Just for another option; here are two 50" long 2 track drop-in bridges I recently made for our train show layout, to interconnect adjoining sets of members modules. They utilize the upper sections of MTH 30" 2 track arch truss bridges and 10" girder truss bridges, fastened to made up boxes consisting of 1/2" plywood upper and 2 x 2 side runners, all painted satin black. The lower portions of al bridges (which would normally support the track) is not used.
These are designed to quickly drop in and connect modules that are 48" apart nominally. They overhang 1" on either end. You could adjust them to suit most any spacing from 30" up, and they could also be made single track width. As is, they will accommodate any track spacing up to 4-1/2" C-C.
Rod
