What is the correct length for ties on a narrow gauge bridge or trestle? According to one book I have, ties on a standard gauge trestle are usually 10 feet long, but I don’t if it would be different for narrow gauge.
Does anyone make I-beams small enough to be useful for garden railroads? They could be steel, aluminum or even brass. Something 2-3 inches wide, with narrow flanges, might be nice for a beam bridge. To build a steel viaduct would require even smaller I-beams.
Here is a start for you. Under 1" legs, aluminum and steel angles run about a dollar a foot.
https://www.metalsdepot.com/products/hrsteel2.phtml?page=angle&LimAcc=$LimAcc&aident= There are a lot of metal suppliers online, so snoop around with google and I’m sure you’ll turn up something you can use. The April 2006 issue of GRR has photos of several excellent bridges constructed of this material by Jengs Bang. BTW, aluminum and steel angles, channels and other shapes are always available locally in a fairly wide selection. Online sources can help you decide what’s available, but a local purchase is usually the cheaper option. Check the yellow pages for ‘steel service centers’.
HTH and good luck.