Thursday, September 28, 2017

THE BRIDGE AT WESTFIR

With the railroad running well and with no critical construction or repair tasks to support operations, I have been turning to model-building projects to enhance the scenes around the railroad.  One of those tasks has been completing and installing the bridge at Westfir.  A “temporary” plywood span has been in place since the original construction of my railroad.  Several items needed to fall into place for me to replace this temporary span with the permanent bridge and its supports.

First and foremost, I needed a suitable deck truss bridge.  The prototype span features a ballasted deck supported by a pair of deck girders for the approaches and a deck truss for the main span.  See the photos of Joel Ashcroft’s “Southern Pacific in the Cascades” website, where the bridge at Westfir is used as the title page image for the website section on structures:
http://spcascades.railfan.net/structures.html  I considered adapting an Atlas “train set” deck truss, but it was too short for my purposes and definitely not detailed enough for the location very close to the aisle.  A second option was to scratch-build using bridge girders from Central Valley. I was somewhat willing to do so, but other tasks always took a higher priority.  This past year, Walthers introduced a new line of bridge kits, including a deck truss bridge (933-4520).  Although not an exact match, this bridge kit was close enough to do the job. 


Deck truss bridge over the North Fork of the Willamette at Westfir.

 With the central deck truss bridge settled, the rest of the bridge started falling into place.  The approach span girders are Tichy girders.  These are shorter (forty scale feet long) than the Micro Engineering spans (fifty feet long) I have used elsewhere.  I needed the shorter spans to fit the space I allowed for this scene.  The ballasted deck was built using my standard technique using 0.040 inch thick styrene for the deck with 0.125 x0.125 styrene strip for the cross beams.  I used this technique for other ballasted deck bridges such as the deck girder bridge over Salmon Creek, at the other end (RR-West) of Oakridge:  https://espeecascades.blogspot.com/2014/04/salmon-creek-mainline-bridge-1.html  I have chosen to use the earlier style wood bridge railings on my railroad versus the pipe stanchion and cable “railing” used in more recent years.

Bridge abutments and piers were built up from styrene sheet and strip.  This allowed me to capture the 12:1 batter (slope) of these supports and to control height.  This also is the way I built these supports for the Salmon Creek bridge: https://espeecascades.blogspot.com/2014/06/salmon-creek-mainline-bridge-2.html 
Different for the Westfir bridge was that I chose to mount/support the end abutments using the “river” plywood plate that undergirds the entire scene.  I was able to select styrene strip thicknesses to adjust the height of the abutments to match the required geometry.


Bridge abutments and piers for the Westfir bridge.

As I built the pieces for the bridge, I also needed to address roughing-in the overall scene.  Critically, I needed to sort out the log pond and river.  My base plate provided too deep a scene for the log pond, but that same depth was needed for the deck truss bridge.  Fortunately, the prototype Western Lumber created their log pond using a series of dams on the North Fork of the Willamette River.  http://spcascades.railfan.net/westernLumberCo.html  Although I rearranged the relative location of the bridge and the pond, the prototype inspiration remained.  I was able to raise the pond and the river beside it by the thickness of a 2x4 on the flat (1.5 inches thick) plus a hardboard sheet for the new water level.  This provided more acceptable geometry for the log chain leading to the de-barker and sawmill.  Still, I needed to rough-in a stepped-down set of levels leading from the sawmill to the log pond.  This needed to be done before the bridge was installed. 


View of Westfir bridge scene with log chain leading up from the log pond through the de-barker to the sawmill.


SP 8529 leads a RR-East train over the new bridge over the North Fork of the Willamette River at Westfir.  Behind the locos is a tunnel portal mock-up for Tunnel 22 which penetrates a ridge leading into Oakridge.  The final model portals are in the packaging propped up against the backdrop.


Another view of the new bridge at Westfir with the sawmill and its support structures in the foreground.

The two-month break in my regular operating schedule caused by the Labor Day Weekend impact on my normal First Saturday schedule provided the final element needed for installation of the bridge.  With a two-month break, I felt more confident in my ability to reassemble the railroad in time for the next operating session. 

The entire scene at Westfir is an important one to my railroad.  It is good to be fleshing it out at last!


1 comment:

  1. Bill,

    That bridge just looks fantastic! Great colors, nice weathering and a neat setting. And those bridge abutments and piers really turned out well, too. It's not easy to get plastic to look like concrete but you have certainly pulled it off. Nice work!

    Tom

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