SINGLE CARRIAGEWAY ROADS
S — safety zone width,
E — distance to "end of road works" sign.
D5.4.6 The recommended lead-in taper length is specified in Table 5.3. This should be used wherever possible. Sometimes it may be impracticable to provide the full taper. If this happens on congested roads with speed limits of 30 mph or less, it is permissible to reduce the lead-in taper to an angle of not more than 45° to the kerb, particularly if the parking of cars is usual.
| Single carriageway road: Permanent speed limit | |||||
|---|---|---|---|---|---|
| 30 mph or less | 40 mph | 50 mph | Unrestricted (60mph) | ||
| Minimum and normal maximum. siting distance D of first sign in advance of lead-in taper in metres |
20* — 45 | 45 — 110 | 275 — 450 | 275 — 450 | |
| Minimum longitudinal clearance L in metres1 | 0.5 | 15 | 30 | 60 | |
| Length of taper T in metres2 | |||||
| 1 | 13 | 20 | 25 | 25 | |
| Width of hazard | 2 | 26 | 40 | 50 | 50 |
| (metres) including | 3 | 39 | 60 | 75 | 75 |
| safety zone S | 4 | 52 | 80 | 100 | 100 |
| 5 | 65 | 100 | 125 | 125 | |
| Minimum lateral safety zone clearance | 0.5 | 0.5 | 1.2 | 1.2 | |
| Distance E to end of road works" sign | 10.30 | 10.30 | 30.45 | 30.45 | |
*When "STOP/GO" signs or portable traffic signals are used the normal siting distance (45m) should be used — see notes in Plans SC5 and SC7.
NOTES:
- The minimum longitudinal clearance applies only for traffic approaching on the same side as the works. See Figure 3.1 for details of safety clearances. Where works extend across the road beyond the carriageway centre, or is in the centre of carriageway, the longitudinal clearance applies for traffic approaching in either direction.
- Lead-in tapers used with traffic control ("give and take", priority signs, "STOP/GO” signs, and traffic signal control), and all exit tapers, shall be at about 45° to the kerb line with cones spaced 1.2 m apart. This does not apply when guide islands are provided. In certain circumstances on congested roads with speed limits of 30 mph or less when there is no traffic control, the taper may also be reduced to 45° (see paragraph D5.4.6).
- When a temporary speed limit is imposed on a two-way single carriageway road, to ensure that the speed limit is enforceable, the signs indicating the end of the speed restriction must be located back to back with those in the other direction that indicate the start of speed restriction. See paragraph D3.7.15.
- A minimum of 1.0m clearance, preferably not less than 1.5m, should be maintained for pedestrian movement where signs are placed on the footway. See paragraph D4.4.1.
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