This object was made in Tinkercad. Edit it online https://www.tinkercad.com/things/4BMO5gWMDBV

This will fit on the tracks in those places where a road crosses the railroad tracks. I've fitted the piece so the train will still have good connection with the tracks and the grade crossing fits snugly. I've made the track impression on the bottom of the crossing so that there won't be any slipping. HO scale, Code 83. The depth of the piece could be adapted to fit Code 100 track, It measures 2.802 (13/16)" X 3.375 (5 3/8)" X .125(1/8)"

UPDATE: By request, I've added a code 100 crossing also. Enjoy