53 Pa. Stat. § 15552
It shall be lawful for, and the right is hereby conferred upon, cities of the first class of this Commonwealth to purchase, lease, locate, construct, and equip, or otherwise acquire, transit facilities, or any one or more of them; and to own, maintain, use, and operate the same within their respective corporate limits, and within the limits of adjacent cities, boroughs, and townships; Provided, Such right shall only be exercised by any of said cities, within the limits of adjacent cities, boroughs, and townships, subject to the consent and approval of the proper authorities of such adjacent cities, boroughs, and townships, lawfully empowered to regulate, or to consent to the construction, maintenance, and operation of, such transit facilities therein: And provided further, That such right shall not be exercised within the limits of any public park or parks, without the consent and approval of the authorities vested with the power to regulate the use of said park or parks.
53 P.S. § 15552