Tasks of railway
--- construct new line
--- maintain line
--- construction of bridges
--- construction of rob/rub
---...
more... production of coach
--- maintenance of coach in pit line
--- construction of station
--- production of loco
--- construction of loco shed
--- Electrification
--- research for high speed / new coach
--- Distribution system of ticket
--- Recruitemnt of guard / TTE / LP / alp for running train
--- maintenance of railway websites for publishing info
And many other small small things which cannot be written
Hats off to IR