Hi Angelah:
If you think about it we are lucky they work at all. We are using something built into Trainz that was originally designed to raise and lower 20 or 30 ft long crossing gate arms in 5 seconds - - - not animate 600 ft long bridges in 30 seconds. The trigger radius they set is fine for a real mocrossing (motorcar crossing). You might say we are pushing the limit by using it for gigantic bridges so I guess we just have to accept the short-comings.
On the happier side, the method could be used for almost any animation one would like triggered by an approaching train. Rearing horses that don't like the loco, kids running toward the train because they want to watch it go by, folks waving, etc.
Ben