§ 120. Power of commissioner to order repairs or changes. If in the judgment of the commissioner, additional tracks, switches, terminals or terminal facilities, stations, motive power, or any other property, construction, apparatus, equipment, facilities or device for use by any common carrier in or in connection with the transportation of passengers or property ought reasonably to be provided or any repairs or improvements to or changes in any thereof in use ought reasonably to be made, or any additions to changes in construction should reasonably be made thereto in order to promote the security or convenience of the public or employees, or in order to secure adequate service or facilities for the transportation of passengers or property, or to overcome or to minimize except by change of motive power nuisances of smoke, soot, or cinders, arising from the operation outside the corporate limits of a city of such common carrier, such changes or additions in equipment not to be in conflict with any federal statute or regulation, the commissioner shall, after a hearing either on his own motion or after complaint, make and serve an order directing such repairs, improvements, changes or additions to be made within a reasonable time and in a manner to be specified therein, and every common carrier shall make all repairs, improvements, changes and additions required of it by any order of the commissioner served upon it. If any repairs, improvements, changes or additions which the commissioner has determined to order require joint action by two or more of said carriers, the commissioner shall, before entry and service of order, notify the said carriers that such repairs, improvements, changes or additions will be required and that the same shall be made at their joint cost, and thereupon the said carriers shall have thirty days or such longer time as the commissioner may grant within which to agree upon the part or division of cost of such repairs, improvements, changes or additions which each shall bear. If at the expiration of such time such carriers shall fail to file with the commissioner a statement that an agreement has been made for a division or apportionment of such repairs, improvements, changes or additions the commissioner shall have authority, after further hearing, to fix in his order the proportion of such cost or expense to be borne by each such company and the manner in which the same shall be paid and secured. But this section shall not be construed to authorize the commissioner to require two or more railroad companies to unite in the erection of a union station.