I am doing a 4x8 layout with three spurs and a frieght yard and around one eighteen inch radius curve I have the track sloping at a 2.5% grade. I wan’t a tunnel over this area but My two spurs will get in the way on one area so I will have to shorten my tunnel quite exstensivly. My main question here is: If I have a fairly short tunnel will it still be realistic?? If the engine is exiting the tunnel and the caboose hasn’t even entered the tunnel will this still be realistice. Im looking at a tunnel about 2.5 to 3 feet long.
Thanks everyone in advance!!!
The club I go to has one that is about 3 feet long so yes it still would be realistic.
Yes. On a 4x8 you need some artistic license. What will sell the tunnel will be the mountian it goes through. I have a tunnel about six incehs long that looks like it needs to be there.
Good luck.
We just hiked through some abandoned Colorado and Midland tunnels a couple of months back. Some of the tunnels were only a couple of hundred feet long.
There are plenty of prototypes for short tunnels:
On the joint UP - BNSF line over Tehachapi Pass (the famous ‘Loop’ route) there are two short tunnels only a couple of hundred feet apart. Neither is more than a few hundred feet long. For all but the shortest trains, the engines are clear of the second tunnel before FRED disappears into the first.
On the former NYC main line on the east shore of the Hudson opposite Bear Mountain there were (and almost certainly still are) several short tunnels. They pass through rock ridges too tall to simply cut. Building around the ridges was not an option - the adjacent river is hundreds of feet deep.
In more than a few places rail lines in cuts have been roofed over to make some of the world’s highest priced real estate available for development. Having a covered cut between two streets with an office building, hotel or hospital on top would not be unreasonable.
There is a classic “Lionel tinplate” tunnel in line with the runway at Yokota Air Base in Japan. The JNR line is in a shallow cut. About 100 meters of it have been roofed over with concrete, then earth-bermed - a long, narrow artificial hill in the middle of otherwise almost level land.
As long as there’s a logical geographic, economic or political reason for it, a short tunnel makes sense.
Chuck (who models a couple of prototypes that had numerous tunnels of assorted lengths, and lives where the Raptors live)
Just don’t build it around one of your curves. It will cause a lot of wrecks, just like mine does.[B)][:O][:I]
Why would biding a tunnel on a curve cause derailments? If enough clearance exists the train doesn’t know it is in a tunnel.
I have a 3 foot tunnel on one of my curves and have never had a derailment in the tunnel.
I agree caellis, I have two tunnels on My HO layout and they both are on curves. and have no trouble at all. One is about two foot long and the other is about 6 foot long. the both have acess places just in case I do have trouble and for track cleaning purposes. The only time I have had any trouble is when I forget to throw a turnout coming into the 2’ tunnel. If your trackwork is right on the money you will not have any trouble with the tunnel over a curve, Just remember that if the tunnel is very long, you will need an acess. Hope this is of some help. Mike
what happens is that a tunnel portal positioned in a curve is not wide enough for trains to go thru using commercially built tunnel portals…the train cars swing out on curves and hit the sides of the tunnel portal rather than going thru it…that’s why i scratch build my tunnels making them wider than the commercially built kind…it’s a lot of work building the jig, pouring the plaster, the sanding, and a lot of cutting with a hobby knife, but the train never hits the side of the tunnel like they otherwise would with commercially built tunnel portals … here is a scratch built tunnel i’m putting in now…it has plenty of room in the curve for the train to pass thru without hitting the sides of the portal
chuck
I also build my own portals. They are too expensive to buy already built. It is not that much of an effort.
I use balsa wood to create the forms on a flat surface. I use anywhere fro 1/2 inch to 3/8inch wood strips. I simply pin the wood forms to the surface, pour a rather soupy plaster mix into them and use a metal or plastic straight-edge to level it and let it dry. Do not use a piece of balsa as a straight edge as it will absorb the moisture and not give very smooth results.
I made four portals using this method for about $5.00 worth of material vs. $25.00 to $30.00 for four commercial portals. And I have no problems with width, as they are custom made for my needs.
I sprayed with concrete paint the same as I would have with the ready made portals.
Yes, this is my problem. I have a 4X8 layout with 2 tracks running twain. The portals- one bought, the other made from sTyRoFoAm, start at the beginning of an 18" radius. Rolling stock on the outer rails, bang their butts, and scrape their sides on the inside track.
Thanks for all your help but how can i tell if my rolling stock will scrape the sides of my tunnel
raptor55
Measure from the center of the track to the overhang. Then add some amount such as 1/2 inc or 1 inch and create a tunnel that does not come within this measurement at any point anywhere in the tunnel.
To measure the clearance needed, put your longest car on the inside track, take a Sharpie and hold it against the middle of the car and mark the roadbed while moving the car through the sectioon where the tunnel will be. Put the car on the outside track and hold the marker at the corner of the car and repeat the process. Add a half inch to each mark and you should have enough clearance for any car or locomotive.
Make sure that your portal is attached to a straight section of track at the beginning. That way, there won’t be any overhangs to interfere with.
With a 4X8, there isn’t a whole heck of room. If I had the guts, I would tear mine up again, and start over.
A tunnel of 2.5-3.0 feet will be plenty realistic. There are plenty examples of prototype tunnels that are shorter than that in scale.