Upon substantial completion of the turnpike extensions and improvements set forth in sections 8911 (relating to improvement and extension authorizations) and 8912 (relating to subsequent extension authorizations), the commission is hereby authorized and empowered to construct, operate and maintain further extensions and improvements of the turnpike at such specific locations and according to such schedules as shall be deemed feasible and which shall be approved by the commission, subject to the waiver of the Federal toll prohibition provisions where applicable, as follows: construct from a point at or near Interstate Route 80 Interchange 23 at Milesburg southwesterly generally along U.S. Route 220 to a connection with the existing U.S. Route 220 Expressway south of Bald Eagle.