Traffic Signs Manual/Chapter 3/2008/1

1INTRODUCTION

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GENERAL

1.1 The Traffic Signs Manual is intended to give advice to traffic authorities and their agents on the correct use of signs and road markings. Mandatory requirements are set out in the current version of the Traffic Signs Regulations and General Directions; nothing in the Manual can override these. The advice is given to assist authorities in the discharge of their duties under section 122 of the Road Traffic Regulation Act 1984 and Part 2 of the Traffic Management Act 2004. Subject always to compliance with the Directions, which, except in Northern Ireland, are mandatory (see para 1.4), it is for traffic authorities to determine what signing is necessary to meet those duties, although failure to follow the Manual's guidance without good reason might well lead to enforcement difficulties. In particular, adjudicators might consider such failure to be evidence that the signing was unclear. Traffic authorities should always remember that the purpose of regulatory signs is to ensure that drivers clearly understand what restrictions or prohibitions are in force.

1.2 The Traffic Signs Manual is applicable in England, Northern Ireland, Scotland and Wales. References to the "Secretary of State" should therefore be interpreted as referring to the Secretary of State for Transport, the Department for Regional Development (Northern Ireland), the Scottish Executive or the Welsh Assembly Government as appropriate. Any reference to the "Department" is a reference to the Department for Transport or the appropriate national office for Northern Ireland, Scotland or Wales as described above.

1.3 Any reference to a "Chapter" is a reference to a Chapter of the Traffic Signs Manual, and any reference to a "section", unless otherwise stated, is a reference to a section in this chapter of the Manual. Where more detailed background information might be helpful, reference is made to Departmental Standards and Advice Notes. These can be found in the Design Manual for Roads and Bridges, published by the Stationery Office.

1.4 Any reference to the "Regulations" or the "Directions" is a reference to the Traffic Signs Regulations and General Directions 2002 (as amended), applicable to England, Scotland and Wales. Reference to a diagram number or to a Schedule is a reference to a diagram or schedule in those Regulations. In Northern Ireland the relevant legislation is the Traffic Signs Regulations (Northern Ireland) 1997. Diagram and regulation numbering occasionally differs in these Regulations (see Appendix D) and there are no General Directions. Sign layouts, meanings and permitted variants are generally similar but can vary; where the NI Regulations apply, the designer is advised to read them in conjunction with the Manual. Not all signs referred to in the text are included in the NI Regulations. References to directions are not applicable in Northern Ireland; where these are referred to, advice should be sought from the Department for Regional Development’s Roads Service Headquarters. Appendix D also lists the appropriate legislation applicable in Northern Ireland where this varies from that in England.

1.5 In this chapter the word "must" is used to indicate a legal requirement of the Traffic Signs Regulations and General Directions that must be complied with. The word "shall" indicates an essential (or mandatory) requirement of compliance with this chapter, and "should" indicates a course of action that is strongly recommended and represents good practice. The word "may" generally indicates a permissible action, or an option which requires consideration depending on the circumstances.

TYPES OF REGULATORY SIGN

1.6 Regulatory signs indicate requirements, restrictions and prohibitions. Most are erected to give effect to a traffic regulation order or other statutory provision (see para 2.2). There are certain signs where the legal requirements are specified in the Regulations; these include STOP, GIVE WAY, Keep Left and mini-roundabout signs.

1.7 Regulatory signs either give positive instructions or indicate a prohibition. Positive signs are generally circular with a white border and symbol on a blue background. They usually indicate something all drivers must do (e.g. keep left) or a facility available to certain classes of traffic (e.g. buses only). The exceptions are the octagonal red STOP sign and the triangular GIVE WAY sign. Prohibitory signs, which generally tell drivers what they must not do, are mostly circular and have a red border. The red ring indicates the prohibition; diagonal bars are used only on signs which prohibit a specific manoeuvre, i.e. banned left or right turns or U-turns. Other regulatory signs give details of waiting and loading restrictions and the use of on-street parking places. These signs are rectangular and generally mounted parallel to the edge of the carriageway.

1.8 Many regulatory signs are accompanied by supplementary plates. There are restrictions on which plates may be used with individual signs; the plates prescribed for use with each sign are indicated below each diagram illustrated in this chapter. Detailed drawings showing the correct layouts for most permitted variants have been produced by the Department for Transport (see para 1.9).

1.9 Precise dimensions for all diagrams are indicated in the "P" series of working drawings, available free of charge on the Department for Transport's website. These also specify the permitted variants of symbols, and show the correct layout of supplementary plates not illustrated in the Regulations. The "S" series of working drawings provides details of the more complex symbols and pictograms.

1.10 Signs to give advance warning of regulatory restrictions are sometimes needed; most of these are dealt with in Chapter 4, e.g. STOP and GIVE WAY ahead (diagrams 501, 502 and 503) and mandatory height restriction (diagrams 818.3 and 818.4).

1.11 Some regulatory signs are accompanied by road markings; details of these are in Chapter 5.

1.12 Certain regulatory signs may be incorporated into directional signs to give advance warning of a restriction (see para 5.3); for design details see Chapter 7. Such additional guidance is purely informatory; the normal regulatory signs must still be provided to make the restriction enforceable.

1.13 Guidance on the use of regulatory signs at road works and temporary situations is given in Chapter 8.

SIGN SIZES

1.14 It is important that signs giving effect to traffic regulation orders, and intended to be read from a moving vehicle, are of sufficient size to enable drivers to recognise them and assimilate the information in time. They therefore need to be of a size appropriate to the prevailing traffic speed on the road on which they are used (see Appendix A). All sign sizes, generally based on the 85th percentile approach speed, are in millimetres unless stated otherwise.

SITING

1.15 It is essential that drivers have an unobstructed view of traffic signs. The distance which should be kept clear of obstructions to the sight line, whether caused by vegetation, other signs or street furniture, is known as the clear visibility distance. The higher the prevailing traffic speeds, the greater this distance needs to be.

Table 1-1 Minimum clear visibility distances

85th percentile speed of private cars (mph)	Minimum clear visibility distance (metres)
Up to 20	45
21 to 30	60
31 to 40	60
41 to 50	75
51 to 60	90
Over 60	105 (120)

1.16 Table 1-1 specifies minimum clear visibility distances. These should normally be measured from the centre of the most disadvantaged driving lane. It is important that the full recommended sight line to the whole of the sign face is preserved. Cutting back of vegetation only in the immediate vicinity of the sign might not be sufficient; sign visibility should always be checked from the appropriate viewing distance.

1.17 The bracketed visibility distance of 120 m in table 1-1 is generally for dual carriageway roads and motorways with a 70 mph speed limit, where the bracketed larger size of sign in Appendix A is used.

1.18 Table 1-1 does not apply to speed limit and speed camera signs (see section 14), signs to diagrams 958 and 958.1 (see paras 15.9 and 17.5 respectively), or to time plates that are parallel to the kerb.

1.19 Regulatory signs that indicate the beginning of a restriction or prohibition and to which direction 8 applies have to be placed in accordance with that direction. The requirement is that the signs must be placed on each side of the road or on each side of the appropriate carriageway of a dual carriageway road, except that signs need only be placed on one side if any of the following circumstances apply:

(i) where the restriction, requirement or prohibition applies only to one side of the road.

(ii) at a junction where traffic turns from a one-way road into the relevant road. The sign should be angled to face towards the driver.

(iii) at a junction where the carriageway of the relevant road is less than 5 m wide and the centre of the sign is no more than 2 m from the edge of the carriageway.

Both directions 8 and 9 also apply to signs indicating the beginning of a speed limit, see section 14. Guidance on siting other regulatory signs such as diagram 606 (direction in which traffic must proceed), diagram 612 (no right turn) and signs indicating waiting restrictions, can be found in the relevant sections of this chapter.

1.20 Signs giving effect to No Stopping orders (see section 9) should, whenever possible, be mounted to face traffic. A driver does not then have to stop to read the sign, possibly resulting in an offence.

MOUNTING

1.21 The normal mounting height measured to the lower edge of a sign or backing board (or any supplementary plate) is between 900 mm and 1500 mm above the carriageway alongside. The greater height should be used where vehicle spray is likely to soil the sign, or above planted areas. Careful consideration should be given to any proposal to mount signs at a low height, such as on railings or bollards, as there is a risk of drivers not noticing them, especially at night or when they could be obscured by parked vehicles or pedestrians. Where signs are erected above footways, or in areas likely or intended to be used by pedestrians (e.g. pedestrian refuges), a headroom of 2300 mm is recommended, with 2100 mm as an absolute minimum. A clearance of at least 2300 mm should be maintained over a cycle track or shared cycleway / footway.

1.22 Supplementary plates should be separated from the sign or another plate by a vertical space not exceeding the x-height of the legend, and ideally half the x-height (but see para 1.28). When mounted on a backing board (see paras 1.31 to 1.33), this space should be 0.05 times the roundel diameter.

1.23 Except where they support a luminaire, posts should never project above the top of the sign (see clause 1204 in the Specification for Highway Works, Series 1200, Traffic Signs). This practice is unsightly, and needlessly increases visual intrusion and clutter.

1.24 Where posts are erected on footways, there should be an absolute minimum of 1000 mm of unobstructed width to allow the passage of wheelchairs. Posts not readily visible to pedestrians or cyclists may be provided with a yellow or white band in accordance with the requirements of direction 41(2).

MOUNTING MORE THAN ONE SIGN ON A POST

1.25 Research has shown that the greater the number of signs which drivers are presented with simultaneously, the greater the difficulty they are likely to have in assimilating the information. This problem in dealing with information overload increases with age, so that older drivers suffer disproportionately. Generally, therefore, not more than two signs should be erected on any one post when intended to be read from an approaching vehicle. This also applies to signs mounted at the same location on separate posts. Where a sign requires a supplementary plate, the combination of sign and plate may be regarded as one sign. Exceptionally, three signs may be mounted on one post, or at the same location, provided none requires a supplementary plate.

1.26 STOP or GIVE WAY signs or signs indicating the start of a speed limit (terminal signs) should not be mounted on the same post as a warning sign. Speed limit terminal signs should wherever possible be mounted alone. For further guidance on mounting speed limit signs, including repeater signs, see paras 14.60 to 14.62. Sign combinations, excluding speed limit terminal signs, which may be mounted together should be placed in the following order from top to bottom:

(i) STOP or GIVE WAY or any triangular warning sign

(ii) speed limit repeater signs

(iii) other circular signs

(iv) rectangular signs.

1.27 All proposed assemblies should be critically examined to ensure that the intended messages are clear. Ambiguity may result in difficulty enforcing a traffic regulation order. Where a supplementary plate with the legend "End" (diagram 645) is used to indicate the termination of a prohibition or restriction, particular care is necessary to ensure that it is clear which sign it applies to when there is more than one.

1.28 Where a speed limit sign is erected on the same post as a clearway sign accompanied by an "End" plate, the plate should be butted directly up to the lower edge of the clearway sign. The speed limit sign should be mounted at the top of the assembly with a space equal to twice the width of the red border between the roundels to ensure there is no ambiguity.

1.29 Generally no assembly should exceed 4 m in height above ground level. This may be exceeded to improve visibility of the signs at particularly difficult sites, but account should always be taken of the potential environmental impact of tall and cluttered sign assemblies.

1.30 It should also be borne in mind that high-mounted signs may receive little light from car headlamps, particularly on dipped beam. Where such signs are not directly lit but rely on reflectorisation to be seen at night, they are likely to be less conspicuous and less legible.

BACKING BOARDS

1.31 To improve conspicuity against a complex or dark background, a regulatory sign may be mounted on a grey or yellow backing board (direction 42, as amended by the Traffic Signs (Amendment) General Directions 2004). A backing board can also make for a neater assembly, e.g. when a sign requires a supplementary plate, and also eliminates the risk of the plate becoming misaligned. A yellow backing board must be rectangular in shape (except when a speed limit terminal sign is mounted with a town or village boundary sign; see para 14.51), but a grey board may be non-rectangular, e.g. to enable a circular sign to be bracketed off a lamp column. A backing board must not itself be provided with a border, nor give the impression of being an additional border. Where it seems that a sign is not being noticed by drivers, it should be checked to ensure that it is well-sited, not obscured by vegetation or other obstructions, and is of the appropriate size and in good condition. Only then should the use of a yellow backing board be considered.

1.32 A yellow backing board may be reflectorised to increase its conspicuity at night, although this is not usually necessary for regulatory signs. In most cases these are lit when placed on lit roads, or are mounted parallel to the kerb, and on unlit roads reflectorisation of the sign is usually sufficient to ensure night-time conspicuity. A yellow backing board may also be fluorescent; this greatly increases conspicuity in dull weather and at dusk. Fluorescence can also be particularly effective in drawing attention to signs mounted in deep shadow, e.g. below overhanging trees. However, fluorescence is visually intrusive and should be used with discretion. The modern true yellow materials are less garish than the original yellow-green type and are much to be preferred.

1.33 There are potential disadvantages to the use of backing boards. The larger overall size of the assembly can sometimes obstruct sight lines. A backing board can deprive non-rectangular signs of a primary recognition aid: their distinctive silhouette. Yellow backing boards can be especially environmentally intrusive, and their over-use could eventually devalue their attention-attracting benefits. A less garish way of increasing a sign’s conspicuity is simply to provide a standard sign of larger size. Not only will this be more noticeable than a smaller sign, but it will also improve legibility and hence reading distance, which a yellow backing board cannot. Detailed guidance on the correct design and use of backing boards can be found in Chapter 7 (paras 14.19 to 14.24). Guidance on the use of backing boards for speed limit signs is given in this chapter (paras 14.50 to 14.53).

ILLUMINATION

1.34 For general guidance on sign illumination see paras 2.5 to 2.7. For illumination of speed limit signs see paras 14.54 to 14.58.

This work has been mirrored or sourced from material provided on the UK Government website at https://www.gov.uk/government/publications/traffic-signs-manual, which states material is available under the terms of the Open Government License unless indicated otherwise. (Crown copyright acknowledged.)

This is NOT an official transcription, and should NOT be considered in any way a controlled copy of the work in question.

This document no longer necessarily represents current practice, as it relates to an earlier version of the regulations (TSGRD 2002 as amended at publication date) rather than the current TSRGD 2016 regulations. It should not be used for actual design or operational use without consulting a more recent edition.

This version was transcribed in May 2015, from a 2008 impression.