| WHITE - | to indicate a traffic lane or centre of carriageway marking. |
| RED - | to indicate a line of studs which should not be crossed. It is used mainly to delineate the left hand edge of the running carriageway; studs are omitted at positions where traffic is permitted to cross, e.g. at lay-bys (where green studs are normally substituted). Where studs are used with chevron markings to diagram 1041, 1041.1, 1042 or 1042.1 they must be coloured red on both sides of the marking. |
| AMBER - | to indicate a line of studs which should not be crossed. It is used to indicate the right hand edge of the running carriageway adjacent to the edge of the central reservation or to traffic cones or cylinders at road works, or the marking to diagram 1040.3. Amber studs are also used on the off side of a one-way road (including one-way slip roads and link roads). |
| GREEN - | to indicate a length of the edge of the carriageway which may be crossed. Green studs are used with markings to diagram 1010 (see paras 4.29 and 4.30) at lay-bys and to mark the boundary of acceleration and deceleration lanes on the left hand side of the carriageway. They must not be used in conjunction with Stop or Give Way transverse markings, or with diagram 1009. At lane-drop junctions, and right turnlanes, (see figure 7-7) green studs are used with the marking to diagram 1010 which demarcates the exit lane. |
6.10 On dual carriageway roads, amber studs placed adjacent to the central reservation may have red reflectors on the reverse for use when contra-flow working is needed for road maintenance purposes.
6.11 The colour of the road stud body may be:
(i) white,
(ii) the same as the reflectors or retroreflecting material,
(iii) a natural metallic finish, or
(iv) any other neutral colour (including black).
In the case of studs placed temporarily at road works, the stud body must be fluorescent green / yellow. The use of temporary studs is described in Chapter 8.
STUD SPACING
6.12 The spacing of road studs used with double white lines is dealt with in para #5.115.11. The spacing of studs used with centre lines and lane lines is described in tables 4-1, 4-2 and 4-3, and studs used in conjunction with continuous edge lines or with diagram 1010 in table 4-5 and para 10.11.
6.13 On dual carriageway roads where red, white and amber studs are used, these are normally spaced at 18 m intervals. There may be some minor advantage in offsetting the white lane line studs 9 m longitudinally relative to the red and amber studs. Where red studs are used adjacent to chevron markings, the spacing should be closed up to 3 m centres.
6.14 The standard 18 m spacing should be reduced to 9 m on bends with a radius of curvature less than 450 m, or on roads particularly prone to fog and mist or where there is a severe dazzle problem caused by glare from the headlamps of oncoming vehicles.
ROAD STUDS AT CROSSINGS
6.15 Road studs to diagram 1055.1 or 1055.2 used to mark a crossing place must be coloured white, silver or light grey (regulation 11(4)). They may not be fitted with reflective lenses or with a steady or intermittent light source, but may be formed from retroreflecting material. Although the Regulations permit the use of stainless steel, aluminium, thermoplastic or paint products, some types of metal studs can be slippery when wet, and the potential risk to two-wheeled traffic should be borne in mind. Similar considerations apply to the studs used at other types of pedestrian crossing.
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