Horses for courses

Dear Michael,

On30 with 8" of XPS foam below track datum
(allows for the trestles, creeks, and the mechanics of the _working_ Highlead yarder system)

6" of Foamcore below track datum, side-by-side HO and O SG

http://carendt.us/scrapbook/page103a/index.html#chicago-fork

6" of foamcore allows for lots of electronics, a worm-drive traverser mechanism, front fascia control panels, dance-party laser lighting-effect unit, and a layout-sound subwoofer.

http://carendt.us/scrapbook/page87/index.html
(scroll down to the pics under "UnderPinnings and Engineering" heading)

FWIW, I tend to focus on between 6" and 8" between "track datum" and "module frame level", even if I'm not carving it away to build creeks/gorges/trestles. It gives a nice ammount of room for accomodating most any ammount of electronics and below-scene mechanics.

Hope this helps...

Happy Modelling,
Aim to Improve,
Prof Klyzlr

I appreciate your modeling

But, 6 inches doesn't seem like an awful lot of room for a canyon. That only scales out to be about 43 feet deep in HO scale. Or is my math all wrong?

Michael

L Girder Elevation

Michael,

All of your L girders don't have to be at the same elevation (height).  If you have a section that will have a very deep canyon, just lower the L girders through that section.  At yards, place the L girders at a higher elevation.

On my last layout I had my zero track level at about 6" above the L girders and that worked out fine.  I'll probably use that on my soon to be started layout as well.

-Jack

Not a big layout

HI Jack,

Thanks for your response. On the surface I agree with you, on my N scale layout I had a whole section of girder lowered. The thing is though this layout is not very big, only 8 X 10.  I was thinking I would just keep the girders all at one height in that small a space.

Michael

First, choose your canyon...

Dear Michael,

Your maths isn't wrong, but the question(s) we need to be asking is/are:

1 - What geographic location/proto scene are you wanting to model?
(do you have a pic of the scene in question?)

2 - With the above in mind, how big a "canyon" do you want/need to model?
(a length of flextrack, a pair of chairs, and something like a towel, blanket, or bedsheet, can work well as a quick way of mocking up most any scale-size/distance "canyon" for checking of the scene concept/presentation/perspective...)

3 - Have another look at the "Nine Mile" youtube. Those "gully" depressions are at most 8" deep "below track datum". That's only 32' in O scale. However, check the long "pig sty pier" scene, and then compare against the proto scene

http://rodgertown.files.wordpress.com/2012/03/image004.png
(Hint: you can't see it in the YT, but the little "glass plate camera" figure in the modelled scene was placed to achieve the exact perspective of the proto image linked above. If the viewer stands "behind the camerman" at his head/eye level, and looks at the scene, the resulting view has been intentionally modelled to achieve the required "proto image". If you can get your hands on a copy, check the Australian Model Railway Magazine Oct 2005 edition for a "model VS proto" photo head-to-head comparison).

4 - Is 8" enough in HO? Does this help?

http://members.optushome.com.au/jdennis/broughton/29.html
(Never had a train fall off this trestle, although many onlookers were concerned... ).

5 - Getting away from the NG for a moment, check these examples

http://www.rrpicturearchives.net/showPicture.aspx?id=893792
If you take the upper bridge track to be "datum", and the lower track to be "below datum",
that's maybe only 20 scale feet? (3" in HO).

http://www.railpictures.net/viewphoto.php?id=388566&nseq=0
http://www.railpictures.net/viewphoto.php?id=385130&nseq=3
http://www.railpictures.net/viewphoto.php?id=384740&nseq=4
All of the above @ Simpson Lumber, Seattle WA, with "under-track scenery" about the same height as the loco, so maybe requiring 20 scale feet below "datum"?

http://www.railpictures.net/viewphoto.php?id=382644&nseq=9
A bit deeper creek besides the Simpson line. Maybe 30 or 40 scale feet required below datum?

http://www.railpictures.net/viewphoto.php?id=112558&nseq=9
Lancaster and Chester SW1200s over a road overpass, with a "clearance 14' " sign on the bridge, I'll say you could get away with maybe 20' or 3" on HO?

http://www.railpictures.net/viewphoto.php?id=256985&nseq=9
Camp Chase SW1500s, same as the L&C pic above

http://www.railpictures.net/viewphoto.php?id=250497&nseq=27
Progressive Rail, another "road underpass"

http://www.railpictures.net/viewphoto.php?id=386789&nseq=23
Nice bridge-over-river-scene, maybe 4' in HO scale?

http://www.railpictures.net/viewphoto.php?id=354997&nseq=144
As above, it's pushing maybe 40'? Ergo, 6" in HO?

http://www.railpictures.net/viewphoto.php?id=300548&nseq=10
A scene that's always had my attention, very modelgenic, and should only need maybe 3" below track in HO?

http://www.railpictures.net/viewphoto.php?id=355535&nseq=140
Looks to be between 40 and 50' from rail to river, so this would be pushing 6" in HO...

http://209.85.120.98/viewphoto.php?id=392469&nseq=1340
OK, I totally accept that a modeller is unlikely to replicate this scene in 6" of vertical depth, even in Z scale

http://www.modvid.com.au/html/body_leight_creek_2004.html
That scratchbuilt trestle in the first shot stretched an _actual_ 3' "below track datum" in HO scale.
The scene itself was over 5' below track level, and stopped just 6" above the layoutroom floor... 

However, a measure of commonsense has to come into play. If modelling a "high trestle" like the last 2 examples shown above is #1 on your list of "gotta haves",
(and please don't mishear me, 
if that's where your personally modelling journey takes you, then by all means go for it! ),

then you'll be unlikely to be happy with anything shallower than, lets say, an actual 2' of benchwork depth "below track"?
(and even 2' won't go far in O scale!)

For myself, many years and layouts worth of experience leads me to build modules with between 4 and 8" of "below track" benchwork as per the original question. Such a depth "works" for me in many regards, including, but not limited to:
- ammount of material required to build the module
- resulting overall dimensions for single-man moves, fitting in cars, navigating thru single-person doorways, etc
- common range of "modelgenic scenes" I tend to lean towards building

If I find a proto scene that I want to build, which requires more than "my standard specs", then IMHO it was obviously a "keynote" scene which was always going to be soo deep as to require "special construction and presentation" anyway...

Just my experience, YMMV...

Happy Modelling,
Aim to Improve,
Prof Klyzlr

PS I don't use "L-girder" as a benchwork format, but none of my layout examples above are more than 2'x4' in standalone module footprint. Unsure how a "small 8x10" layout footprint with L-girder benchwork affects the ammount of under-track space available?

I follow what you're saying....

But there are a couple of things I should point out. I don't really model any one set prototype or any "certain" scene. I know it goes against the grain of what a lot of modelers do these days but I'm not fanatically obsessed with some certain prototype. Basically my layouts have always been "somewhere out west" and would most likely hook up with the SP or D&RGW at some point and even that is not set in stone. Some may look at this as blasphemy but most of my scenes come from my IMAGINATION!! They have elements of things I've seen in photographs  but they are not of real places.  They are usually a montage of things I've seen in prototype photos and in photos of other peoples modeling that have influenced me.

Just Figure out where you want your layouts zero limit to be

After I get that basic level then the floor is the limit. You can build canyons rivers and valleys that run all the way from eye level or higher down to the floor and Mountains that start at your feet and run beyond the ceiling above your head.

That is unless you are building a multi deck Railroad then I suggest you start with what I found to be the best starting point for multi deck RR to come to print for Model Railroading. It's a Book by Tony Koester called "Designing & Building Multi-Deck Model Railroads" This Book will Tell you everything about multi-Deck Railroads what ever scale you model in and your only limits are the decks above and below the deck your working on.

For me I am building a Railroad on a single Deck with multiple grades with high mountains and deep valleys so I've chosen 42 inches as my base level and sea level to be the floor of the room. I build in Basic HO Scale and my trains are HOn3 narrow gauge. You need only decide where or at what height from the floor your main deck level will be and then build up and or down from there and make your own limits.

Dan 

I've built floor to ceiling scenery before, just never L girder

Maybe I'm thinking about this wrong or over thinking it but if I make my L-girder + joist height 6 inches below my track level and then suddenly I decide two months from now I'm going to build a 16 inch deep canyon, then I will have to cut into my L -girder to do so. That's what I'm trying to avoid. What am I missing here? Lowering the L girder in some places where I want a deep canyon makes sense if the layout is a basement sized empire but a spare room sized 8 x 10, it seems kind of overkill.

Overkill = no

Dear Michael,

If you need the canyon, you gotta build the "drop-deck module". It's no harder or easier than that.
If your intended benchwork system is incapable of adapting to suit such a (clearly identified) request/change-of-topography at some later point in time, it's a good thing you caught it now!

(FWIW, I didn't _know_ where or what-size/shape the depressions on "Nine Mile" would be when I first built the modules. All I knew was that the trestle in the proto picture was approx 1x "train height" below track level, and that I could carve away as much XPS foam as I needed to make the scene "work")

While the room is 8x10, how large are the layout sections/modules?
(You are building this thing in sections, 
so that it can be taken out thru the single-person door if it ever comes time to move, yes?)

if each "module" is only around 2x4 (or less), then 
- build basic benchwork out of the desired L-girder 'domino' modules
- work out where the "canyon" should go
- then replace the required module with a suitable 'goosneck' or 'drop deck' module to gain the required depth

and go for it...

Just because the layout is 'small' by conventional US "home layout" perception, 
doesn't change your "givens and druthurs" list,
(you obviously really _want_ a "canyon" _somewhere_ on the layout)

nor does it somehow allow you to fit a HO 115 scale-foot deep canyon in 6" of benchwork thickness...

In short, IMHO No, it is _not_ "overkill" to build a drop-deck module for such a "small layout", 
if the layout specs/"Givens and Druthurs" truly require it...

Happy Modelling,
Aim to Improve,
Prof Klyzlr