Tunnels

Model Railroader Layouts and layout building
1

I’m looking for opinions regarding tunnels, how long can they be without an access port? For reference I am modeling HO. Plan looks like I could make a tunnel up to 4 feet, but I could shorten pending advise from the forum.

I’m sure this can be solved many ways, as I repsect the opinons here and look forward to all comments.

Jeff Shaw

2

A derailed car more than a foot from open access is going to be tough to get out unless your tunnel bore is oversize.

You can have an access panel underneath, or do like we did and make lift-off mountains for easy access.

3

I agree. What some folks do is to place a rerailer section somewhere in a tunnel to afford the operator a bit of safety, but they aren’t foolproof.

I have no rerailers, and my tunnels are about 6’ in length. All are accessible from below or from behind, even if a reach up and over to where the track is…placed close to the edge so that I can get to the cars relatively easily, but with a strip of MDF acting as a fence at the very edge…just in case.

The secret is to keep things very simple and do a first class job of the roadbed and the tracks. That way, you should have smooth running. Then, in the very odd case you need that insurance you designed into it, it means getting on hands and knees and reaching up in a hook-like fashion to get your mitts on the derailed cars. So, a simple reach hole may do it for you, something large enough to haul a passenger car or autorack through it…or your Big Boy.

5

So far, all of my trackage (2 fair-size yards and 55 feet of main track) will be hidden once scenery-building gets started. My longest ‘tunnel’ will be something like 2 scale kilometers long!

I have designed for side access from the operating aisles. One otherwise-unreachable section (not yet built) will swing down like John Armstrong’s ‘dehydrated canal lock.’ I have installed several rerailers already, and will be installing more. Places where derailments are more likely (specialwork) will be accessible through the openings behind swing-down control panels. All the rest will be behind easily-removed (screwed on) sections of fascia.

For safety, all of my hidden track is (or will be) fenced.

The ‘cosmetic’ tunnels, which will be built as part of the scenic effects, will only be a few hundred millimeters long. Taking a leaf from my prototype’s book, all will have guard rails full length (and a non-prototypical rerailer in the exact center.)

I strive to build absolutely derailment-proof trackage. However, Murphy is alive and well, so I have allowed for access on the theory that, with derailments or other rolling stock problems on hidden track, it’s not whether, it’s when.

Chuck (modeling Central Japan in September, 1964)

6

Hi,

The previous posters all had good advice and you can’t go wrong with any of it. I would add or emphasize the following:

Make sure your trackwork in the tunnels is “bulletproof”, in gauge, no kinks, sharp curves, or turnouts, etc. You might consider using code 100 track in hidden areas too.

If its longer than 2 feet (3 if you can reach in both ends), then make sure you have an access (mine is from under the layout).

And lastly, as was mentioned, if you can put a rerailer or two in it, do so.

Mobilman44

7

Thanks all for the good advise. The use of a rerailer makes alot of sense, as does the making the track under the tunnel as bullet proof as possible. However, as Chuck points out Murphy is alive and well in everybodies layout. It’s just is matter of providing a plan for when the inevitable happens. I think I will find a way to take the top off of the mountain as I have 4" inches of foam underneath. Any thoughts how make a ‘take off top’ still look real? Thanks.

Jeff

8

My take on a ‘take-off top:’

  • Make it irregular, and have the edges follow terrain features that provide a natural break point - ditch lines along roads, weed-grown fence lines, the strata in a rock face… Avoid crossing anything where the break line is going to be obvious, like a hard-surfaced road.
  • Several small lift-offs will probably be better than one king-size one.
  • Provide an easy, inconspicuous place for the laying on of hands - the holes under removed buidings being a good one.
  • Make sure that there’s a safe place to put the lift-off, other than the sceniced surface of the layout.
  • Arrange to hide the ‘earthquake fault’ with a LITTLE ground foam ‘weed growth,’ or similar.

Just my [2c]. Other opinions may vary.

Chuck [modeling (mountainous) Central Japan in September, 1964]

9

“You might consider using code 100 track in hidden areas too.”

I think the transition from a (presumably) smaller sized rail would add another potential glitch, if you’re looking for absolutely bulletproof trackwok in a tunnel.

It has not been my experience that C100 track means fewer derailments than smaller rail. Well-laid C83 or C70 or even C55 is just as reliable.

Of course, C100 is cheaper, if you’re building a two-scale KM tunnel…