172.—(1) The undertaker must before commencing construction of any specified work supply to Peel proper and sufficient plans of that work for the reasonable approval of Peel and the specified work must not be commenced except in accordance with such plans as have been approved in writing by Peel or settled by arbitration under article 49 (arbitration).
(2) The approval of Peel under sub-paragraph (1) must not be unreasonably withheld or delayed, and if by the end of the period of 28 days beginning with the date on which such plans have been supplied to Peel and Peel has not intimated their disapproval together with the grounds of any such disapproval of those plans, Peel will be deemed to have approved the plans as submitted.