24.(1) When an order under section 7 has been made in favour of a promoter of an aerial ropeway for public traffic, not being the Government, or a local authority, the Government, or a local authority specified in the order published under section 7, shall, on the expiration of such period, not exceeding fifty years, and of every such subsequent period, not exceeding twenty years, as shall be specified in such order, have the option of purchasing the undertaking, and if the Government, or the local authority with the previous sanction of the Government, elect to purchase, the promoter shall sell the undertaking to the Government or to the local authority as the case may be, on payment of the value of all lands, buildings, works, materials, plant and apparatus of the promoter, suitable to, and used by him for the purposes of, the undertaking, such value to be in case of difference or dispute determined by arbitration: Provided that the value of such lands, buildings, works, materials, plant and apparatus shall be deemed to be their fair market value at the time of purchase, due regard being had to the nature and condition for the time being of such lands, buildings, works, materials, plant and apparatus, and to the state of repair thereof, and to the circumstance that they are in such a position as to be ready for immediate working, and to the suitability of the same for the purposes of the undertaking: Provided also that there shall be added to such value, as aforesaid, such percentage, if any, not exceeding twenty per cent. of that value, as may be specified in the order passed under section 7, on account of compulsory purchase. (2) Where a purchase has been effected under sub-section (1)- (a) the undertaking shall vest in the purchasers free from any debts, mortgages or similar obligations of the promoter or attaching to the undertaking: Provided that any such debts, mortgages or similar obligations shall attach to the purchase money in substitution for the undertaking; and (b) save as aforesaid, the order published under section 7 shall remain in full force, and the purchaser shall be deemed to be the promoter: . Provided that where the Government elects to purchase, the order under section 7 shall, after purchase, in so far as the Government is concerned, cease to have any further operation. (3) Not less than two years' notice in writing of any election to purchase under this section shall be served upon the promoter by the Government or the local authority, as the case may be. (4) Notwithstanding anything hereinbefore contained, a local authority may, with the previous sanction of the Government, waive its option to purchase, and enter into an agreement with the promoter for the working by him of the undertaking until the expiration of the next subsequent period referred to in sub-section (1) upon such terms and conditions as may be stated in the agreement.