N.J. Stat. § 48:5-23
If two or more bridges shall have been constructed by any such company at different times, the per cent of the total cost to be paid therefor shall be applied to each bridge as of the date the same shall have been opened for public use.
The right to acquire two or more bridges under section 48:5-22 of this title may be exercised if any one of the bridges shall have been in operation for five years. If a second or other bridge shall not have been in operation for five years, then such second or other bridge shall be taken at such total cost thereof, plus fifteen per cent.
If, at the time of the taking of such second or other bridge, it is in process of construction, it shall be acquired at the total cost of the construction up to the time of acquisition, plus fifteen per cent thereof, and upon assumption by the states of all obligations and liabilities incurred in such construction.
N.J.S. § 48:5-23