Its a safety rule! On my copy of G.C.O.R. Rule 5.8
5.8.1 Ringing Engine Bell
Ring the engine bell under any of the following conditions
. Before moving,except when making momentary stop and start switching mvmnts.
. As a warning signal anytime it is necessary.
. When approaching men or equipment on or near the track
. When whistle signal (7) is required(that is the long,long,short loooooong signal)
. Approaching public crossings at grade with the engine in front and sounding the
whistle is prohibited, start the signal at the crossing sign. If no sign,or if
movement begins between sign and crossing,start signal soon enough before
crossing to provide warning. Continue ringing bell until the crossing is occupied.
On the BNSF the following timetable instruction for the Chicago Subdivision of the Chicago Division applies as well (this covers the "Aurora Racetrack")
5.8.1 - The engine bell must be rung when approaching and passing through all station
platforms,pedestrian and street crossing on all tracks.
