10.4 The edge line should be continued along the slip road. Where raised rib markings are used, the rib spacing should be reduced to 250 mm on motorway slip roads. Red reflecting road studs should be used on the near side and amber on the off side, both at 18 m centres except as detailed in para 10.5.
10.5 The main carriageway edge line should change to diagram 1010, with green reflecting road studs at 8 m centres, across the slip road over which traffic joins or leaves. Along the same length, the spacing of the red studs associated with the edge line to diagram 1012.1, 1012.2 or 1012.3 at the near side of the slip road is reduced from 18 m to 9 m. The bifurcation arrow to diagram 1039 should be used as shown in figure 13-8 at the lengths specified in para 13.12.
10.6 Conventional lane lines to diagram 1005 or 1005.1 (see table 10-4) on the main carriageway should be continued through the junction.
10.7 An entry layout for two-lane slip roads is shown in figure 10-2, allowing each lane of the slip road to join separately. The ghost island between the joining lanes should be to diagram 1042, bordered by red studs. This layout is suitable where the main line flow is light, the main carriageway is three or more lanes wide and the merging flow exceeds the capacity of a single lane.
LANE GAINS
10.8 The principal dimensions for lane-gain layouts are given in table 10-1. There are two basic situations; the number of lanes gained will either be the same as, or less than, the number of lanes on the entry slip road.
10.9 Where the number of lanes gained equals the number of lanes on the entry slip road, the markings in figure 10-3 should be used. All lane markings to diagram 1005.1 on both the main carriageway and the slip road should change to 1004.1 as indicated (or from 1005 to 1004 on roads where the speed limit is not more than 40 mph; see table 10-4). If only one lane is gained, the ghost island is not used.
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