Marine Drive Overpass Diorama

[BCR 570]

Road Test
One of the stated goals with this diorama is to learn how to do some things I havent attempted before.  One of these is paved (asphalt) roads.  I will have one or two on the layout so would like to develop a satisfactory technique for them. I hope I dont upset anyone, but the best model roads I have seen tend to be those made using some form of plaster.  I am growing quite fond of the Dyna Patch Pro Patching & Spackling Compound I have so will go with that. 

I have made note of the Woodland Scenics road system with the foam tape forms, and like the idea of creating forms on either side to contain the plaster.
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One requirement for my road building system on the diorama is that all of the roads are on inclines across the 1/4" contour levels.  This means that the forms will have to step down across the contour layers, which in turn means that I will need to be able to sand them down to the desired incline.  It occurred to me that balsa wood would work well as it sands easily, and is fairly inexpensive.

So, balsa wood forms for the forms, and patching plaster for the road surface.  Here goes!


I built my test road on an off-cut from the 1/4" cardboard used for the contours, as it will take pins.  I marked out the road with thin strips of painters tape, and then glued the 1/16" x 1/8" balsa wood forms on top of the tape with CA glue.  I figured that the tape underneath the balsa would make it easier to release it from the cardboard after the plaster has set.  I pinned the balsa in a few places to prevent any movement while the glue dried:




After the glue had set, I began adding the plaster.  I was interested to see if this material could fill the 1/8" depth within the forms in one application, or if a two-step application might be required:




A wider putty knife was used to smooth out the plaster and level it with the tops of the balsa wood forms:




This was then left to set overnight.  I could see a few minor defects and holes, but doesn't the real thing have those too?!  And I can always add a skim top coat later:




Next day I peeled away the balsa wood and tape.  This proved to be more difficult than I had anticipated; perhaps I need to remove the forms before the plaster fully cures?  Defects not withstanding, I quite liked the overall look of the road surface:




I then sanded the road surface with 220 grit sandpaper, pressing lightly with the middle finger and more strongly with the outer ones in hopes of introducing a subtle crown to the road surface.  Next time I might try a rougher grit to see what surface result it might yield:




So far so good.  The next step will be to try a road on an incline to see how well I can angle the forms to the desired gradient, and how well the plaster will set when on an incline.


Tim

[basementcalling]

Looks good Tim. You might try tinting the plaster next time so if you get chips later on they don't expose the white underneath your colored surface layer.

[wm3798]

I like how you do more with test dioramas in a month than some of us do on a layout in a life time.

Obviously it's because of the wealth you've amassed from your career as a hand model!

I second the motion about tinting the plaster before applying it.  The problem I've always faced with plaster roads, especially on portable layouts and modules, is the slightest bump or flex and it goes to crap.  Of course, if you're modeling the Pennsylvania Turnpike, that's pretty accurate...  You'll need more road cones, though. (The PA state flower)...

I recall Dan Crowley's method of using craft foam as a base, with skim coat of either spackle or plaster of Paris for the finish.  I remember it being pretty effective.
Lee

[BCR 570]

Thank you both for the comments about tinting plaster.  What does one use for tinting and would it integrate with the spackling compound?

Tim

[BCR 570]

Road Test (cont.)
The next step was to try out this method on an incline transitioning across the cardboard layers.  I began by building up the balsa wood forms on top of painters tape.  This time I used WS Foam Tack Glue in hopes of an easier release after the plaster had set:




After letting the softer glue set up overnight, I sanded the balsa wood forms down to the desired slope:




In went the plaster.  I wetted the first road where the second one was to join it.  Due to the depth at the transitions between cardboard layers, I applied the plaster for this road in several applications to reduce setting time and minimize cracking.  This seemed to work well:




Here is the incline road after removal of the balsa wood forms.  They were definitely easier to remove this time.  I am pleased with the results:




These test roads will now be used to develop a satisfactory painting, lining and weathering method.  Many of the model roads I have seen are painted too dark, so will be looking to achieve a nice light grey with faded markings.  In the meantime I can get going on making the roads on the diorama, but more balsa wood is needed, as well as paint for the test roads.  Fortunately our new local hobby shop opens this weekend (Intercity Hobbies formerly Central Hobbies now in Langley, B.C.) so a shopping trip is in my near future.


Tim

[Van Horne]

Thank you both for the comments about tinting plaster.  What does one use for tinting and would it integrate with the spackling compound?

Tim

Tim - any acrylic paint will work with the spackling compound. I used to use Polly S but now use Vallejo. Woodland Scenics also has some tinting agents in road-type colours.

Dave

[BCR 570]

Tim - any acrylic paint will work with the spackling compound. I used to use Polly S but now use Vallejo. Woodland Scenics also has some tinting agents in road-type colours.

Dave

Yes, would like to try the WS Smooth-It and tinting agents.  I see that Pelle Soeborg tints the water that gets mixed with the plaster so might try that.  Time for a trip out to our new hobby shop!

Tim

[BCR 570]

Right-Of-Way
While working on tests for the roads, I am also working on preparations for the right-of-way on the diorama.  I want to be able to lay out the right-of-way on the 12 degree reverse curves and 0.60 gradient of the prototype.  I have had good success with balsa spline sub-roadbed on my layout, which allows precise alignment of curvature and easements, and it can be sanded fairly easily.  A rigid sub-roadbed can be shimmed to the exact gradient as it transitions between the cardboard contour layers.

To obtain the desired 12 degree curvature I am using a Tracksetta 36" radius template which equates more or less to a 12 degree curve in N Scale.  The first piece is pinned in place next to the track alignment gauge on a sheet of paper, with some of the extra double wall cardboard underneath to take the pins.  The next piece is glued to the first with wood glue, and pinned in place until dry:




Additional strips of balsa wood (1/8" x 1/16" I think) are added either side to get out to the desired width of an inch or so.  This can be done while previous strips are setting so the work goes fairly quickly.  A water bowl and paper towel are kept on hand for removing glue from fingertips after applying:




The track template is moved along and additional strips of wood added to extend the curve.  This section is equivalent to approximately three times the length of the template:




The completed section of sub-roadbed is then sanded on top for an even surface, and on the bottom to remove the paper which has glued to the underside:




The completed curve is shown in position on the left end of the diorama.  It matches the curvature of the track transferred from the municipal drawing to the diorama perfectly:




The next two sections will include spiral easements for the reverse curves, but I have to track down some more balsa wood!


Tim

[BCR 570]

Road Test (cont.)
Prior to getting started with roads on the diorama, I wanted to try the Woodland Scenics Smooth-It road system, as I discovered that I had a learning kit on hand.  I also wanted to try the suggestions given here with respect to tinting the plaster.  As the Smooth-It system involves mixing plaster with water, it would be possible to tint the water prior to mixing it with the plaster.

The WS system uses foam tape to create borders for the plaster pour.  Prior to putting that down I applied painters tape once again for an easy (hopefully!) release.  The road is about 35 scale feet wide plus five scale feet each side for sidewalks, which I want to try this time around:




The foam tape was then applied on top of the painters tape:




The Smooth-It plaster was mixed according to the instructions with one exception:  I waited until all of the water had been absorbed by the plaster before stirring to avoid lumps.  I also tinted the water lightly before mixing.  Next time I think I can afford a higher degree of tinting (e.g. darker) but at least the plaster is not white.  The plaster was then poured into the form and levelled using the styrene scraper supplied.  I actually did two pours as the first one settled a little:




I was pleased to find that the paving tape removed very easily and there was virtually no chipping or cracking of the plaster.  At this point I let the plaster harden fully overnight:




The next day I sanded the road surface smooth using the supplied 220 grit sandpaper.  I tried to form a slight crown in the road as I sanded:




This process will now be repeated with a trial for adding sidewalks on either side.


Tim

[BCR 570]

Road Test (cont.)
After trying out the Woodland Scenics system for roads, I wanted to my hand at sidewalks using the same method.  I will need to install sidewalks along both sides of Marine Drive on the diorama.

The forms for the sidewalks were added using the WS foam paving tape:




I then added the plaster for the sidewalks, which was tinted to look like concrete:




This is what the sidewalks looked like after curing overnight:




I carved expansion lines at five foot intervals to match what I am seeing on Marine Drive.  I used the back of an Xacto blade:




I was quite pleased with the results as shown in this view:




I will now use these road tests to learn how to paint and weather the roads, but I can also now go ahead and start on the form work for the roads on the diorama.


Tim

[Ed Kapuscinski]

Did you see how it works over slopes? That's one of my big concerns with such thin plaster.

[Scottl]

Nice work.  Not many roads in West Van are so nicely paved and the sidewalks are often quite rough.  Needs some patches and repairs 

[BCR 570]

Hi Ed

I was thinking of an initial layer of the DynaPatch and then the Smooth-It on top . . . . .


Scott:

yes, my OCD has me making things too neat and tidy . . . . 


Tim

[BCR 570]

Right-of-Way (cont.)
The next step in establishing the right-of-way across the diorama was to complete the sub-roadbed for the reverse spiral easements.  My friend Greg (PGE Modeller) drew the spiral easements for me based on a 1935 PGE Track Profile.  The tracks come out of a 12 degree curve one way via a spiral easement and then reverse into a spiral easement and a 12 degree curve the other way.  The transition point is just off the Marine Drive overpass.

I printed the drawing out full size N Scale at Staples:




I then pinned lengths of 1/8" wide balsa on either side of the centreline all the way through the reverse easements:




Additional strips of 1/8" balsa were then glued beside these to achieve the desired width of one inch:




After sanding the completed sub-roadbed, it was test-fitted in place on the diorama:




Here is a view of the diorama with all three sections of the sub-roadbed lying in place.  The middle section is the reverse spiral easements, and the sections on either side are the 12 degree curves.  Some of this will be cut away where the overpasses will go.




I will hold off gluing this down until the bridges are manufactured and test-fitted in place, but for now it is another step forward.


Tim

[BCR 570]

Roads and Sidewalks
I am back to work on the diorama after a very busy fall.  Having undertaken several successful tests with the spackling/patching compound and the WS Smooth-It system, and having received some sage advice here, I have elected to go with several layers of the Dyna Patch Pro to reduce shrinkage and cracking and build up the basic slope, and then add a top coat of the Smooth-It which can be tinted as suggested.  I want to get the roads and right-of-way in place before adding the scenic base elsewhere.

My roadwork began with installation of the balsa wood forms which were glued down on strips of painter's tape for easy removal afterwards.  The formwork as terraced to accommodate the transitions between layers of cardboard.

Here is the view of Dickinson Crescent toward the rear of the diorama, which is basically a narrow lane:




And here is Marine Drive and 31st Street at the other end of the diorama:




 then sanded the form work into the gradient needed for the roads:




More sanding here, along with the first infill of plaster between cardboard layers for 31st Street:




Plastering in progress along Dickinson Crescent (at this early stage things are still quite rough):




And also in progress along lower section of 31st Street:




More layers of plaster required, and then a lot of sanding!


Tim