In the most recent System Bulletin reissue 100 4/1/06, it mention in no case should the horn be blown more than a quater mile from the crossing, about 1300 ft, even if less than 15 seconds from crossing. But I noticed that the whistle post here in western New York are 3800 ft from the crossing, an attached graph states that at speeds of 45mph and above the horn should be sounded at the whistle post. Of note also the FRA notice stated that it is better to err on the side of caution and sound sooner and longer. I suggest for the fans out here to try to judge time and distance yourselves. Pick a spot head of you while driving and try to figure the distance in seconds (15-20).
Harleys and EMDs, some of my favorite rides