Page:UK Traffic Signs Manual - Chapter 7 -The Design of Traffic Signs 2013.pdf/117



This section covers the design of signs for lane restrictions and lane changes on motorways and all-purpose dual carriageway roads as described in Chapter 8. These signs are shown in diagrams 7201, 7201.1, 7210 to 7240 inclusive and 7260 to 7288 inclusive in Schedule 12 to the Regulations. Other signs in Schedule 12 are detailed in the "P" series of working drawings (see Appendix A).

The complete signs, shown in diagrams 7201, 7201.1 and 7210 to 7240 inclusive, are illustrated in Appendix F. These generally comprise three sign panels, the central panel forming the main sign. The top panels, shown in diagrams 7260 to 7264 inclusive, and the bottom panels, shown in diagrams 7270 to 7275 inclusive, are also illustrated in Appendix F. The combinations of top and bottom panels which may be used with each main sign are shown in the table of combinations accompanying each diagram. Reference should therefore be made to the Regulations when designing any of these signs. Diagram 7201.1 does not have a table of combinations.

The main element of the signs shown in diagrams 7201, 7201.1 and 7210 to 7240 (generally the central panel) can be varied to suit the circumstances. Diagrams 7280 to 7288 inclusive show these variations. Additionally, the number of arrows and the position of the red blocks representing the closed areas of carriageway may be varied. Signs to diagrams 7201 and 7201.1 do not use red blocks.

The sign elements shown in diagrams 7280 to 7286 inclusive may be used with all the main signs. Diagram 7287 (red bar denoting a closed lane ahead) may be used only with diagram 7201, and diagram 7288 (white downward pointing arrow) which indicates a contra-flow system is in operation, may be used only with diagram 7201.1. It should be noted that this arrow in diagram 7288 represents the opposing flow of traffic, and therefore only one arrow should be used, irrespective of the number of opposing lanes. Because the contrast between white and yellow is poor, especially when daylight is fading, it is important to ensure that the black border, which provides the outline to the white arrow, has the correct width (see figure 13-3).

The regulatory signs shown in diagrams 7282 to 7284.1 inclusive show measurements for weight, width and height restrictions (see figure 13-3). There are two sizes; 750mm diameter for imperial-only signs and 900mm for metric/imperial width and height restriction signs (diagrams 7283.1 and 7284.1). The 900mm weight limit sign (diagram 7282) is used only when placed on a sign which incorporates either diagram 7283.1 or 7284.1. All roundels on a particular sign should have the same diameter (e.g. diagrams 7283 and 7284.1 should not be used on the same sign - both restrictions should be either imperial only or metric/imperial). Metric-only roundel signs must not be used.

There is only one prescribed size for each of the various components that make up the complete sign. Therefore, the dimensions are given in millimetres rather than stroke widths. This is particularly useful as the complete signs will generally have different x-heights for particular legends (e.g. the top panel has an x-height of 150mm and the bottom panel has an x-height of 165mm). A stroke width dimension could not, therefore, be easily related to an x-height. For those using computer aided design, where stroke width dimensions would be easier to handle than millimetres, it is suggested that a stroke width of 25mm is assumed (nominal x-height 100mm). All dimensions in the following figures can then be converted to stroke widths by multiplying by a factor of 0.04. Care will need to be taken when applying these stroke width dimensions as the various x-heights will not be equivalent to 4sw. Other elements will also have non-standard sizes (e.g. border width is 2sw and arrow head width is 9.6 sw).

The legend in the top panel is always in black capital letters (Transport Heavy alphabet) on a yellow background. Design details are shown in figure 13-1.

The number of lines of legend in the top panel will depend on the overall width of the sign. Where the top panel is the critical element in determining the width of the sign, the legend should be on two lines if this results in a reduction in the overall size of the sign, or where the width of the sign needs to be kept to a minimum for siting purposes.

The legend in the bottom panel is always in black lower case letters (Transport Heavy alphabet) other than the first character of a worded legend which will be in upper case. The background colour 116