Marine Drive Overpass Diorama

[BCR 570]

Introduction
Hopefully this is the right place for this build thread.  As the layout is now back together and operating, I am looking for a change of pace for a few months and an opportunity to practice some techniques such as roads, scenery, trees, etc. before attempting the same on the layout.  So I have decided to build a small portable diorama on which I can practise and learn a few things.

I am also wanting to take a stab at earning the Prototype Model certificate for the NMRA's Achievement Program.  The requirements for this certificate include replication of a prototype scene (no minimum size requirement), inclusion of a railway structure, and supporting documentation for the prototype scene and the model build.  For more on the requirements I refer you to the NMRA website:  https://www.nmra.org/prototype-models


The Prototype
I wanted to select a scene on the British Columbia Railway, and one that was fairly close at hand for ease of field research and photography.  The scene also has to include a railway structure (e.g. bridge, station, etc.).  The scene and the structure have to be ones for which supporting documentation (e.g. drawings, photographs) are available to meet that specific requirement.

I selected the railway's overpass above Marine Drive at 31st Street in West Vancouver, which is about a ten minute drive from home.  There are some historical photographs online at the West Vancouver Archives website, site drawings are available online, and plans for the bridge are also available from a former member of BC Rail's Engineering Department.

The bridge was built in early 1914 during construction of the Pacific Great Eastern's North Shore Subdivision, and was in service from 1914 to 1928.  The central span is a 56'-6" skewed through plate girder and the approach spans were originally frame trestles.  The line was removed but not abandoned from 1928 until 1956, when the tracks were relaid to join the rest of the PGE network.  At this time the approach spans were renewed with pile trestles.  In 1975 the British Columbia Railway replaced the approaches with pre-cast box girder spans.  BC Rail undertook some upgrades to the spans during the 1990s.  The span continues in service today with CN Rail who took over the line in 2004.  The central span is therefore historically significant as the oldest bridge span on the entire former BC Rail network.


Drawing and Photographs
The following site map illustrates the area to be modelled.  It indicates the railway's right of way which is on a 12 degree reverse curve with spiral easements.  It also indicates Marine Drive which passes underneath the railway, and 31st Street which intersects with Marine Drive and also passes underneath the railway.  There is also a road (Dickinson Crescent) which intersects 31st Street and parallels the right of way.




This drawing was modified by my friend Philippe Whyte to include the contour lines which show the elevations in one metre increments.  When printed out full size in N Scale those increments equate to 1/4 inch.  These will assist me in achieving the correct profile for the terrain.  The area to be modelled works out to be 5'-6" long and 1'-9" wide which will fit into my car should i wish to take it to a show.  The reason for the unusual shape of the diorama is to avoid having to model the adjacent hpuses which would not be practical to research or model accurately.

This photograph taken in September 2022 is looking west along Marine Drive toward the overpass as a CN train was passing overhead.  The intersecting 31st Street comes in at right, and on the left it comes in behind the camera.  There are municipal bus stops on either side of Marine Drive at the bridge site:




This photograph is looking east (opposite direction) toward the railway bridge and illustrates the central span and abutments well:




This view at grade is looking south across the span.  The tracks go around the bend and then over 31st Street:




And this view at grade is looking north across the span with the tracks curving around in the opposite direction:




I think it will be an interesting scene to model and I hope it will enable me to earn the Prototype Model certificate.

Tim

[Specter3]

Tim

That is a very scenic bridge you have chosen. Lots of different tree species, overlapping power lines, grade, superelevation. Certainly a challenge to any modeler. Good luck with the build!

[BCR 570]

Thank you; yes power lines are another thing to learn how to do on this project.

Tim

[BCR 570]

Styrofoam Base
I was looking to create a base which was firm and rigid yet lightweight for transport.  I decided to try laminating together three one inch thick sheets of rigid styrofoam insulation.  The sheets were 2' x 8' but the shop kindly cut them down to 2' x 6' for me so they would fit into my car.  The adhesive of choice for this material is LePage's PL300 which I applied with a caulking gun:




I am working on the base in our school's Maker Lab where there are nice large workbenches and power tools, and across the hall is the Health & Wellness Centre so I borrowed some weights:




With the first two layers glued together, I added the third for a total thickness of three inches:




The assembled styrofoam base - now 2' x 6' x 3" thick:




The base was then trimmed to a final width of 21" on the table saw:




It was then cut to a final length of 5'-6" with square and flush cuts on each side:




Here is the base after trimming to a size of 5'6" long x 21" wide x 3" thick:




Next step will be to cut the profile of the front and rear curves.


Tim

[nickelplate759]

Are three laminated 1" sheets significantly stronger or weaker than one 3" sheet?

I used 2" sheet on my last layout, but laminated 1" sheets would have been easier in some areas.   Also, with lamination it might be possible to lap the seams.

[craigolio1]

Oooooooo as you know I have thing for modules based on bridges. Following.

Craig

[BCR 570]

Yes Craig do follow; as a builder of several dioramas you will be able to provide much guidance!

Tim

[BCR 570]

Styrofoam Base (cont.)

I used the full size N Scale printout of the site drawing to trace the profile of the front and rear curves onto the styrofoam base:




Here is the styrofoam base with the final size and shape drawn on it:




Gary Hinshaw recommended a particular jigsaw blade made by Festool for cutting styrofoam insulation (Model 155/W):




As luck would have it, the school's shop has a Festool jigsaw so it was used to cut the front and rear profiles:




Here is the styrofoam base cut to the final size and shape:




Again, the odd shape is to avoid the houses adjacent to the right-of-way which I dont want to have to build.  Fortunately there is no minimum size requirement for the Prototype Model scene other than to be sufficiently large to adequately recreate the intended scene in miniature.

Cardboard contour layers are next.


Tim

[BCR 570]

Are three laminated 1" sheets significantly stronger or weaker than one 3" sheet?

They might be.  There was very little of this material in our local shops and 1" was the thickest I could find.


Tim

[BCR 570]

Cardboard Contours
As mentioned previously, when the site drawing is printed full size, the one metre contour levels equate to 1/4 inch.  I purchased some 1/4" thick double wall cardboard with which to build up the contour levels accurately.  My first step was to colour the different contour levels with different colours to avoid getting confused when tracing and cutting out the contours:




I then aligned the drawing on top of a pair of sheets of cardboard (which are 24" x 36") and pinned it in place.  I made sure that the drawing was pinned in the same location on each successive pair of cardboard sheets so I can use the pinholes to align the cardboard layers later.  I then transferred the contour lines onto the cardboard using an Excel tracing wheel:




This left a faint perforated line on the cardboard which I then went over with a Sharpie marker:




I cut the cardboard along the contour line with a utility knife.  This worked but was significantly more difficult than expected likely due to the double wall construction of the cardboard:




This is the first pair of cardboard sheets after cutting out the contour line and right rear angle.  The lowest elevation on the drawing is 17 metres above sea level so this first layer of cardboard will represent 18 metres:




Here are the first three layers representing 18m, 19m and 20m after cutting out.  They are arranged on top of the styrofoam base to see how well this method will work.  Note that I have also transferred the locations of the railway and the roads where relevant:




I am pleased with how well this will work, but I need an easier way to cut the cardboard, particularly as the curvature of the contour lines starts to get tighter.  My friend Philippe has recommended a jigsaw with a blade for cutting cardboard so we will give that a try.  I have the layers for 21m to 35m all marked out on the cardboard so the next step will be a major cutting session!

Once all the layers are assembled, I will devise a method for covering them with something to get the initial scenic base.  At present I am considering strips of masking tape with a coat of plaster on top.


Tim

[BCR 570]

Cardboard Contours (cont.)
As mentioned, an easier way to cut the double wall cardboard was required.  Philippe suggested using a jigsaw so over to his newly finished garage/workshop to cut the remaining thirty or so sheets of cardboard.  As luck would have it, the Festool jigsaw blades I purchased fit into Philippe's DeWalt jigsaw, so away we went:




The jigsaw was able to cut around sharp corners much more easily than the utility knife, and the work went much faster:




As can be seen here, the special blades did an excellent job of cutting the cardboard cleanly, and there was no mess:




Here is the project with contour layers for 21 to 25 metres cut out and placed roughly in position:




And here we are with all layers up to to 36 metres above sea level placed roughly in position:




This gives a fairly good idea of how the terrain will look.  The cutting was finished in about two hours.  Here are views from each end:






The project was taken back to the Makers Lab at school where I will now glue the layers in place one by one. 


Tim

[GaryHinshaw]

That is quite awesome Tim.  It's almost a shame to cover it up as it looks like a really nice architectural model.

[craigolio1]

This does look outstanding. When building to scale it’s a great resource to have those maps and such to translate into an accurate model! No different than a freight car or a building.

Craig

[Scottl]

Really enjoying following this build.  It is a familiar location to me, as we walk my brother's dog down the street and usually turn around when we get to the bridge. 

The contours are so accurate you can see the crowning of the road surface!

[Ed Kapuscinski]

Next level. I love it.