Section 121 - Substitution of motor vehicles or trackless trolleys for cars on tracks; supplemental or extended operation1. Whenever the commissioner shall find, after a hearing, had upon the application of any street railroad company or railroad company, that the public interest will be served by the operation of stages, buses, motor vehicles or vehicles known as trackless trolleys, as such trackless trolleys are defined in the vehicle and traffic law, wholly or partly in place of or supplemental to cars or trains upon tracks, on any portion of the route of such railroad, the commissioner may make an order authorizing such whole or partial substitution or such supplemental operation, and thereupon such company shall have the power and privilege and shall be authorized to operate stages, buses, motor vehicles, or trackless trolleys on such portion of its route and if such operation be by trackless trolleys to install and maintain all necessary additional wires paralleling its existing trolley wires on such portion of its route and such other wires and appurtenances as may be necessary for such operation. Such an application or such an order, however, shall not be made unless the local authorities of each city, village or town in which the portion of the route affected is located shall have consented to such substitution or such supplemental operation, by resolution, a certified copy of which shall be presented with the application, which consent may contain such terms and conditions as such local authorities may deem to the best interest of any such city, town or village, and which terms and conditions so contained in such consent may include limitation, reduction or shortening of the period of any franchise or consent under which such street railroad company or railroad company is operating, and also may include, anything in any charter, general, special or local law to the contrary notwithstanding, changes in and modification of the terms and provisions of any franchise or consent under which such street railroad company or railroad company is operating, and of any obligation of such street railroad company or railroad company to any such city, village or town under any such franchise or consent or under any statute, provided, however, that such changes and modifications shall not extend or lengthen the duration of such franchise or consent. If any such portion of the route within a town shall be wholly within an incorporated village, the consent of the board of trustees shall be sufficient, and the consent of the town board shall not be required. If such consent shall require the abandonment of a route or any portion thereof the application to the commissioner shall comply with the provisions of section one hundred eighty-four of the railroad law, and shall require the separate approval by the commissioner of such abandonment. The commissioner may also make an order authorizing any street railroad company or railroad company to operate stages, buses, motor vehicles or trackless trolleys upon streets, highways and public places not included in but forming a route or routes or portion of a route connecting with any part of the route of such railroad or forming deviations or detours therefrom or in connection therewith, provided such company obtains the consent or consents of the local authorities, which consent may be given in like manner and to the same extent as hereinabove provided in respect of the substitution of stages, buses, motor vehicles or vehicles known as trackless trolleys wholly or partly in place of or supplemental to cars or trains upon tracks.2. Wherever the commissioner has made an order authorizing a substitution as provided in subdivision one, and such substitution is made, the commissioner may on further application by the street railroad company or railroad company, such application to be made in the same manner and subject to the same conditions as provided in subdivision one, revoke such order in whole or in part and make a new order authorizing the operation of stages, buses, motor vehicles or trackless trolleys.