A simple stone bridge with slab rails.

Uses core_1/blubrik1 for the texture.

Bridge runs east/west relative to target brush.

Align the template brush so the depth is as wide as you want the walking surface of the bridge. Align the top surface so it is where you want the bridges walking surface. The hight does not matter. The rails are added to the outside of the walking area, so the bridge will be slightly larger than the template brush.
