I live across the road from the BNSF main line in Idaho USA and frequently see BNSF pick up trucks on rails. I am unsure if they trigger the crossing gates or purposely override them - anyone know?
I have yet to see them transition from rail to road or vice-versa.
As an aside, I also see the little work train engines and tiny flat cars at times, and the funniest was a porta-potty strapped to a tiny flat car. I wish I had a pic of that.