4. —(1) The Authority must not exercise the powers conferred by article 23 (power to survey and  investigate land, etc.) and article 28 (power to acquire land) in respect of any railway property  unless the exercise of such powers is with the consent of Network Rail.  (2) The Authority must not in exercise of the powers conferred by this Order prevent pedestrian  or vehicular access to any railway property, unless preventing such access is with the consent of  Network Rail.  (3) The Authority must not exercise the powers conferred by sections 271 (extinguishment of  rights of statutory undertakers: preliminary notices) or 272 (extinguishment of rights of electronic  code communications operators: preliminary notices)( a ) of the 1990 Act as applied by Schedule 9  (provisions relating to statutory undertakers) in relation to any right of access of Network Rail to  railway property, but such right of access may be diverted with the consent of Network Rail.  (4) The Authority must not under the powers conferred by this Order acquire or use, or acquire  new rights over, any railway property except with the consent of Network Rail.  (5) Where Network Rail is asked to give its consent pursuant to this paragraph, such consent  must not be unreasonably withheld but may be given subject to reasonable conditions.  5. —(1) The Authority must before commencing construction of any specified work supply to  Network Rail proper and sufficient plans of that work for the reasonable approval of the engineer  and the specified work must not be commenced except in accordance with such plans as have been  approved in writing by the engineer or settled by arbitration.  (2) The approval of the engineer under sub-paragraph (1) must not be unreasonably withheld,  and if by the end of the period of 28 days beginning with the date on which such plans have been  supplied to Network Rail the engineer has not intimated disapproval of those plans and the  grounds of disapproval the Authority may serve upon the engineer written notice requiring the  engineer to intimate approval or disapproval within a further period of 28 days beginning with the  date upon which the engineer receives written notice from the Authority. If by the expiry of the  further 28 days the engineer has not intimated approval or disapproval, the engineer is to be  deemed to have approved the plans as submitted.  (3) If by the end of the period of 28 days beginning with the date on which written notice was  served upon the engineer under sub-paragraph (2), Network Rail gives notice to the Authority that  Network Rail desires itself to construct any part of a specified work which in the opinion of the  engineer will or may affect the stability of railway property or the safe operation of traffic on the  railways of Network Rail then, if the Authority desires such part of the specified work to be  constructed, Network Rail must construct it without unnecessary delay on behalf of and to the  reasonable satisfaction of the Authority in accordance with the plans approved or deemed to be  approved or settled under this paragraph, and under the supervision (where appropriate and if  given) of the Authority for an agreed cost.  (4) When signifying approval of the plans the engineer may specify any protective works  (whether temporary or permanent) which in the engineer’s opinion should be carried out before  the commencement of the construction of a specified work to ensure the safety or stability of  railway property or the continuation of safe and efficient operation of the railways of Network  Rail or the services of operators using the same (including any relocation, de-commissioning and  removal of works, apparatus and equipment necessitated by a specified work and the comfort and  safety of passengers who may be affected by the specified works), and such protective works as  may be reasonably necessary for those purposes must be constructed by Network Rail or by the  Authority, if Network Rail so desires, and such protective works are to be carried out at the  expense of the Authority in either case without unnecessary delay and the Authority must not  commence the construction of the specified works until the engineer has notified the Authority  that the protective works have been completed to the engineer’s reasonable satisfaction.  ( a ) Section 272 was amended by paragraph 103 of Schedule 17 to the Communications Act 2003 (c. 21).  67 (b) use its reasonable endeavours to avoid any conflict arising between the application of  those procedures and the proper implementation of the authorised development under this  Order. 