The provisions of this Part--
(a) do not limit or restrict the operation of the road transport legislation with respect to roads or road related areas within the meaning of section 4(1) of the Road Transport Act 2013 or the Roads Act 1993 with respect to public roads, and
(b) do not authorise the erection of any device if the erection of any such device is inconsistent with a function exercisable under the Road Transport Act 2013 with respect to roads or road related areas within the meaning of section 4(1) of that Act or under the Roads Act 1993 with respect to public roads.