BASIC PRINCIPLES OF COLOUR CODING
3.5 Colour coding is one of the most important aspects of directional sign design. Since 1964 blue backgrounds have been used on motorway signs, green backgrounds on primary routes and white backgrounds on other roads (non-primary routes). The Traffic Signs Regulations and General Directions 1994 extended this colour coding to panels and patches which indicate the status of routes reached directly or indirectly from a junction ahead.
3.6 The layout in figure 3-7 shows a typical highway network comprising primary and non-primary routes. The signing of the network using the colour coding rules is illustrated by the five advance direction signs (labelled A to E inclusive).
3.7 Sign A is placed on the primary route and therefore has a green background with a white border. Although Longchurch is reached by travelling along a non-primary route (B1144), it is shown directly on the green background of sign A. This is because at this location the route to Longchurch continues along the primary route. Note that the route number (B1144) is not shown on a white patch. Route number patches are used only to indicate routes of a higher status (i.e. blue motorway patches on white and green background signs, and green patches on white background signs). As the A123 is a non-primary route, the place names and route numbers are shown on white panels. Had the B1255 been a primary route then the bracketed route number would be on a green patch on the white panel. It should be noted that the white panel indicates the status of the route and not that of the destination. Dorfield, for example, could be a primary destination.
3.8 Sign B shows the same junction as viewed from the non-primary route. The green panel indicating the primary route to Lampton also includes Longchurch. The same principle applies as for sign A. It is not appropriate to place Longchurch (B1144) on the main white background of the sign outside the green panel. There is no significance in the fact that a stack type sign is illustrated here, whereas sign A on the primary route is a map type sign. The type of sign used will be the most suitable for the approach to the junction. Note that all white background directional signs (other than MoD signs) have black borders. The use of blue borders on local signs was discontinued in 1994. Existing blue-bordered signs must be removed by 31st December 2014.
3.9 Sign C shows the sign at the previous junction on the A123. As this is a junction between two non-primary routes the use of green panels is not appropriate. However the sign does indicate that the primary route A11 can be reached at a junction further ahead and therefore the route number is shown on a green patch. This is similar to the current practice of signing routes to motorways by using blue motorway number patches. Had the A123 been a primary route from its junction with the A11 to Hopford then the route number A123 (unbracketed) would also be shown on a green patch. Longchurch is not indicated at this junction, but if it were the route number would not be on a green patch since the B1144 is not a primary route (see Dorfield on sign E). Green patches are used only to indicate those routes that have primary status. Although the B1144 is reached by travelling along the primary route (A11), it is itself a non-primary route and therefore a green patch is not appropriate.
3.10 Sign D shows that some situations can arise where all destinations are shown on panels. In the same way that Longchurch is shown on a green panel on sign B, Dorfield is also shown on a green panel although the A123 is a non-primary route. A green panel shows all destinations that can be reached by turning directly onto a primary route. As explained in para 3.7, white patches are not used and therefore it is not appropriate to use white patches on green panels.
3.11 Sign E indicating a junction between two non-primary routes demonstrates that other non-primary routes ahead (in this case A123) do not have their route numbers on green patches even though they are reached by travelling along a length of primary route. Sign E also demonstrates the use of a route number (B1144) not directly associated with a place name.
3.12 The background colour of direction signs (e.g. flag type signs) at a junction will be appropriate to the route indicated. Green or white panels are not used except where two directions are indicated on rectangular signs at junctions (see diagram 2127). Route number patches are used in the same manner as on advance direction signs. Where a rectangular direction sign, showing a route number only, is used to indicate an exit slip road leading directly to a non-primary route from a primary route, the background colour should be white, not green with a white route number panel or patch.
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