14. Nothing in regulation 3, 4, 5, 7, 8, 9 or 10 shall prohibit a person from using a motorway in contravention of those regulations where—
(a)he does so in accordance with any direction or permission given by a traffic sign;
(b)he does so in accordance with the permission of a constable and for the purpose of investigating any accident which has occurred on or near the motorway;
(c)it is necessary for him to do so to avoid or prevent an accident or to obtain or give help required as the result of an accident or emergency, and he does so in such manner as to cause as little danger or inconvenience as possible to other traffic on the motorway;
(d)he does so in the exercise of his duty as a constable or as a member of a fire brigade or ambulance service;
(e)it is necessary for him to do so to carry out in an efficient manner—
(i)the maintenance, repair, cleaning, clearance, alteration or improvement of the motorway; or
(ii)the removal of a vehicle from the motorway; or
(iii)the erection, laying, placing, maintenance, testing, alteration, repair or removal of any structure, works or apparatus in, on, under or over the motorway; or
(f)it is necessary for him to do so in connection with an inspection, survey, investigation or census which is carried out in accordance with a general or special authority granted by the Department.