I built this O scale 30" truss bridge using Plastruct's HO plans (no O scale plan was available) enlarged at a FedEx Office store and figured out the BOM from the enlarged plan. That was 15+ years ago; Plastruct now offers the bridge kit in O scale for $39.95.
The bridge is extremely strong. It fell from about 6' and landed on hardwood floor. Some pieces separated but went back together easily and only needed a few cosmetic pieces fabbed or reattached.
When I built mine, I used a Zona razor saw and an aluminum mitre box.