Donaldon wrote a textbook, but it's a good one! Here's a little more ... footnotes, perhaps?
Many layouts are built with a framework (called "benchwork") covered by a thicker (say 2") layer of styrofoam building board. You design your track layout FIRST, then build the benchwork with solid wood directly below where the track will be. Then, on top of the thick styrofoam, you lay track with one of the several roadbeds: EZtrack with built-in roadbed, or Atlas (etc.) track with pre-formed homasote, ground corr or foam trapazoidal-profile roadbed. The principle is that you want a solid support under the train and rails, so they don't sway or twist. But you want to save on weight and materials and (as you will read below) have access for electrical wiring from below the layout. On the other hand, you want your layout to look as realistically like a real railroad in a real countryside or town, as you can make it. Study the real world itself, like an artist, and then see how other model railroaders have solved various problems of duplicating reality in miniature. Finally, be creative
on your own, try new things, and expand on the ideas that turn out to look good.
By the way, where you are building a switchyard, you'll find the full-scale real-world railroads have NO roadbed. The whole yard is a roadbed, in effect.
It helps, of course, to understand why these various things are done on the prototype roads. Roadbed is gravel that will hold the ties in place so they don't shift, and also drain off rainwater so the ties don't rot (creosote helps, but drainage is still important). In a railyard, it's virtually all gravel all over. Ties are square timbers, not the flat pieces you see on most model track. You put that down on top of a "roadbed" and fill in around it with a little sand, so it LOOKS like the top of a big square cross-tie buried in the little mound that is the roadbed.
You, of course, attach the tie with liquid nails or maybe metal ones (there are schools of though on this, concerned with whether you want to pull it up and reposition it next year or not). That's part of creating the illusion but being practical. One more reason for the solid foundation under the track is to cut down noise and rattle. Homasote is simply very dense pressed paper; it will absorb sound energy, but transmit it down to whatever is below it. It does have some disadvantages; like most things in this hobby, there are those who swear by it and those who think it's the worst crap in the world. That's what makes life interesting -- they are both right, according to their own standards. Styrofoam is light and foamy, so it swallows up the sound energy. The goal is to keep that train rumble from resonating in the frame of the benchwork. That's where you get a noisy train room. Well, yes, a lot of the noise goes into the air: sound-absorbing walls and ceiling help, too. And a carpet or rubber mat on the floor is a very good idea!
Why use that more expensive (but not that much more) 2" styrofoam? For one thing, you can dig ditches, arroyos, creeks, and what-have-you easily and naturally. You can add hills by gluing down a chunk and then sculpturing it. And you can do this afterwards, if you are still finding your way. Styrofoam take most glues (some will eat it up, to test on a scrap first) and water-based paints and scenic pastes. Be careful, though, with spray paints like Krylon. Most of these will also eat styrofoam. Test on a scrap.
Flowing hills are part of making scenery natural. Except for railyards, airport runways and football fields, most ground has undulations of some sort. You can create this on a thick styrofoam base with a rasp or even a wire brush, then sand and scenic (if you are new to the hobby, "to scenic" is a verb used only in this hobby that means "to put scenery on the layout so it looks realistic like the real world").
Another advantage of having thick styrofoam without a solid layer of [ply]wood under the whole thing is that you can put wires through to light buildings and power train rails, just by poking a skewer or even a piece of coat-hanger wire, through the stuff. Just go at an angle under the track so you miss the reinforcing piece directly below.
Yes, I said power train rails. DON'T rely on rails and rail-joiners to conduct the juice from one feed point, unless it's a very small layout (a single loop, say). Use heavy copper wire (building wire, 16 gauge or heavier if it's a big pike) under the layout. Every ten feet or so (there are many opinions about the proper distance, and you will form your own soon enough), run a smaller wire up to each side of the track from that main buss wire to the correct rail or the track itself. Use the insulation color as a code to guide you (as any electrician would do!) so you don't cause a short circuit and blow out your power supply. Always solder the wires and insulate with electrician's tape. There's a trick to soldering the wire to the rails: using the lightest touch and the minimum amount of solder, gently tack it to the "back" side where you don't see it from the front of the layout, and don't make a bump that will derail a wheel. You may have to file down some solder when you're done (no, don't wrap THIS joint with tape!).
It's all part of making your layout LOOK realistic, but work well with the systems (i.e., electricity on rails instead of real steam or diesel -powered locos) we have to use at 1/87 of the real world to create the illusion of reality in miniature.
Happy rails to you!
.......................................railsider
Many layouts are built with a framework (called "benchwork") covered by a thicker (say 2") layer of styrofoam building board. You design your track layout FIRST, then build the benchwork with solid wood directly below where the track will be. Then, on top of the thick styrofoam, you lay track with one of the several roadbeds: EZtrack with built-in roadbed, or Atlas (etc.) track with pre-formed homasote, ground corr or foam trapazoidal-profile roadbed. The principle is that you want a solid support under the train and rails, so they don't sway or twist. But you want to save on weight and materials and (as you will read below) have access for electrical wiring from below the layout. On the other hand, you want your layout to look as realistically like a real railroad in a real countryside or town, as you can make it. Study the real world itself, like an artist, and then see how other model railroaders have solved various problems of duplicating reality in miniature. Finally, be creative
on your own, try new things, and expand on the ideas that turn out to look good.
By the way, where you are building a switchyard, you'll find the full-scale real-world railroads have NO roadbed. The whole yard is a roadbed, in effect.
It helps, of course, to understand why these various things are done on the prototype roads. Roadbed is gravel that will hold the ties in place so they don't shift, and also drain off rainwater so the ties don't rot (creosote helps, but drainage is still important). In a railyard, it's virtually all gravel all over. Ties are square timbers, not the flat pieces you see on most model track. You put that down on top of a "roadbed" and fill in around it with a little sand, so it LOOKS like the top of a big square cross-tie buried in the little mound that is the roadbed.
You, of course, attach the tie with liquid nails or maybe metal ones (there are schools of though on this, concerned with whether you want to pull it up and reposition it next year or not). That's part of creating the illusion but being practical. One more reason for the solid foundation under the track is to cut down noise and rattle. Homasote is simply very dense pressed paper; it will absorb sound energy, but transmit it down to whatever is below it. It does have some disadvantages; like most things in this hobby, there are those who swear by it and those who think it's the worst crap in the world. That's what makes life interesting -- they are both right, according to their own standards. Styrofoam is light and foamy, so it swallows up the sound energy. The goal is to keep that train rumble from resonating in the frame of the benchwork. That's where you get a noisy train room. Well, yes, a lot of the noise goes into the air: sound-absorbing walls and ceiling help, too. And a carpet or rubber mat on the floor is a very good idea!
Why use that more expensive (but not that much more) 2" styrofoam? For one thing, you can dig ditches, arroyos, creeks, and what-have-you easily and naturally. You can add hills by gluing down a chunk and then sculpturing it. And you can do this afterwards, if you are still finding your way. Styrofoam take most glues (some will eat it up, to test on a scrap first) and water-based paints and scenic pastes. Be careful, though, with spray paints like Krylon. Most of these will also eat styrofoam. Test on a scrap.
Flowing hills are part of making scenery natural. Except for railyards, airport runways and football fields, most ground has undulations of some sort. You can create this on a thick styrofoam base with a rasp or even a wire brush, then sand and scenic (if you are new to the hobby, "to scenic" is a verb used only in this hobby that means "to put scenery on the layout so it looks realistic like the real world").
Another advantage of having thick styrofoam without a solid layer of [ply]wood under the whole thing is that you can put wires through to light buildings and power train rails, just by poking a skewer or even a piece of coat-hanger wire, through the stuff. Just go at an angle under the track so you miss the reinforcing piece directly below.
Yes, I said power train rails. DON'T rely on rails and rail-joiners to conduct the juice from one feed point, unless it's a very small layout (a single loop, say). Use heavy copper wire (building wire, 16 gauge or heavier if it's a big pike) under the layout. Every ten feet or so (there are many opinions about the proper distance, and you will form your own soon enough), run a smaller wire up to each side of the track from that main buss wire to the correct rail or the track itself. Use the insulation color as a code to guide you (as any electrician would do!) so you don't cause a short circuit and blow out your power supply. Always solder the wires and insulate with electrician's tape. There's a trick to soldering the wire to the rails: using the lightest touch and the minimum amount of solder, gently tack it to the "back" side where you don't see it from the front of the layout, and don't make a bump that will derail a wheel. You may have to file down some solder when you're done (no, don't wrap THIS joint with tape!).
It's all part of making your layout LOOK realistic, but work well with the systems (i.e., electricity on rails instead of real steam or diesel -powered locos) we have to use at 1/87 of the real world to create the illusion of reality in miniature.
Happy rails to you!
.......................................railsider