Bob - What exactly are you trying to achieve with a grade crossing? Are you meaning a grade crossing horn signal, like press one button and have the locomotive automatically blow the correct sequence? If that's what you're looking for, the answer is no. That is not available on Railpro right now. It could be added, but it's easy to blow the horn/whistle by pressing the button.
If you are looking for something to control crossing lights, gates, and sounds the answer is yes. You can either use a AM-1S (Accessory Module with sound) or a plain locomotive module (LM-3S). The locomotive module can be put into "accessory mode" by loading the accessory program. Once there a program can be written to control whatever accessories you need. Either the AR-1S or LM-3S can control lights, sounds, and motor control (for movement of gates). You will need to hook up a detector somehow if you are wanting things to happen automatically.
-Kevin
