Local air quality management: policy guidance

Updated guidance for local authorities to take account of Environmental Standards Scotland's recommendations to strengthen the local air quality management regime.

11: Air quality and transport


11.1 Cleaner Air for Scotland (CAFS) sets out the policy framework for air quality and transport, and describes the key responsibilities of central and local government. The guidance in this chapter supplements the information contained in CAFS, and the Scottish Government expects local authorities to ensure that both documents are taken into account by all relevant departments.

11.2 Road transport is a major source of local air pollution, particularly in our towns and cities. In urban areas, road traffic accounts for a major part of the total emissions of nitrogen dioxide and particles – the objectives of most concern for human health. This has been borne out by the fact that, with one exception (the Grangemouth industrial complex, declared on the basis of sulphur dioxide), all the AQMAs currently in place in Scotland are based on nitrogen dioxide and/or particles concentrations related to transport activities.

11.3 In 2014 there were around 2.8 million road vehicles licensed in Scotland, of which 84% were cars. In the same year, 69% of Scottish households had access to a car, compared with 57% in 1990[12]. This steady increase in car ownership, together with the car's flexibility and convenience, has enabled more people to travel further, with a corresponding increase in vehicle usage. Emissions from buses, taxis and goods vehicles can also make significant contributions to poor local air quality in some urban areas.

11.4 Cutting road transport emissions is therefore a key part of LAQM. Local authority officers dealing with air quality duties should liaise regularly with transport and planning colleagues, and with Transport Scotland where the pollution arises from trunk roads and motorways.

Scottish and UK context

11.5 The policy framework at both Scottish and UK level has already led to significant improvements in local air quality and will continue to do so in the future. Key transport initiatives include:-

  • The development of integrated transport strategies that support sustainable development;
  • Regulatory measures and standards to reduce vehicle emissions and improve fuels;
  • Tax-based measures that encourage people to supply and use cleaner fuels and also encourage them to buy more environmentally-friendly vehicles; and
  • Research and development to reduce emissions from HDVs (especially public transport).

Regulatory measures to cut vehicle emissions

11.6 Overall emissions of key air pollutants from road transport have fallen by about 50% over the last 20 years, despite increases in traffic, and are expected to reduce further over the next decade. This is mainly a result of progressively tighter vehicle emission and fuel standards agreed at European level and set in UK regulations - the Euro standards. Euro standards control the emissions level of vehicles when new. Over time the Euro standards have become progressively tougher and apply to new vehicles manufactured on or after specific dates. At the same time there is now a substantial body of evidence suggesting that real world emissions are not decreasing as rapidly as predicted for some vehicle classes.

11.7 There are systems in place to ensure compliance with vehicle emission standards. Through its Type Approval work, the Vehicle Certification Agency ensures that all new models of cars coming onto our roads meet EU emissions standards. Almost all types of vehicles must go through an emission check as part of the annual MOT testing procedures. In service testing is one of several measures designed to reduce pollution from vehicle emissions. The MOT tests are kept under review in response to developments in vehicle technology to ensure an appropriate framework.

11.8 The Road Traffic (Vehicle Emissions) (Fixed Penalty) (Scotland) Regulations 2003 allow local authorities to adopt powers for undertaking roadside vehicle emissions testing. These powers are optional, but provide authorities with a useful additional tool for addressing air quality issues in their areas. Currently 13 local authorities are making use of the powers, supported by Scottish Government funding. Guidance and further information is available on the Government's website[13].

National Transport Strategy

11.9 Scotland's National Transport Strategy was originally published in 2006 and sets out the Government's long term vision for transport, together with objectives, priorities and plans. It focuses on three strategic outcomes which will set the context for transport policy making over the next 20 years:

  • improve journey times and connections between Scotland's cities and towns and global markets to tackle congestion and provide access to key markets;
  • reduce emissions; and
  • improve quality, accessibility and affordability of transport.

A refreshed version of the National Transport Strategy was published in 2015.

11.10 The National Transport Strategy is supported by the Strategic Transport Projects Review (STPR), published in 2008, which recommends 29 investment priorities for delivery in the next 20 years.

The Transport (Scotland) Act 2001

11.11 The provisions of the Transport (Scotland) Act 2001 are arranged in five Parts:

  • Part I – Joint Transport Strategies.
  • Part II – Bus Services.
  • Part III – Road User Charging.
  • Parts IV and V – Miscellaneous and Supplementary, containing various measures not related to the other main Parts of the Act, and also the usual supplementary provisions including the territorial extent, and short title of the Act.

The key elements relevant to local authorities' LAQM duties are contained in parts I, II & III of the Act[14].

The Transport (Scotland) Act 2005

11.12 The Transport (Scotland) Act 2005[15]:

  • sets out provisions for Regional Transport Partnerships and Regional Transport Strategies (see paragraph 9.19 for further information);
  • enables a national concessionary travel scheme;
  • creates new procedures for tackling roadworks;
  • transfers to the Scottish Ministers certain rail functions; and
  • creates the Office of Scottish Road Works Commissioner.

Transport Scotland

11.13 Transport Scotland was established in 2006 as an agency of the Scottish Government. Its key responsibilities are:

  • management of the Scottish trunk road and rail networks;
  • delivery of major transport infrastructure projects; and
  • operation of the national concessionary travel scheme.

Low emission vehicles

11.14 In 2013, Transport Scotland published Switched On Scotland: A Roadmap to Widespread Adoption of Plug-In Vehicles. The Roadmap sets out a vision for Scotland's towns and cities to be free from the effects of petrol and diesel fuelled vehicles by 2050. It also outlines the roles and responsibilities of all who have a part to play in this process, and local authorities should have regard to the Roadmap when developing and updating their air quality action plans.

Road Traffic Reduction Act

11.15 The Road Traffic Reduction Act 1997 requires local traffic authorities to review and report on existing and forecast levels of traffic on local roads. This information should be included in Local Transport Strategies.

Emissions from shipping

11.16 Ships release a significant fraction of the total emissions of man-made air pollutants. These include NOX, sulphur oxides (SOX), particulate matter (PM), and volatile organic compounds (VOC), which all affect local air quality. Emissions from shipping can be an issue for local authorities with major ports. Also, as emissions from other sources decline, global emissions from shipping are becoming more and more significant.

11.17 The global nature of shipping makes the International Maritime Organisation (IMO) a natural forum through which to agree a global policy response to air pollution from ships. This is covered by Annex VI of the Convention on Marine Pollution (MARPOL), which was revised in 2008.

10.18 Marine fuels used within the EU are currently regulated by the Sulphur Content of Marine Fuels Directive 2012/33/EC which amends the Sulphur Content of Liquid Fuels Directive 99/32/EC. This Directive implements the revised MARPOL Annex VI within the EU, as well as containing additional measures to control the sulphur content of marine fuels used by ships in EU waters.

Local transport measures

11.19 Traffic management and other local transport schemes are likely to be key elements in any air quality action plan or local air quality strategy. This section summarises some of the measures available to local authorities.

Local roads

11.20 Local authorities, in their role as highways authorities, have a range of powers, including compulsory purchase of land for road building and restrictions on and the stopping up of roads.

11.21 Funding for local roads, both capital and revenue, is provided through the overall local government finance settlement, under formula arrangements agreed with COSLA. This funding is not ring fenced and it is for each local authority to decide the priorities for local roads and bridges as part of overall spending plans.

Regional Transport Partnerships and Strategies

11.22 Regional Transport Partnerships (RTPs) were established in 2005 to strengthen the planning and delivery of regional transport in Scotland so that it better serves the needs of people and business. The main task of each RTP is to prepare a Regional Transport Strategy. Some RTPs are also responsible for the delivery of transport services, and all RTPs will be able to seek additional powers if required to deliver their strategies.

Local Transport Strategies

11.23 Local Transport Strategies are significant for LAQM as they set out local authorities' plans and priorities for the development of an integrated transport policy within their area of responsibility. They cover all forms of local authority provided transport and set out how authorities plan to tackle the associated problems, including those related to poor air quality. Among other things, Strategies may contain any proposals to utilise the road user charging powers, promote Green Transport Plans, and provide the context for Quality Bus Partnerships and walking and cycling strategies. The Scottish Government considers it important that air quality action plans and local air quality strategies are consistent with, and where appropriate linked to, Local Transport Strategies.

11.24 The Scottish Government and Transport Scotland work closely with local authorities to ensure that Local Transport Strategies are properly co-ordinated with Regional Transport Strategies.

Scottish Government Emissions Reduction Register

11.25 The Scottish Government, in partnership with the Energy Saving Trust, provides funding for local authorities to retrofit vehicles in their fleets with emissions reducing equipment, as part of the air quality action plan grant fund. The Energy Saving Trust has developed a register of approved suppliers and equipment which are available for potential funding under the scheme.

Road user charging

11.26 The Transport (Scotland) Act 2001 introduced discretionary powers for local authorities to bring in road user charging schemes. All the revenue raised by any charging schemes can be recycled locally. These powers therefore create a new, additional source of income to fund improvements to local transport. Before any schemes can be introduced, local authorities will have to demonstrate that they have improved public transport in advance to ensure that people have good alternatives to car use.

Traffic regulation

11.27 Sections 1, 6 and 9 of the Road Traffic Regulation Act 1984 (RTRA) give traffic authorities extensive powers to make traffic regulation orders (TROs). These can prohibit, restrict or regulate traffic or particular types of vehicle. They may apply to part of a road, a single road, or a number of roads. They may be in force all the time or only for specified periods. Traffic authorities may exempt some classes of vehicle or permit holders.

11.28 Paragraph 36 of Schedule 22 to the 1995 Act extended powers for making TROs to include pursuit of the air quality objectives outlined in the Air Quality Strategy. TROs made on air quality grounds cannot normally restrict access to premises for more than eight hours in any 24. Schedule 22 also ensures that authorities must take explicit account of the Air Quality Strategy when using their traffic regulatory powers.

Low Emission Zones

11.29 A Low Emission Zone (LEZ) allows only vehicles meeting minimum emissions standards to enter pollution hotspots in towns and cities. The main purpose of an LEZ is to improve air quality, though it may deliver additional congestion and quality of life benefits by reducing traffic noise and overall traffic volume. No LEZs have been introduced in Scotland to date. CAFS sets out initial proposals for a national low emission framework in Scotland and local authorities should refer to this for more detailed information.

Home Zones

11.30 A Home Zone is a residential area that seeks to meet the needs of all road users equally, where pedestrians, cyclists and vehicles share the road space. Section 74 of the Transport (Scotland) Act 2001 enables local authorities to designate roads for which they are the transport authority as Home Zones. Regulations came into force in 2002 setting out the procedure to be followed in the designation process and also published guidance.

Access restriction

11.31 Local authorities can use the Roads (Traffic Calming) (Scotland) Regulations 1994 to create narrow gateways to urban centres. This technique may discourage car access to particular areas, as long as there are suitable alternative routes for through traffic. But if traffic must queue at the gateway, there could be an increase in local emissions. Authorities could use the same technique at the entrance to bypassed communities to discourage drivers from taking a short cut. Authorities may not, however, use traffic calming techniques by themselves to prevent access by any class of vehicle - this requires a TRO.

Traffic calming

11.32 The Roads (Traffic Calming) (Scotland) Regulations 1994 and the Road Humps (Scotland) Regulations 1998 allow authorities to introduce a wide range of physical measures to slow traffic. Traffic calming schemes not only have the direct effect of slowing vehicles, but also the indirect effect of deterring traffic from using residential roads as a short cut. It is important that traffic authorities design schemes to encourage a smooth driving style that avoids repeated acceleration and deceleration. The spacing between each calming feature, whether vertical or horizontal deflections, will greatly influence driving style. Spacing of between 40m and 90m should provide the smoothest flow.

Reallocation of road space

11.33 Local authorities may also make TROs to introduce bus or cycle lanes. Conventional with-flow bus lanes, with setbacks at signal-controlled junctions, will normally have less of an effect on junction capacity than contra-flow lanes. Reallocating space to buses and cycles can make these forms of transport more attractive. Authorities can also create advisory cycle lanes (which would not require TROs), but these might not be as effective. Authorities must be careful not to increase congestion and pollution when reducing capacity, particularly during the short term while travel patterns adjust.

High occupancy vehicle lanes

11.34 A significant proportion of vehicles contains only one occupant. This is particularly so during peak periods. High occupancy vehicle (HOV) lanes are, in principle, a means of using the road network more efficiently and encouraging car sharing. Traffic authorities can make a TRO to authorise them. They can introduce HOV lanes by creating an additional lane or by converting an existing one. HOV lanes might, in some circumstances, be able to share bus lanes. There has been no use of HOV lanes to date in Scotland, and little experience elsewhere in the UK, but they may be an appropriate measure to reduce traffic levels, with a consequent reduction in emissions, on some road networks. Effective enforcement of HOV lanes also requires careful consideration.

Pedestrian/vehicle restricted areas

11.35 A local authority may wish to restrict access to a road or area to some or all vehicles at different times of the day. The Environment Act 1995 added 'improving air quality' as a reason for making TROs under the Road Traffic Regulation Act 1984. Where there are objections to an order which would have the effect of restricting or prohibiting access outside peak hours, the local authority would first need to hold a public enquiry. The reason for restricting vehicle access may be to create a pedestrianised area. Typically these allow vehicular access for all or some parts of the day. In any case, authorities will need to ensure that delivery and service vehicles have suitable access.

11.36 Restricting access to town centres has been shown to improve the local environment. There are plenty of examples of pedestrianisation schemes that have maintained or improved local economic activity. But this does not happen automatically - people must still be able to get to the area by other means. These could include:

  • good public transport, perhaps with park and ride;
  • facilities for cyclists and pedestrians;
  • peripheral car parking;
  • access for people with limited mobility; and
  • access for taxis, where appropriate.

Parking controls

11.37 A big influence on whether people drive is whether they can park. The Road Traffic Regulation Act permits local authorities to determine where motorists can park and how much it will cost them. They may also restrict parking in other ways. Residents' parking schemes, for example, can be a good way of encouraging non-residents to find other ways of travelling into town centres. Authorities can also use the planning process to regulate the amount of private non-residential parking (PNR) associated with a new development.

11.38 Parking restrictions need the right level of enforcement. Effective enforcement of parking restrictions allows more efficient use of existing parking provision and can improve parking flow as drivers have to spend less time finding a parking space. The Road Traffic Act 1991 provided for the decriminalisation of most non-endorsable parking offences. Decriminalisation transfers responsibility for enforcing most parking restrictions from traffic wardens to parking attendants employed by the local authority and funded out of revenue received from penalty charges and from paid parking. This gives local authorities greater control over enforcement.

Traffic control systems

11.39 Before doing anything to improve traffic flow, highway authorities should think carefully about what to do with the road capacity they will release. Authorities should consider re-distributing it in favour of buses, cyclists and pedestrians. Where signals control junctions, a SCOOT[16] traffic control system, which responds automatically to changing conditions, will give better traffic flow than an older Urban Traffic Control system and a much better flow than uncoordinated signals.

11.40 SCOOT systems can hold queues outside an area when congestion exceeds a pre-set threshold. Overall journey times might well remain similar, but drivers would queue for longer while approaching the area, then make faster progress through it. This method may be appropriate if the queue is where relatively few people are exposed to any increased emissions.

11.41 When a SCOOT system detects buses, either through an accurate automatic vehicle location system, or by transponders and special loops, it can give them priority. This cuts delay to buses and makes bus journey times more predictable, although it does not help as much as dedicated bus lanes.

11.42 Where coordinated traffic signal operation is not required, traffic signals will operate in an isolated control mode. Isolated operation can provide quicker responses to rapidly changing traffic conditions and reduce unnecessary delays, particularly during quiet periods. A SCOOT or Urban Traffic Control system may revert to isolated operation at night. If the signals are to operate efficiently, it is important that the relevant vehicle detectors are installed and working correctly. Traffic signal controllers incorporating the MOVA (Microprocessor Optimised Vehicle Actuation) control strategy can improve flows and reduce delays at traffic signal controlled junctions.

11.43 Other traffic management measures may also help improve traffic flow at junctions, such as TROs to ban right turns, with traffic signs reinforced in some cases by physical measures. Introducing parking restrictions can reduce exit blocking at junctions.

Speed limits

11.44 Local authorities can set speed limits by making orders under the Road Traffic Reduction Act. Reducing maximum speeds is likely to do more to improve flow and capacity on roads outside towns and cities than in urban areas, but it may still have some benefit.

11.45 Some authorities have piloted experimental variable mandatory speed limits on road safety grounds. For instance, some authorities have cut speed limits outside schools from 30mph to 20mph when children are arriving or departing. These very low speeds are unlikely to reduce emissions significantly, however, and may actually increase emissions of some pollutants. However, traffic calmed 20mph zones have proved to be very effective in reducing road traffic casualties. Guidance for local authorities on setting appropriate general speed limits was issued in 2006.


11.46 Rail-based park and ride depends on there being enough secure off-street parking at stations. Local authorities also have to consider the capacity of the road network around the station. A further issue is that informal rail-based park and ride can lead to conflict between commuters and residents and increased illegal or inconsiderate parking. Authorities may need to boost enforcement efforts to deal with these side effects. Co-operation between neighbouring authorities is important, as park and ride schemes often originate in one local authority area and terminate in another.


11.47 Buses provide the sustainable mass public transport necessary to support economic growth, accessibility and reduce emissions, meeting the Government's strategic objectives of a wealthier, fairer and greener Scotland. There was a total of 420m journeys made on local bus services in 2014-15. The Bus Action Plan sets out a vision for Scotland to develop a comprehensive bus network where sustainable services are delivered to a high quality. Since the Plan was issued in 2006, a series of bus policy guidance documents has been produced, intended to support improvements in bus services.

11.48 The use of measures such as Statutory Quality Partnerships is being actively taken forward by some local authorities, which can play an important role in improving air quality. Local authorities can also use the planning and traffic management processes to help to increase bus speeds reducing the amount of emissions through the use of increased bus priority.

Scottish Green Bus Fund

11.49 The Scottish Green Bus Fund[17] was launched in 2010 and has provided funding for 209 low emission buses. In 2014/15, £3.7m was awarded to nine operators for 83 vehicles. Transport Scotland is working with local authorities and operators to review and improve the scheme, taking account of technological and market developments since 2010.

Scottish Traffic Commissioner

11.50 The post of Traffic Commissioner is a cross border public authority with both devolved and reserved responsibilities. The Traffic Commissioner enforces good practice from bus service operators, ensuring that services are introduced, varied or cancelled in an orderly fashion. The Traffic Commissioner's responsibilities include the licensing of bus operators and registration of local bus services. Further information can be found on the Traffic Commissioners' website.

11.51 In January 2008, the Public Service Vehicles (Traffic Regulation Conditions) Amendment (Scotland) Regulations came into force. An amendment to the Transport Act 1985 by the Transport (Scotland) Act 2001 allows any local authority to ask the Traffic Commissioner to attach a Traffic Regulation Condition (TRC) to an operator's Public Service Vehicle licence for the purposes of reducing or limiting air pollution. There is a power in the 1985 Act to add, by regulations, new matters that can be covered by TRCs. The 2008 regulations allow the Traffic Commissioner to set TRCs regulating emissions from buses.

11.52 The 2008 regulations have been introduced primarily for addressing poor air quality. In Scotland, all but one of the AQMAs declared to date has been based on transport emissions. In many areas, buses can be a significant contribution to these emissions. A TRC covering emissions standards for buses therefore provides local authorities with an additional measure to be considered as part of an air quality action plan. However, any application made by a local authority to have a TRC imposed must satisfy the Traffic Commissioner that there is a compelling case for doing so.

11.53 The Traffic Commissioner would need to weigh any potential costs, such as a reduced service for passengers if services are withdrawn or rerouted as a result of a TRC being imposed, against the environmental benefits of improved air quality and reduced emissions. A transport authority or bus company with services that are, or will be, operated in the area affected by a TRC can ask the Traffic Commissioner to hold an enquiry.

11.54 The 2008 regulations do not specify how bus emissions should be regulated, but the most straightforward method would be to specify the minimum Euro standard that vehicles affected by the TRC would have to meet. The Scottish Government has produced guidance for local authorities intending to submit an application to the Traffic Commissioner.

Park and ride

11.55 Local authorities need to design park and ride schemes carefully and should see them as just one measure in an integrated transport policy. Without complementary measures such as reductions in town centre parking or pedestrianisation, park and ride may not significantly affect town centre traffic levels. Park and ride with a dedicated bus service may result in fewer cars on the urban network, but more buses. This may increase overall emissions in town centres, especially if the park and ride buses are older models. Overall emissions may also increase if older, higher emitting buses are used on park and ride routes. Park and ride schemes will generally be most successful where:

  • they are some distance from the town centre, ideally where radial and orbital routes intersect;
  • the town centre is served by a number of high quality sites on the outskirts, with lighting, staff, information for users and CCTV; and
  • bus priority measures complement park and ride services, while cars are restricted in the town centre.


11.56 HGVs are required to meet Euro standards and their emissions are regularly tested. In many areas, HGVs can account for a high percentage of total road transport emissions and authorities may wish to consider measures such as freight quality partnerships to tackle this. The Scottish Government actively encourages the transfer of freight from road to rail and water. Further information on freight can be found in Cleaner Air for Scotland.


11.57 Airports operators are responsible for setting up Airport Transport Forums (ATFs), the objective of which is to improve public transport access to airports. They are also responsible for preparing airport surface access strategies (ASAS), which feed into Local Transport Strategies. ASAS should include challenging short and long term targets for increasing the proportion of journeys made to airports by public transport, strategies to achieve these targets and system to oversee implementation of the strategy. ATFs should include representatives from local authorities, transport operators, local people and other interested parties.


11.58 Walking is an ideal activity for both health and transport purposes. The National Walking Strategy[18] was published in 2014 and outlines the Scottish Government's vision of a Scotland where everyone benefits from walking.


11.59 The Scottish Government is keen to increase cycling levels and in 2010 published the Cycling Action Plan for Scotland. Amongst a series of actions, commitments and outcomes, the Plan encourages local authorities to develop cycling strategies as part of their Local Transport Strategies, and to link these with education and health improvement initiatives. It also provides support to local authorities for cycling projects through dedicated allocations for cycling, walking and safer streets projects. Funding for the National Cycle Network in Scotland is provided through sustainable transport charity Sustrans and there is also provision of core funding to Cycling Scotland.

Safer Routes to School

11.60 The Scottish Government has made available to local authorities the Cycling, Walking and Safer Streets allocation to help encourage more children to cycle, walk or take public transport to school instead of private car. The Government has also provided funding for 20mph zones around primary schools and related safety projects, School Travel Coordinator places in all local authorities and the Sustrans Safe Routes to School team. Some local authorities have successfully introduced parking restrictions on streets in the vicinity of schools at the start and end of the school day.


Email: Andrew.Taylor2@gov.scot

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