16 Pa. Stat. § 5755
When the county commissioners find that a bridge is necessary and that the erection of such bridge will require more expense than it is reasonable that the one or more adjoining townships, boroughs or cities of the third class should bear, and the county commissioners do not deem it advisable to enter such bridge on record as a county bridge but shall consider it proper to assist such township or townships or such city of the third class or such borough in building the same, they may either build such bridge or any portion or portions thereof or furnish such township or townships or city of the third class or borough the whole or part of the money necessary to build it, without entering such bridge on record as a county bridge.
16 P.S. § 5755