to above, the question isn't one of speed - it's one of mass and momentum. Something with a huge mass and very little speed still has a lot of momentum, and could slice through a bridge no problem... likewise, something with very little mass and high speed could slice through the bridge. Take, for example, a bullet and a wrecking ball. Fire a bullet into a brick wall, it might penetrate an inch... take a wrecking ball, traveling at a much slower speed than the bullet, and it'll punch right through the wall. So we really need some more information to answer to originally posed question - what was the mass of the truck? How wide was the bridge? How thick was the bridge? Yes, i'm an engineer. Not a mechanical, structural, or civil engineer, so i don't know exactly how to go about solving the question... but i do know enough to ask more questions in return
