A Train Horn, which is a powerful air horn, serves as an audible warning device for the railway guards, staff, and passengers.
It not just indicates the arrival or departure of the train, but every horn and its duration has a different meaning behind it.
Here is what some signals mean.
One short horn – signals that the motorman will be taking the train in the yard for a wash-up and cleaning.
Two short horns – he is asking the guard to direct the railway signal to start the train. *
Three smaller horns – means that the motormen have lost control over the motor. This is a signal for the guard to immediately pull the vacuum break.
Continuous horn – is blown to alert the passengers that the train will pass through stations without any halt.