Whenever the center line of any road constitutes a dividing line between a township and a city or borough located in an adjacent county, the board of commissioners of the county and the commissioners or supervisors of such township may enter into a contract with the city or borough providing for the grading, curbing, macadamizing or paving of the roadway of said road. The cost thereof shall be borne one-half by the city or borough and one-half by the township and the county in which such township shall be situated, in equal portions.
16 P.S. § 5929