Just like Rome, this bridge wasn't built in a day, but I finally finished it and placed it on the layout to see how it will look.
My new layout design needed a curved bridge to span the 2 mainlines and some sidings into the diesel maintenance area. I used 3 MTH bridges for most of it, since it was a straight run, but had trouble finding curved bridges. I'm sure someone makes at least the side walls that could be bent to conform to an 054 curve, but I needed to go cheap after paying for the other 3 bridges. Since I had an assortment of Evergreen Plastics styrene sheet and a variety of square and rectangular pieces, I decided to build one myself.
It would have been fairly easy to just do a flat deck bridge, with the big steel I beam structures underneath to support the bridge, but I had clearance issues on the tracks below. The grade is already fairly steep to be able to pull off this design in such a small space. Besides, a portion of the bridge extends out beyond the edge of the layout, so to protect the trains in case there's a derail on the curve, I decided to build what's called a pony plate bridge, which has walls to prevent falls. I placed the curve sections of the track on a piece of heavy cardboard and traced around the tie footprint, then figured out the angles and dimensions. I knew I had to add extra width for the swing and the overhang of the equipment as it goes around the curve. I flunked trig and calculus in school (wait - I don't think I even took them), so I had to rely on common sense and a lot of eyeballing. I'm sure it wouldn't pass railroad standards, but since I'm in charge on this section, I'll do the q.a. Passed.
All of the pieces were cut with either a hobby table saw or utility knife. Styrene is easy to work with, as it requires only scoring the surface and then snapping it off. I used "Micro-Mark Same Stuff Professional Plastic Welder", and it lives up to its name, because there's no separating pieces once this stuff dries after about 30 minutes. It will set in less than 5 seconds, which I like.
The stone bridge abutments are not where they will finally end up. I just stuck them under there to support the bridge temporarily. However, I did need a permanent support, seen in the last photo to span the inside main and support the bridge ends. Both have different levels on the ends, so I used two I beams offset from one another to match up the level plane on top.
I just read about the rivet decals on here a little while ago, and heard pros and cons about using them. How difficult are they to apply? That would certainly dress up this bridge.
Mike