Section 249. Investigation by the department of transportation

The
  department of transportation shall upon the receipt of  such  resolution
  or  concurrent  resolution, investigate and determine whether the bridge
  so sought to be abolished is of sufficient  public  importance  to  come
  within  the  provisions  of  this  article, taking into account the use,
  location and value of such toll bridge for the purpose of common traffic
  and travel and shall also investigate as  to  the  value  of  such  toll
  bridge and from the estimate and data transmitted by the board or boards
  of  supervisors,  or  from  such  other information as the department of
  transportation may secure, prepare an estimate of the probable  cost  of
  acquiring  such toll bridge. After such investigation such department of
  transportation  shall  certify  its  approval  or  disapproval  of  such
  resolution. If it shall disapprove such resolution, it shall certify its
  reasons  therefor  to  such  board or boards of supervisors. If it shall
  approve such resolution it shall certify its  approval  thereof  to  the
  attorney  general,  and  shall  transmit to him the estimate made by the
  department of transportation of the probable cost of acquiring such toll
  bridge, together with any data the department of transportation may have
  in its possession in relation to the value thereof.