caused by the construction, on operation or maintenance of that part of the authorised  development,  the undertaker must compensate the owners and occupiers of the building or structure for any loss  or damage sustained by them.  (9) Nothing in this article relieves the undertaker from any liability to pay compensation under  section 10(2) (further provision as to compensation for injurious affection) of the 1965 Act.  (10) Any compensation payable under paragraph (7) or (8) must be determined, in case of  dispute, under Part 1 (determination of questions of disputed compensation) of the 1961 Act.  (11) In this article “protective works” in relation to a building means—  21. —(1) The undertaker may fell or lop any tree or shrub within or overhanging land within the  Order limits, or cut back its roots, if it reasonably believes it to be necessary to do so to prevent  the tree or shrub—  (2) In carrying out any activity authorised by paragraph (1) the undertaker must do no  unnecessary damage to any tree or shrub and must pay compensation to any person for any loss or  damage arising from such activity.  (3) Any dispute as to a person’s entitlement to compensation under paragraph (2), or as to the  amount of compensation, is to be determined under Part 1 (determination of questions of disputed  compensation) of the 1961 Act.  22. —(1) The undertaker may acquire compulsorily so much of the Order land as is required for  the authorised development or to facilitate it, or as is incidental to it.  (2) This article is subject to article 24, article 25 (acquisition of subsoil only) and article 33.  23. —(1) After the end of the period of five years beginning on the day on which this Order  comes into force—  17 (a) no notice to treat may be served under Part 1 (compulsory purchase under Acquisition of  Land Act of 1946) of the 1965 Act; and  (a) underpinning, strengthening and any other works the purpose of which is to prevent  damage which may be caused to the building or structure by the construction, operation  or maintenance of the authorised development; and  (b) any works the purpose of which is to remedy any damage which has been caused to the  building by the construction, operation or maintenance of the authorised development.  (a) from obstructing or interfering with the construction, maintenance or operation of the  authorised development or any apparatus used in connection with the authorised  development; or  (b) from constituting a danger to persons using the authorised development; or  (c) from obstructing or interfering with the passage of construction vehicles to the extent  necessary for the purposes of construction of the authorised development.  Time limit for exercise of authority to acquire land compulsorily  Compulsory acquisition of land  PART 3  POWERS OF ACQUISITION AND POSSESSION OF LAND  Powers of acquisition  Felling or lopping of trees 