If a bridge or viaduct is built by a municipality and does not cross any place over which the county may construct a bridge but crosses merely railroad or railroads and private property, the county commissioners of counties of the second class A may contract to pay an amount of money, not exceeding 30% of the entire cost of the proposed bridge or viaduct. The bridge or viaduct shall thereafter be maintained as a municipal structure, and the county may not be liable for any part of the cost of maintenance or repair thereof.
Pennsylvania Legal Code