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Normand Levert

This web page was last updated on May 25th, 2009.

SEDIMENTARY MY DEAR WATSON!

P2280035
NORD Rly PA approaching single track.  The floor of Shirley's Bay Transfer is now fixed to the module, but railfans still have to build their platform.

It's a bad joke I know.  You may notice the next time you drive along the 401 near Kingston -  Napanee, that in some areas the limestone deposits are tilted at an angle from the horizontal.  On one side there is a rocky bluff while the other the ground rises gradually, normally covered with vegetation.  The angle between the tilted strata and the road (or railway) can either accentuate or diminish the apparent grade of the road or railway.

I wanted a rock cut scene for my HOTRAK module "CONNAUGHT" and I wanted the sedimentary rock strata to be on a slant.  I strove for a visual break to separate the scene from the adjoining conventional module, so a low rock escarpment that had to be pierced by the railway would fit the bill perfectly.  It would provide a wall and a logical break in the scenery.  CONNAUGHT is a transition module; the other end is built to Freemo standards.

I used an old trick for the rock face: broken suspended ceiling tiles.  One can easily find discarded tiles somewhere.  This is why it is important to finish the layout room first.  The tiles are made from pressed paper, and when broken, the edges are random projections of stratified layers.  One then stacks layers of broken tiles to achieve the desired height of rock face.  A coat of latext paint then transforms the tiles into rocks.  This time I wanted a tilted strata and to keep weight low.  The solution was to build a hollow hill.  I used only enough ceiling tile to build the rock faces and added pieces of Styrofoam for the top surfaces.

To achieve this effect, I broke a ceiling tile in two - three inches wide planks.  I needed to get both sides of the rock cut to slope equally.  In theory we have blasted our right of way through the rock and the layers on side should continue on the other.  As well, I wanted a flat bottom surface, so that the rock strata would appear to continue below ground level.  The basic HOTRAK module construction is two-inch thick pink Styrofoam insulation framed on edges. 

I staked five or six planks, turned them on edge and used an old hand saw to cut diagonally at a low angle across all the planks at once. This way, I obtained “slabs of rocks” with a bevelled flat surface to lie against the insulation.  With all planks sawn at once, the bevel angle matches perfectly.  Flip over the other half of the stack and both sides of the rock cut slant at the same angle.  My hill is hollow: the rock faces are about two or three inches thick walls covered by a one inch thick Styrofoam “roof” shaped ground surface.  Don’t worry if you break a plank, real rocks split vertically too!  For the front face of the escarpment, all I needed were a regular few broken chunks without bevel.


P2240029 Sedimentary rock article 3
 This is the "escarpment" side of the rock outcrop.  Faces the conventional end.
P2240028 Sedimentary rock article 2
Same as on left, but from further away and more head on.  Show front Plexiglas quite well.  Shirley's Bay platform is in place, but the building is at excavation stage - notice the pink Styrofoam on the left.  Notice how the ground slopes up to the building foundation.

Before building up the rock cut, I cut drainage ditches on either side of the rail line. (Professional deformation – I’m an engineer)  just use a utility knife at about 45 degree to cut to “V” groves in the insulation a little distance from the edge of your ballast, say about ½ inch - oops one metre (HO) deep and then smooth the contour with rough sandpaper. Doing ditches first before the rock faces are in place is easier and also helps in locating the rock faces correctly!

To start my rock cuts, I supported the non-bevelled end of the first layer of rock on a block of Styrofoam.  This block was carved at about 45-degree angle for the front face where the talus would be, and with the top slanted to match the bevel cut.  I lined up the front supports on either side of the rail line by eye, so that the escarpment would line up. I started the side of the rock cuts some distance from the ditches, about 4 – 5 HO feet.  From then on, it was a bit like building a brick wall; I would place a bevelled broken ceiling tile plank on the rock cut face, then continue along the escarpment with chunks until past the module edges.  The ceiling tiles can be trimmed easily with a utility knife to get the piece to fit against each other.  Once in a while, the texture of the ceiling tile (I place the finished side up) might be a bit too apparent.  You can break off some layers of the tile top to create more irregularities.  I use a combination of yellow glue and bamboo skewers to fix the Styrofoam and ceiling tiles in place.  Trim any overhang past the framework with a large handsaw.

Once the first “slabs” were in place, I was able to stack the "planks" so that the escarpment was also at an angle from the vertical and the sides of the rock cuts sloped back from the vertical.  OVAR members may remember presentations by a geological engineer; you want stable rock faces in the cut!  Having said this, since the ceiling tiles do not break in very straight lines, you will still have some parts of the rock faces overhanging nooks and crannies.  Limestone can be quite stable, so one needs only to put a minimal amount of slope in the cuts.



P2280033
Looking "South" toward the front of the Module, this portion of the rock cut rests against the front Plexiglas. The Railfan platform is not built yet.
P2280031
Looking "North" toward the (conventional) back of the Module.  Reader should note the "station board" with name.Railfan platform will be built behind the "station sign".

While the broken tiles already look somewhat like sedimentary rock faces, the next steps change broken ceiling tiles into rocks.  The first is to paint the rock face with household latex paint.  You might whish to brush the broken ceiling tile edges with a stiff bristle brush first, but I find that the first coat of paint needs stiff brushing anyway.  I use a one-inch brush.  This time, I used flat black for the first coat – because I had some and because it would add depth to the finished rock faces.  The first coat of paint has to go into every nook and crannies.  My usual trick is to have flat white primer and flat black latex.  You then mix a lighter colour on a scrap of cardboard – or directly on the Styrofoam frame.  Brush your rocks lightly with the lighter colour, leaving the deeper crevices dark.  A nice variation is that often one layer of sedimentary rock is different than the others.  Add a dash of brown or just mix a different shade of grey and paint one layer differently from the others.  If you are subtle, it adds to the realism without being too obvious.  You can then mix a paler colour still, and dry brush the tips of your strata, to bring out the relief even more.  The next step comes when you add “ground” and vegetation to the top.  In areas where there is too much top of ceiling tile showing, add sand to simulate debris build up and then add a bit of vegetation. My last step was to use commercial talus debris.  These can be dyed, but I was too impatient.  I used mostly medium and fine, in small amounts along the rock cuts.  Place most on the flat surface by the ditches, but use some as well on the larger portions of flat “rock”.  I used a few larger size debris on the talus at the base of the escarpment, but otherwise used vegetation to cover the slope.

The top of the hill was done by shaping one-inch Styrofoam into terrain by using knife, surform plane and rough sand paper to add contours, tapering thin to the edges.  I used a bit of Scuptamold to build the transitions from ceiling tiles to Styrofoam, and to build a bit of a talus at the bottom of the rock cuts.  I did this in fact before painting the rock faces.  The talus along the escarpment is bigger; remember we used a Styrofoam block to support the first rock strata.  I bevelled the front at 45 degree, but 30 would have been better.  I could not really sand contours in this Styrofoam after the rock face was in place.  Instead, I used red cedar sawdust - never throw away anything! – to build a base slope, saturated it with rubbing alcohol and then dripped diluted white glue.  It is essentially the same technique I use for ballast. 

The rest of the scenery work is the classic latex paint and ground foam treatment.  As we add ground foam, saturate again with sprayed on rubbing alcohol (or “wet water” with a few drops of detergent)and then diluted white glue. 

The result is a saw tooth profile ridge, the long rise is covered with vegetation and the sharp drop is a rock escarpment.  The railway blasted a level notch through the rock, ensured good drainage and good alignment.  Most passengers hardly notice the cut.

Happy railroading!

Ottawa Valley Associated Railroaders - Interchange, February 2002.



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