Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:5239270.

Highly customizable parametric bridge. OpenScad script - Use Customizer so that all parameters are set with sliders.

Parametric

Set bridge height, length, width, side girder type, perforated walkway, arch type, arch placement, etc.

Assembly from parts will require some light clamping.