The Subway Cover
One important aspect of the subway that needed to be solved was how to access the train for maintenance, cleaning, and future scenery work (I’d like to eventually be able to run a train equipped with a camera through the tunnel and have it look like a tunnel, not a bunch of styrofoam). Access from the front is possible with a removable fascia, but this would be limited to a fairly narrow (two inch) slot, making anything more than simple cleaning quite awkward. More problematic is the inner section of the subway on the River Crossing scene and where the tunnel crosses to the back of the River Station scene. Neither of those is near a front edge.
For a broader overview of the subway, see the Subway Design page.
The obvious solution is some kind of removable lid. But that lid has to support structures (buildings, viaducts, and part of the elevated Urban Station scene), or provide a surface used for roads or roadside scenery. Metal, such as thin aluminum sheet, could be used, but would be hard to work and difficult to attach to plastic elements. Painting a structure that mixes metal and plastic could also be problematic. And finally, expansion/contraction due to seasonal temperature changes would be a problem if it were permanently attached to styrene elements such as buildings or strip styrene used for sidewalks.
Plastic sheet, on the other hand, lacks structural strength and tends to crack under repeated flexing. There are two main forms of large sheet plastic: acrylic (plexiglas) and polycarbonate (lexan). Sheet styrene (ordinary model plastic) could also be used.
My initial plan had been to go with Lexan, with a thickness around 0.090 inches (3/32”), which is readily available from home supply stores in large sheets as a window pane material. After some research into this, and more thought, I changed my mind. What I ended up with was ordinary styrene sheet, in 0.080” thickness (2 mm), which is adequate for a double-track tunnel if there isn’t going to be any substantial weight on it (a building should be okay).
One problem with Lexan was that it doesn’t glue to other things easily, and the glue needed tends to be pretty nasty stuff (MEK, which isn’t something I want to be breathing fumes off of), although super glue can be used if lateral forces aren’t going to be strong. It would also have been a pain to cut in shapes other than straight lines. Styrene is a bit easier to work. And while styrene glue is still nasty stuff (it contains Toluene, which affects the nervous system if inhaled in quantity, so good ventilation is important) it’s okay if handled carefully. I’ve also used Liquid Nails to glue cork, vinyl-foam ballast, and styrofoam scenery elements atop the styrene.
Above is a cut-away view of the revised plan for a subway tunnel (the original along with larger versions of the new ones can be found in the Diagram Album). I discovered that some of my 2” foam wasn’t really two inches thick (some was as much as a 1/4” thinner), and ended up adding a layer of Gatorboard in places. Gatorboard is like foam-core: it’s a layer of foamed plastic, essentially dense styrofoam, between two outer surfaces. In ordinary foam-core, the surfaces are paper, and exposure to water (as in scenry) can warp it. With Gatorboard, the outer layers are actually wood fiber in a resin binder. Not only will this not warp when exposed to water, it works well with carpenters glue. I’ve used it in a few places, although in this application ordinary foam core would probably have also worked.
The hard part was making the notch in the foam to inset the styrene flush with the ground. This required quite a bit of work with a knife and rasp, and some places ended up very rough, and needed to be patched with plaster (as seen in photos below).
In addition, for the station front support, instead of a block of wood with cut-outs, I used a strip of 1/8” aluminum bar stock, held up on wooden posts (the front fascia still has cut-outs). Here, the platform overhead helps support the wider expanse of styrene (and in this particular section, there is styrofoam, plaster and track with trains above, so there’s a significant weight involved).
Station Subway Tunnel
Notched foam and aluminum support
And the end result looks fairly good:
Subway roof with incline (before plaster or paint)
Subway Roof (left foreground) beneath the Rapid/Shinkansen tracks
For more on the subway, see the Subway construction page and the Subway Scene page.