For posterity, I shot video of one of the first trains through the completed installation - TVLA, the most important westbound train on the schedule. It's a good fit! Turn your speakers on and have a look:
Like the prototype, the bell starts upon activation, and runs until the gates are closed (down). Then the bell shuts off. Some units trigger the bell again as the gates reopen, but others do not; I modeled the latter with bells only upon activation and closing.
What a hoot! Thanks for watching!
~RGDave