gandydancer19I think you need to stop thinking about building a tunnel for your model railroad, and start think of about your model railroad as if you were building a real railroad through the countryside.
Here are the classic Gallitzin Tunnels at Tunnel Hill between Johnstown (West Slope) and Altoona (East Slope) -- A few miles west of the Horseshoe Curve.
The prototype originated as a 4-track Pennsylvania Railroad mainline, and is now a 3-track Norfolk Southern mainline. Note how the mainline actually splits in two as evidenced by the prototype's pictures, and as an overhead satellite view from TerraServer:
[1] Gallitzin Tunnels at North East Rails.
[2] Gallitzin Tunnels via TerraServer.
The two tunnels travel directly under Gallitzin/Tunnel Hill, and trackage is engineered "with a wye" at AR Tower -- Turning helpers for the return trip down Horseshoe Curve (and its East Slope) into Altoona. This is truly mountaintop railroading at the Cresson Summit, and; the Gallitzin Tunnels arguably offers a "little more" up-close railfanning than Horseshoe Curve.
Also note how at the East Tunnels -- The tunnels are at two different side-by-side elevations, and how one track was abandoned to go from a 4-track to a 3-track mainline. You can also see the before & after photos of tunnel reconstruction at the West Tunnels.
Conemaugh Road & Traction circa 1956
I think you need to stop thinking about building a tunnel for your model railroad, and start think of about your model railroad as if you were building a real railroad through the countryside.A real railroad runs through land forms or terrain that already exist in the world. As model railroaders, we have to work backwards to make our model railroad LOOK real. That is, we design a track plan and lay the track. Now what we need to do is figure out what type of terrain or land form (also known as scenery) we want our trains to run through. If we want foothills or mountains, we need to determine where the high spots will be, and where the low spots will be. The terrain in between those spots will usually be made up of some type of sloping and rolling country. This is where your imagination should come into play to determine if you want rugged mountains or something less so, and how the railroad would get over or through those obstacles.Now, if we have a track that runs through that area, it will usually run in a cut or a tunnel because railroads want to avoid steep grades and long routes. They build tunnels, bridges, and cuts so the route the train travels will be shorter than going around the hill, mountain, or other obstacle. That includes rivers too. Basically, a tunnel is just a big hole in the mountain. At each end there is usually some type of tunnel portal that holds back the dirt and rocks at the opening of the tunnel so they won't slide and fall on the tracks.I hope this gives you the big picture view to tunnels and bridges and how to plan for them.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
One other thing to consider is that tunnels are hugely expensive to build. Real railroads think twice before building them, and even then they make them as short as possible.
Just remember that the mountain was there first, and that the railroad may have dug into the side of the mountain for a considerable distance before actually starting to tunnel.
Connecticut Valley Railroad A Branch of the New York, New Haven, and Hartford
"If you think you can do a thing or think you can't do a thing, you're right." -- Henry Ford
I can think of basically two priorities when designing a tunnel : 1) clearance and 2) access. Regardless of what your tunnel goes under or through, you will want to have enough clearance at the entrance so that your traffic does not hang up going into or exiting the tunnel. Until I wised up a touch and adapted commercially cast portals, I found that enthusiasm for scenicing always crowded the rails too much. I have a 60" long tunnel that was built as a homage to the tunnels through the Cascade Mountains. This tunnel works only because once the track is past clear sight lines from the portals, the back side is completely open, aside from the 1x2" blocks that support the tunnel roof. Anything that long and hidden will sooner or later need to be cleaned, or otherwise serviced ( it is not pleasant to barely be able to reach a derailment).
I constructed a mountain that, including the upper level, has 5 tracks underneath it. I built it using various techniques. The bottom edge that goes around the base of the lift-off part using foam. Using a hot glue gun, I glued and stapled a lattice made from cardboard strips. I covered that with plaster cloth. Then it got painted and ground cover added. If anything derails, I can lift the entire top of the mountain off. In case of any derailments that occur where I can't reach them from the top, I cut sections of foam that are snug fit from below.
Marlon
See pictures of the Clinton-Golden Valley RR
What do you really want, tunnels or mountains with tunnels underneath them?
My layout has a subway system beneath the "normal" tracks. So, I've got tunnels, but no mountains. Also, I planned from the beginning to have a video camera mounted in the subway train, so the tunnels have full scenery, even though they're hidden below ground.
watch?v=jQ5OvZtI QU
Generally, though, tunnels are invisible. The bes thing to do is to provide some tunnel walls for the first few inches, and then leave the rest open for easy access. Trust me. You will have derailments in your tunnels.
It takes an iron man to play with a toy iron horse.
Consider using rerailers if they're hidden and your tunnels are long enough. They'll save you some grey hairs! Don't forget easy access pop out scenery or access open from below in case of a derailing or cave in ;-) Also remember to caulk or glue your track down before you build the tunnel/scenery.
I'm at that stage right now and I have to remind myself to do the above as I go! Scenery hunger takes over all common sense if you let it, even when ya know better!
Raised on the Erie Lackawanna Mainline- Supt. of the Black River Transfer & Terminal R.R.
There is no right way or wrong way. Some work better than others. My tunnel goes under part of the stairs that are in my garage and it was a perfect fit for the portal from my base to the bottom of the stairs. I used some thick strips of cardboard taped to the wall and the layout base and then covered with paster of paris soaked paper towels. Let it dry good and then add scenery
Model Train Help
How to Build Foam Tunnels for HO Scale Model Trains
Dr. Frankendiesel aka Scott Running BearSpace Mouse for president!15 year veteran fire fighterCollector of Apple //e'sRunning Bear EnterprisesHistory Channel Club life member.beatus homo qui invenit sapientiam
Can someone direct me to a good source explaining how to construct tunnels for HO?