Design Frequently asked questions
As more design rules and regulations are implemented by the Department for Transport, the job of sign design becomes more and more complicated.
Our NEW sign design feature shows traffic signs with common mistakes explained and corrected.
We have compiled a list of common questions and issues raised by our customers:
- WBM - What does this mean?
- What is widespan channel?
- What is the average lane width on UK motorways?
- What happened to 3M VIP and LDP?
- Grey or yellow: what colour backing board should i use on my sign?
- How big should the backing board be on chevrons (515)?
- Where does the 'Parking' symbol go on my sign?
- Where does the 'Aircraft' symbol go on my sign?
- What does the 'Motorway' symbol mean, and where should it be used?
- Why is there a 2s/w gap between 2-line destinations?
- Why do some local directional signs have blue borders?
- What is the difference between 'x-height' and 'CAPITAL height'?
- When and where are capital letters used on a sign?
- What is the difference between BLOCK spacing and LINE spacing?
- How far from the carriageway should the sign be located?
- What makes steel posts passively safe?
- WBM - What does this mean?
WBM is an abbreviation of "Worboys series B - Metric". In 1964 the Worboys report completely changed how the UK signed its road network. New fonts were introduced (transport medium & transport heavy), symbols were introduced and the familiar colour-coding system we see today.
back to top - What is widespan channel?
Widespan channel is made specifically for use on Lattix posts. It adds extra rigidity to the sign plate, meaning that fewer Lattix posts are needed.
back to top
- What is the average lane width on UK motorways?
3650mm. This is important for the design of Gantry-type signs, where overhead arrows must be aligned in the centre of the lanes.
back to top
- What happened to 3M VIP and LDP?
These two 3M products have now been discontinued, replaced by a single product: Diamond Grade Cubed (DG3) with improved combined performance.
back to top
- Grey or yellow: what colour backing board should i use on my sign?
Generally, warning signs are mounted on a yellow backing board and regulatory signs either grey or yellow. Directional signs must be mounted on grey backing boards.
Yellow reflective backing boards can be very effective in drawing attention to signs mounted in shadows, such as below overhanging trees.
There are some disadvantages to using backing boards: rectangular boards deprive triangular & circular traffic signs of a primary recognition aid - their silhouettes. Yellow backing boards can be environmentally intrusive, and over-use can devalue their attention-attracting benefits.
Chapter 7 regulations suggest that simply increasing the size of the sign would make the sign both more noticeable and more legible.
back to top
- How big should the backing board be on chevrons (515)?
Many customers request backing boards for their 515 chevrons which are well below the minimum required in chapter 7 guidelines. The backing board should be 0.5 x the chevron width:
back to top
- Where does the 'Parking' symbol go on my sign?
Unlike other symbols, the 'P' parking symbol always goes to the left of the associated legend, regardless of direction of travel.
If the symbol is to be placed on a tourist sign, the 'P' should then be placed between the legend and the tourist attraction symbol (if any). If there is no tourist symbol, then the 'P' symbol should be placed in accordance with the normal rules for symbols (ie at the opposite end of the tourist attraction name to the arrow)
back to top
- Where does the 'Aircraft' symbol go on my sign?
The aircraft symbol is placed to the right of the airport name. It should be rotated to point in the same direction as the associated arrow or route arm. The symbol should never point below the horizontal, rather horizontal left or right depending on the direction of the arrow.
back to top
- What does the 'Motorway' symbol mean, and where should it be used?
This symbol means that the road now has motorway status (ie motorway regulations apply, such as no stopping).
It should NOT be used on signs directing traffic around an island towards the motorway slip road. Rather, it should be used at the top of a slip road, past which the road becomes 'motorway status'.
back to top
- Why is there a 2s/w gap between 2-line destinations?
If there is a 2-line destination in the block then all destinations are to be separated by 2s/w.
This is to make sure the 2-line destination does not get confused with other destinations - if there was no gap, people might be looking for Lutterworth Market' and 'Harborough'
back to top
- Why do some local directional signs have blue borders?
You may still see old signs on the highway with blue borders. Originally, they were meant to denote local destinations, but there was confusion as to the exact definition of a 'local destination'.
Subsequently, in 1994 the blue borders were dropped from the regulations in favour of using black borders, as per non-primary route signs.
Any of these signs still on the public highway therefore DO NOT comply with the regulations and must be replaced before 01/01/2015. (The Design and Use of Directional Informatory Signs, 1994)
back to top - What is the difference between 'x-height' and 'CAPITAL height'?
The following applies to any of the 'Transport' Fonts', these being 'Transport Medium', 'Transport Heavy', 'Motorway White' & 'Motorway Black'.
The height of the letters used are not only measured in Capital Heights (The full height of any letter with a flat top & base, so for example, the letter 'T' but not the letter 'O') but they are also measured by the 'x height'.
The 'X Height' is a standard trade name and is the measurement from the base of any flat "lowercase" letter to the top of any flat "lowercase" letter, this measurement is called the 'x Height' as the letter x is an example of such a letter, other examples are the letters 'n' 'r' & 'm'. 'x Height is just a general term to indicate this rule.
The 'x Height' and Capital height of any of the transport fonts are in direct correlation, the capital height is always 1.4 times the size of the 'x Height' and in the case of the two 'Motorway fonts' the capital height is twice the size of the 'x height'.
back to top
- When and where are capital letters used on a sign?
In addition to being used at the beginning of sentences, capitals are used for unique named places: 'Wolverhampton Grammar School' is capitalised, whereas 'town centre' is not. The use of capitals on signs is consistent with UK English grammar rules.
back to top
- What is the difference between BLOCK spacing and LINE spacing?
A block is a list of destinations all associated with the same route number. The spacing betweeen different blocks is called BLOCK SPACING. The spaces between each destination within the same block is called LINE SPACING.
back to top
- How far from the carriageway should the sign be located?
Signs should be set at least 450mm from the edge of the carriageway. This should be increased to 600mm where there is a severe camber or crossfall and where signs are mounted on the central reserve of dual carriageways. On high-speed dual carriageway roads the clearance should be at least 1200mm and where there is a hardened verge the nearest edge of the sign should be not less than 600mm behind the edge of the hardening. Traffic Signs Manual Chapter 1 p.14 paragraph 1.48.
back to top - What makes steel posts passively safe?
DEEMED TO COMPLY STEEL TUBULAR SIGNPOSTS
Rules for deemed to satisfy steel tubular posts are given in Annex F of EN 12767 and are summarized as follows:
i) Steel tubular posts up to 89 mm diameter and 3.2 mm wall thickness have been crash tested by TRL and classified as 100 NE2.
ii) Post centres for multiple post signs should not be less than 1500 mm (so a car is unlikely to hit more than a single post in an impact).
iii) Steel posts of 76 mm dia and 3.2 mm wall thickness may be used as close as 750 mm.
In crash tests these small tubular steel posts flatten under the vehicle and are very unlikely to breakaway. For smaller signs these posts provide an economical and passively safe solution for all locations.
Larger steel thin walled posts tested to EN 12767 are being proposed and may provide economical solutions to passive safety for medium sized signs and traffic lights.
back to top
