What do train whistles mean?
* 'o' : denotes a short blast on the horn.
* '--' : denotes a comparatively long blast on the horn.
* '-----' : denotes a longer blast on the horn.
* '----------' : denotes a very long blast on the horn
* Code [ o ] - Before Starting:
o Indication to driver of the assisting engine that driver of leading engine is ready to start.
o Acknowledgement by the driver of the assisting engine.
o Engine ready to leave yard
o Engine ready to go to loco yard
o Light loco or shunter about to move
* Code [ o ] - On the run:
The older steam whistles were almost always actuated with a pull cord (or sometimes a lever) that permitted proportional (tracker) action, so that some form of "expression" could be put into the sound. Many locomotive operators would have their own style of blowing the whistle, and it was often apparent who was operating the locomotive by the sound. Modern locomotives often make use of a pushbutton switch, which takes away the fine control over the way the whistle is sounded.