Section 489-F. Relationships among elements used in computation of railroad ceiling

In order to effectuate the legislative policy that the amount
  of exemptions from real property taxation granted to railroads should be
  related to their individual rates of earnings, and in order to provide a
  uniform and equitable method for implementing  this  policy,  the  state
  board   shall   establish   and   maintain  relationships  among  system
  reproduction cost, railway earnings, local  reproduction  cost  and  the
  state equalization rates, so that:
    (1)    System reproduction cost, local reproduction cost and the state
  equalization rates shall be based so far as may be practicable upon  the
  same period price levels;
    (2)    System  reproduction  cost  shall  include  so  far  as  may be
  practicable the property constituting the railroad system from which the
  railway earnings were derived  for  the  latest  year  included  in  the
  average railway earnings; and
    (3)    The  aggregate  of the local reproduction cost of each railroad
  company shall approximate the amount included in the system reproduction
  cost of such railroad company on account of  the  property  included  in
  such local reproduction costs so far as may be practicable.