Prototype Information
Trestle.
Definition and use.
- nomenclature of girder parts and pic side and inside use micro 50 foot bridge as example with red lines and lettering.
Engineering
girders are slightly wider in spacing than the rails
Multi-span deck plate girder bridges are not connected to each other. The rails and end bearings on the top of the bridge pier hold the bridge in line. The end stiffeners transfer the weight of the bridge and the train down onto the bridge pier. The end stiffeners are mounted on pedestals which are used to ....
The WWSL
The Satsop River Bridge N5 is a Plate Girder Bridge. The prototype
structure was on the original Tacoma eastern main line, purchased by the
Milwaukee Road, and after abandonment used by the Mt. Rainier Scenic
Railroad (MRSR).
A search of the internet found a couple of
pictures of the trestle when it was used by the both the Milwaukee Road
and the MRSR. pictures show nine 6-
Modeling Information
The WWSL uses Union Pacific Common Standards whenever possible. In this
case I could not find any Milwaukee Road timber pile trestle plans, but I
did find a Union Pacific 5-bent trestle standard drawing. I also found a
Southern Pacific Standard Drawing for a 6-pile ballasted deck trestle.
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| Union Pacific 60 foot plate girder bridge |
Designing the bridge
Selective compression of the pile trestle will require construction of a wood bulkhead, five 6-pile bents. The maximum height of the pile bents will be distance from the top of the section base (the 3/4 inch plywood) to the top of the subroadbed (bottom of the mainline ties). That distance has been measured as 3.64 inches (actual) but for modeling purposes I will size the jigs for 3.5 inches and shim the bridge as required at installation.
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Plate steel riveted or welded to angle steel formed the sides of these
girder type bridges. These sides are fastened to each other by angles
and other shapes such as "I", "WF", "T" and channel shaped steel.These
fabricated beam types can either carry the deck on top or have the deck
pass between the sides.
I have made several modeling decisions based on the common standard diagrams above for my model:
The bridge is front and center in the Satsop River Section and it will be built of dimension wood, with appropriate bridge details (bolts, spikes, guard rails.
I will use the SP standard drawing for the generic 6-pile bent construction, using UP standard materials.
I will use the UP common standard drawing for all
other trestle construction (guard rails, stringers, fire safety,
bracing, etc.
The piles will be field cut timber close to the
common standard dimension. The piles will be field creosoted at the
base, with additional creosote along its length depending on the age of
the structure.
The bents will be of the same height but appear to
be different heights to accommodate the unevenness of the terrain on
the Satsop River Bridge Section.
The concrete abutment construction information is located at Satsop River Bridge N5 (Concrete Abutment).
The three pile and timber bent construction information is located at Satsop River Bridge N5 (Timber Pier)
steel bent construction information is located at Satsop River Bridge N5 (Steel Pier) .
Designing the bridge
Selective compression of the pile trestle will require construction of a wood bulkhead, five 6-pile bents. The maximum height of the pile bents will be distance from the top of the section base (the 3/4 inch plywood) to the top of the subroadbed (bottom of the mainline ties). That distance has been measured as 3.64 inches (actual) but for modeling purposes I will size the jigs for 3.5 inches and shim the bridge as required at installation.
Bridge this size is very fragile and I am using a technique called long bridge construction. I have six Atlas Thru Plate Girder Bridges, each of them have 10 identically spaced steel plates. The odel length is about 65 scale feet. Close enough.
- The prototype 21 panel plate girder bridges would be selectively compressed to 14 panels. To kitbatch this
bridge I need to add 4 panels. Total length of those two
bridges will be 25 inches.
- The 16 panel bridges would be selectively compressed to 10 panels. To kitbatch this bridge I need to shorten the height of the plate girders by approximately 1/3rd. Total length of those two bridges will be 18 inches.
Project Process
Step 2 Cut the channel and construct the bridge core
Step 3 Paint the Plate Girders
Step 4 Prepare and Attach the Bridge Ties
Step 5 Add Final Track Detail
Step 7 Assemble the Bridge
Construction
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Tool List Hobby table saw. Testors Cement |
Materials 1 - 3/4 inch aluminum trim channel 48 inches long (Hillman) 4-Evergreen 4x12 styrene strips |
Process Step 1 - Kitbatch the Plate Girders
Construction - 10 panel deck plate girder bridge.
The intent is to kitbatch two 10-panel bridges by reducing the girder height relative to the 14-panel plate girder bridges.
Pic of Modification
- Cut the through plate girder bridge apart. I used a 3 inch table saw. (4 bridges)
- Sand the back to remove the knee braces. I used an 18 inch belt sander (8 panels).
- Cut the end stiffeners from each end and save. I used a QEP Trim Shear tool for a quick, clean, sharp snip.
- Measure the plate girder depth and mark a line xxxx down the panel parallel to the base. Cut the plate girder panel at the cut line and sand the panel cut line smooth. I used double stick tape and a metal ruler to mark the line and then used a belt sander to remove the excess plastic. Remove any fused plastic from the sanding.
- Glue an Evergreen 4x12 strip to the bottom of the plate girder to replicate the rivet stiffener plate. Putty any gaps in the girder.
- Glue the end stiffeners to each end. NOTE: The Atlas bridge rivet stiffener plate along the bridge end now becomes the bottom of the plate girder.
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Shorten the height |
Add bottom plates |
Replace end stiffeners |
Construction - 14 panel deck plate girder bridge.
The intent is to kitbatch four 10-panel bridges into two 14-panel bridges.
Pic of Modification
- Cut the through plate girder bridge apart. I used a 3 inch table saw. (4 bridges)
- Sand the back to remove the knee braces. I used an 18 inch belt sander (8 panels).
- Cut 4 plate girder bridge panels at the x panel from the center as shown in the example and sand the c panel cut lines smooth. I used the Trim Shear tool for a quick, clean, sharp snip.
- Cut 2 plate girder bridge panels at the x panel from the center as shown in the picture above and sand the end panel cut lines smooth. I used the Trim Shear tool for a quick, clean, sharp snip.
- Check for square then align and glue the two end panels to either side of each center panel.
- Glue an Evergreen 4x12 strip to the bottom of the plate girder to replicate the rivet stiffener plate. Putty any gaps in the girder.
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Process Step 2 Channel Fabrication
- Utilizing 2 14-panel girders and 2 10-panel girders, layout the girder locations on the side of the aluminum trim channel. Leave a space of one bridge tie width between each plate girder.
- Mark the length on the channel and cut it with a hacksaw. Clean up any burrs with a file.
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Process Step 3 Plate Girder Painting
- Double stick tape girders to paint paddle/stirrers.
- Spray 1 red primer
- Spray 2 black color
- Spray 3 black shadow color
- Remove plate girders from the aluminum core
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Process Step 4 Preparing and attaching the Bridge Ties
- Prepare the bridge tie strip for attachment and painting.
- Gently adjust the tie spacing as necessary. The Union Pacific Common Standard was 4 inches between ties.
- Flip the bridge tie flex track upside down and along the straight edge. Starting at the concrete abutment end, lay the ttachment and painting.See 4.1.9d Laying Bridge Ties for additional details.Add initial tie detail.
- Add additional bridge details as appropriate. See4.1.9d Bridge Details
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Attaching the Bridge Ties
- L-girder the length of the bridge
- upside down track
- glue on the ties1. Apply contact cement to top of aluminum channel. Center and attach bridge tie strip to top of aluminum channel. Clamp and allow to dry.
- center aluminum channel
- clamp and weigh down channel
- adding bridge guard rails and guard timbers
Process Step 5 Bridge Tie Painting
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Process Step 6 Bridge Assembly
2. Apply contact cement to side of aluminum channel. Identify the edge of the panel that does NOT have the xxxx and attach 14 panel girder to the side of channel and along bottom of the tie strip. Align end of girder to the edge of tie. Clamp and allow to dry.
3. Repeat step 2 with a 10 panel girder. Ensure a gap between the 14 panel and the 10 panel the gap between two ties. Clamp and allow to dry.
4. Repeat 3 with second 10 panel girder. Clamp and allow to dry.
5. Repeat 2 with second 14 panel girder. Clamp and allow to dry.
6. Turn aluminum channel and complete other side in an identical manner as 1-5 above.
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Process Step 7 Adding Final Track Detail
The assembly of bridge track on
aluminum channel is light, strong, and easy to move to the workbench for
detailing. I attached the girders to the side of the channel with CA.
Atlas Model Railroad Co., Central Valley, and Micro Engineering are
among the suppliers of these parts. Then I added other details to match
the prototype I was modeling.
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Process Step 8 Weathering
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Union Pacific 60 foot plate girder bridge
materials.
I will use the UP common standard drawing for all
other trestle construction (guard rails, stringers, fire safety,
bracing, etc.
The piles will be field cut timber close to the
common standard dimension. The piles will be field creosoted at the
base, with additional creosote along its length depending on the age of
the structure.
The bents will be of the same height but appear to
be different heights to accommodate the unevenness of the terrain on
the Satsop River Bridge Section.
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