N.J. Stat. § 40:67-33
The governing body of such municipality with the mayor or other chief executive officer may enter into contract with the owner or owners of lands fronting on all or any part of said proposed tunnel or tunnels or approaches, or with any person or persons who may prefer a tunnel to other means of connection as aforesaid, whereby such owner or persons may themselves build or erect said tunnel or tunnels and approaches, or whereby they may contribute towards the building of the same such sums of money as in the judgment of the governing body and the mayor or other chief executive officer may be just and fair, in consideration of the authorities vacating the whole or any portion of such street or streets over and above and on each side of the proposed tunnel or tunnels or approaches, which vacation the authorities are hereby empowered and authorized to make in consideration thereof, any law, usage or charter to the contrary notwithstanding, but no contract or act of vacation under this article shall impair the public right in any such street or part of street until the tunnel is completed.
N.J.S. § 40:67-33