I have been doing a series of models in 1:100 scale and while many of them can be scaled to 1:160, or N-Scale, this is the first model designed for that scale. It is my first attempt and there are a number of things about the design that I don't like and will alter in future designs. That said it is still a nice example of what can be done ... ASSUMING YOU HAVE A SMALL NOZZLE FOR YOUR PRINTER (please see the notes under print settings)!
Note that the roadbed is 160x17mm with the total width, including the walkways, being 26mm. The bridge structure, not including the handrails or support pillars, is 18mm tall.
Update of 22-May-2016: One of the Sketchup components was corrupt (though not the corresponding STL) and the side panels needed extra bracing at the ends.
Update of 24-May-2016: Embarrassing but I just noticed that when I borrowed the railing from another model I must have miss-scaled it as it ended up being two feet tall. Picture of assembled bridge still not accurate but the renderings are updated with the STL file.
Update of 30-May-2016: Bottom.stl may have been corrupt. Walkway now four feet wide as it should be.
All models, source and STLs, are saved in full scale and need to be factored down to N-Scale! This means downsizing by/to 0.625. I model in full scale because Sketchup Pro solid functions seem to get confused by tiny little things.
This model will not print well, if at all, with a "normal" sized nozzle. It is designed for a 250 micron (or smaller) nozzle with the walkway demanding an extrusion width of 250 microns. You can force a larger nozzle to small extrusion widths but the quality will degrade the further you push.
Note that the road bed and the assembly jigs can both be printed with a standard nozzle.
There are two model files that can be printed to provide assembly jigs for the bridge. One goes on the outside of the top with the two sides then positioned on that piece with the other jig on the inside holding the sides in place. The inner jig can also be used to help position the inner cross braces.