36 Pa. Stat. § 670-523
The department may change the width, lines, or grades of the streets taken over under the provisions of any act of Assembly, or any section thereof, without the consent of the city, evidenced by an ordinance duly passed in accordance with laws applicable thereto. In the event of any change of width, lines or grades, in accordance with the provisions of this section, the Commonwealth shall be responsible for the payment of any damages which may be occasioned thereby, such damages to be ascertained and paid out of moneys in the Motor License Fund. Nothing contained herein shall prevent the county or the city, or both, from contributing to or sharing in the payment of the damages occasioned by any such change of width, lines or grades of a street under the terms of an agreement entered into by the interested parties. For such purposes counties shall have power to expend county moneys or moneys allocated to the county by the Commonwealth for expenditure for highway purposes. All sums, if any, due by such county or city as its share under any such agreement with the Commonwealth shall be paid by such county or city to the Commonwealth and shall be credited to the Motor License Fund.
Whenever it shall appear to the secretary that any part or portion of a State highway route in a city of the second class A, or third class, as now or hereafter defined or described, is dangerous or inconvenient to the traveling public in its present location, either by reason of width, grade, length, curves, or other conditions, or that the expense to the Commonwealth in the construction or maintenance thereof could be materially lessened by a change of location, the secretary may, with the consent of the Governor, change the location of such State highway route, including the terminal points thereof, to pass over existing streets or new streets, laid out and opened by the city, in such manner as, in his discretion, may seem best in order to correct such danger or inconvenience, or lessen the cost to the Commonwealth. A plan showing the new location, approved by the Governor, shall be recorded in the office of the recorder of deeds, in the county in which such city shall be located.
36 P.S. § 670-523