46.  Network Rail must, on receipt of a request from the undertaker, from time to time provide  the undertaker free of charge with written estimates of the costs, charges, expenses and other  liabilities for which the undertaker is or will become liable under this Part of this Schedule  (including the amount of the relevant costs mentioned in paragraph 45) and with such information  as may reasonably enable the undertaker to assess the reasonableness of any such estimate or  claim made or to be made under this Part of this Schedule (including any claim relating to those  relevant costs).  47.  In the assessment of any sums payable to Network Rail under this Part of this Schedule there  must not be taken into account any increase in the sums claimed that is attributable to any action  taken by or any agreement entered into by Network Rail if that action or agreement was not  reasonably necessary and was taken or entered into with a view to obtaining the payment of those  sums by the undertaker under this Part of this Schedule or increasing the sums so payable.  48.  The undertaker and Network Rail may, subject in the case of Network Rail to compliance  with the terms of its network licence, enter into, and carry into effect, agreements for the transfer  to the undertaker of—  49.  Nothing in this Order, or in any enactment incorporated with or applied by this Order,  prejudices or affects the operation of Part 1 (the provision of railway services) of the Railways Act  1993.  50.  The undertaker must give written notice to Network Rail if any application is proposed to be  made by the undertaker for the Secretary of State’s consent, under article 49 (transfer of benefit of  Order, etc.) of this Order and any such notice must be given no later than 28 days before any such  application is made and must describe or give (as appropriate)—  51.  The undertaker must no later than 28 days from the date that the documents submitted to and  certified by the Secretary of State in accordance with article 60 (certification of documents) are  certified by the Secretary of State, provide a set of those documents to Network Rail in the form of  a computer disc with read only memory.  52.  In relation to any dispute arising under this Part of this Schedule that is referred to arbitration  in accordance with article 62 (arbitration), the process referred to in article 62(2) must be varied  by the arbitrator where Network Rail demonstrates to the arbitrator’s reasonable satisfaction that  Network Rail is unable (acting reasonably) to comply with the process due to timing constraints  that may arise for Network Rail in—  the variation being to the extent reasonably necessary so that Network Rail is able (acting  reasonably) to comply with that process.  (a) obtaining clearance conditions;  (b) obtaining any engineering, regulatory or stakeholder (internal or external) consent; or  (c) assessing any matter of concern with regard to the safe operation of Network Rail’s  railway,  140 (a) the nature of the application to be made;  (b) the extent of the geographical area to which the application relates; and  (c) the name and address of the person acting for the Secretary of State to whom the  application is to be made.  (c) any rights and obligations (whether or not statutory) of Network Rail relating to any  railway property or any lands, works or other property referred to in this paragraph.  (b) any lands, works or other property held in connection with any such railway property; and  (a) any railway property shown on the works plans and the land plans and described in the  book of reference; 