Mine shafts - support size?

Model Railroader Prototype information for the modeler
1

Hi all,

In preparing the scenery for my layout, I need to scratchbuild a mine entrance. I was just wondering how thick the support timbers would be - does 8" x 8" sound about right?

Thanks in advance,

tbdanny

2

I’d say 8"x8" would be about right. Of course some depends on the material the digging is going through. I have seen some mine enterances in solid rock with no supporting structure.

Have fun,

3

How long is a string?

In order to give a meaningful answer, you have to consider several questions:

  • What is the nature of the ground? Homogenious rock might not need any support, while loose sand or gravel will require a strong, elaborate support system.
  • Are you planning a shaft (vertical,) adit (horizontal) or drift (sloped) mine entrance?
  • How big an opening? For a barely man-size adit, 8 by 8 is probably excessive. If the adit is going to be used by diesel trucks the 8 x 8s had better be heavy-gauge steel H beams.
  • What shape are you planning. The requirements for a flat roof are very different from those of an arch roof.
  • Is this a quick, cheap and dirty operation, or one meant to last for years of sustained production?

The design parameters are also driven by the value of the product. Strangely, a decent coal seam will probably produce more value in shippable product for the mining expense buck than a precious metal mine. The latter were usually carload consumers - trainloads of food and supplies in, a few sacks of nuggets and a couple of carloads of high-grade out.

Also, who is doing the developing. Is it one prospector with the usual hand tools and limited finances, or a major corporation with a big bank account and a staff of university-trained engineers?

Funny how a seemingly simple question can open a rather large can of worms!

Chuck (Modeling Central Japan in September, 1964 - with two very different drift coal mines)

4

Chuck,

To answer your questions:

  • It’s homogenous rock - the entire mine site has been blasted out of the side of a mountain in the Colorado rockies, close to river level

  • Probably an adit, or drift sloping upwards.

  • The opening will be a square large enough for two men to walk side-by-side, or to wheel in a small trolley.

  • Flat roof.

  • In the backstory I’ve come up with, this mine has already been operating for years, and plans to do so for years more. Unfortunately, the company will be wiped out by the stock market crash of 1929.

The product of the mine is coal, and the mine is owned/operated by a medium-sized, family owned company. They started out small, but expanded as the mine started bringing in money.

Thanks in advance,
tbdanny

5

On the east coast prop timber could be anything from 4x4 or 4" diameter logs to 8" diameter logs.

Search Google or Bing images for mine interiors to see what size props they used.

6

In the Rockies logs are in abundant supply on scene. Milled timber has to be brought in. I would go with lots of logs and a smattering of 4 x 4s up to 12 x 12s. I have seen old mines in my backroads travels in the Canadian Rockies and that’s what you’ll see.

Brent

7

Don’t forget the canary!

8

Being from Colorado I have had a chance to see these kind of openings. the openings are generally pretty heavily braces. something like railroad tie size (narrow guage) should be about right.