# Traffic Signs Manual/Chapter 5/2009/7

SIMPLE JUNCTIONS
7.1 Figure 7-1 illustrates the layout of simple T-junctions. Guidance on the use of Give Way lines(diagram 1003) can be found in paras 3.14 to 3.23, on warning lines (diagrams 1004 / 1004.1) in paras 4.12 to 4.26 and on edge lines (diagrams 1009 and 1010) in paras 4.28 to 4.30. Table 7-1 gives details of the warning line, road studs and the minimum number of marks to be used where practicable. This number may not always be achievable on the minor road if this is narrow.
GHOST ISLAND JUNCTIONS
7.2 Ghost island junctions are usually provided to afford right-turning vehicles some protection and assist free flow of major road through traffic.
7.3 The use of ghost islands on unrestricted rural single carriageway roads can sometimes pose safety problems. Where overtaking opportunities on the major road are limited, the presence of a widened carriageway, albeit with hatched markings, might result in overtaking manoeuvres which conflict with right turns into and out of the minor road. Where this proves to be a problem, consideration should be given to the use of kerbed islands to prevent overtaking and to guide traffic through the junction. Alternatively, double white lines as described in paras #7.11 and #7.12 may be used.
7.4 The through lane in each direction ((c) in figure 7-2) should not be more than 3.65 m wide, exclusive of hard strips, nor less than 3 m. The desirable width of the turning lane (d) is 3.5 m, although this may be reduced to 3 m (but see para #7.5). At urban junctions it can sometimes be advantageous to use a wider turning lane, not exceeding 5 m. This provides some degree of shelter in the centre of the road, helping vehicles turning right from the minor road to make the turn in two separate stages. On rural roads, with speeds above85kph (50 mph), or where hard strips are present, widths greater than 3.65 m are inadvisable because wide ghost islands in these situations create a sense of space which could encourage overtaking at hazardous locations. Where space is very limited, a reduced width may be unavoidable. In such cases the width of ghost islands should not be less than 2.5 m, except as described in para 7.5.7.5 On narrow urban roads it might not be possible to provide full width right-turning lanes. It might still be worth offsetting the main road centre line towards the minor road and using hatched markings to diagram 1040, even if the hatched width is less than 2.5 m. This can create space to help ahead traffic pass right-turning vehicles and make the junction more conspicuous. However, this technique is not appropriate where the speed limit is more than 30 mph, or the carriageway is less than 7.3 m wide. No through lane should be narrower than 3 m.
Table 7-1 Warning lines at major / minor junctions on single carriageway roads :
| Diag No. | Speed limit (mph) | Mark (m) | Gap (m) | Width (mm) | Spacing of studs if used (m) | Minimum number of marks on each approach | Minimum number of marks on each approach | Minimum number of marks on each approach |
| Speed limit(mph) |||
| Diag No. | Speed limit (mph) | Mark (m) | Gap (m) | Width (mm) | Spacing of studs if used (m) | Over 40 | 40 | 30 |
| 1004 | 40 or less | 4 | 2 | 100 (see note) | 6 | – | 7 | 5 |
| 1004.1O | Over 40 | 6 | 3 | 100 (see note) | 9 | 7 | – | – |
NOTE: The width should be increased to 150 mm if the road is 10 m or more in width with no ghost island.
​7.6 Central islands should normally be developed to their maximum width symmetrically about the centreline of the major road using diagram 1040 at the tapers set out in table 7-2.
7.7 The right turn lane is made up of the following elements (see figure 7-2):
(i)turning length (a); this allows long vehicles to position themselves correctly for the right turn. The turning length should be 10m, measured from the centre line of the minor road irrespective of the type of junction, design speed or gradient. Where capacity calculations indicate that for significant periods of time there will be vehicles queuing to turn right from the major road,the turning length should be increased to allow for a reservoir queuing length to accommodate them. Where this is necessary, consideration should be given to providing physical islands to afford greater protection to turning traffic,
(ii)deceleration length (b); this component of the right turn lane depends upon speedand gradient; its length can be found from table 7-2,
(iii)lane widths (c) and (d) (see para 7.4), and
(iv)direct taper length (e); this is the lengthover which the width (d) of a right-turning lane is developed. It should be introduced by means of a direct taper which is part of the deceleration length. Its length depends upon the traffic speed and can be found from table 7-2.
7.8 At left / right staggered junctions (see figure 7-3), the deceleration lengths will overlap, but the width of the ghost island should not be increased to accommodate them. The starting points of the right turn lane should be joined by a straight line to diagram 1004 or 1004.1 over the direct taper length(which will be common to both right turn lanes).
7.9 Where the 85th percentile speed is 40 mph or more, two deflection arrows to diagram 1014 (see figure 13-6) should be used on each approach to a ghost island marking; they may also be used where the speed is lower. A third arrow may be used if visibility is limited or if late overtaking is a problem. The spacing depends on the speed limit in the same manner as for double white lines (see para 5.15). The location of arrows in relation to the start of the taper is equivalent to the distances in table 5-1 indicating the position of arrows relative to the start of a continuous white line. The use of deflection arrows in association with double white lines is shown in figures 5-2 and 5-3.
Table 7-2 Ghost island dimensions :
| 85 percentile speed (mph) | Taper either side of centre line | Deceleration length (b) (m) | Deceleration length (b) (m) | Deceleration length (b) (m) | Deceleration length (b) (m) | Direct taper length (e) (m) |
| 85 percentile speed (mph) | Taper either side of centre line | Up gradient | Up gradient | Down gradient | Down gradient | | Direct taper length (e) (m) |
| 85 percentile speed (mph) | Taper either side of centre line | 0-4% | Over 4% | 0-4% | Over 4% | Direct taper length (e) (m) |
| Up to 30 | 1 in 40 | 25 | 25 | 25 | 5 | 25 |
| 31 to 40 | 1 in 40 | 30 | 30 | 50 | 10 | 25 |
| 41 to 50 | 1 in 45 | 50 | 50 | 75 | 15 | 35 |
| 51 to 60 | 1 in 50 | 75 | 75 | 105 | 25 | 50 |
| 61 to 70 | 1 in 55 | 100 | 100 | 135 | 30 | 70 |
7.10 Lane indication arrows should be used as follows:
(i) bifurcation arrow to diagram 1039 at the start of the direct taper length, except where the right turn lane is less than 2.5 m wide (see paras 7.5, 13.10 to 13.14, 14.7 and figure 13-6),
(ii) lane arrows to diagram 1038 (figure 13-1) should be placed as shown in figures 7-2 and 7-3. Except in the case of a short right turn lane for the left / right stagger, at least two arrows per lane should be provided whenever possible, the last being opposite the minor road entry. A right turn arrow should not be used in the ahead lane, as traffic does not turn from that lane. The 4 m arrow should be used for speed limits up to 40 mph and the 6 m arrow for 50 and 60 mph limits.
7.11 To discourage overtaking on the immediate approach to a right turn lane, double white lines may be provided as shown in figure 7-4 using diagrams 1013.1 and 1013.3, even where the usual visibility requirements are not met (but see para 5.7). The maximum width of the former marking is 1200 mm. The lines must not be splayed over a greater width. Unless the visibility criteria are satisfied, the lines should not be extended beyond the immediate area of the junction. Coloured surfacing may be used under the hatched marking to improve conspicuity and discourage encroachment. The Regulations provide an exemption (regulation 26(6)) permitting vehicles to cross the continuous line to enter any other road or private access joining the road along which the line is placed. A gap in the line is therefore not necessary. However, where there is a dedicated right turn lane this should be marked as shown in figure 7-4. Deflection arrows to diagram 1014 are required at the start of the double white line, but not where the double line recommences on either side of the junction (see para 5.16).
DUAL CARRIAGEWAY JUNCTIONS
7.13 The standard layout for right turns on dual carriageway roads is shown in figure 7-7. The through lanes should maintain their width, and be separated from the right turn lane by a line to diagram 1010, with a width of 100 mm for a speed limit of 40 mph or less, 150 mm for 50 or 60 mph and 200 mm for 70 mph (see table 4-5).
7.14 The lane line through a dual carriageway road junction should be formed of a warning line (to diagram 1004 or 1004.1 as appropriate) in each carriageway as indicated in figure 7-7.
SINGLE LANE DUALLING
7.15 For guidance on determining the appropriate length of right turn lanes see para 7.7. For details of the markings used at grade separated junctions see section 10.
7.16 At single lane dual carriageway junctions (see figure 7-8), the through lane in each direction should be 4.0 m wide, exclusive of hard strips which will normally be 1.0 m wide. Motor vehicles can be discouraged from encroaching onto the hard strips and hatched areas by the use of coloured surfacing as shown in figure 7-8.
7.17 The central reservation opening should be marked to provide a priority arrangement. This should help to reduce uncertainty and discourage parallel queuing of cars in this area.
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This version was transcribed in May 2015, from a 2009 impression.
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