N.J. Stat. § 27:19-12
When two or more counties contemplate the joint acquisition by gift, purchase or condemnation, or the building and construction of any viaduct or bridge over any ravine, marsh, river or stream forming in whole or in part the boundary between them, a proposed agreement shall be prepared setting forth the viaduct or bridge to be acquired, or the work to be undertaken, the plans and specifications therefor, the estimated cost thereof, and the estimated cost of maintenance and operation after acquisition or completion, the proportion of the original cost and the cost of maintenance and operation thereof to be borne by each county, and any other provision deemed necessary to be inserted therein.
If for any reason no proposed agreement shall have been prepared, and no agreement shall have been entered into between them, all costs and charges for acquisition, construction, maintenance, repair, rebuilding and operation shall be borne equally by each county.
N.J.S. § 27:19-12