I will be building a tunnel through an existing be

[vsmith]

Hi There, just had to stick my nose into this one, MAKE SURE YOU TEST THE LONGEST POTENTIAL CARS BEFORE you cover it up. No use going thru all the trouble of building this thing only to have a long passenger car get wedged into the middle. Hope this reply isnt too late.

[Anonymous]

I guess I should have read all the other replies before I put MY 2 cents in. So, it IS going to be a curved tunnel. "Hmmm..", I think that if I were to build something like this, I would make the interior of the tunnel itself large enough to fit my big butt into, for maintenance, derailments, etc. Possibly using a "lift-away" portal, or access hatch from above. With a straight tunnel, it's easy enough to stick a 2X4 through one end to shove out derailed cars, but with a curved one, you will need to get into it yourself.
If you have a big enough budget for this project, you might consider purchasing a "man-hole" from a local utility. If that is too much money, try bricking up an access hatch yourself and using a plate of steel on top. Either way, it sounds like a pretty big project. If you can get away with a straight tunnel, it will be much easier. As the folks said earlier, make sure you have a high point in the middle, otherwise the tunnel will flood when it rains.
Hope this helps... Todd C.

[Anonymous]

At the risk of sounding too funny, how about using dynamite? Check your home insurance policy first! NO, I'm just kidding.. Using concrete blocks sounds like a good idea, if you don't want a "permanent" tunnel, just don't use mortar on the blocks. I don't know if your tunnel will be straight, or curved. If it is to be straight, you might want to use PVC pipe of the appropraite diameter. Consider the length of the pipe, and pre-mount track on a 2X6 plank, then slip the assembled track into the tunnel after all else is ready.
Just an idea...

[Anonymous]

Thanks all..plenty of good advice...did I mention I was 7' tall and have a 4' stretch :D! JK...That's why the top would be removable at least in the center section.

[Anonymous]

Hello, I jumped into this, because of your comment that the tunnel will be 6 to 8 feet long. Most Garden Railroaders will tell you to NOT make your tunnel longer than you can reach into it! If your train is going to derail anywhere, you can bet it will be inside the tunnel! If the tunnel absolutely must be 6 to 8 feet long, I would split it into 2 shorter tunnels with a distance between that would allow you to get at either tunnel from either end.
The skinny cement blocks could be stood on edge and made to go around a curve, I used them on a straight tunnel and covered the top with a piece of exterior grade 3/4 inch plywood which I sealed and painted before installation. The tunnel was in a reasonoably dry area of the railway and the plywood lasted over 5 years.

Hope this helps, Rich

[Anonymous]

I just want to emphasize that you also need to grade the tunnel so that one mouth is lower than the rest of the length so it drains. You could also bevel the cinderblocks to make a curved top. Good Luck - Ed

[Anonymous]

Instead of the PVC pipe, since you're on a curve, you might consider strips of the material used for outdoor pond liners...either the rubber type or heavy plastic type. Many garden centers sell it by the foot, off a large roll.
regards / Mike

[Anonymous]

OK - Seems as though that is going to be the approach...however this tunnel will be a quarter circle, so don't know how to make the pvc pipe work with either a 8' or 10' diameter track...

Will dig a trench..fill with gravel/sand/ and then put thin cinder blocks on each side...may need to mortar them in. I'll put crusher fines like normal as ballast, and than may try and get some sort of plastic/pvc for the top that can just be covered with mulch...would like some way of removing the top in case the trains get stuck as it will be about 6-8 feet long. Seems like I got my next few weekends work cut out!

[Anonymous]

I think your most important question is how to make sure your tunnel doesn't fill up with water. Set it up so that there are no low points in the tunnel and that the roadbed is free draining so water will easily run out of the tunnel.

I would probably dig a trench and lay a half section of PVC or something in the bottom. Then fill the PVC with coarse sand to fine gravel. Put a thin cinder block on each side of this and cover with another half section of PVC pipe. Then backfill the portion outside the cinder blocks with sand. If the tunnel has a grade of a half percent, and you take these kinds of precautions against poor drainage, the tunnel will probably work fine for a very long time.

Good Luck.

Funny thing about G scale, sometimes you have to build it like the real thing cause you are fighting the elements. Not like us indoor guys. - Ed

[Anonymous]

Your right it is G scale...and my challenge is what to cover the track with...thinking of building the tunnel out of concrete block at this point, but not sure if I want something that permanent.

[Anonymous]

TIA,

It sounds like you may be modeling outdoor "G" scale, but anyway, my suggestion, even though I model HO scale, would be to trench through the area you want the tunnel to be in, lay the road bed and track, cover the track with flexable conduit or drainage line to protect the track from caveins then cover over the conduit with dirt and hope vermin don't take up residence.

Ken, D&J Railroad, Stafford, VA

[Anonymous]

primarily dirt and mulch. Are there any hints/links for how best to do this? TIA!