Said alteration or improvement shall be constructed and subsequent repairs shall be made under the supervision of the authorities of the city or borough, in compliance with laws governing such construction or improvement by such city or borough, and in further compliance with plans and specifications to be agreed upon in writing between such municipality and board of commissioners of the county and the commissioners or supervisors of the township. The cost of repairs shall be borne one-half by the municipality and one-half by the township, or by the county and township in equal portions or such other proportion as may be agreed upon by the county and township.
16 P.S. § 5930