In researching the NKP Cloverleaf Division in Toledo, OH, I have been looking at what I think is a rather unique railroad bridge. The bridge is a 500’ ballasted through girder design that carries the current NS over a six lane boulevard (aka: the Anthony Wayne Trail) and a single lane service road. Here’s what makes this bridge unique in my view. The right-of-way crosses the street at a rather acute angle and sits on three piers and two abutments. This makes it a skewed design with the girder spans offset. In addition there are three sets of girders in each span and they are of different construction at one end. I believe this bridge was rebuilt around 1922 from a single track to double track when the Toledo, St. Louis, & Western RR was merged into the NKP. At that time, the NKP trackage was moved to run parallel with the Wabash RR through this area and I think the bridge was rebuilt to handle the change. In addition, the eastern end of the bridge splays out to allow the NKP track to turn away from the Wabash and rejoin the original NKP main line that ran along the boulevard. The NKP main having been abandoned from this point west to Maumee. So in summary, this is a through girder bridge with three runs of girders and the three runs are not always parallel. As an aside, the boulevard was originally a canal that ran through Toledo and in 1936, the road was an unpaved dirt road that was the bottom of the abandoned canal and was called Canal Boulevard.
You will find that railroads may have had some cookie cutter girder bridges but nearly every application had unique factors that made the vast majority custom builds. I suspect that just about anything can be found with one exception. That being that curved girder bridges are either extremely rare or noexistent. While the track may curve the structural members will be always be straight
These curved bridges are made of a series of straight (of course) girder bridges.
(Not my layout)
Mark
Looks great.
The ‘flare’ at one end of a through-girder bridge - or any other type, except maybe a through-truss - is rare, but not unheard of, esp. in urban areas. It would have been a pain to design and build because every dimension would have been computed by hand . . . [sigh]
Curved bridges are now feasible in some circumstances with modern advances in structural analysis and dimensioning, fabrication shop techniques, and more sophisticated contractors, etc.
An example of both is the early 1970’s Burlington Northern Latah Creek Bridge over Hangman’s Creek in Spokane, Washington. It actually splits in mid-span - kind of like the Keddie Wye bridge in northern California - and several of the steel box-girder segments are supposedly actually curved. See -
http://wikimapia.org/1634915/Latah-Creek-Bridge
http://www.flickr.com/photos/80651083@N00/104439917/in/photostream/
Crossing a creek in style
Trains, March 1984 page 31
Burlington Northern’s Latah Creek bridge
( BN, BRIDGE, “KALBACH, JOHN”, SPOKANE, TRN )
Paul, I can’t tell from any of those photos that the bridge girders are curved.
Mark
Some bridges are even MORE fun. On a layout a club was building some 20 years ago, one curved track had to cross above another curved track. One place where the pier for the bridge holding the upper track should have been had a rail line running smack dab under the suppoort point. The ends of two girder spans were supported on a beam that ran across the lower track to an upright pier well off to the side of the bridge it indirectly supported. Wish I had a picture.
I have seen this on one or two real railroad bridges, and on lots of interstate highway interchanges. Rarely modeled except where absolutely necessary.
And of course never built in full size except…