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Different roadbed profiles

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Different roadbed profiles
Posted by kasskaboose on Saturday, July 19, 2008 11:09 AM

I have 150ft of HO scale cork strips for the roadbed.  Should I get chipboard (thin cardboard) and put it underneath the cork to slightly elevate the mainline?  Doing that avoids having to order, wait, and then, use N scale cork for the yards/sidings.  What to do?  If I should use two different scales of cork, how to transition between the two w/o derailments?  The cheaper, easier, and preferred choice is only using HO scale with chipboard underneath the mainline.  Will doing that create enough of a realistic difference in height?

TIA!

Lee

 

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Posted by tomikawaTT on Saturday, July 19, 2008 3:03 PM

How thick is the chipboard?  Depending on how long the track has been in service, how well it has been maintained and the desires of the civil engineers in charge, main tracks may be anything from a few inches to several feet above passing sidings, yard tracks and industrial spurs.

My way of creating different 'under roadbed' height is to put shims between the subgrade (plywood) and the roadbed (extruded foam, thin, but thicker than cork.)  Materials (also used for leveling the roadbed base and superelevating curves) have ranged from cereal box cardboard to corrugated cardboard (suitably doctored) to drywall mud.  Since they are all UNDER the roadbed, they should be (and, so far, have been) relatively immune to any scenery or ballast installation technique except sustained, long-term flooding.

The latex caulk I use from the bottom of the roadbed up is waterproof and accepts latex-based paints.  I haven't tried any other kind of adhesive.

Chuck (modeling Central Japan in September, 1964)

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Posted by pcarrell on Saturday, July 19, 2008 8:25 PM

You could get some cork and use a rasp to shape it, or you could just lay the track and ballast it.  Once the ballast is secured I don't think you'd have any more problems.  You could also cast plaster ramps on site.

Myself, I've used Latex Caulk (the same stuff I use to lay track) to make ramps and have found it to be very simple.  I made them a couple of years ago and I think it's superior to the plaster or cork method because it's much easier to shape (and less messy too!).

First, lay in your roadbed on the main.  Then squeeze out a bunch of the caulk in roughly the shape and area you want the ramp to be.  Obviously you use more caulk on the high end of the ramp.  Next I use a scrap piece of 1/4" foam with the plastic film still on it and press it down on the caulk making sure that I make the ramp shape I want.  Whatever shape the bottom of the foam is, that'll be the end shape of your ramp.  You could probably use a piece of wax paper secured to a piece of wood if you don't have the foam.  Next, wait for it to dry.  It takes a while.  Mine took about 48hrs to dry.  Once it's dry you can remove the foam piece (just peel it up - it won't damage the ramp if it's dry) and you'll have a nice flat ramp, but the edges will be ragged.  If you'd like to clean that up, just grab your handy dandy xacto knife and cut the edges to shape.  If you start to peel the foam up and it's not dry (and messes the ramp up), or if there are voids that didn't get filled in the ramp, just add some more caulk and stick another piece of foam on.  When thats dry the void will be gone.

Using this method you can cast a ramp of any width, curvature, or angle in place anywhere on your layout.

Philip
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Posted by doctorwayne on Saturday, July 19, 2008 10:42 PM

I use regular HO scale cork roadbed, fastened to the plywood subroadbed wityh yellow carpenter's glue, under most of my mainlines, with the sidings right on the plywood subroadbed.  Depending on the length of the siding, I usually run the cork a foot or so into the siding.  Then, using a piece of #36 garnet paper over a block of wood, I taper the cork down to the plywood - it takes only a few minutes sanding with such coarse paper.

It's difficult to find a picture that illustrates the results, though.

 

Wayne 

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Posted by loathar on Sunday, July 20, 2008 12:29 AM
Real yards don't really have built up roadbed. There's another option if you don't want to order N scale for your yards. Office supply stores sell rolls of 1/8" thick sticky back cork that you can cut and use for your yards. (They're about 1'x3' rolls for $6.) Some people use these for there roads too. (with a topcoat of plaster)
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Posted by DeadheadGreg on Sunday, July 20, 2008 12:40 AM

Charlie Comstock has a SICK picture of this transition on a diorama he built that, imo, is the best represenation of real life.  His mainline track profile is PERFECT, and you can really see the transition to the lower elevation on the siding. 

http://s145079212.onlinehome.us/rr/dioramas/redland/redlanddiorama_09.htm

PHISH REUNION MARCH 6, 7, 8 2009 HAMPTON COLISEUM IN HAMPTON, VA AND I HAVE TICKETS!!!!!! YAAAAAAAAY!!!!!!! [quote user="jkroft"]As long as my ballast is DCC compatible I'm happy![/quote] Tryin' to make a woman that you move.... and I'm sharing in the Weekapaug Groove Wake up to find out that you are the eyes of the world....
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Posted by pcarrell on Sunday, July 20, 2008 9:11 AM

 loathar wrote:
Real yards don't really have built up roadbed.

Even in a "flat" yard, there is some drainage built in.  Notice the way the drainage is set up in this yard in Anderson, Indiana.  There are low spots between the tracks to funnel water away from the rails (and the wooden ties).

http://i83.photobucket.com/albums/j319/pcarrell/Prototype%20Train%20Photos/Captured2006-8-500004.jpg

A thought just occuered to me.......yes, it happens!  To get you down from the mainline height to the yard height you could also use carpenters shims (those wedges of wood that carpeters use to set door and window frames).

Philip
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Posted by loathar on Sunday, July 20, 2008 11:15 AM
pcarrell-Agreed, but you can simulate yard drainage with just ballast thickness.
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Posted by BATMAN on Sunday, July 20, 2008 12:00 PM
How would it look if you were to lay the yard track directly to foam and then gouge out small trenches in the foam between the track to simulate drainage?

Brent

Brent

"All of the world's problems are the result of the difference between how we think and how the world works."

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Posted by doctorwayne on Sunday, July 20, 2008 12:33 PM

 loathar wrote:
pcarrell-Agreed, but you can simulate yard drainage with just ballast thickness.

You can also do this with no differences in elevation:  simply "imply" such with the ballast colour.  In the photo below, all of the track has been layed directly on the plywood:

 

 BATMAN wrote:
How would it look if you were to lay the yard track directly to foam and then gouge out small trenches in the foam between the track to simulate drainage?

Brent

In most yards of any size, I believe that the drainage system is underground, so there would be few, if any, ditches is the yard itself - these would be a major safety hazard for any personnel working on the ground, especially in the dark.

Some years ago, there was an article in MR about cutting roadbed and ballast profiles using a hot wire cutter.  It showed several examples, including one where the ballast and sub-ballast profiles, plus trackside drainage ditches, and a siding roadbed (lower than that of the main line) were all cut in one pass, using a wire bent to suit the situation.  I've always felt that this was the only advantage of using foam instead of open grid benchwork. Smile,Wink, & Grin [swg] 

Wayne 

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Posted by pcarrell on Sunday, July 20, 2008 4:12 PM

 loathar wrote:
pcarrell-Agreed, but you can simulate yard drainage with just ballast thickness.

Indeed, that would work quite well I imagine.

Philip
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Posted by pcarrell on Sunday, July 20, 2008 4:13 PM

 BATMAN wrote:
How would it look if you were to lay the yard track directly to foam and then gouge out small trenches in the foam between the track to simulate drainage?

Brent

I've seen that done and it works very nicely.

Philip
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Posted by Medina1128 on Monday, July 21, 2008 8:22 PM

I extended the cork for the diverging route, then sanded it flush with the benchwork. Make sure you make it long enough so that the change in track height doesn't cause unintentional uncoupling.

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Posted by twhite on Monday, July 21, 2008 8:33 PM

I 'impllied' the difference in elevation by using a different color ballast and a smaller size rail.  In my case, my mainline is code 100, and my yard track is code 83.  The ballast on my mainline represents crushed Sierra granite gravel, and the ballast in the yard represents everything from decomposed granite to dirt to cinders.  They're on the same elevation, but the difference in both track and ballast gives the impression of a 'lower' yard. 

Tom

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Posted by markpierce on Monday, July 21, 2008 9:02 PM
 twhite wrote:

I 'impllied' the difference in elevation by using a different color ballast and a smaller size rail.  In my case, my mainline is code 100, and my yard track is code 83.  The ballast on my mainline represents crushed Sierra granite gravel, and the ballast in the yard represents everything from decomposed granite to dirt to cinders.  They're on the same elevation, but the difference in both track and ballast gives the impression of a 'lower' yard. 

Tom

This is a good technique because transitioning among different track levels can cause operational (principally derailing) problems.

Mark

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