Section 7. The board of aldermen of a city or the selectmen of a town, upon petition executed in accordance with the by-laws or a vote of the directors of a company organized or in process of organization under this chapter, or organized under a special act, for an original location of tracks in such city or town, shall give fourteen days' notice of the time and place for a hearing on such petition by publication thereof in one or more newspapers, if any, published in said city or town; otherwise, in such newspapers published in the county where the city or town is situated as shall be designated by the board of aldermen or the selectmen thereof. They shall also give like notice in writing of the time and place of such hearing to all members of the general court representing the district or districts in which such city or town lies, but the validity of the proceedings shall not be affected by failure to give notice to such members. If, after a hearing, they deem that public necessity and convenience so require, they may grant said location, or any portion thereof, and may prescribe how the tracks shall be laid, and the kind of rails, poles, wires and other appliances which shall be used, and, in addition to the general provisions of law governing such companies, and in respect of matters not treated of in such provisions, impose such other terms, conditions and obligations, incidental to and not inconsistent with the objects of a street railway company, as they deem the public interests may require; but no such location shall be valid, until the department after public notice and a hearing shall certify that such location is consistent with the public interest.
If the department requires an alteration in such location before certifying that the same is consistent with the public interest, it shall notify the board of aldermen or selectmen granting such location of such alteration; and thereafter said board of aldermen or selectmen may amend such location accordingly; provided, that, if such alteration involves a change in the route of the railway, public notice and a hearing shall be given as provided in the case of an original application for a location; and thereafter the department may, as a part of the original proceedings before it, certify that such location so amended is consistent with the public interest. A location so certified to be consistent with public interest, shall be the true location, if, within sixty days after the issue of notice of said certification to the company, it shall file a written acceptance of such location, executed in accordance with its by-laws or a vote of its directors, with the board of aldermen or selectmen. A location granted by a board of aldermen or selectmen, but refused certification hereunder by the department, or not accepted as herein provided, shall be void. Such location shall also be void, if the certificate of incorporation of the street railway company is not issued, and its organization is not completed, within eighteen months after the issue of notice of certification, or if application for said certification is not made to the department within thirty days after the grant of said location by the board of aldermen or selectmen. If in any city or town the original location of a company expires, is revoked, or otherwise becomes void, this section shall apply to a new petition for an original location therein.