Engineering quiz....

Better question...can you tell me what is wrong with those pictures?

 

I am an engineer so here are my best guesses (I know engineers just have to take it literally because its fun).

Assuming truck was going about 60mph I estimate about 77mph to cut bridge in two. Energy is proportional to speed squared.

If it stops at the point it cuts the bridge in two, a big if, average speed 38.7mph=17.4meters per second, deceleration distance approx 12m therefore 0.7seconds to stop (assuming linear deceleration), ie pretty damn quick. Enjoyed that, I know I know engineers are a strange breed.

Now that is an expensive oops! Cool photos.

 

Damn low flying bridges anyway, working for a trucking company as I do. You would be amazed at the amount of bridges we have tried to deliver. I never understood what the loose nuts behind the wheel don't understand about a 13' 2" tractor/trailer not being able to fit under a bridge that is not @ least 13' 3" from the road surface. I have only run across one instance where the driver was not totally @ fault & that was because the county the particular bridge was in put a fresh layer of asphalt on top of the existing road surface decreasing the distance from the road surface to the bridge girders. Result topped the sleeper, bent the exhaust & peeled the top of the trailer open from front to back. I've seen a couple of trucks that have tried to park in the area between the support pillions & the embankments of I state over passes; two words - NOT PRETTY. Pretty much a million dollars worth of scrap metal & damaged product(depending on the load), along w/ many thousands of dollars of fines & fees.

 

can you imagine driving on the bridge when this happened? what a story that would be to tell you grand kids in about 30 years.

 

What the he!! was that driver thinking? He wasn't an inch or two too high, he was 10 feet too high! I work for a semi-trailer repair shop, and see all kinds of accidents, but that one takes the cake. If it weren't for stupid/careless drivers, I'd be in the soup line.
I was riding through Memphis a few years ago, when 3 huge concrete pipe sections rolled off of a flat bed trailer, and rolled right for me. Is is a good thing I have dirt bike experence because I had to take out the median on my '82 Sabre at 65MPH! I thought I was going to have to ride through one before I could get stopped. Driver forgot to chain them down. Only had a few blocks of wood under them.

 

The boom is higher in the picts than when it hit. It didn't cut all the way up at the point of impact. I'll bet that driver had some soiled Fruit of the Looms after that one.:washing:

 

Where did it enter the bridge at? Both sides ahve no breaks where it allegedly hit the bridge. And yes it is way higher than the bridge which would lead one to believe that a moron loaded it as it would have been loaded incorrectly. The boom should be down, not up. But I bet that pic was photochopped.

 

The only way I can see that happening is that the boom hit the bridge, then the force of the impact pulled the boom up. But you can be sure that at least one moron was involved in that one.:doh:

 

i think that was in vagas and the boom was only 3 1/2" over the hight lemet, the boom dosent set that far back it was forsed back in the impact i have the full story if you want it i will try to find it ?

 

I am an Engineer (Ocean/Mechanical) currently working in Naval Research. One thing confuses me about those pics. It is clear from which direction the boom struck the bridge, by the larger amount of damage on one side than the other, but then the boom protrudes up in the opposite direction??
did they back it in further or something?
Either way, one could calculate that, there are coefficients for the amount of energy that can be absorbed by those materials, yield strengths, then its all F=MA, but wow, all geekery aside, that is impressive!

 

I just can't believe that the boom is that long. If you look at the pic on top of the bridge the boom is a good 10-12 feet above the road surface and that is doubled because it goes back down to the underside, and under the bridge you can see about 10 feet of boom and then another 6-7 feet on the bucket end. and if you figure in the amount that is stuck in the bridge that you can't see your looking at a boom thats at least 50 feet long probably more. I'm no engineer but i do know equipment and thats not probable.

 

electric train driver here, but it looks like:

he boom hit only part way up the bridge span initially.. look at the top pick - the edge/guardrail of the bridge is never hit by the boom.

Seems that initial impact in the side redirected the boom up through the bridge deck and riped the hydraulic rams appart. Once the boom was ripped to an erect position, the the twin rams at the base were only kept from being ripped by the engine/counterweight as the momentum successfull ripped through the reinforced concrete overpace. likely prestressed concrete, not steel I-beams (?) [where are the dudes that do sewage & mud?... yeah, the civil engineers.... they'd know this] did the truck hitch rip off and the truck continued sans trailer? or was the truck torched out from under the trailer?

Vinnie, thanks for leaving a few of Stuka's crack pictures up. :smile: