Tunnels in Mountains

Make them out of foam and removable.

https://ogrforum.com/...8#182325628988620168

Cut a hole under the mountain. Locate it so your track runs next to it. Make it big enough to be able to reach in and retrieve you stuck trains.

Make the "mountaintop" [PA] removable so you can active the "5 fingered" crane!

If you do not have access to the rear of the layout, the tunnel must be removable.

My 10’-by-5’ layout has a lightweight removable tunnel/hill in the northwest corner. It is constructed from portals and stone walls (made of urethane, available on a major scenery website) and extruded pink foam (from a home improvement store). These items are lightweight and easy to cut and shape. I used Mold-a-Scene plaster and plaster rock-molds to cover the exterior of the hill, followed by the usual materials for ground cover and trees. My tunnel covers a section of Atlas O-54 curved track. I suggest that you lay the track first, then build the interior walls of the tunnel around the track to ensure clearance, and then add pieces of extruded pink foam to create the exterior shape of the hill. In my case, the interior stone walls of the tunnel consist of several straight sections. They are not curved.

The four interior corners of the tunnel fit around four square pieces of basswood (1-inch by 1-inch by 1/8-inch thick and glued to the table surface) to position the tunnel accurately on the table and to prevent it from moving. The tunnel can be lifted right off the layout.

My tunnel covers about four feet of track, so I can reach in through either end to remove derailed cars and clean the track with a rag. It also has an opening (about 6-inches by 6-inches) in the back so that I have direct access to the track and tunnel interior from the rear of the layout – which may not be possible in your case. The rear edges of my layout are about one foot from the walls, so I can access the rear of the tunnel. That also makes it easier to take the tunnel off the layout.

The layout has been in operation for eight years and I’ve never had a derailment in the tunnel. I’ve also never removed the tunnel from the layout during that time, but it could easily be done if necessary.

MELGAR

I did a corner mountain like Mel did, except his came out much more believable.   However, I too cannot reach the back so I made the top removable, in other words, not glued or attached, the top just sits there by gravity alone.  If I get a derail in there once in a blue moon, I can lift it off and replace.   I attached the link to my corner mountain build thread from a few months back where many of the Gents on here guided me with sound advice.  It came out good enough for me, but not nearly as good as Mel's.   It's a 3 page thread so you can see the process through pics, so let it load.   Hope it helps make your process easier and better than mine.   I still have more work scenery wise to make mine more believable, since it is going to have a mining or logging scene up top with a conveyor belt or something coming down the front at an angle.   Anyway, good luck.

https://ogrforum.com/...c/176694689222382124

Corner Mountain suggestions Help.

If reaching to lift mountain tops is an issue, I use a 4 foot "Reacher" to grab inaccessible items on my layout.  I use the "Reacher" to quickly grab engines and cars.   For more prolonged work I have a Topside Creeper.  When the none of this works, I make a custom platform I can stand on.  I temporarily secure the platform to the layout for safety.

I agree with the other posts that a removable piece is necessary for access. I had the same issue with a long tunnel along the back wall of my layout, which is also in an enclosed space. I built up (3 levels!), but knew I was going to need access to the long run in the tunnel. In my case, it was not a mountain, but a retaining wall that hid the track. It had to be thin for clearances of the track in the tunnel and adjacent track.

I decided to use foam board and cover it with two products: paper walls above from Micro Mark and rocky walls below using a Heki Foil product. I had 4 boards across the length of track and fastened them in place with velcro strips. After a few months of operation, I decided I wanted some views of the train passing through that enclosed tunnel, so cut out 3 portals. Helped to know where the train was and added some visual attraction.

Here are some photos. First the layout to show the back wall in the enclosed space.

Now here's 2 of the panels removed, the portals, and velcro strip.

I also realized that when there was no train in the portals of the tunnel, I had to create something that appeared as the inner wall of the tunnel, so glued some of the Heki Foil to the wall of the room.

Hope this helps!

Michael

PS: Only 1 derailment over several years that required removing some of the walls!!

Thanks to everyone for their input on this matter. I am still in the planning mode of my future layout. I have yet to lay any track, but I have a good idea of the challenges that I face. Now I feel like I can move ahead.