4.1.9.5.3a Satsop River Bridge N5 (Wood Bulkhead)

Prototype Information

Timber trestles usually, but not always, have timber bulkheads as their abutments. Those bulkheads can be engineered as straight, winged based on the terrain. 

Here are two Union Pacific Common Standard Timber Bulkheads, one straight, one winged.

Straight Timber Bulkhead

Winged Timber Bulkhead

Modeling Information

Both of these bulkhead types can be modeled in wood or plastic. 

The WWSL

This project builds the timber bulkhead for the Satsop River Bridge Timber Trestle N5b.

Engineering 

I wanted to build a 6 pile bent timber trestle. I could not find a Milwaukee Road timber pile trestle plan. I did find a Southern Pacific Standard Drawing for a 6 pile ballasted deck trestle. I also found the Union Pacific Common Standard for a Straight Timber Bulkhead. Both drawings are similar however the UP Common Standard is for a 5 pile bent and the bulkhead planks are shorter in length. Visually it makes the bulkhead look too small horizontally for the 6 pile bents (UP's 18' compared to the SP's 27' at the top of the bulkhead.

Based on the design of the Satsop River bank, I am therefore using the SP Standard Drawing for the Satsop River Bridge straight timber bulkhead.

I have made several assumptions based on the photographs above for my model. 

1. The bridge is front and center in the Satsop River Section so it will be built of dimensioned wood.
2. The bulkhead will be approximately1 inch in height, to reflect the vertical height of the river bank at that location (the bank sharply drops off and then slopes down to the water line).
3. The two piles on either side of the bulkhead will be 3.5 inches in height (the same as the piles in the timber pile trestle project).
   
4. The Bulkhead Slope Planks will be stregthen by adding two other vertical planks on the reverse side, located approximately at the second pile left and right of the roadway center line. 

Note: I am using the part of the drawing marked by the red box. I am not using the ballasted deck sections of the bulkhead plans.

Scratchbuilding

Materials Needed

Bulkhead Planks - 3"x 12" 281' (4 12" strips)

Timber Piles -

Bulkhead Slope Planks - 3"x 12"

Preliminary Preparation

1. Build the Bulkhead Jig
2. Wood parts will be cut and stained prior to assembly.
3. Nut Bolt Washer (NBW) parts will be painted prior to installation.

Building the Bulkhead Jig

I imported the SP Standard Drawing into Microsoft Word as an Object (picture), sized it to HO scale using the Format Object function and a scale ruler, printed it, resized it as necessary (the 100% size on the monitor didnt match the 100% size on the printed page ... go figure!), cut out the bulkhead specific portion and glued it to a piece of masonite. The red lines indicate project parameters.

Building the bulkhead

1. I put two strips of clear double stick tape onto the jig to hold the bulkhead planks in position until glued.
2. Cut the horizontal bulkhead planks to length and place in the jig. In this instance I measured the planks to the plan, then used a chisel blade to mark the cut.
   
3. Cut the bulkhead slope plates to length and cement to the bulkhead planks.
4. Flip the bulkhead over to the reverse side.
5. Cut the bulkhead piles to length and cement to the bulkhead planks.
6. Touch up the cut edges with stain as required
   

When you have the bents assembled (a different project), attach the bent.

1. take one small piece of stringer and lay it on top of the bulkhead. 
2. Take one pile bent, apply a light amount of glue to one side of the top cap and legs and place the bent in the proper location in the bulkhead jig. (My bridge stringers are sized differently than the SP Standard Drawings stringer size). Adjust your bent as appropriate.
3. Apply weight to the assembly and allow to dry.

Weathering the timber bulkhead.