53 Pa. Stat. § 1894
In addition to the remedies now vested in the cities and boroughs of this Commonwealth to make repairs to sidewalks, the said cities and boroughs shall have power to make emergency repairs to sidewalks, within corporate limits, where, in the opinion of the officer or head of the department or committee lawfully having charge of sidewalk repairs, a dangerous condition exists that can be repaired by an expenditure of not more than twenty-five dollars: Provided, That, before the said repairs are made, a notice to make the repairs within forty-eight hours shall be served upon the owner of the said property. If the owner cannot be served within the county, notice may be served upon the agent of the owner or the party in possession, if any there be, or, if there be no agent or party in possession, the notice may be served by posting upon the most public part of the said premises.
53 P.S. § 1894