36 Pa. Stat. § 3522
Said commission, acting either as a joint or an independent commission, shall have the power and it shall be their duty to have prepared the necessary and proper plans for the construction of said bridge or tunnel, to select the location for the same, to plan and fix the boundaries and approaches thereof, to make all necessary estimates of the probable cost of its construction and of the acquisition of the ground for its site and approaches, to enter into the necessary contracts, to build and equip said bridge or tunnel, and to obtain the necessary consent of the Government of the United States and the approval of the Secretary of War: Provided, however, That no contracts shall be entered into, and no expense whatsoever incurred, by said commission, unless a previous appropriation shall have been made therefor by the General Assembly: And provided further, That all moneys expended, or appropriated to be expended, for the purposes of this act, shall be used and expended under the supervision of said commission: And provided further, That the Commonwealth of Pennsylvania shall not be liable or pay for more than the cost of the construction of said bridge or tunnel to the middle of a navigable stream.
36 P.S. § 3522