Hi
Im currently landscaping part of my garden to change a waterfall. However I would like some time in the future have a garden railroad passing through a tunnell under the waterfall.
What I would like to know is how wide and tall are tunnells expected to be. I will be making it oversize, and probably having some sort of face plate on the entrances. However as the Garden Railroad is a plan for the future I havent as yet any idea on what sort of dimensions I’m looking at.
Hi Bpbill
I am afraid the answer is not going to be very help full .
The loading gauge is determined by your trains IE height width. not knowing what trains you want to run or the scale or not of your trains makes it a bit hard to give a definitive answer.
However don’t make the tunnel longer than you can comfortably reach or make sure you have real good hidden access to the tunnel.
Also keep your tunnel straight remember to put track bed and track in the tunnel when you build it.
Do a good job of the track work as it is a potential trouble spot for later
You are wise wanting an oversize bore you never know what is going to come visiting in the way of trains.
Just watch out for bunnies and other critters that might want to make a nice home in your tunnel.
Oh don’t forget to put the cess drains each side of the track to drain water out of the tunnel cast them in the concrete tunnel floor along with the track bed.
that’s the best I can offer in advice
regards John
Bpbill
I put my tunnel under my waterfall and it does just great. I used cinderblocks to construct the tunnel. I dug out a “foundation” for the cinderblocks and stacked them to form the tunnel. Since my tunnel makes a ninety degree turn under the waterfall. I made mine 10 inches wide and 16 inches tall. Yes it is a bit oversized but I have no “clearance problems” when the trains go through. I have had to “down size” the openings with portals to achieve the look I was after. The portals are removable so I can reach inside to retrieve cars, and can be replaced with “plugs” to keep out any wildlife.
As far as the length of the tunnel goes, if you cannot reach the middle, it is too long, put in an “air shaft” so you can reach the middle. When putting your track inside the tunnel, use “flex” track, you will want as few rail joints as possible in the tunnel to prevent any problems. I soldered two pieces of 5ft flex rail and then cleaned and trimmed the joints to ensure the joints were smooth, nothing for the wheels to “pick” and derail. I cut a “floor” for my tunnel out of 3/8 plywood. Several layers of enamel paint, followed by three layers of model airplane fabric and aircraft paint, to seal and preserve the plywood. The track is glued to this “floor” should I ever need to remove it to perform any maintenance. It’s been in position for most of three years and have not had any problems yet, other than colliding with a dog that was taking a nap.
As John said “don’t forget to put the cess drains each side of the track to drain water out of the tunnel.” You will NOT want any water to stay inside the tunnel.
Since you will have water above the tunnel you might consider doing as I did to waterproof the roof of the tunnel. Across the top of the cinderblocks I used re-bar and cinder “cap stones”, 2 layers of roofing felt, a piece of 3/4 inch marine plywood (well pre
Bpbill, you have to plan for a worst case scenario. This has to include what the largest possible scale you would purchase or build, and the largest dimensions of any of the cars or engines, even then, you should add some extra space around the train for working, track height (including ties), and footings or foundations of sand, gravel, etc. If you are building this in an area where moisture is a problem, then you need to keep a grad for drainage too.
Thanks for the answers.
I’m proposing to use ‘G’ scale 45mm track with the smaller Euro rolling stock, but just in case would make the tunnell able to take the larger US stock.
However as the whole idea is a long term project and next summers starting layout wouldnt include the tunnell area, I’m now wavering with the idea of ignoring it for now. Rebuilding the waterfall for a temporary two year construction and then seeing if my idea remains the same then.
This obviously gives me the chance to experiment and learn with much easier constructions first 
I must be looking in the wrong places but nowhere have I actually seen things like the actual loco dimensions etc.
If you need deminsions search ebay for a short pasanger car or a dummy loco. This way there is no guessing, and the euro trains will clear not a problem.
Just another thought. I used a section of 12 inch plastic sewer pipe for my tunnel ( about 10 feet long) It handles USA Trains double stacked containers, so that’s about as high as you are likely to find. Check around either suppliers or jobsites and see if anyone dropped and broke an end, then it goes for considerably less money. (Tell 'em you want it for a garden railway and you may get an even better deal.) The pipe is UV light sensitive, after 50 years or so it starts to breakdown, but when it’s buried, no UV light, so who cares.
I picked up more pipe than I could ever use by doing it this way. Go check out the local road construction/new housing projects. I grabbed some larger 12" and 14" pipe that I believe was leftover water main pipe. (bad ends, too small, cracks, etc.) This was stuff that was going to the dumpster, so it just cost me a case of beer and a thank you.
I used 12 inch clay chimney tile liner for my tunnel under my waterfall with a piece of roffing shingle over the joints. I then made the entrace to the tunnel out of cedar to the size that I needed and glued it on to the face of the chimney tile with girilla glue. I did stain the out side of the entrance the I had built before I attached it.
It’s really a simple straight forward process. I have a double track tunnel running under my waterfall and this is how I did it.
First, determine the area you will need to make the tunnel. Do this by laying down your track at the place you have determined the waterfall will be. Assuming you are using a tub with a spillway to act as your waterfall, if you have that handy, set it down on top of the track. If not, go to your nearest garden center or pond supply place and measure out the one you think you’ll want to use.
Looking at the footprint of both the track and tub, give yourself at least two feet in all directions and mark it. You may even want to consider making the waterfall side even larger so as to support whatever stones you will be placing beneath the spillway. Dig this area down about four inches and fill with concrete, creating a pad for which your track, tunnel materials, waterfall, stone, lining, and whatever else you may use to create your waterfall. All of these things combined, gets very heavy. A sturdy base is important.
Give the base a week or two to cure and then re-lay the track where you want it. At this point, I highly recommend that you screw the track into the concrete. The length of your tunnel will most likely be short enough that you need not worry about expansion or contraction at this point.
The materials that I used for my tunnel were 12" x 12" x 2" pavers that I got from Home Depot. These were my walls. The width of my tunnel, BTW is 16" due to the double track. I later created portals that reduced the size of the opening. I used concrete construction adhesive on the bottoms sides and tops to glue everything together. For the roof of the tunnel, I used leftover PT 2" x6"'s. to keep the tunnel walls from leaning forward or back, I places 4" to 6" pieces of PT 2" x 2"'s on both sides of the tunnel walls so that it created an interlocking effect. This
Markperr.
If you go to the MODEL RAILROADER forum section, you should find a section at the top of the Forums that tells you how to contact MRR and also how to post photo’s to the forum sites. I spotted it there around the middle of last week and it appeared to be locked in at the top of the Forum section that I was in.
Hope this will help you.
Blue Flamer.
I have several tunnels even a double decker, but what i have doen which would be of interest to you is that i used a 230 mm (9") storm water pipe that was on sale at a plumbing supply place. It is 1.8 m (6’)long and i did have a bit of trouble with it initially but its been on for a few uears now. I have a jigstone kit and made tunnel portals out of small concrete (cement) blocks.
My theme is middle Europe pre WW2.and i have all concrete type stuff and it is quite a different look to most.
Rgds ian
One suggestion: Aristo and probably the other manufacturers as well sell prefab face plates for one-track and two-track tunnel entrances. (Here’s a link to Aristo’s tunnel portals.) That might be a good place to start to determine a minimum dimension for the entrances.
I used a 230 mm or 9" storm water pipe for one of my tunnels and i actually make my own portals out of concrete (cement) using a Jigstones kit.
Rgds ian