I’m working on an HO scale module at a club layout, and part of my plan for the module calls for a tunnel. It is a corner module, and the tracks going into the tunnel are part of a 30.5" radius superelevated curve. The track spacing is about 2 1/8 inches. I model the PRR in the 40s and 50s, but modern equipment (double stacks and hy-cubes) is run on the layout too. I looked for tunnel portals wide enough for the double track-curve-superelevated clearances, but the only one I found was a Woodland Scenics portal that didn’t look wide or tall enough.
I finally decided that the only viable option is to carve one myself from plaster, but I have no experience in this area. If anybody can provide step-by-step or tips in this area, it will be much appreciated.
I’m also looking for diagrams of a PRR tunnel mouth that I could model. I checked the site http://prr.railfan.net/standards/standards.cgi?sortby=1&sortdir=up, which has PRR standard plans, but they didn’t have the plans for a tunnel. So does anybody know where I could find some plans?
Have you thought about using foam for the portals. This can easily be done with a small scroll saw. Here are some pictures of portals that I created for my Virginian railroad.
First, I am a bit concerend about your track center separation. Please verify using trials that all possible combinations of rolling stock will pass by each other safely, trailing and being shoved. Seriously, you have to do it…now.
Secondly, I found that a safe separation doing into a tunnel portal is probably not achievable unless you are willing to craft or bash the available portals. I can’t be bothered making my own, which would have worked nicely, so I cut the double-wide Woodland Scenics ones in half at the apex and glued shaped plugs of either wood or extruded foam board into place. It isn’t a photo meant to show it specifically, but if you look closely, or use the screen magnifier, you can see what I mean. And my curvature there is 36" on the inner curve. The separation is rather generous there and more than I really needed, I think about 3".
For the shell/mountain, fashion a lattice of cardboard strips, or use risers and hot glue window screen to it, stuff under it with crumpled newspaper stuffed into grocery bags to keep it from sagging, and layer something like sculptamold or a ground goop over the screen. Then apply ground foam. For a liner behind the portals, use the same screen and goop or sculptamold slatherd on the inner face of an arch of the screen and paint it black leading to grey toward the back of the portal.
I too am concerned w/ your track spacing, especially on a club module that “who knows” what will be run in the future. A track center of 2 1/2" will allow any length or pilot overhang to have sufficient clearance. I have modified the WS portal much the same only cut two portals slightly off center making the keystone larger and glued them back together. A bit of hydrocal was needed to “doctor” up the stone work. Hint: when calculating the cut try to keep the stone sizing in mind. If you feel the portal may be somewhat weak from the work, glue it to a piece of thin ply or foamcore.If base is cut properly (held back from portal opening) it can also act as to attach tunnel liner material.
Another consideration w/ doublestacks and autoracks is to make sure there is clearance @ the upper curved portion of the portal. Instead of creating a “too” wide a portal, I simply raised it for the clearance.
Thank you for your suggestion about using foam for the tunnel portals. I have tried carving foam before, but I have found it “trying”, and I can’t seem to get the shapes that I want. I will consider foam as an option and “try” again. Thanks again.
I used the 3/4" foam. I used a Woodland Scenics portal as a template and cut the portal with the scroll saw. I then used a ball point pen and ruler to etch the lines before removing the plastic sheet that covers the foam. Good luck.
Thank you for your concern about the track spacing. It’s been a while since I laid the track, and I think that the spacing is more like 2 3/8", not 2 1/8". The club has run full-length passenger cars past each other around the curve without problems, and with plenty of clearance. Sorry about that, I was going from memory, but I knew that it was very close to the NMRA reccommended spacing for a curve of that radius.
Thank you for your suggestion to kitbash a wider portal - you would think that they would offer “curve” portals with wider clearances, but NOOOOO… [:D] (sorry, SNL fan.) The tunnel is in the middle of the module, and I plan to use cardboard strips covered in plaster-soaked paper towels to make the mountain. I also make a low-relief mountain that fits up against the wall of the layout room to add depth to the scene.
Thank you for your suggestion for the inside of the tunnel. It sounds interesting and I would be interested in seeing pictures of how it looks when finished.
In my post to SELECTOR, I corrected the spacing - sorry about that. The doctored stonework on your tunnel portal looks great - it’s hard to tell that it was once two portals. Thanks for the tip to raise the tunnel portal up to allow the double-stacks. Otherwise some HO scale workmen would be getting pretty mad when all the containers coming out the other end of the tunnel were missing their tops.[(-D]
Your layout looks great - I love the working grade crossing, I’ll have to put one in on my home layout…
Could you clarify what foam you used? What I have been trying to use is pink foam insulation board, which doesn’t have a plastic sheet covering it, so I’m interested in what type of foam you use.
Thanks for the tip about using a ballpoint pen - that’s a great way to get the narrow mortar lines!
S&S, I used Owens Corning 3/4" insulated foam sheathing (pink) that I picked up either at Home Depot or Lowes. The foam is covered on both sides with a plastic film. By drawing the lines before you remove the film you don’t have the ink from the pen. Any touch-up work I did after the film removal I did with a letter opener. You don’t want to puncture the foam with a sharp object.
I cut the portal from regular pink foam board, carved what I wanted into it, make it look like concrete, painted it, than added the "stone’ trim around the opening using the quick-set drywall mud, painted that, then positioned it in to the rock cliffs.
Those are great looking portals how do you create the mortar marks or expansion joints what ever they might be. they really add so much to those tunnels.
Tunnel portals can be made from wood (maybe not for the Pennsy). I had a situation where two tracks came at a mountain in close proximity. Had they been level with each other, I might have been able to use a double portal. However, one was about an inch and a half higher than the other. So, I separated the tracks a bit more and made a wood portal from Evergreen siding and strip wood beams. The project was fun, not difficult at all and worked out well.
To create the mortar lines on the foam portals I drew the lines with a small amount of pressure using a ball point pen. By doing this before removing the plastic film, I left the depression without the ink lines. After painting the portals I used a black wash to highlight the lines. You can experiment with other utensils to scribe the lines, but you want to avoid using sharp ones that would cut the foam.
Thank you very much everyone for your suggestions for making the portals. Your advice has been very helpful, and I now know of more options than I did before.
I’m still looking for photos/diagrams of PRR tunnels. Standard plans would be great, but photos would also work. If anybody can share some photos or a site that has some plans, it would be appreciated.
