6. —(1) Any specified work and any protective works to be constructed by virtue of paragraph  5(4) must, when commenced, be constructed—  (2) If any damage to railway property or any such interference or obstruction is caused by the  carrying out of, or in consequence of the construction of, a specified work, the Authority must,  regardless of any such approval, make good such damage and must pay to Network Rail all  reasonable expenses to which Network Rail may be put and compensation for any loss which it  may sustain by reason of any such damage, interference or obstruction.  (3) Nothing in this Schedule imposes any liability on the Authority with respect to any damage,  costs, expenses or loss attributable to the negligence of Network Rail or its servants, contractors or  agents or any liability on Network Rail with respect of any damage, costs, expenses or loss  attributable to the negligence of the Authority or its servants, contractors or agents.  8.  Network Rail must at all times afford reasonable facilities to the Authority and its agents for  access to any works carried out by Network Rail under this Schedule during their construction and  must supply the Authority with such information as it may reasonably require with regard to such  works or the method of constructing them.  9. —(1) If any permanent or temporary alterations or additions to railway property are  reasonably necessary in consequence of the construction of a specified work, or during a period of  24 months after the completion of that work in order to ensure the safety of railway property or the  continued safe operation of the railway of Network Rail, such alterations and additions may be  carried out by Network Rail and if Network Rail gives to the Authority reasonable notice of its  intention to carry out such alterations or additions (which must be specified in the notice), the  Authority must pay to Network Rail the reasonable cost of those alterations or additions including,  in respect of any such alterations and additions as are to be permanent, a capitalised sum  representing the increase of the costs which may be expected to be reasonably incurred by  Network Rail in maintaining, working and, when necessary, renewing any such alterations or  additions.  (2) If during the construction of a specified work by the Authority, Network Rail gives notice to  the Authority that Network Rail desires itself to construct that part of the specified work which in  the opinion of the engineer is endangering the stability of railway property or the safe operation of  traffic on the railways of Network Rail then, if the Authority decides that part of the specified  work is to be constructed, Network Rail must assume construction of that part of the specified  work and the Authority must, regardless of any such approval of a specified work under paragraph  5(3), pay to Network Rail all reasonable expenses to which Network Rail may be put and  compensation for any loss which it may suffer by reason of the execution by Network Rail of that  specified work.  (3) The engineer must, in respect of the capitalised sums referred to in this paragraph and  paragraph 10(a), provide such details of the formula by which those sums have been calculated as  the Authority may reasonably require.  (a) without unnecessary delay in accordance with the plans approved or deemed to have been  approved or settled under paragraph 5;  (b) under the supervision (where appropriate and if given) and to the reasonable satisfaction  of the engineer;  (c) in such manner as to cause as little damage as is possible to railway property; and  (d) so far as is reasonably practicable, so as not to interfere with or obstruct the free,  uninterrupted and safe use of any railway of Network Rail or the traffic on it and the use  by passengers of railway property.  7.  The Authority must—  (a) at all times afford reasonable facilities to the engineer for access to a specified work  during its construction; and  (b) supply the engineer with all such information as the engineer may reasonably require with  regard to a specified work or the method of constructing it.  68