21. Application of Public Works Act 1981---Notwithstanding section 30
 of the New Zealand Railways Corporation Act 1981, nothing in sections 40
 to 42 of the Public Works Act 1981 applies to---
   (a) Land that is held or occupied by the Crown for railway purposes:
   (b) Land that is held by the Corporation, or by a transferee company,
         or by a railway operator.