The whistle should be blown with duration and intensity commensurate with the circumstances presented
on wide open level crossings the driver will short blow the whistle at the whistle board (a White X ) some 100 meters before the crossing and another short blow just prior to passing over the crossing.
If he notices a moving vehicle approaching, he will extend the length of whistle and keep blowing till he is happy the vehicle has noticed the train, or has stopped.
If the crossing does not allow the train crw to observe the approach of vehicles he will blow long and hard till he enters the crossing.
At all other times the whistle will be sounded if the crew think animals, workers or trespassers are in danger of being struck by the train.
Whistle codes (modern Australian)
http://www.artc.com.au/library/ANTR 408 Using train whistles I 1 Rev 2.pdf?300610
Emergency whistles are short sharp repeated whistles continued till the emergency has been passed,or other trains have come to a stand. In addition the locomotive headlight will be rapidly flashed, day or night.
Train is about to move short sharp whistle
Pass train departing Moderate long whistle.
Signalman or other authorised person signals the driver by hand short sharp whistle
Train is setting back three short sharp whistles
Call up the guard 4 short sharp whistles This might be used to call the guard back to the train if he was sent back to protect the train by applying detonators to the track.
A long whistle when stopped by a signal that is locally controlled.
That's about all I remember
Cheers
Rod

on wide open level crossings the driver will short blow the whistle at the whistle board (a White X ) some 100 meters before the crossing and another short blow just prior to passing over the crossing.
If he notices a moving vehicle approaching, he will extend the length of whistle and keep blowing till he is happy the vehicle has noticed the train, or has stopped.
If the crossing does not allow the train crw to observe the approach of vehicles he will blow long and hard till he enters the crossing.
At all other times the whistle will be sounded if the crew think animals, workers or trespassers are in danger of being struck by the train.
Whistle codes (modern Australian)
http://www.artc.com.au/library/ANTR 408 Using train whistles I 1 Rev 2.pdf?300610
Emergency whistles are short sharp repeated whistles continued till the emergency has been passed,or other trains have come to a stand. In addition the locomotive headlight will be rapidly flashed, day or night.
Train is about to move short sharp whistle
Pass train departing Moderate long whistle.
Signalman or other authorised person signals the driver by hand short sharp whistle
Train is setting back three short sharp whistles
Call up the guard 4 short sharp whistles This might be used to call the guard back to the train if he was sent back to protect the train by applying detonators to the track.
A long whistle when stopped by a signal that is locally controlled.
That's about all I remember

Cheers
Rod