what are the best ways to create a tunnel for HO scale?
There are multiple ways to create tunnels, but no best ways. That depends on your skill and comfort level with materials. The main thing from my point of view is to make sure you have access. Things happen in tunnels, like derailments or uncouplings. You need to be ablt to get to your tunnel without disturbing your scenery or track work. I like to access tunnels from underneath.
I usually put rerailers at each end of long tunnels and at least one in the short tunnels.
This way I might be lucky and have the problem cars rerail themselves to get the train out of the tunnel.
BOB H - Clarion, PA
As Chip says, there’s no best way. Construction will depend on length, type of benchwork, scenery methods and position on the layout. Short tunnels are the easiest, however when they are used, make sure there’s enough mountain height over it. Just having a random bump w/ a hole through it can be very unrealistic. Real RR would have just blasted a cut instead. The main concern for long tunnels, make sure there is access for derailments, track cleaning etc. The access can be from under if enough room, side or back within reason or a lift out section or removable top. Removable sections are the most troublesome and hard to disquise and not continue wrecking the scenery when used. Generally a removable side access velcroed or hindged panel works for the average tunnel/ mountain application.
To actually construct the mountain, you have countless methods to pick from. Many use foam. The foam can be stacked in layers and have a removable top/ hat if needed. Cardboard lattice can be shaped and supported as needed be foam/ wood supports and glued, stapled to supports and backdrop. The other method is shaped wire or screening stapled and supported like the cardboard. When making the tunnel, always figure what portal you want first. There are different ways to set them. Some glue directly to foam cutout, others glue them into the cardboard w/ wings strips. I like to set a pine or plywood base that is shaped to accomadate surrounding scenery and rough portal cutout just large enough to anchor tunnel liner/ sides. Remember to ballast and fini***he track/ liners before setting the portal though. One other important thing, is when selecting a portal, especially on a curve, check for side clearances due to the pilot and side overhang of equipment. The NMRA standards guage will only work for min clearance on straight track, it doesn’t take this into consideration.
Good luck on you tunnel, check out some scenery books to get a good feel of what will work “best” for you.
Bob K.
Another thing to consider (as if you need more stuff to worry about) is interior detailing of the tunnel. I use a small video camera mounted at the front of my subway train, so I built the tunnels up with scenery inside. Even if you’re not using a camera like this, at least the first few inches of the interior should have scenic details, because you will see them from outside.
I have a number of lift-off sections above the tunnels. My scenery is still largely in the pink foam stage, so I haven’t yet dealt with the problem of hiding the edges of the liftoff sections yet. Lift-offs give me good access to the inside of the tunnels, not only to fix derailments, but also to do more major stuff like track maintenance.