Backhoe Crashes Into Highway Bridge

Backhoe Crashes Into Highway Bridge

A Backhoe weighing 8 tons is on top of a flat-bed 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 reobars 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.

Answer: Who cares, the trucking company just bought themselves a bridge.

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Date: 4 Aug 2008 | Author: mesmerX | Category: News, Pictures | Views: 21437

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Comments: 15

Guest | 28 Jul 2011 - 22:01

It's an excavator. My 5yr old knows this. TO the author : They may have miscalculated the height of the bridge but your grammar skills lack depth.

Lubomyr Prytulak | 24 Mar 2011 - 04:16

Damage occurred in two stages. First, the horizontal motion from right to left resulted in the arm cutting through the underside of the bridge only (the pedestrian guard rail was left untouched). At the same time, the impact rotated the backhoe CW until its tracks hit the underside of the bridge (see underside of bridge on the left). This CW rotation allowed the backhoe arm to pass under the right-hand edge of the bridge. Once in the middle of the bridge, the backhoe rotated CCW to settle into its normal horizontal position, and this rotation pushed its arm up through the middle of the bridge. Presumably, this surface is less strongly reinforced and easier to penetrate than the edges of the bridge.

Joe | 21 Jun 2009 - 18:01

....I'm applying for the driver position that just opened....

josh brown | 4 May 2009 - 10:45

wow

RCH | 5 Mar 2009 - 08:11

John - If you think a truck towing a backhoe/excavator (even at the lesser weight of 8 tons) can go 204MPH you need to double check your math.

John Erickson | 28 Feb 2009 - 08:44

p.s. I did this for a 8 ton backhoe... if it really does weigh more like joe said (36 ton?!?!) than those numbers below will change big time.

John Erickson | 28 Feb 2009 - 08:42

Yes it is solvable (or at least close enough). There are a few assumptions to be made but it shouldn't effect the answer too much. All I'm gonna do is find the maximum shear force that the bridge can withstand (horizontally) and then using F=ma to determine the acceleration that the bridge exerts on the backhoe. Once that is known I just used kinematics to find the required velocity to make it through the whole 24 feet (span of the bridge). I just did a rough estimate and got about 300 ft/s (204 mph). Like I said this is a rough estimate and I very well could have made a mistake but with a little bit of research on the construction of the bridge a much better estimate could be found.

Joe Cuppa | 25 Feb 2009 - 22:12

Unsolvable math problem, not enough factors. But a good caption for the photos.
It took me a few minutes but if you know what you are looking at you can tell just what happened.
First, that is not a 8-ton Backhoe. It is a 25-ton Hyundai 210 Excavator, Huge difference.
That thing travels with the arm extended out to the front. The highest point in pic-3 hit first slicing
into the first few feet before the arm collapsed, folding up and puncturing the overpass.
The damage over the cab in pic-2 is from the bucket slapping the bottom of the overpass.
Notice that leverage and sheer weight crushed the trailer. Amazing

Joe | 25 Feb 2009 - 21:39

That is not a 8-ton Backhoe.
It is a 26-ton Hyundai 210 Excavator,
Huge difference.

springhill | 18 Feb 2009 - 04:54

The hoe was hard-up?

JR | 4 Feb 2009 - 16:49

I hope the driver was wearing a seatbelt... Ouch!

Piano2man | 20 Jan 2009 - 08:25

I ran into a hoe!

Jetster | 15 Dec 2008 - 03:48

Well, technically that isn't a backhoe. It's an excavator.

mesmerX | 5 Aug 2008 - 01:16

«If your driving on top of the bridge, and you hit the Backhoe Shovel, how do you explain that to your insurance company?»

Haha. That would be a hilarious situation. The look on their faces...

Thomas S. | 5 Aug 2008 - 00:02

If your driving on top of the bridge, and you hit the Backhoe Shovel, how do you explain that to your insurance company?

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