I created this generic bridge structure to span the modular river sections that I’m making. Currently, the design has 2 deck and ramp options to use depending on which rails you prefer. I plan to add bridge decks of different lengths, but for now, these are the dimensions when printed for 28mm:
Width of deck surface: 77mm
Height to bottom of the deck: 15mm
Span between abutment ramps: 270mm
Total length: 337mm
These files will print well on FDM printers with no supports. Test prints were done on an Ender 3 with .2mm layer height, 10% infill at 70mm/s.
The river sections are inspired by a great blog / tutorial from Purple Lion on creating modular rivers for tabletop gaming. https://www.facebook.com/purplelioncreations/photos/pcb.3093058384066885/3093052217400835