I am creating a plate girder bridge for my model railroad from scratch. It is loosely based on a prototype from my childhood. Hopefully, someone can answer this for me. On a ballasted floor girder bridge, is the construction of the girders below the concrete deck the same as on an open deck design? The reason I ask this is that I am kind of a perfectionist and it will drive me nuts if I don't do it right... Any help would be appreciated. Thanks! Joseph
The primary load bearing surface on an open deck bridge consists of two large beams, one under each rail, with cross members for strength connected to the outside girders. On a ballasted deck bridge the load is borne solely by the cross members out to the side girders. There are several cross members welded together to form a continuous surface under the ballast. The appearance is like corrugated metal building siding.
There are many ways of achieving a ballast trough on a brige - Al's is one. I get the impression that the most common is to have multiple crossmembers (maybe 5 to 10 times more than on an open deck) but of a much smaller depth (say half) on top of which is placed a concrete deck with side walls or a cast trough. No doubt there will be examples of an open deck converted by the addition of a trough - so you can probably do what you like underneath. Just please don't make any of those obvious errors like curving the girders to get a bridge on curved track
Al & Mike, Thank you for your quick responses. You both have definately pointed me in the direction that I want to take. And Mike, don't worry... Thanks, Joseph
