When to sound the horn when approaching a grade crossing. All times are relative to passing the 'W' sign.

Train speed	Delay to sound whistle
Source: "jg greenwood" from http://www.railroad.net/forums/viewtopic.php?p=138265#138265
40 MPH	3 seconds
35 MPH	6 seconds
30 MPH	10 seconds
25 MPH	16 seconds
20 MPH	25 seconds
15 MPH	40 seconds
10 MPH	1 minute, 10 seconds (70 seconds)
5 MPH	2 minutes, 40 seconds (160 seconds)