I know San Diego Trolley had some problems, and I think many transit operations have similar issues. The basic problem is this - LRT/DMU approaches a station where it is going to stop for a minute or so. There are crossings on both sides of the station. So how do you limit the activation of the crossings or signal preemption immediately beyond the station to prevent pissing off impatient motorists? What I have seen, is the crossings are set up to ignore the approaching movement beyond the station, and triggering the next crossings about after allowing a minute or so for the station stop. This sometimes require a train signal connected to the crossing activation. (I seem to have observed the Sprinter actually has its block signals tied into the crossing gates for leaving a station.

But, how do you allow for an express or a freight movement not stopping at the station? Whatever San Diego Trolley initially tried, I heard they had an issue where a deadheading set in express mode apparently did not activate a crossing and ate a vehicle. I heard they now use some kind of override signal being transmitted by trolleys stopping at the station to delay activation of the leaving crossings, and have observed some loops in PVC in the center of the tract at stations that must be antennas or detector loops.

Gated crossings create the additional issue that traffic has no other option than to wait until the crossing times out or a signal maintainer shows up. Then again, too many people totally ignore crossings regardless of any warning provided.