I would suggest that the current crossing safety measures are very adequate WITHOUT the train horns.  The issue is not that individuals don't know a train is coming.  The barriers are "down", the lights are flashing, the bells are ringing.  Persons who are struck by trains at such crossing knowingly disregard the existing warnings and barriers.  They're in a hurry and don't want to wait for "that damn train", so they drive around the barrier, ride their bike around it, or walk around it......after all they will "beat" the train to the crossing.  Breaking news: at such crossings the "tie" always goes to the train.

Those loud, obnoxious horns are appropriate and needed at rural crosssing where there are no barriers and,often, are no signals.  Having trains sound those horns at each crossing in a city is unnecessary.  Requiring millions of dollars to "up-grade" the crossings is unnecessary.  What's necessary?.......that people quit being so "stupid" in decisions to ignore the warnings...