what is the difference between up and down train?

Answer 1

In the US, on SP's Pacific Lines, all trains headed away from San Francisco, California, were "east bound" and when moving toward the city it was moving "west bound", regardless of compass direction.

On the SSW, a subsidiary of the SP, trains moving toward were "north bound" and away were "south bound".

These designations were essential, so that when issuing clearances and train orders the dispatchers would address the conductor and engineer of the "Extra 4125 West" (as an example) so that there was no confusion about the train's ID or direction of travel. It removed "compass direction" from the equation, reducing misunderstanding, which reduced collisions.

So, I'd say the gentleman above is correct as I have heard this explained the same way as before, except the country where the question was posed concerned railway operations in India.

Answer 2

In the UK at least, the "up" trains always head in the direction of London, or one assumes, the nearest large city. The "down" trains head in the opposite direction.

Answer 3

Down refers to a train travelling away from its headquarters (i.e., the homing railway) or from its Divisional headquarters, whichever is closer. Up refers to a train travelling towards its headquarters or divisional HQ, whichever is closer. Eg, 2903 DN Frontier mail is down travelling away from its HQ (Bombay) and from the division that homes it (Bombay division) and similarly 2904 UP refers to it travelling back towards Bombay, its HQ and division. Usually the numbers for the "up" and "down" trains differ by just 1.

As for the Shatabdis, the odd number indicates the Down run and the even number for the Up run. E.g. New Delhi - Bhopal Shatabdi (the first Shatabdi) is numbered 2001 DN (away form Delhi) and 2002 UP (towards Delhi).