but for the purposes of such a defence it is not relevant that the Authority had arranged for a  competent person to carry out or supervise the maintenance of that part of the highway to which  the action relates unless it is also proved that the Authority had given the competent person proper  instructions with regard to the maintenance of the highway and that the competent person had  carried out those instructions.  17.  If the Authority abandons the construction of, or permanently ceases to operate any of, the  authorised street tramway (“the discontinued tramway”), it must as soon as reasonably practicable  and unless otherwise agreed with the street authority—  18. —(1) A street authority and the Authority may enter into agreements with respect to—  19. —(1) The Authority may construct and maintain the authorised tramway so as to enable  tramcars upon it to cross on the level any highway or other road for the time being crossing the  route of the system.  15 Level crossings  Agreements with street authorities  Restoration of streets if street tramway discontinued  (b) the standard of maintenance appropriate for a highway of that character and used by such  traffic;  (c) the state of repair in which a reasonable person would have expected to find the highway;  (d) whether the Authority knew, or could reasonably have been expected to know, that the  condition of the part of the highway to which the action relates was likely to cause danger  to users of the highway; and  (e) where the Authority could not reasonably have been expected to repair that part of the  highway before the cause of action arose, what warning notices of its condition had been  displayed,  (a) remove from any street in which the discontinued tramway is laid the rails and any other  works, equipment and apparatus which have become redundant; and  (b) restore, to the reasonable satisfaction of the street authority, the portion of the street along  which the discontinued tramway was laid, or redundant works, equipment and apparatus  were laid, regard being had to—  (i) the condition of the street before the tramway was laid; and  (ii) the nature of the traffic using the street at the time of the discontinuance.  (a) the construction of any new street under the powers conferred by this Order;  (b) the strengthening, improvement, repair or reconstruction of any street under the powers  conferred by this Order;  (c) the maintenance of any street along or across which the authorised tramway is laid, or of  the structure of any bridge or tunnel carrying a street over or under the authorised  tramway;  (d) any stopping up, alteration or diversion of a street under the powers conferred by this  Order; or  (e) the execution in the street of any of the works referred to in article 12 (power to execute  street works).  (2) Such an agreement may, without limitation on the scope of paragraph (1)—  (a) provide for the street authority to carry out any function under this Order which relates to  the street in question; and  (b) contain such terms as to payment and otherwise as the parties consider appropriate. 