In Sonnenberg v. Erie Metropolitan Transit Authority, 137 Pa. Commw. 533, 586 A.2d 1026 (Pa. Cmwlth. 1991) the plaintiff was leaving a bus operated by the Erie Metropolitan Transit Authority when the doors suddenly closed on her, causing physical injury. The Court held that immunity was waived because the closing of bus doors by the bus driver was an act normally related to the operation of a bus. Sonnenberg, 586 A.2d at 1028.