Have you tested the specific blueprint you uploaded? My test was quite simple: I placed some tracks, then dropped your print on top, then hooked the tracks into a loop and put a nuclear-fuelled locomotive through it.
As wired, you do not close the incoming signal when a player is in the crossing. Instead, it is set to close if the outgoing signal is also closed, as a sort of poor man's chain signal. I assume this is needed because of the tight spacing of the block signals (which is poor practice in general, and in any case there should be no need for an outbound signal anyway). The gates do provide an output, on channel G, but nothing in the circuit network does anything with it.
The gates are raised if a train is coming. But that's all they're doing. And because they have to be raised, which doesn't happen right away, you can actually manage to cross even with a train incoming as well. That's why my design -- and most other ones I've seen -- default to the crossing being closed.
