Coloured road surface treatment is a familiar sight on roads in the southeast and elsewhere. It has been used to make drivers aware of a change in environment or to highlight other traffic management measures.
Good practice guidance has been developed to address the following concerns.
- A coloured road surface has no defined meaning to road users and is of dubious value as a road safety measure.
- It has no proven speed reduction nor accident reduction potential when used in isolation.
- It is difficult to quantify its effect in highlighting other measures.
- Road users are confused by different colours being used in different circumstances by different authorities.
Coloured surface treatment should not be used unless it can be clearly justified on the grounds that it enhances the effectiveness of a scheme.
In such circumstances, the following convention should be adopted:-
GREEN – for cycle facilities
RED – any other traffic management purpose
No other colours should be used.
This convention is consistent with a recently produced document from the County Surveyors Society, in collaboration with Surrey County Council and neighbouring authorities, with the aim of ensuring a consistent approach to the use of colour throughout the southeast.
The County Asset Management (Materials) Group must be consulted where the use of colour is proposed. In order to achieve county-wide consistency, the shade of green and / or red used must be within a permissible range. The use of vivid colours is not encouraged and muted colours are preferred. BBA / HAPAS certification for colour durability is a requirement.
Applying the Policy
The policy is not applicable in Conservation Areas nor to anti-skid surfacing.
The policy is not retrospective.
When assessing whether the use of coloured surface treatment enhances the effectiveness of a scheme, the following factors must be considered:-
- the accident reduction potential of the use of colour in isolation is unproven.
- on typical black asphalt carriageways, black / white provides the greatest colour contrast and is most conspicuous in dark conditions.
- introducing a coloured surface treatment will require local consultation (of a scale dependent upon the proposed measures) and may be contentious.
- colour can highlight unsightly marks on the road surface such as those caused by skidding.
- colour will fade and require maintenance.
- the 'new' colour soon becomes familiar to regular road users and thereby any impact quickly diminishes.
- a bus lane may be only operational for part of the day and in this event, colour does not add clarity to mandatory signing.
- any benefit from the use of colour is most likely to be in highlighting the presence of other (usually more physical) measures.
Despite the above, there may be some circumstances where the use of coloured surface treatment could add value to a scheme. For example, the Department for Transport suggest that the use of green asphalt to highlight an advanced stop line reservoir at traffic signals reduces vehicle encroachment. Apart from assisting cyclists, this may also benefit pedestrian safety and reduce any feeling of intimidation they may feel due to the proximity of vehicles at the stop line.
All coloured surface treatments shall have a textured surface to provide a skidding resistance value (SRV) of not less than 45 at all locations.
- non-trafficked areas:- edge strips, ghost islands, central hatching and deflector islands.
- non-carriageway areas:- central reserves, central refuges, pedestrian areas, shared surfaces, remote cycle lanes.
Additionally where the coloured surface is used immediately adjacent to the trafficked area and is not separated by any physical presence, the included aggregate shall have a polished stone value (PSV) in the same category of skidding properties as that of the carriageway.
The aggregate PSV requirement shall be commensurate with the road type, site category and traffic levels, and material will be in the range of 55 minimum to 70 minimum PSV. The County Asset Management (Materials) Group will provide guidance for the selection of PSV for any given site location.
Impact on Local Transport Plan 2 Themes
Positive effect, if used appropriately
There is no impact.
Inappropriate use is detrimental.
Possible positive effect, if used appropriately.
Colour fades incurring additional reinstatement costs.