February 23, 2010

Potomac Creek Bridge Construction Steps

Here are some step by step photos showing how I made the piers and installed the bridge at Potomac Creek.

I made the base layer for the piers from laser cut 1/8th inch plywood. This kept the taper constant and ensured that both piers are the same size.

I covered the piers with embossed sheet plastic. To fill in the seams I used CAA glue and baking soda. The baking soda makes a slightly gritty texture when it cures that works well with the stone surface. I used Zip Kicker to accelerate the glue set.
The wood beams on the top of the pier are necessary because the truss is wider than the piers. Since the USMRR built the truss around the existing trestle bridge, it ended up wider than the original truss. Thus they needed these wood beams to support the new wider truss on the original piers.

To blend the terrain around the abutments with the precast rocks below them, I hand carved Durhams Water Putty.

Once it was cured, I painted the rocks with the base scenery colors to blend everything together and then added some basic texture with ground foam and static grass.

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