Tunnel construction questions

[tangerine-jack]

Hey all! Now that the cooler weather is arriving, I am planning a major expansion of my RR, just about doubling the footprint and 120% trackage increase. My plans include at least one tunnel and a small industrial town. What I need to know is how to build the tunnel(s) for durability and ease of maintenance. As of now, the planned tube is about 12ft long, but I am still in the planning phase so length could increase. What do you guys use, and what do you recommend against? Wood, concrete, something else? Thanks in advance![oX)]

[cacole]

If the tunnel is straight, a piece of large diameter PVC pipe is a possibe choice.

[kstrong]

Here's a thread on tunnel construction that you may find helpful:
http://www.mylargescale.com/forum/topic.asp?TOPIC_ID=23353

My only concern with your plan is the length of the tunnel. My general rule of thumb for tunnels is to not build them any longer than twice the length of your arm, unless you build some kind of access into the middle. A straight tunnel certainly allows for easier access than a curved tunnel, but if a train was to derail halfway through, it's there to stay until something pushes it back out. Gravel ballast and paint don't exactly peacefully coexist.

Later,

K

[tangerine-jack]

Rock on kstrong! Excellent link, I got a ton of ideas! I was also concerned about the length of the tunnel, but I see now how I can have removeable access ports in the event of a derail disaster. Maybe I will even make the new branch line a subway, that would be cool! Now it's on to the back yard with a piece of string and some spray paint to see how closely my first draft plan will fit.[oX)]

[Anonymous]

Perhaps another suggestion is a 13" by 13" chimney flue liner (18" long) and wrap plastic around the joints to keep any water out. Just cover with dirt and or concrete and a portal on each end.

[Anonymous]

Here is a tunnel that my brother made for our display outside our bed and breakfast.

http://redbarnvillage.com/b&b/train.html

be careful... we are running aristo craft 1:29th scale. After we made this we learned that I we wanted to run LGB 1:22nd scale they would not tin in the tunnels.