law: Railways Act, 1989
  3. Zonal Railways. 
  (1) The Central Government may, for the purpose of the efficient
  
  administration of the Government railways, by notification, constitute such
  
  railways into as many Zonal Railways as it may deem fit and specify in such
  
  notification the names and headquarters of such Zonal Railways and the areas in
  
  respect of which they shall exercise jurisdiction.
  (2) The Zonal Railway existing immediately before the
  
  commencement of this Act shall be deemed to be Zonal Railways constituted under
  
  sub-section (1).
  (3) The Central Government may, by notification, declare any
  
  unit of the railways engaged in research, development designing,, construction
  
  or production of rolling stock, its parts or, other equipment used on a
  
  railway, to be a Zonal Railway.
  (4) The Central Government may, by notification, abolish any
  
  Zonal Railway or constitute any new Zonal Railway out of any existing Zonal
  
  Railway or Zonal Railways, change the name or headquarters of any Zonal Railway
  
  or determine the areas in respect of which a Zonal Railway shall exercise
  
  jurisdiction.