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Setting Local Speed Limits: Guidance for Local Authorities: ETLLD Circular 1/2006

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Section 6: Rural Speed Management

This section provides guidance on the setting of local speed limits in rural areas.

Key points:

The national speed limit on the rural road network is 60 mph on single carriageway roads and 70 mph on dual carriageways

The majority of drivers do not reach or exceed the 60 mph limit on many single carriageway roads because it is often difficult to do so due to the characteristics and environment of the road

Nonetheless in 2004 more than half of serious or fatal road casualties, and more than two-thirds of road deaths occurred on rural roads.

Speed can be a major factor in the severance of local communities

The speed limit on rural roads should take into account traffic and road user mix, the road's geometry and general characteristics, its surroundings, and the potential safety and environmental impacts

Building upon the Institute of Highways and Transport's Rural Safety Management Guidelines, Traffic Authorities are encouraged to adopt a two-tier hierarchical approach which differentiates between roads with a strategic or local access function

Higher speed limits should be restricted to 'upper tier' or high quality strategic roads where there are few bends, junctions or accesses

Lower speed limits would be appropriate on 'lower tier' roads passing through a local community, or having a local access or recreational function. They would also be appropriate where there are significant environmental considerations or where there is a high density of bends, junctions or accesses, or the road is hilly

A Speed Assessment Framework has been developed to help achieve an appropriate and consistent balance between safety and mobility objectives on single carriageway rural roads. Traffic Authorities are initially encouraged to consider its use on those roads with high accident rates or simply as a way of helping decisions in borderline cases where the choice of the appropriate speed limit is not clear cut

Lower speed limits should be considered on dual carriageway rural roads if the accident history indicates that a 70 mph limit may be unsafe.

It is government policy that where appropriate a 30 mph speed limit should be the norm in villages.

It is recommended that the minimum length of a village speed limit should be at least 600 metres. However, Traffic Authorities may lower this to 400 metres, and in exceptional circumstances, to 300 metres.

80. The vast majority of the rural road network, including Class C and Unclassified roads, is subject to the national speed limit of 60 mph on single carriageway roads and 70 mph on dual carriageways. The majority of drivers do not, however, reach or exceed the speed limit on many single carriageway roads because it is often difficult to do so. This is especially evident on Class C and Unclassified roads where the geometric characteristics include narrow roads, bends, junctions and accesses.

81. Nevertheless in Scotland in 2004 more than half of serious or fatal road casualties, and more than two-thirds of road deaths occurred on rural roads. The reduction in road casualties on rural roads has been at a notably slower rate than on urban roads. It is also here that environmental and landscape factors, along with a wide variety of other road uses, need to be especially considered. Speed can be a major factor in the severance of local communities from essential facilities and lead to a reduced quality of life. Consequently there is a need to improve speed management in rural areas, and in particular further help drivers to understand underlying risks and to tackle the problems caused by inappropriate speed. In particular, Traffic Authorities should intervene on roads where there is a case for encouraging use by or safeguarding the needs of vulnerable road users.

82. As elsewhere, speed limits should be considered as only one part of rural safety management. What the road looks like to the road users, the road function, traffic mix and road and rural characteristics should be taken into account. Traffic Authorities are encouraged to adopt the Rural Safety Management Guidelines published by the Institute of Highways and Transport. Building upon these, Traffic Authorities are encouraged to adopt a two-tier (upper and lower) hierarchical approach which differentiates between roads with a strategic or local access function. Using this approach, higher limits should be restricted to 'upper tier' or high quality strategic roads where there are few bends, junctions or accesses. Similarly, lower limits would be appropriate on 'lower tier' roads with a predominantly local, access or recreational function. They would also be appropriate where there are significant environmental considerations, or where there is a high density of bends, junctions or accesses, or the road is hilly.

83. This guidance seeks to assist Traffic Authorities by helping to define the appropriate traffic speed on different types of rural road taking into account traffic and road user mix, geometry, general characteristics of the road and its surroundings, and the potential safety and environmental impacts.

84. Where accident rates are high Traffic Authorities should seek cost effective improvements to reduce these rates, by targeting the particular types of accident taking place. To help in this process a Technical Guide on Accident Analysis on Rural Roads has been developed by TRL, which provides information on typical accident rates and typical proportions of different accident types, on different types of rural road. This can be used to assess where there are above average accident rates and provides help to Traffic Authorities in identifying the types of site or route specific intervention measures that might be appropriate to manage speeds and reduce accidents along the route.

85. Traffic Authorities should also consider the use of Vehicle Activated Signs ( VAS), which have proved particularly effective at the approaches to isolated hazards, junctions and bends in rural areas.

86. In rural areas every effort should be made to achieve an appropriate balance between speeds, speed limits, road function and design, the differing needs of road users and other characteristics. This balance may be delivered by introducing one or more speed management measures in conjunction with the new speed limits, and/or as part of an overall route safety strategy. The aim should be to align the speed limit so that the original mean speed is at or below the new posted speed limit for that road.

87. Widespread implementation of speed management over the whole minor road network could require a costly and environmentally sensitive increase in the level of signing. Traffic Authorities should seek to ensure that a sensible balance is achieved.

6.1 Single Carriageway Rural Roads and the Speed Assessment Framework

88. In most instances the road function, characteristics and environment and actual speeds being driven should enable Traffic Authorities to determine the appropriate limit on single carriageway rural roads.

89. However, an Assessment Framework has been developed by TRL to help achieve an appropriate and consistent balance between safety and mobility objectives on single carriageway rural roads. Providing a method of assessment of options for speed limits, the assessment framework is designed to help decision-makers weigh up, in a more transparent way, the advantages and disadvantages of each speed limit option and reach a well-founded conclusion.

90. The Assessment Framework differentiates between two tiers of roads based upon their traffic function:

a) Upper Tier - those with primarily a through function where mobility is important, typically Class A and B roads; and
b) Lower Tier - those with primarily a local or access function where quality of life benefits are important, typically Class C and Unclassified roads.

91. The Assessment Framework methodology is based on the presumption that single carriageway rural roads should operate at speeds near to those that give the minimum total costs taking safety, mobility and environmental impact into account. The framework is designed to take into account safety benefits and mobility costs and also allows environmental and accessibility factors to be described in ways that make transparent how the balance between the costs and benefits changes with different choices of speed limit. The Assessment Framework, which includes an electronic spreadsheet, automatically calculates the safety and mobility costs associated with different speed limit options. Although the framework provides a consistent approach, it is not rigid or prescriptive and allows local conditions and constraints to be taken into account.

92. As recommended in paragraph 35, mean speeds should be used where the Assessment Framework is being applied. Local issues in relation to particular routes can be further reflected through final decisions on the acceptable mean speed for each limit, on the importance given to local environment or social factors, and on the choice of additional engineering or educational measures.

93. The framework is designed to assist local decision making and promote greater consistency. The principles of the framework and a user guide can be found at Annex C. A draft Traffic Advisory Leaflet has also been produced ( TAL 2/06) giving fuller details of how the Assessment Framework works and advice on how to apply it. The framework spreadsheet itself can be downloaded from the TRL website www.trl.co.uk. For many cases the principles will indicate the most likely appropriate limit without use of the detailed spreadsheet.

94. The framework has been trialled during development using data from a cross section of single carriageway rural roads supplied by a number of Traffic Authorities. Initial trials using the Assessment Framework principles proved the practical value of the methodology, resulting in speed limits for upper tier roads which were generally accepted as reasonable by local safety officers in relation to speed, accident risk and road character. The trials also demonstrated that the detailed spreadsheet was useful for assessing roads where the decision to change a speed limit was marginal or where more detailed data were needed on cost trade-offs - but its use is not essential for simpler cases.

95. The Assessment Framework is still relatively new. In the first instance Traffic Authorities should consider its application to those roads with high accident rates, or simply as a way of helping decisions in borderline cases where the appropriate speed limit is not clear cut.

96. The Department for Transport intends to monitor its use on the ground and, subject to the above results being confirmed through wider use and the framework successfully delivering more appropriate speed limits, it should ultimately be used more widely across the single carriageway rural road network to help determine the most appropriate limits according to road function and type, taking into account accident rates.

97. In this instance, and subject to meeting local needs and considerations, recommended speed limits for the two tiers toward which, over a period of time, Traffic Authorities are encouraged to move are :

Upper tier A and B roads

  • 60 mph: high quality strategic roads with few bends, junctions or accesses. When using the Assessment Framework the accident rate should be below a threshold of 35 injury accidents per 100 million vehicle kilometres
  • 50 mph: lower quality strategic roads which may have a relatively high number of bends, junctions or accesses. When using the Assessment Framework the accident rate should be above a threshold of 35 injury accidents per 100 million vehicle kilometres and/or mean speed is already below 50 mph
  • 40 mph: where there is a high number of bends, junctions or accesses, substantial development, where there is a strong environmental or landscape reason, or where the road is used by considerable numbers of vulnerable road users
  • 30 mph: should be the norm in villages where appropriate.

Lower tier Class C and Unclassified Roads

  • 60 mph: only the best quality roads with a mixed function (i.e. partial traffic flow and local access) with few bends, junctions or accesses (in the longer term these roads should be assessed using the upper tier criteria)
  • 50 mph: lower quality roads with a mixed function where there are a relatively high number of bends, junctions or accesses. When using the Assessment Framework the accident rate should be below a threshold of 60 injury accidents per 100 million vehicle kilometres
  • 40 mph: roads with a predominantly local, access or recreational function, or which form part of a recommended route for vulnerable road users. When using the Assessment Framework the accident rate should be above 60 injury accidents per 100 million vehicle kilometres
  • 30 mph: should be the norm in villages where appropriate

A summary table can be found at Annex E.

98. It is important to note that the above does not imply that speed limits should automatically be reduced. Indeed in some cases the assessment may suggest that the existing speed limit may already be inappropriately set or too low and an increased limit should be considered.

6.2 Dual Carriageway Rural Roads

99. Rural dual carriageways are not covered by the speed assessment framework. Roads with segregated junctions and facilities for vulnerable road users would generally be suitable for 70 mph limits. However, a lower limit may be appropriate if, for example, an accident history indicates that this cannot be achieved safely.

6.3 Villages

100. Fear of traffic can affect people's quality of life in villages and it is self-evident that villages should have comparable speed limits to similar roads in urban areas. It is, therefore, government policy that where appropriate a 30 mph speed limit should be the norm in villages.

101. Traffic Advisory Leaflet 1/04 ( TAL 1/04) sets out current policy on achieving lower speed limits in villages, including a broad definition of what constitutes a village. For the purpose of applying a village speed limit of 30 mph a definition of a village can be based on the following simple criteria relating to frontage development and distance:

  • 20 or more houses (on one or both sides of the road); and
  • a minimum length of 600 metres.

102. If there are just fewer than 20 houses, Traffic Authorities should make extra allowance for any other key buildings, such as a church, shop or school.

103. The above criteria should give adequate visual message to drivers to reduce their speed. However, many drivers are unlikely to reduce their speed to the new 30 mph limit if it is over a very short stretch of road, particularly if the end of the limit can be seen at the entry point. It is, therefore, recommended that the minimum length is at least 600 metres to avoid too many changes in speed limits along a route. Traffic Authorities may, however, lower this to 400 metres when the level of development density over this shorter length exceeds the 20 or more houses criterion and, in exceptional circumstances, to 300 metres. Shorter lengths are, however, not recommended.

104. In some circumstances it may be appropriate to consider an intermediate speed limit of 40 mph prior to the 30 mph terminal speed limit signs at the entrance to a village, in particular where there are outlying houses beyond the village boundary, or roads with high approach speeds. For the latter, Traffic Authorities might also need to consider other speed management measures to support the message of the speed limit and help encourage compliance so that no enforcement difficulties are created for the police. Where appropriate, such measures might include a vehicle activated sign, centre hatching or other measures that would have the effect of narrowing or changing the nature and appearance of the road.

105. Where the speed limit commences at the village boundary, the village nameplate sign and speed limit roundel may be mounted together using the format prescribed in diagram 2402.1 of TSRGD. The combined sign should be located as near as practicable to the start of the development so that drivers see housing at the same time as the signs, reinforcing the visual message for reduced speed.

106. If there are high approach speeds to a village, or the start of the village is not obvious, village gateway treatments can also be an effective way to slow drivers down. Further guidance on the use of Gateways is included in Annex B. Advice can also be found in Traffic Advisory Leaflets 1/94 ( VISP - A Summary) and 1/04 (Village Speed Limits).

107. In situations where the above criteria are not met, and there is a lesser degree of development, or where engineering measures are not practicable or cost-effective to achieve a 30 mph limit, but a reduction from the national 60 mph speed limit is considered appropriate, Traffic Authorities should consider alternative lower limits of 40 mph or 50 mph.

108. It may be appropriate in some larger villages to introduce 20 mph speed limits or zones, or Home Zones if lighting and other considerations allow. Other than 20 mph speed limits around schools, such limits should not, however, be considered on roads with a strategic function or on main traffic routes.