Considering that decibels are base 10 logarithmic, 96 to 110 is a very wide range. If Amtrak's were near the top and the freight RR's were near the bottom of the acceptable range the OP's observation could be well correct. I'd say the higher speed of Amtrak trains calls for horns at the upper end of the range. And some folks still ignore them.(a) Each lead locomotive shall be equipped with a locomotive horn that produces a minimum sound level of 96 dB(A) and a maximum sound level of 110 dB(A)
Hey! You'd better get off the tracks, there's a train coming! What? I can't hear you the train horn's making too much noise. hboy: