If anyone ever warns you not to put a tunnel on a curve, you might want to listen. I found out why you shouldn’t do this the hard way… Now I’m very limited on what length of rolling stock can fit through it. Passenger cars do okay, but no auto carriers or husky stacks with containers over 40’. I guess I could rip it all out and start over, but that’s such a hassle. I’d rather just leave it alone and gripe about it…
Tracklayer
If one makes sure the radius is sufficient and the inside clearances are sufficient, then things will work okay. Which is to say, planning, planning, planning. With this, tunnels on curves work fine.
PennsyHoosier, where were you when I was planning the **** thing ?..
Oh well. Live and learn. I guess if I’d take the time to alter the tunnel portals a bit I could probably get anything I wanted to go through. But, like I said, what a hassle…
Tracklayer
Proper radius and track spacing worked for me. I did have to reach in and rip out some cardboard mountain supports for clearance, but all the plaster was dry and they weren’t
needed anymore. I did make sure to leave arm size access holes so I can reach in and take care of future access problems. The big thing is to make sure your track work is done right before you build the mountain.
I too will like to run container cars
but
You won’t regret taking a file or chisel to the tunnel as you will be able to run anything, and repainting. It will be worth the effort. Just think for a moment, all that effort and you cannot run what you want. Or if your at a show or shop you see something you just have to have but oops, I cant run that because I didn’t allow clearance in my tunnels. Come on man just do it. You will be a very happy camper.
The real railroads did, and gress what they had the same problems!, They too had to make the tunnel bigger or daylight it. Here in south Alabama at a place called Tunnel Springs is a tunnel about a half mile long that has a curve about half way through,you can get standard cars but no over size one’s through. It’s on an old L & N branch, that is now called the Alabama
The track here went together smoothly, most trains running ok, so I started carving foam and when the cloud of styrofoam grommets settled, all the terrain was roughed in.
There were a few brushes with styrofoam here and there, but a little nudging and repositioning had everything running smooth until the next time the foam was jostled. Then Christmas came, new locomotives and rolling stock and minor problems started to build up. The layout moved from one room to another, the foam being set to the side for transport, and problems with the track became too much to deal with. One 35 year old Atlas #4 in brass in particular had to go, closeby a temp section of roadbed needed replaced by the now complete bridge deck, another #4 down at the bottom of the same grade was spanning a tiny height difference between roadbed sections causing derailments when backing in, so I yanked the entire section.
New roadbed, with the breaks between pieces located in non-critical spots in the middle of a continuous piece of track, belt sanded smooth at all joints, and rebuilding the grade all the way up to allow for a smoother transition up top left us with one last section of problem track where two Peo small radius curved turnouts abutted each end of a six inch section of flextrack, 18’ radius, 19.5 inch on turnout 1, who knows what radius on the short connector, 19.5 inch on turnout 2, then back to 18 inch, disaster after disaster happening there, Saturday I ripped that out, made a siding into a spur, tweaked the arc and railheigths at joints, and now, every locomotive and piece of rolling stock we have, including Bachman’s mile long 200 ton crane boom and Model Power’s H-207 railmounted artillery piece all run the mainline with no clicks, no thumps, smooth as silk.
A day or two to tweak up some minor details, one branch of a turnout powerless, another decades old #4 to be replaced, and we are back to laying foam, after a two month retrenchment.
This time around, the first two layers
I have a single-wide WS stone portal in two places using 22" radius curves. In both cases I have no problems getting my BLI Niagara and Lionel Challenger throught those spots. I had neither of those engines when I built it back in March. Some of us are just lucky…I guess.
Tunnel portals also need to be wider on curves. A simple method of a wider portal is to cut 2 identical ones just slightly off center to gain the required width for clearances. Use a cardstock template for the pattern. Remember that inside radius needs clearance for body overhang of long equipment (passenger, high cube and especially double stacks). Out board clearances need to be figured for the largest articulating/ pilot swing say for exanple if you ever plan to run a Challenger or Big Boy. The NMRA gauge will not help for clearances on a curve. I had kitbashed a WS stone double track portal by this method and still had a couple of the containers on double stacks just graze the upper inside radius of the portal. Should have worked but, no, shimming up the portal solved the problem. Now I’m extra careful on checking the clearances.
Bob K.
I’m glad you brought this up. I’m planning on building a tunnel on an 18" curve. Now I will look at the plan again and maybe make some changes or make sure the is plenty of clearence inside the tunnel. Thanks
Steve
I put tunnels on curves but you’ll have to scratch build them…the commercial tunnels won’t work because they are too narrow for the trains to pass thru them due to the cars swinging out over the radius of the track that cause the cars to hit the side of the tunnel…I build a jig from 3/4" x 1/2" wood and use card stock strips to form the curved sections of the tunnel …then i’ll make a plaster of paris pour to fill in the jig…once the plaster dries, I’ll carefully remove the tunnel from the jig and then i’ll take a hobby knife and etch the brick or stone into the tunnel fascia, smooth any rough edges with sand paper, and then install the tunnel on the layout…chuck
Hey…don’t forget height! (don’t ask) but you can’t run double stacks through a 1940’s tunnel portal! OOPS, LOL jc5729
I HAVE to put tunnels on curves, because all of my straight track is taken up with bridges, LOL! Seriously, though, it is a bit tricky. Most of my tunnel portals are off-center (I have 34 and 36" radius curves) to clear the overhang on my articulateds, and those clearances are TIGHT! I still have one tunnel on Yuba Pass that I have to be careful about–too many cars on my L-131 and it pulls the boiler to the point where the steps catch on the portal. I’ve done some judicious carving on the rockface of the tunnel to clear everything, but I still have to watch it. It CAN be done, but you really have to do some serious planning. Test run your equipment and locos while you position the portals and LONG before you enclose everything.
Tom [:D]
All my tunnels will be on curves as well.
The one tunnel I have set up right now has almost 2 inches clearance on either side & this is on a 22" curve.
My Walthers cars have no problem going through this, neither did my buddy’s Rivarossi Challenger.
The portals are not done yet as my scenery faze has not started yet but I do plan on taking everyones advice & testing the portals with various equipment before I finalize anything.
Gordon
I’m just finishing a tunnel on a 28" radius curve, at each step I ran my highest/longest equipment thru it to be sure it had sufficient clearance.
I have tunnels inside mountains on curves and have never had any issues in the way you are. I allowed (in the planning phase) for 2 inches of clearance on each side of the track. While building the tunnel walls I regularly ran 80’ heavy passenger cars around the bend to check clearances. I read somewhere in one of my “Model Railroads for Beginners” books that you should always run your longest rolling stock/engines over your track to make sure all clearances are acceptable.
Sorry for you troubles.
Trevor
When I really think I have the track perfect, I back long trains over the layout. Here is where I find those tiny glitches that dont show up by pulling a train…John
Good advise for all track that is not easily accessable… Actually that is just good advise for your track! I have several tunnels on my layout, and most are on curves. I never completely enclose them and have access to all portions of them. One of the advantages of Spline Latticework and Cookie Cutter types of benchwork I guess. Where i am using foam for basework, I still will leave plenty of space to get to the track, and any derailed locos, cars, etc. With that in mind I only “finish off” the first few inches of tunnels. After that you really can’t see it anyway. Of course, modeling 1925 means that I don’t have anything much over 40’ except passenger stock.
I’ve build many tunnels on curves. The key is planning and testing. When installing tunnel portals I always test and retest, the clearances, with my double stack and Hi-Cube cars.
Sometimes I’ve altered or scratchbuilt portals. Other times, I just need to shim the portals up some.
Don’t forget, some prototype railroads notched out the tops of their older portals to clear double-stacks and autoracks.
Nick