The Lower Rollstone Bridge

[daveleo]

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This is one of the oldest (1870) of the surviving iron bridges in the US . . . it's about 4 miles from here, and it's a "national historic landmark" (whatever that means).

 

It is rotting away and surrounded by weeds and wire fence and it lies below the "bridge" that replaced it (which is a horrid, offensive piece of shytt . . . if you will excuse my Italian).

 

If you understand bridges, this is a simple, not very efficient design . . . it looks like they did what they knew how to do with what they had to work with (I-beams in tension?), but that's not my point. My point is that it's a sad, tired, rotting, dying old bridge that 99.99% of the local people don't even know is there . . . and wouldn't care anyway.

 

But I know, and I made a visit today and took her picture.

[elansprint72]

Dave,

I'm glad you took the time; shame that it is left to rot. btw, I disagree about it being "simple", quite a bit of stress-calc must have gone into that design and I wonder how they measured the torque when they put the tension on? Each "spoke" would have altered the tension on all the others as they did the nuts up. There is (fortunately) a lot to be said for massively over-engineering things (especially bridges) as I was discussing only today with my Father-in-Law as we stood on a very old stone bridge (150 yrs?) with two huge semi-trailers stationary alongside us.

[daveleo]

Pete

so true . . . i should have said "crude" (by todays standards) but certainly not simple, given the calculation processes they had to work with.

engineers call that design there "statically indeterminate" which means you have to add a bunch of wisdom over and above whatever numbers you calculate.

 

i greatly admire those old-age bridge builders . . . . esp the wooden bridges the railroads built on the fly using local trees ! !

 

nowadays very few people understand or care about that old stuff . . . even the young engineers don't get it. . . knock it down and use a computer to design the next optimumly perfect ugly . . . i go on and on, i do.

 

o well . . . progress moves on, i think ?

 

someday i'll tell my story about an optimized structure that almost ended my career.

[pauledell]

Dave,

 

A picture you may be glad to have taken. A record of a piece of history that will most likely be torn down and forgotten. I can't begin to tell you of the missed oppurtunities of recording old buildings before being razed that I had.

 

Paul