Section 56. State to maintain roads improved by state appropriations under special laws

When any highway has been constructed or improved under  a  special  law,  with moneys taken from the state treasury and under plans
  prepared by a state department, the commissioner of  transportation  may
  at  any  time  inspect  such  highway  and  if  he determine it to be of
  sufficient importance and properly constructed, he  may  make  an  order
  directing  that  such  highway  become  a  part  of  the system of state
  highways in such county, and thereafter such highway shall be maintained
  as a state highway. Such order shall be served upon the chairman of  the
  board of supervisors, and a certified copy thereof shall be filed in the
  office  of  the  county  clerk  and  one  in  the  office  of  the state
  comptroller.