14SPEED LIMITS
GENERAL
14.1 Traffic authorities have a duty under section 85 of the Road Traffic Regulation Act 1984 to erect and maintain prescribed speed limit signs on their roads in accordance with the Secretary of State's directions; i.e. the signs must be prescribed by and provided in accordance with the Traffic Signs Regulations and General Directions 2002 unless they have been specially authorised. Signs that do not strictly follow the Regulations and the Directions (see para 1.4 in respect of Northern Ireland), or have not been specially authorised are not lawfully placed and the speed limit might be unenforceable. To avoid the risk of failed prosecutions, it is of the greatest importance that speed limits be signed lawfully. It is equally important that speed limits be signed clearly and in accordance with this guidance, so that at no time will drivers be in any doubt about the prevailing limit.
14.2 Speed limits are defined in regulation 5 and are referred to in this section as follows:
(i) National speed limit, being 70 mph on motorways and dual carriageway roads and 60 mph on single carriageway roads (see regulation 5(2))
(ii) Maximum speed limit, being an upper limit (see regulation 5(1)). This includes restricted roads (sections 81 and 82 of the Road Traffic Regulation Act 1984), which are those roads with a speed limit of 30 mph by virtue of the presence of a system of street lighting (carriageway lighting in Scotland) where lamps are placed not more than 183 metres apart (185 metres in Scotland)
(iii) Minimum speed limit, being a speed below which vehicles must not be driven (see regulation 5(1)).
Any maximum speed limit below 30 mph (other than a temporary limit made under section 14 of the Road Traffic Regulation Act 1984, or a 20 mph limit or a 20 mph zone) requires the consent of the Secretary of State (paragraphs 13 and 14 of Schedule 9 to the Act as amended by the Road Traffic Regulation Act (Amendment) Order 1999); such limits are unlikely to be agreed. References in this section to street lighting should be taken in Scotland to be references to carriageway lighting.
14.3 The Directions set out the requirements for the placing of signs to indicate speed limits. These are described in detail in the following paragraphs (see para 1.4 in respect of Northern Ireland). In most cases these are minimum requirements; additional signs may be provided where appropriate. This section supersedes Traffic Advisory Leaflet 1/95, which is now withdrawn.
TERMINAL SIGNS INDICATING MAXIMUM AND NATIONAL SPEED LIMITS
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670 Maximum speed limit in miles per hour
The numerals may be varied (see para 14.4)
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671 National speed limits apply
14.4 Terminal signs to diagram 670, provided in accordance with directions 8 and 9, are used to indicate the beginning of maximum speed limits. These signs will indicate a speed of 20 mph (except for a 20 mph zone; see paras 14.30 to 14.32), 30 mph, 40 mph or 50 mph. On dual carriageway roads only, they may indicate a speed of 60 mph. Diagram 670 is not used to indicate the national speed limit; the appropriate sign is that shown in diagram 671. All speed limits, except those for tramcars (see para 14.49) are signed in miles per hour.
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