Whenever in the judgment of the board or body having control of the streets of any city of the first or second class, public interest or convenience requires an extension therein of street railway tracks to connect or make a detour of existing tracks, such board or body may:
No one extension constructed pursuant to this section shall exceed one-half mile in length nor shall any authority or requirement to operate the extension be for a longer term than fifty years.
For such extension it shall not be necessary to obtain the consent of any of the owners of the land fronting on the line thereof.
No privilege granted, or requirement made, by or under the authority of this section, shall be valid or effective until approved, after hearing, by order in writing by the board of public utility commissioners.
N.J.S. § 48:15-34