4.—(1) The provisions of article 3 above shall apply only during such times and to such extent as may from time to time be indicated by traffic signs.
(2) The provisions specified in article 3 above shall not apply in respect of —
(i)any vehicle being used for the purpose of those works, or for fire brigade, ambulance or police purpose, or
(ii)anything done with the permission or at the direction of a police constable in uniform or a traffic warden.