Interstate highway overpass - part 1

With all this time on my hands these days, there's plenty of opportunity to get going on some projects on the layout.  Next up is the interstate highway bridges and embankment.  I thought this would make a good scenic break in the layout.  When you're in a present day urban setting, one of the main points of interaction you have with trains is when they go over/under a roadway.

I started with the Rix Products 150' modern highway bridge kit.  The piers feature adjustable height, which helps a lot when trying different arrangements.  Figuring this out required the answer to the question, "how high is a highway bridge supposed to be?"  I looked up info from Union Pacific's design standards, which when converted to HO scale dimensions meant that there should be 3.2" clearance.  This was confirmed by a bridge engineer I know.  When I tried this, I decided I wanted a little more clearance, so I'm planning it for 4" over the rails.  That height should easily clear any train, as well as not look too out of scale.

For the embankment by steel mill, I used white styrofoam pieces with some of those Woodland Scenics risers.  The white styrofoam was easy to cut but really messy to work with.  For the embankments along the river shore, I used cardboard strips covered with plaster cloth.  I still had to use Sculptamold plaster to even out the surface.  For this I tried using that pink insulation foam.  They pieces are 1 inch thick.  I tried some 3M spray adhesive I had from the backdrops and it didn't melt the foam.  I glued the pieces together and then cut the embankment.  The tricky part was the corner pieces in back - since it's at an angle, I had to cut and fit these separately.  I still need to add a small layer of white sytrofoam underneath to get the height right.  Four one-inch pieces together doesn't include the height of the rails and roadbed.  When it' set, I plan to use some plaster cloth for the sides and then some Smooth-It for the pavement on top.  So far I don't know if I like this method of building terrain any better, but for now it was something different to try.

I wasn't sure whether to build another foam embankment (a very small one) on the other side.  It was going to be an odd space, and was going to make the scene a bit like a tunnel.  For now, I'm going to use the second set of piers and just pretend that the bridge had to go further.  The danger is that someone might catch this and knock it off - so my plan is to leave the bridge unattached (just sitting on) the piers.  That way it can be knocked off without breaking the whole thing.  We'll see how it works.

Next up: fitting the foam underlayer; building the bridge itself (I'm going to use a piece of styrene, because the pieces that Rix includes are too thin for two lanes).