One more note! These are largely bespoke models crafted in Sketchup using its Pro features for solid modeling. Those features don't make it the best 3D modeling tool out there but they help a lot ... and since I am an old dog that has been using Sketchup for a long time ... anyway ... the models are in Sketchup!
Curved Railroad Bridge and a Steel Pier
Concrete Railroad Bridge Pier
Ship - Cheated a little here as my prototype is a model from the Wrightsville Port N-Scale Layout!
Plate and Girder Railroad Bridge - Bridge No. 1276, Sideling Hill Creek Crossing
Bailey Bridge [Thingiverse] [Blog] [Instructable]