When such bridge is proposed to be located or erected in any municipality, the county may agree that such municipality may bear a portion of the cost of the locating, laying out, opening and constructing of such bridge and its approaches and appurtenances, and that the municipality may provide the approach therefor and bear the cost of the maintenance of any approach within the respective municipality, as shall be agreed upon between any such county and such municipality.
16 P.S. § 5777