(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.  ( a ) Section 272 was amended by paragraph 103(1) and (2) of Schedule 17 to the Communications Act 2003 (c. 21).  135 (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 undertaker  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 undertaker 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 undertaker 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 undertaker.  (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 undertaker may serve upon the engineer written notice requiring the  engineer to intimate his approval or disapproval within a further period of 28 days beginning with  the date upon which the engineer receives written notice from the undertaker. 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.  (4) The undertaker must not under the powers of 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 under this paragraph, such consent must not  be unreasonably withheld but may be given subject to reasonable conditions.  35. —(1) The undertaker 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.  (3) The undertaker must not exercise the powers conferred by sections 271 (extinguishment of  rights of statutory undertakers: preliminary notices) or 272( a ) (extinguishment of rights of  electronic communications code operators: preliminary notices) of the 1990 Act or article 35  (statutory undertakers and utilities) 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.  (2) The undertaker must not in the 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.  34. —(1) The undertaker must not exercise the powers conferred by articles 4 (development  consent etc granted by the Order), 10 (permanent stopping up of private means of access), 11  (temporary stopping up and restriction of use of streets), 12 (access to works) 14 (use of private  roads for construction), 15 (discharge of water), 16 (protective works to buildings), 17 (authority  to survey and investigate land) 18 (felling or lopping of trees), 19 (trees subject to tree  preservation orders), 22 (compulsory acquisition of land), 26 (compulsory acquisition of rights,  etc), 27 (acquisition of subsoil and airspace only), 28 (private rights over land), 29 (power to  override easements and other rights), 30 (rights over or under streets), 33 (temporary use of land  for carrying out the authorised development), 34 (temporary use of land for maintaining the  authorised development), 35 (statutory undertakers and utilities), 36 (apparatus and rights of  statutory undertakers and utilities in stopped up streets), 43 (maintenance of authorised  development) and 44 (subsidiary works and operations in Lake Lothing) or the powers conferred  by section 11(3) (powers of entry) of the 1965 Act or the 1981 Act as applied or modified by this  Order in respect of any railway property unless the exercise of such powers is with the consent of  Network Rail. 