Plate Girder Bridge
09/11/2005
For the CrystalCreek module I needed several bridges, but they needed to be simple and shallow. The plate girder bridge seemed to be the right type of short, but sturdy bridge for this module. This page shows how I made them. They are fake plate girder bridges because I simply attached the sides to the sub-roadbed, thereby providing the look of the bridge, but yet keeping a solid support for the track. To speed up the overall process of creating seven of these bridges, I decided to make them all the same length. Most of the bridges are skewed over the two creeks on the module, so the longest bridge came out to be 20 scale feet. I consulted the book "Bridge and Trestle Handbook" by Paul Mallery to find out more about plate girder bridges. It has design diagrams and a couple of prototype photos in it. I built these bridges out of 0.040" styrene. I used a knife and a small file to cut them to size. Styrene can be snapped once a score mark has been made on its surface. Taking a large enough piece of 0.040" thick sheet of styrene, I measured and marked a 20 scale foot section. Then I used a metal ruler and a knife to score this section. After I snapped it off, I marked 5.5 feet sections and snapped those off. The side panels are shown in the first photo.
Plate Girder Bridge
A popsicle stick made just the right template for the curves some plate girder bridges have. I used that to trace the curve out and using a knife and a file I finished both top corners of each side panel.
Plate Girder Bridge
Here's the final shape of the side panels. The curves are probably a bit too much, but it still looks nice.
Plate Girder Bridge
The prototype has a thin railing over the top of the side panels, so I cut these from strip styrene.
Plate Girder Bridge
I then put the side panels in an alligator clip stand and held the strips in one hand, while applying glue with the other hand. I prefer Testor's plastic cement for gluing styrene.
Plate Girder Bridge
Next, I needed to curve the styrene strip around the corners and hold them to apply glue and to give them time to dry. I did all this work on a sheet of glass, and I used weights to hold the styrene strips in place.
Plate Girder Bridge
I wanted some distance (clearance) between the trains and the side panels of the bridge, so I glued these square tubes to the inside of the panels. In the real world this would have been part of the bottom of the bridge.
Plate Girder Bridge
There are triangular pieces of plate used to hold the sides panels in place in the prototype, so I cut these. I got a rough measurement of the height and width needed. I first cut rectangular pieces from 0.010" styrene. Then I cut those diagonally, by eye. I glued them in place by eye. I placed one in the middle, one on each end, and one in between these. It seems to look right.
Plate Girder Bridge
In the real world the side panels are made out of steel panels that are bolted together. To simulate these bolt flanges, I simply glued some 0.010" strip styrene to the outside side and trimmed them to length. They probably should be thinner, but it looks good enough.
Plate Girder Bridge
I painted the side panels with a cheap spray paint bought at Walmart. It makes the panels look like stainless steel. After the module is further along, I will come back and weather these down a bit.
Plate Girder Bridge
This was a fairly straight-forward project. I enjoyed making them. Below is an updated photo showing the bridge in action with track and ballast installed.
Plate Girder Bridge