Well, you’re wrong!
The NP had an “S” curved trestle up in the Silver Valley.
On logging lines, that’s about the only kind of trestles they had, as the rails curved up and down the mountains.
They are prolly more prototypical than straight ones.
I have two on my layout: both over 12 feet long.
There’s a big one called the Foss River Bridge that GN built…It’s even on a 2.2% grade as well
(http://www.jiffywebdev.com/SHS/img/FR-03.JPG)
Been over it a few times too 
I think what modelers refer to as curved bridges are bridges structures that are curved. Steel curved bridges are just a bunch of short straight bridges at different angles to each other. The track curves, but the bridge sections ‘remain straight’.
Check out the double tracked one in WV sometime or the viaduct in Maryland …
Straight chords between supports. Totally correct. What is NOT correct is R1 curved bridges as wide as the tie supported every two feet.
Easy explanation:
Draw a line between towers. Unless the bridge deck is wide enough to support the ties fully, and fully supported across the ends, it will fall when you get 150 tons outside the line.
The bridges shown are straight decks between support pillars.
Big difference.
Amazing photo Steve.
I learned long ago that pretty much anything in the model world was prototypical at some point.
(http://www.trainminder.com/assets/images/picCurvedBridgeChina.jpg)
(http://www.mountainbikebill.com/images/Trails/CarrizoGorge/CarrizoGorge-1JAN04-Eric-17.JPG)
(http://www.mendorailhistory.org/images/railroads/howe_truss3.jpg)
Don’t forget to check out the link that I included. It’s highlighted in blue…
well here’s my version. Up hill to boot!
(http://i1234.photobucket.com/albums/ff403/dave2-8-0/BRG-35.jpg)
(http://i1234.photobucket.com/albums/ff403/dave2-8-0/BRG-34-1.jpg)
(http://i1234.photobucket.com/albums/ff403/dave2-8-0/BRG-32-1.jpg)
BTW it has weathered quite well…
And looks good Dave…
As an Engineer I can assure you that curved bridges are most definitely possible and are used regularly.
As far as someone building an R1 radius curved bridge. I say go ahead, use what you have to work with, we are not holding 150 ton loads here. It is toys and sometimes you have to cheat to get the track in where you want it.
Ken,
Isn’t that ex WP?
Bob C.
Bob Cope said:
Ken,
Isn’t that ex WP?
Bob C.
Yup, that’s the Keddie Wye…
I think it would be more accurate to say these are “bridges and trestles on a curve”. As others have pointed out, they actually consist of short straight segments.
Ray Dunakin said:
I think it would be more accurate to say these are “bridges and trestles on a curve”. As others have pointed out, they actually consist of short straight segments.
Some are “short, straight segments”. Some are not.
Ralph
Ralph Berg said:
Some are “short, straight segments”. Some are not.
Ralph
Ralph said “Segments”
The BNSF Wye in Spokane Wa. It is a true curved viaduct, not sectioned.
(http://freightsheds.largescalecentral.com/users/jebouck/spokaneY.jpg)
Dang that’s a busy spot!
I like it!