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Tunnel construction

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  • Member since
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Tunnel construction
Posted by Tortuga Man on Sunday, August 3, 2008 7:26 PM
Looking for help with tunnel clearance. I am planning on using a solid flexpipe for
my tunnels. Should I use a 10" or 12" diameter pipe. I am modeling in 1:20.3.
Also any ideas for building in an access hatch in a 10 ft. tunnel?
Any help is appreciated.
Thanks
  • Member since
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Posted by altterrain on Sunday, August 3, 2008 8:14 PM

You're going to need larger pipe than that, my man. 1:20 equiptment needs a 10 inch clearance and you will not be able to get that kind of internal clearance with a 12 inch pipe. 16 inch pipe is more like it. Sprinkler valve boxes make for good hatches.

-Brian 

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Posted by two tone on Monday, August 4, 2008 9:02 AM
Hi Tortuga Man, A tunnel should not be more than 2 arms lenth. Reason if any thing happens you can reach to remove the train or what ever, by putting in a hatch you will not be able to remove an item that way. As all ready stated you will need a BIG pipe if tunnel on curve you are asking for a lot of trouble as loco and carrages /frieght need good clearance

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Posted by ttrigg on Monday, August 4, 2008 8:28 PM

Tortuga

I would like to emphasize what Brian and John have said. If you can not reach it that is where it will derail. When using "pipe" as a tunnel liner, only about 55% of the pipe diameter is usable. Remember that the bottom of the pipe is round and roadways are flat, so the bottom of the pipe is "lost space". The tops of most cars are (somewhat) flat; the top of the pipe is round, more "lost space". Have you considered cinderblock construction? Two blocks tall, using cinderblock caps for a roof, then cover with tarpaper. That way you can achieve 14 inches of clearance all the way around with ease. The flat surface of cinderblock construction makes it easier to build in sprinkler valve access hatches. If you plan a curve, then add in MORE access hatches, and wider clearances. One point they did not cover; drainage. In your profile, you say your location is +0 GMT that probably makes you one of our friends in the British Isles. Which means, and I'm guessing here, you get a bunch of rain. Water will find places to hide inside tunnels. You will want to put a drainage pipe in under your rails, or at least 4~5 inches of small rock "French Drain". Drainage is another advantage that cinderblock construction has over "pipe" construction of tunnels.

One more point:  Wider and taller tunnels give more room for maintenance, and can easily be concealed by smaller tunnel portals.

Tom Trigg

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Posted by smcgill on Thursday, August 7, 2008 8:06 AM

I did it with block!

I also spray-painted the inside flat black!

Remember it will alway's derail were you can't get to it!

Good luck !

Sean 

Mischief

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Posted by rpc7271 on Monday, August 11, 2008 2:52 PM
If you go with a big enough diameter pipe you won't need any access hatches, you will be able to crawl in and get any derailed train yourself!
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Posted by skeenapac on Tuesday, August 12, 2008 6:26 PM

I guess I've been doing it wrong11Big Smile [:D]

My tunnel is 12" sewer pipe and a little over ten feet long. So far, the few derails I have had have been 'pull throughs', recovery by keeping the train moving. Okay, so once I did have to use  a 2x4 8 feet long to prod a car clear, but who's counting. My 'yunnel' overall lenght is about 40 feet, but, except for the sewer pipe, it is 'cut and cover' with the cover being 2 inch styrofoam and out of sight.

http://www.skeenapacific.ca/railway/gardenrail%200202.htm sort of shows the install. This pipe handles double stack 1/29th containers, but you do need a straight approach or some surgery will be necessary.

http://www.skeenapacific.ca/railway/gardenrail%202006p5.htm

Hope this helps

 

James http://railway.skeenapacific.ca

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Posted by altterrain on Wednesday, August 13, 2008 11:49 AM
 skeenapac wrote:

I guess I've been doing it wrong11Big Smile [:D]

My tunnel is 12" sewer pipe and a little over ten feet long. So far, the few derails I have had have been 'pull throughs', recovery by keeping the train moving. Okay, so once I did have to use  a 2x4 8 feet long to prod a car clear, but who's counting. My 'yunnel' overall lenght is about 40 feet, but, except for the sewer pipe, it is 'cut and cover' with the cover being 2 inch styrofoam and out of sight.

http://www.skeenapacific.ca/railway/gardenrail%200202.htm sort of shows the install. This pipe handles double stack 1/29th containers, but you do need a straight approach or some surgery will be necessary.

http://www.skeenapacific.ca/railway/gardenrail%202006p5.htm

Hope this helps

 

Not wrong just different from what was asked about. It looks like you're using PVC drain pipe -

and not the corrugated polyethylene flex pipe asked about -

which has a smaller internal diameter than the stated 12 inches.

I don't know how tall a double stack is but 1:20 equipment gets pretty tall and wide.

-Brian 

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Posted by Anonymous on Wednesday, August 13, 2008 10:28 PM

Like Alt. said flex pipe is used alot and many have used it but they also used creet blocked sides also. I would use creet cause I know it best and know how to work it.

Toad

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Posted by skeenapac on Thursday, August 14, 2008 12:29 PM

Brian,

Thanks for the information. I hadn't thought of flex-pipe for a tunnel.

You are right in that I don't run 1:20.3. Just for comparison, the USA Trains double-stack is 8.75 inches above the railhead, over the rail (not centred to the track). I have my track mounted on 1x4 inch cedar plank inside the sewer-pipe tunnel to allow for ease of maitenance (the track in the tunnel is soldered together and screwed down. I have rail-clamps at each end for removal.) It gives 9.75 inches of clearance above the railhead.

Info for future reference.

Cheers!

James http://railway.skeenapacific.ca

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Posted by Anonymous on Friday, August 15, 2008 4:06 PM
 skeenapac wrote:

(the track in the tunnel is soldered together and screwed down. I have rail-clamps at each end for removal.) 

Very smart move soldered, screwed and rail clamps!

Toad

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Posted by skeenapac on Friday, August 15, 2008 4:27 PM

Hey, Toad.

Because I started with sectional track, I ended up with a lot of joins. Being track powered, that sometimes created problems, so I developed a method of soldering track sections that are then joined by rail clamps. I have a tendency to lay and relay tracks as rethink or have a "better" idea. At this point, all switches are in place with rail clamps and hard-to-reach sections are laid on a wood base that can be pulled out in one section.

If you are interested in my "method", I did an article that I reprinted on my website at:

http://www.skeenapacific.ca/railway/Track%20Construction%20Soldering%20Tip.htm

Cheers!

 uh, sorry, tortuga, I'm getting off your topic. Oh well, hope this helps.

James http://railway.skeenapacific.ca

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