Large Scale Central

Tunnel tube minimum diameter

General Discussion
#1

I’m beginning work on my railroad, and the first task is to put a portal into the basement. A deck is going over this area, and I don’t want to be in there with a jackhammer once the deck is there.

This won’t be visible, so I’m planning to just use a large diameter PVC or ABS pipe. It’s a stone foundation, so I’ll remove some stones, place the pipe, and grout around it.

My question: How big should it be? What is the maximum rolling stock height that I might encounter?

It will be a straight run, so I don’t have to worry about length of cars.

Thanks.

#2

Eric, what scale are you running? Makes a difference. If you want to support almost everything, then you need to look at 1:20.3… I think the tallest thing I had was a Bachmann shay, but my double stack 1:29 USAT container cars were right in there.

I normally figure 10" from top of rail head, but I’m in 1:29.

You could also look at the prototype standards for clearance, and convert that to your scale.

Greg

#3

I lowered my USAT double stack intermodal cars when fitting them with body mount Kadee 907s, and they still needed about 10, 1/4 inch clearance from the railhead.

USAT Intermodal Double Stack Car Lowered & Kadees

-Ted

#4

What sizes are available in your area?

I say 12" if it’s 12" inside … track , gravel , stock etc…

#5

I think a square would require less material to be removed than a circle. I would make it 7" wide and 12" tall and be done with it.

If the lead up to the foundation opening is to be under the deck you could build a long box. you don’t want the trains to have too much room to derail and tip over in there.

#6

I suppose I could build a box from PT plywood. That would also be easier to seal up when not in use.

In any case, thanks for the all the size info. I’m modeling 1:29, but I suppose there’s a chance of other scales at some point. I wouldn’t have thought of that.

#7

Don’t use wood, some better alternatives…

There’s big corrugated plastic drainage pipes that have been used… also chimney flue material (usually clay):

This is from some extended discussions we had years ago… that rectangular stuff is really good.

Greg

#8

Eric, I would also consider the distance from the edge of the deck to the building wall where the tunnel goes through to the inside will be. My recommendation would be to install the clay tile as Greg recommends for the penetration into the building, but leave the track under the deck open. Then, depending on the distance, make an access opening in the deck to allow you arm’s reach to any position on the under deck track for either re-rail capability, or car removal in the event of a derailment under the deck. A secondary suggestion might be to consider using a concrete road bed under the deck, making for a stable and true location for the track to follow, minimizing the possibilities for derailments.

It is never a good idea to place track work in a location where you have no access to it for either derailments or maintenance. A bit more information regarding the relationship between track and deck might also aide in suggestions/recommendations.

FWIW, Bob C.

#9

Greg: The flues are a great idea. And easy to get in a short section. I’ll likely go with that.

Bob: The deck will be quite high in this area (36" or so), and easy to crawl under if needed. It’s only 4 to 5 ft. out from the house. I’m not worried about being able to get to it. I just don’t want to be under it with a jackhammer.

#10

There’s an axiom about building tunnels that hasn’t yet been mentioned. Never build a tunnel that you can’t reach the middle of, from both ends.

#11

I have 3 tunnels on the RR where I used 12x12 flue liners. They come in 2’ long sections. I have another where I used a length of black corrugated pipe. There is a spot on the RR that goes under our addition and it is pretty tight under there but I can crawl in if needed. I put together PT 2x4 to form a “T” beam and it has held up well for 10 years now.

Here is a youtube link to one of my videos that might inspire you a bit.

https://www.youtube.com/watch?v=G_fPQ0LlKhU&t=190s

Even if you are planning on modelling in 1:29 you will want to overbuild for additional clearance. I have a lift out girder bridge that was built to fit my widest train and it was all good until a friend brought over his large Bachmann loco and guess what, it didn’t fit.

Steve is so correct in saying that you need to make sure you can reach into a tunnel because if something bad is going to happen it will happen out of your reach ! LOL

#12

The tunnel will be about 24" long, which is about the thickness of the foundation. Open track on both sides. I’ll easily be able to reach through it.

For this particular tunnel, I really only have to worry about what I might model, as any guest equipment wouldn’t go into the house. It’s just to get the equipment out of the weather when not in use.

Thanks for all the ideas. I’ll be tackling this over the weekend.

#13

For what its worth, I have found when cutting/framing openings through structures; Figure out just how large the opening has to be, width and height, for all your needs. Then make the hole a few inches bigger in both directions. It is far easier to fill in a too large hole than it is to make it bigger at a later date.

Rick

#14

Much better to go bigger than you think you will ever use. 16x16 for a single track is perfect IMO. As Rick stated you can always trim it out to your needs.

I learned that lesson myself when I built rather tall passenger cars to run on my already built RR with tunnel clearances. I also learned a lesson with width as well. You never know when someone might bring a circus train over and the elephant might just decide to stick his trunk out.

Also remember that this is going into the house so you will probably want a (nailer) to fasten doors or something to close off that entrance when not in use.

BTW …loved your Amtrak placecard reader video …that was killer

#15

Eric, yes go a tad bigger then you think. I started out in 1:24th scale, turn of the century equipment, and I had a tunnel that was fine for those locomotives and cars. Then I somehow ended up with a Bachmann Shay. Totally out of my genera. I had to raise the tunnel a bit. Then I ended up with some Aristo streamline passenger cars that followed an Aristo Pacific around, and I had to adjust the tunnel again. Both of these acquisitions were NOT in my original plan. And so many other folks have a similar story. So plan for a bit bigger.

BTW, one year, after a good wet spring, my tunnel sank, and in raising it back up it broke in half. That’s why there is no tunnel on the P&CS anymore.

#16

Eric,

what are you going to do about the critter factor? lots can come in thru that opening.

AL P.

#17

That’s the next thing I need to work out. For now, I will probably just make a couple of plugs and seal it up for the winter.

#18

I found a discarded aluminum 12 inch culvert pipe 4 foot long.

This does give me the 10 inch rail head clearance and I have had no issues with this height and I have run 1/20.3 engines through it.

My widest rolling stock is the Aristo snow plow and my tallest is mogul bear trap and the wizard on the bubble car. I do not own any thing larger than the LGB 1/22.5.

I painted the inside of the ends black.

#19

I cut a hole in the foundation about 10 x 14, boxed it in with 2 x 8’s treated. Added a couple of doors, out of cedar. I use 4 inch foam on the inside for winter.

Don

#20

I believe this pipe that I picked up surplus from a job site is 24". As you can see it has plenty of room for 1:20.3 rolling stock…

The opening size was reduced with the portal…

Which was even further reduced with the finished portal…

I obviously agree with the suggestion to go bigger than you think you will need and trim it out so it looks right. My basement entry is through a window. The opening is 12" tall, but the portal is made of plywood so it could be expanded in the future if needed.