When a railroad has been laid out, located or constructed so near a highway as, in the opinion of the selectmen of any town, the mayor of any city or the warden of any borough within which such highway is situated, to endanger public travel, such selectmen, mayor or warden may bring a petition to the Commissioner of Transportation, setting forth the facts; and the commissioner, after reasonable notice to the railroad company to appear and be heard in relation thereto, shall, if public safety so requires and a change of the location of such highway is practicable, immediately order such company to make such change, in such manner as the commissioner may determine. The expense of such change, including the cost of fencing such relocated highway, shall, if such railroad has not been constructed at the time of bringing such petition, be paid by the company, but, if the railroad has been constructed at such time, one-half of such expense shall be paid by the company and one-half by such town, city or borough.