principles in this paragraph apply also where the main carriageway of a motorway terminates at a roundabout.
14.29 Where a motorway terminates at a grade separated junction and the main carriageway becomes an all—purpose road, the motorway regulations usually continue through the junction to the point where the entry slip road joins. If the all—purpose road has a lower speed limit than the motorway, this will be signed as described in para 14.28. However, this speed limit might sometimes commence some distance before the slip road joins and the motorway regulations end. A short section of the motorway will then be subject to a speed limit other than the national limit. This must be indicated by terminal and repeater signs. No additional signs are required where the motorway adjoins the all—purpose road; the repeater signs will continue at the appropriate spacing. In the opposite direction, terminal signs to diagram 671 must be provided on the motorway where the national limit commences. A repeater sign indicating the lower limit should be placed at the point where the motorway starts (see para 14.27). The size and spacing of repeater signs are the same on motorways and all—purpose dual carriageway roads subject to the same speed limit (see table 14-4).
20 MPH ZONES
14.30 A 20 mph speed limit is indicated by terminal and repeater signs to diagram 670 in exactly the same manner as any other speed limit (other than a 30 mph limit on a lit road where repeater signs are not permitted) as described in paras 14.4 to 14.24. However, a 20 mph zone, indicated by the sign shown in diagram 674, may be introduced without needing repeater signs (direction 11(3)), but only if it complies with direction 16. This specifies that the sign to diagram 674 may be used only if no part of a road (not being a cul—de—sac less than 80 metres long) within the zone is more than 50 metres (measured along the road) from a traffic calming feature, where a traffic calming feature is defined as:
(a) a road hump constructed pursuant to section 90A of the Highways Act 1980 ("the 1980 Act") or section 36 of the Roads (Scotland) Act 1984 ("the 1984 Act") and in accordance with the Highways (Road Humps) Regulations 1999 or the Road Humps (Scotland) Regulations 1998;
(b) traffic calming works constructed in accordance with section 90G of the 1980 Act or section 39A of the 1984 Act and in accordance with the Highways (Traffic Calming) Regulations 1999 or the Roads (Traffic Calming) (Scotland) Regulations 1994;
(c) a refuge for pedestrians which was constructed pursuant to section 68 of the 1980 Act or section 27(c) of the 1984 Act after 15th June 1999 and is so constructed as to encourage a reduction in the speed of traffic using the carriageway;
(d) a variation of the relative widths of the carriageway or of any footway pursuant to section 75 of the 1980 Act or section 1(1) or 2(1) of the 1984 Act which—
(i) was carried out after 15th June 1999 for the purpose of encouraging a reduction in the speed of traffic using the carriageway; and
(ii) had the effect of reducing the width of the carriageway; or
(e) a horizontal bend in the carriageway through which all vehicular traffic has to change direction by no less than 70 degrees within a distance of 32 metres as measured at the inner kerb radius.
The traffic calming features ensure that the speed limit is self—enforcing and hence repeater signs are not necessary, although direction 11(3) does not prohibit their use. Speed limit zones with such features are generally more effective than 20 mph limits relying on signs alone.
14.31 Signs to diagram 674 must be provided at each entrance to the zone, even where the adjacent speed limit is 20 mph (without traffic calming features). Directions 8(3), 9(2), 9(3) and 9(4) apply to these signs in the same way that they apply to the speed limit signs shown in diagram 670 (see paras 14.5 to 14.14.11). In practice this means that where the zone commences in a side road at a junction, one sign only is required, provided it is located within 20 m of the junction and direction 16 is complied with. However, should a zone commence part of the way along a road, not at a junction, two signs are required, one on each side of the carriageway. This
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