Trains don't have gears like trucks/buses to 'change gears' , so it can't be that. I am assuming you're sitting next to the cab on an A series EMU. It's the ATP confirmation system. It makes a sound at change of throttle, change of speed, signals and interlockings.
Posted: 20 Dec 2013 13:25
Last edited by SantaFe5811 on 20 Dec 2013 13:25; edited 1 time in total