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Bridges on the B&CCRR The B&CC layout has four bridges. Given the setting of 1870, I wanted the style used in the Rocky Mountains in the 19th century. Not finding any kits that looked good, I stumbled across the website for the Black Bear Construction Company which sells jigs for building various types of bridges. After some research, I decided to buy and use their "Truss Bridge Kit" What comes from Black Bear This kit comes in different forms: just the jig and instructions, just a materials pack, or the jig and materials pack combined. For ease in getting started, I bought the jig and materials pack. The instructions include a table for determining which size lumber matches up with the various scale sizes required for building bridges (so that you can buy lumber at your local hobby store) and supplied scale lumber is comparable in quality to that provided by Northeastern Scale Lumber The jig (pictured below) is made out of acrylic, so assembly should be with white or carpenters glue (CA or super glue will eat away at the jig). The jig is set up for modular operation when building large bridges and includes jigs for pier braces in both narrow and standard gauge sizes (these double for stringer spacing on the bridge itself). 
The plans include information on spacing of floor beams as well as different tension rod options. The instructions are relatively clear and include diagrams to help clarify any confusing text. Assembly Side Frames The first step in assembly is to build the two side frames. To do this, cut a piece of 12”x12” stock long and insert into the bottom of the jig (this will be the bottom chord and will be cut to length later). Second, cut and trip a piece of 12”x12” stock for the top chord and insert nto the jig. Now cut two 12”x12” vertical posts and insert into the jig at the ends of the top chord. Use these posts to miter the corners of the top chord for the diagonal braces. After mitering, glue these pieces together with white glue. 
Now, add the rest of the vertical posts and cut the diagonal braces. Miter the edges and insert into the jig using white glue for assembly. 
The jig is modular for assembling longer bridges. For bridges with an even number of panels, no additional work is needed. For bridges with an odd number of panels, two diagonal braces are cut for the middle section and joined with a lap joint to form the central X (see pictures below for examples). Adding the deck Once the two side frames are finished and the glue has dried, align the two side frames parallel to each other and cut 8”x12” stock for the floor beams. The first set of floor beams are placed next to each of the vertical posts as shown in the following picture: 
Continue cutting floor beams and placing between the two side frames. Notch the floor beams to fit around the diagonal braces. Add bracing At this point the bridge could be painted and put in the layout. If desired, additional support can be added by drilling holes into the frames for adding tension rods. I’ve used the in-line approach for tension rods as it fit the road concept I’ve been following. Tension rods are 0.025” piano wire and Grandt Line nut-bolt-washer (NBWs) are used at the top and bottom of each rod. The following four photos show the bridges I’ve build: a 30’ Queen’s Post Truss Bridge (one panel section) 
a 50’ Howe truss bridge (three panel sections) 
a 70’ bridge (five panel sections) 
an 80’ bridge (six panel sections) 
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