The answer is connected to a job, job title , profession etc.
The clue is: Doesn't stop trains (9).
I have seen various suggestions including signalman, conductor, stationer but none of them seem 100 per cent. Any ideas out there?
something to do with mules?(Mule trains)
I suggested SIGNALMAN previously but I agree that although there is such a role in the army there is also a signalman on the railways who does stop trains