Paul Ooi Modelworks

Building a better world, one scale model at a time

Tutorial 18 – Building a small wooden bridge

Bridges add focus and create interest in a diorama. In many cases, entire battle scenes can be built around a single bridge. How to build one? Let’s get started! You determine the span of the bridge between the banks (sometimes called the length) and its beam (also called the width). To build this example here with a span of 6″, beam (width) of 4 inches, I used the following:

  1. 1/4′ square strip bass wood – 4 ft
  2. 3/16″ square strip bass wood – 6 ft
  3. 5/32″ square strip bass wood – 4 ft
  4. 1/4: diameter dowel bass wood – 3 ft
  5. 1/16″ x 1/4″ plank strip balsa wood – 3ft
Start by building the main trestle beams that will determine the width of your bridge. The beams are 1/4″ square bass wood strips. I cut out the Dado joint to fit the piers using a micro saw to a depth of 1/8″, and then chiseling out with a sharp Xcto knife.
This is the completed trestle beam with the Dado joint indents. You can make as many as needed depending on how many trestles you intend to have and the span of your bridge. For this one, I needed only two.
Completed trestles with the pier beams attached. I use a super strength Elmers wood glue for the joints. They drive within 2 minutes and can be handled within 5 minutes.
The main span is easily made with two or three main support parallel beams using 6″ long 1/4″ square strips (visible in the next picture), and then the rafters/boards each 3/16″ square or 1/4″ dowel are laid across to form the surface of the bridge. I varied the edges and even types of wood (planks and dowels) to give a rustic finish to the bridge.
Attaching the trestle to the underside of the bridge. Here you can also see the two main parallel span beam pieces that the rafters attach to.
IN this particular bridge, engineers had laid long wooden planks to help vehicles to roll over them without jarring their suspensions (and vibration over the bridge). I use flat 1/4″ balsa strips to simulate these planks. They do needs to be clamped down to stay flat while the glue cures.
The railings are added last, the bottom plate is about 5″ long 3/16″ square strip, a corresponding top rail of similar or slightly shorter length, and support balustrade pieces 3/4″ tall. These are simply butt joined to the rails.
I finished the bridge with an oil stain made from Turpenoid and Burnt Umber oil paint.

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