The Road Traffic Regulation Act 1988 says
14.
Temporary prohibition or restriction on roads.
� (1) If the traffic authority for a road are satisfied that traffic on the road should be restricted or prohibited�
(a) because works are being or are proposed to be executed on or near the road; or
(b) because of the likelihood of danger to the public, or of serious damage to the road, which is not attributable to such works; or
(c) for the purpose of enabling the duty imposed by section 89(1)(a) or (2) of the Environmental Protection Act 1990 (litter clearing and cleaning) to be discharged,
the authority may by order restrict or prohibit temporarily the use of that road, or of any part of it, by vehicles, or vehicles of any class, or by pedestrians, to such extent and subject to such conditions or exceptions as they may consider necessary.
A notice under section 14 of this Act shall not continue in force�
(a) if issued for the reason mentioned in paragraph (a) or the purpose mentioned in paragraph (c) of subsection (1) of that section, for more than five days from the date of the notice;
(b)if issued for the reason mentioned in paragraph (b) of that subsection, for more than twenty-one days from that date;