Section 15
SEC. 15. At any time after twenty years from the date of this Act the Government of the Philippine Islands, or b any political subdivision thereof to which the right may be assigned, may purchase, and the grantee shall sell thereto, all of its plant, poles, wires, buildings, real estate, and all other property used in the enjoyment of this franchise at a valuation based in part upon the net operating income of the grantee, proper allowance being made for depreciation, in part upon the cost of reproduction new of said property less depreciation, and in part upon the original cost of said property less depreciation, said valuation to be determined after hearing evidence by the Board of Public Utility Commissioners or its successors, sitting as a board of arbitrators, whose decision by a majority of the members thereof shall be final.