As someone who works on the US transit systems after 20+ years on BR, I think I can provide some background.
This crossing is, to all intents and purposes, an AHB - on a non-electrified line such as this, what's used is a "predictive" system where the change of impedance in the rails is used to determine how fast a train is approaching and (in theory) give the same warning time (typically 20 seconds) irrespective of how fast the train is approaching. If an approaching train stops, the crossing will de-activate once the system "realises" it's stopped and will then reactivate once the train gets on the move again.
The logic, be it relays or a processor-based system, is generally simple: approach track, "island" track (the actual crossing area - occupying this one will activate the crossing no matter what) and exit track. However, if a train doesn't clear the "exit" track and comes back the way it came, the crossing won't activate because the directional logic hasn't reset itself. Not wishing to speculate too much, but there's what may be a maintenance truck parked just beyond the crossing. Another interesting thing is that the crossing activates 30 seconds after the train first enters it.