Category: Engineering Blog

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April 3, 2016 -- A year or more ago, Walthers announced their "Engineered Bridge System", which offeres a variety of bridge components of different sizes that are interchangeable. Their latest releases included four lengths of through girder bridges. Based on the parts and assembly instructions, I am highly confident that they either purchased or subcontract with Central Valley for these bridges. I've used the Central Valley 70' bridges in the past.

At a suburban Lewistown location, right near where route 322/22 cross Electric Avenue, there is a three span through girder bridge crossing the Kishacoquillas Creek. I didn't have the room for all three spans, but two spans was ideal. Since Central Valley didn't offer anything longer than 70', I waited for the Walthers 90' spans, which recently arrived.


Both the prototype and my model have the bridge crossing the creek at roughly a 45-degree angle. The kit would require adaptation to be on this angle, but the mods were actually pretty simple. 

Many modelers overlook the features of the prototype and just abut two straight bridges, as is, across the span. This results in the girders extending across land at opposite corners which was not typical of the prototype. It also leaves the connection of the spans over the water at an angle to the flow of the water. A pier would not be placed at an angle across the flow. What these modelers often then do is put the pier in line with the flow of water. This leaves the connections of the spans floating in the air and not supported by the pier!

My design required the girder ends to be offset. This proved to be a simple task at 45-degrees. I just cut back along the framing where the 45-degree bracing was...

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I also made the bridge shorter to fit my space. In the end, the girder length on either side proved out to be 144'. This required the girders of each span to be shortened. I used my True Sander from Northwest Short Line to finish the ends square. Here is a test fit...

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The girder "surgery" left slight gaps at some of the joints which were filled with Squadron Putty. Here are two shots before and after sanding...

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Here are two shots of the progress...

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The result after painting can be seen at the top of this blog, as well as this closeup shot...

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Next up: Cutting Chooch Enterprises stone abutments down to the correct heights, as well as a central pier. Also, scenery base for the banks of the stream and weathering of the bridge.

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April 14, 2016 -- Most of the actual bridge construction was covered in my last blog. The next step was to line the Kish Creek with rough scenery in the form of styrofoam. Meanwhile, the hardboard backdrop has received a coat of primer...

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After that, Chooch bridge abutments were cut down to size and a coat of Sculptamold applied to finish the scenery form...

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Jacks are placed between the bridge and the shelf of the abutment (the glue was wet and disappeared when dried). This is a prototypical feature that most modelers overlook.

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A base coat of paint has been applied and the backdrop has been painted...

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...and ground cover has been added around the abutments since these spots will be hard to get to with the bridge in place. I'll complete the bank and "water" later.

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The shot at the top of this blog shows the bridge in place. The center pier will be added when I complete the scenery; it is not required for support. The weights are holding down the track until the adhesive dries. Should be running the first train across tomorrow!