Digital telecommunications: planning guidance

4 Siting and design factors

4.1 This chapter explains the benefits of carefully planning and designing proposals for digital infrastructure and the steps involved.

The paragraphs include references to technical terms so you may find it beneficial to read in conjunction with Annex B of this guidance which provides a basic technical summary of how digital communications and fixed line networks operate. NatureScot standing advice on planning consultations for telecommunication masts in National Scenic Areas, National Parks and Wild Land Areas may also be helpful.

General principles

4.2 The Scottish Government’s national planning policy is intended to encourage, promote and facilitate the roll-out of digital infrastructure, including fixed line and mobile connectivity, across Scotland.

4.3 As set out in NPF4, development proposals will be supported where the visual and amenity impacts of the proposed development are minimised through careful siting, design, height, materials and landscaping, taking into account cumulative impacts and relevant technical constraints. Infrastructure which is carefully planned from an early stage of the development process can mitigate adverse impacts and is vital in fulfilling policy aims. There should be no physical obstruction to aerodrome operations, technical sites, or existing transmitter/receiver facilities e.g., minimum antenna operating heights.

4.4 Good siting and design principles should not only be respected in sensitive areas but should be applied to proposed development across all areas of Scotland. This can create better places in which we live and work and help to make development acceptable to communities.

4.5 A range of constraints can affect site selection and the siting and design of electronic communications equipment, including:

• terrain or topography affecting radio coverage and wireless radio transmission backhaul.
• natural and historic environment considerations.
• capacity in urban areas where the data usage is in high demand.
• relationship with the landowner.
• availability and cost of access to the site and a power connection.
• availability of fibre to provide transmission links to the surrounding network.
• potential need for additional equipment may be needed where there is no clear line of sight (LOS) as objects and obstructions in way can cause signal weakness, resulting in slow and unpredictable service.
• radio frequency and compliance with ICNIRP (see paragraphs 4.6 and 4.7)

Protection from exposure of radio frequency electromagnetic fields

4.6 It is a statutory requirement that applications for planning permission or prior approval should be accompanied by a declaration that the development, if it involves the construction of one or more antennas, has been designed to operate in full compliance with the requirements of the radio frequency public exposure guidelines of the ICNIRP. This aims to protect people and the environment against adverse effects of non-ionizing radiation.

4.7 Public compliance is determined by mathematical calculation and implemented by careful location of antennas, access restrictions and/or barriers and signage as necessary. Members of the public cannot unknowingly enter areas close to the antennas where exposure may exceed the relevant guidelines regarding public access.

Site sharing

4.8 The Electronic Communications Code (Conditions and Restrictions) Regulations 2003, as amended, (“the Code Regulations”) require an operator to share the use of electronic communications apparatus, where practicable. Site sharing minimises the number of sites required and reduces proliferation. In the light of this, operators have site sharing arrangements with each other and with the wholesale infrastructure providers. They also have similar arrangements with the utilities and some large landlords.

4.9 When operators are seeking to deploy new sites, they will therefore look first at maximising site sharing opportunities and facilitating prompt delivery without the need to search for new parcels of land and to have to enter into potentially lengthy negotiations and legal agreements on an individual basis. These potential sites may offer additional benefits, such as having existing or ready access to a power supply, access to fibre or an existing vehicular access. Sharing will often enable quicker and more economic installation and, subject to requirements, additional equipment may be undertaken under PDR.

4.10 The Scotland 5G Centre’s Infralink toolkit can help to facilitate the process of facilitating site sharing on public assets. Comprising standard leases, wayleaves and pricing guidance, Infralink focuses on making the process of siting and operating mobile network equipment easier and faster. The toolkit is freely accessible at Home - Scottish Futures Trust – Infralink

Installing the smallest suitable equipment, commensurate with technological requirements

4.11 Although operators will aim to install apparatus providing the optimum radio solution, appropriate alternatives should also be considered. For example, for a new mast located on a public road, instead of a lattice mast with headframe and exposed antennas, a slimline pole with tightly packed antennas within a shroud may be preferred.

4.12 Small cell technologies (such as microcells and picocells – discussed at Annex B) usually consist of small antennas. These do not look dissimilar to an alarm box on buildings and can be installed on other structures in built-up environments like street lighting columns. These are not a replacement for a base station, as they can only provide coverage and capacity over small areas, such as individual streets and buildings. They compliment the existing macro network, improving capacity or covering partial not spots, particularly, though not exclusively, in urban areas and the use of 5G technology.

Concealing or disguising equipment

4.13 Operators can use techniques or design solutions that help to camouflage or conceal equipment in order to minimise visual impact. This practice is encouraged wherever appropriate. However, using certain techniques can come with compromises in radio performance and so may not be achievable in all circumstances and/or may lead to the requirement for additional base stations. In addition, some camouflaging techniques can present bulkier and more obtrusive features, where the existing pole mounted antennas may represent a slimmer design requiring less support bracketing and ancillary support equipment.

4.14 Antennas may also be effectively concealed by similar methods. These can include features such as:

• flagpoles
• slimline poles or telegraph pole style designs
• church towers (generally behind louvres).

4.15 These techniques may not be appropriate for larger antennas or where ancillary development needs to be located around the antennas, in the case of 5G, solutions intended to conceal the development may have limitations where they add to the overall massing of apparatus and increase wind loading.

4.16 When a base station is upgraded, there may be a need to install additional antennas and equipment onto the site – this can result in increased height and width and possibly an increase in the footprint. Upgrading an existing base station is important because each one creates the parameters for the neighbouring stations; where the impacts of additional or larger equipment are not acceptable, another base station will need to be found to house the additional equipment.

New ground based mast

4.17 Should mast or site sharing not be possible then land suitable for a new ground-based mast is sought.

There are two main stages in the operator’s site selection process.

1. The operator uses computer-based radio planning tools (or increasingly user evidence) to identify gaps in coverage, then predict levels of signal strength and coverage from nominal locations to fill these gaps. This analysis includes both geographic coverage gaps and capacity gaps or ‘bandwidth’.

2. The operator looks at specific options to fill the gap(s). This starts with the operator identifying a specific area of search within which a number of alternatives may be suitable. However, within this search area, topography, physical features and existing development can limit siting options and design solutions. The search for a suitable site also takes into account local development plan requirements, landscape character, natural and historic environment considerations and visual and landscape impacts.

4.18 Whilst mast sharing or use of other infrastructure should always be considered, it may not be an appropriate environmental or technical solution in all cases. Whilst the overall landscape, visual and other impacts (e.g., peat and archaeology), of a network is minimised by mast sharing, localised visual impact may not be. Alternatives to mast sharing may sometimes be preferable – for example, where additional equipment would lead to clutter, detract from the aesthetics of the existing installation, or increase the structure height to an unacceptable level. Other constraints on mast sharing could include:

• coverage problems: the existing mast may be poorly located or of insufficient height to give the required coverage. Where multiuser third party sites originated for other purposes, such as utilities management and other forms of broadcast, these may not be optimum locations for radio coverage.
• radio interference: in many cases, antennas need a set amount of vertical separation. This may result in an increased height of a mast.
• structural loading: the existing mast may not be able to safely hold extra equipment. The existing mast may need to be strengthened or replaced with a larger structure, which could affect visual amenity.

4.19 There are many ways that the environmental, landscape and visual impact of a ground-based mast can be mitigated. These include:

• placing a mast close to similar structures. Visual impact can be lessened by siting masts in locations that already contain engineered forms and structures such as industrial and commercial premises or major road junctions where road signs, lamp posts and traffic lights are present.
• placing a mast in or adjacent to existing trees, which may include planting trees to help integrate it in the landscape. This option is likely to be more feasible in or near wooded areas. Care should be taken to avoid the unnecessary loss of existing trees and siting outwith the crown of the tree should be sought. In addition, it should be borne in mind that antennas would need to be located above the tops of the trees to operate effectively (with allowance of future tree growth for non-mature trees). NPF4 Policy 6 has an intention to protect and expand forests, woodland and trees, reflecting Scottish Forestry’s Control of Woodland Removal Policy.
• where no visual screening is available, slimline lattice masts may be the most effective design solution. Their light-permeable structure can help to reduce the visual mass and bulk of the development. Locations where the mast can be backdropped by topography in main views are preferred.
• appropriate colouring – for example, masts that are most often viewed against the sky, are best left with a galvanised finish or coloured pale grey. Against a wooded backdrop, colouring the equipment a matt green or brown colour could be more appropriate.

Equipment housing cabinets

4.20 Equipment housing cabinets can range in size from small street-side cabinets to purpose-built buildings which can contain apparatus for a number of operators. These are needed at every base station to support networks. They need to be located as close as possible to antennas, to reduce feeder loss through the connecting cables, and must be of sufficient size to allow for air circulation to reduce the potential of equipment overheating.

4.21 The cumulative impact of cabinets can be significant, especially when located on pavements or other areas of ‘public road’. The cabinets should be coloured to blend in with its surroundings and, where appropriate, screened with landscaping and/ or planting.

Equipment compounds

4.22 With the exception of street pole installations (apparatus sited by statutory undertakers), fencing is normally required around ground-based masts and equipment housing. The scale of fencing required is dependent on the location. In urban areas, higher fencing may be required. In all cases its form and colour should be appropriate to the setting. In rural areas, there may be no need for fencing, or a post and wire stock proof fence may suffice. Security measures should be appropriate to the circumstances.

4.23 The impact of an equipment compound can be minimised if the compound is unsurfaced or by using natural surface material appropriate to the landscape’s character. In some cases, the equipment can be attached directly to solid rock where it is exposed at surface level. Any hard surfacing should be permeable and kept to the minimum necessary. Compound enclosures will need to reflect local requirements - high palisade or chainlink fencing may be needed where security is an issue, timber stock proof or deer proof fencing may be suitable in some cases, and in other situations where locations are visually sensitive drystone walling may be utilised. Planning authorities should discuss appropriate options with the applicant.

Access Tracks

4.24 Access is required in order to build and maintain base stations. This can be a constraint in some locations due to a combination of soft ground, topography and the large heavy machinery needed to bring in the apparatus and construct the base station. Access tracks can also be vital for resilience reasons - some remote sites are backed up by generators for when power sources fail. At such times, when connectivity is most needed (e.g., during extreme weather), any maintenance may not be possible without an access track.

4.25 Frequent use by vehicles on wet or soft ground can itself lead to deep rutting, particularly where several operators are sharing a mast or site with hydrology impacts leading to significant ‘scouring’. In these circumstances, the construction of a new access may be less harmful. ^[5]NatureScot’s good practice guide, ‘Constructed Tracks in the Scottish Uplands’ aims to increase understanding and awareness of the natural and historic environment impacts of track construction, management and use. The impact of a new access track can be reduced by:

• relating it to field boundaries and other features.
• following the boundaries of natural vegetation.
• following the contours of the land and fitting with the landscape.
• addressing land drainage issues.
• redressing all cuttings and banks with the existing indigenous vegetation stripped along the route.
• avoiding adverse impact on historic environment assets.
• using appropriate surface materials and greening of tracks.

4.26 Proposals should be designed and constructed in line with NPF4 Soils Policy 5. This will include following the mitigation hierarchy by first avoiding and then minimising the amount of disturbance to soils on undeveloped land and in a manner that protects soil from damage including from compaction and erosion and that minimises soil sealing. For the design and construction of temporary and permanent access tracks, best-practice should be followed, informed by site survey data (e.g., peat depth surveys). Mitigation measures include avoiding areas of deep peat and use of bog matting and low-pressure vehicles to minimise disturbance, floating tracks, appropriately designed cut batters and ensuring verges are quickly re-vegetated.

Ancillary equipment

4.27 Ancillary equipment can include handrail, ladders, fences, steps and ramps. These ancillary elements are often installed under PDR and their appearance and location may be defined by health and safety requirements. Where possible, the impact of ancillary equipment can be reduced by:

• installing equipment in areas that are inconspicuous.
• keeping equipment to the minimum and as uncluttered as possible.
• avoiding contrast with or compromising architectural detail to minimise impact.
• concealing equipment or exploiting architectural detail to minimise impact.
• colouring equipment to blend in with background.

Installation on buildings or other existing structures

4.28 Operators need to bear in mind the height, scale and architectural style of the building or structure when considering the appropriate design of the equipment to be used. Particular attention will need to be given when considering installing equipment which may affect the fabric or setting of historic environment assets (paragraphs 4.44 to 4.47 refer). Developments in designated areas may require other consents in addition to planning permission and PDR such as listed building consent. When placing equipment on existing buildings or structures, operators should aim as far as is practicable for development to:

• keep in proportion to the building or structure.
• respect architectural style.
• have minimal impact above the roofline as far as practicable.
• minimise impacts on important views and skylines.
• avoid creating excessive clutter.
• minimise fixings and other physical impacts on the building fabric.
• use clean lines and maintain symmetry.
• be coloured to correspond with the background or to reduce contrast.

4.29 A variety of solutions may apply, to minimise the visual impact e.g., placing equipment below a roofline or against existing rooftop structures, such as a plant room, and colouring it to match. Where possible, positioning equipment in a group with symmetrical order can help achieve a balanced composition.

4.30 New technologies can have different radio characteristics and, in order to meet ICNIRP guidelines, antennas may need to be located above a building’s roof or may not be capable of being, for example, face mounted. To accommodate more technologies and more frequencies, more ancillary apparatus to support antennas may be required – this apparatus generally needs to be close to the antennas to limit signal loss. These technical considerations will need to be taken into account in the assessment of planning applications.

Urban Areas

4.31 In urban areas, increased call and data transfer volumes put high demand on the capacity of networks, potentially leading to the need for more infrastructure.

4.32 Antennas on tall buildings often cannot reach the street immediately below due to the shadowing of the building itself. The roofscape of a whole town or city needs to be considered in planning a network within a dense urban area with mixed roof heights. Thick stonework and other building materials can inhibit signal strength within buildings and in lower floors such as basements. All buildings can block radio signal from antennas on adjacent buildings and street level antennas may not provide coverage to the taller surrounding buildings.

4.33 The way in which the 5G radio network operates means that additional elements of equipment are required to combine and regulate the interplay between the antennas and the radio equipment. This combined with the apparatus providing 2G, 3G, and 4G services, will lead to apparatus which may be significantly taller and have a greater visual impact than the networks which went before.

4.34 Most new apparatus will be concentrated in urban areas, where user demand is greatest. Areas that already have engineered forms and structures usually offer the best opportunity for siting equipment. However, these options may not always be available within the operator’s coverage, or search, area. Less visually sensitive areas where the use of standard equipment may be more readily acceptable could include:

• industrial areas
• commercial buildings and business parks
• traffic junctions
• land close to railway lines
• land adjacent to main roads
• pylons
• telephone exchanges

4.35 Where located in suburban or residential areas, larger new masts should, where possible, be located away from direct views from main habitable windows. In these areas, operators often install smaller apparatus on roadsides and pavements as this represents the best balance of radio coverage and environmental and visual impacts.

Rural and Remote Rural Areas

4.36 ‘Not spots’ (both total and partial^[6]) can, and are more likely to, occur in remote locations. Historically, the operators have provided coverage to population centres, as this made more commercial sense. This has left large areas and dispersed communities with little in the way of mobile coverage. There are also large unpopulated areas where there may be no population but there are visitors and those travelling through on road or rail. Furthermore, the Scottish and UK Governments both aspire to have ubiquitous coverage because mobile broadband is a facilitator technology, and it is needed in these areas for interconnections via the internet of computing devices embedded in everyday objects. This enables technology to send and receive data to serve various applications (for example for agriculture, tourism, emergency services, monitoring protected species, air quality, applications for drone guidance etc). The Shared Rural Network (SRN) has been instigated to deal with both these total and partial not spots.

4.37 The often rugged and mountainous topography of rural Scotland adds to this challenge and signals can be blocked by hills and forests. Adding to the problem of receiving coverage from base stations is how the data is linked back into the network (backhaul). A lot of rural areas have no existing fibre infrastructure and the lack of existing masts, combined with topography, can make LOS between masts difficult to achieve. Likewise, easily accessible power also introduces complexity and expense in the provision of coverage in rural areas. This will have implications for the siting and appearance of new masts, where taller masts are expected but that should reduce the overall number of sites that may otherwise be required in some sensitive landscapes.

4.38 Whilst ground-based masts will be essential to provide these services, the landscape quality of rural areas can be damaged by insensitively sited electronic communication installations. The impact can be heightened where equipment can be seen over long distances. Understanding an area’s landscape will help in designing sensitive proposals. Landscape sensitivity is a measure of the ability of a landscape to accommodate change arising from specified types of development or land management. Landscape Character Assessments covering the whole of Scotland are available from NatureScot and can be used to inform sensitivity studies where relevant.

4.39 For equipment cabinet in rural areas, existing landscape features such as planting or rocky outcrops can provide effective screening.

4.40 Often the way to provide power to a remote location is by installing new overhead powerlines, but this will usually add to the landscape impact and in forested areas it will require maintenance of a clear corridor. When choosing a location close to a sensitive site e.g., SSSI, consideration should be given to any underground trenching work required. Impacts on the historic environment as a result of overhead or underground provision should be understood and mitigated. Planning authorities should be aware that power lines are often installed by electricity suppliers exercising their own PDR.

4.41 Another option in rural areas, often for resilience purposes, is to use a generator, though refuelling and maintenance will add to the operator’s costs and where there is no access track, all-terrain vehicles can cause erosion, through operators typically visit sites for maintenance rarely and try to reduce this as much as possible. Ideally, a generator should be sited where it can be refuelled from an existing road or access track and connected by cable to the base station. The installation of a generator should comply with the design standard set by The Water Environment (Oil Storage) (Scotland) Regulations 2006.

4.42 In areas where a permanent mains power source is not achievable then solar arrays may be used as the primary power source to power base stations. In comparison to the mast these are relatively low profile pieces of infrastructure that typically site within the telecoms base station compound. Power via solar arrays usually works in tandem with a long-life battery and a back-up generator so that the base station can remain operational at times of low sunlight. The solar arrays can drip re-charge a battery (as will the generator) and, between them, significantly reduce the time a backup generator may need to be running.

4.43 Power via solar array has many benefits. This is a renewable power source so significantly reduces the carbon footprint of running a base station. It can negate the need to impact a landscape by using overhead power lines or underground trenching and it will significantly reduce the need to visit a site to refuel the generator, as the vast majority of the power will be supplied via the solar power and battery meaning the generator is only running by exception.

Historic Environment

4.44 NPF4 recognises the social, environmental, economic value and cultural identity of the historic environment. The planning system should protect and enhance the care and protection of the historic environment including listed buildings, scheduled monuments, conservation areas, historic gardens or designated landscapes, world heritage sites and historic battlefields, as well as non-designated heritage assets.

4.45 Historic Environment Scotland, as a statutory consultee in the planning process, provides specialist advice and should be involved in certain circumstances, which may include pre-application discussions. The Historic Environment Policy for Scotland (HEPS^[7]) should be taken into account whenever a decision will affect the historic environment.

4.46 Potential impacts on historic assets and places need to be balanced against the benefits that increased coverage brings – at both the local and national level. Where possible, site selection processes should avoid historic environment assets (and their settings). However, where this is not possible, any detrimental impacts should be minimised. This could include the use of micro-siting or alternative design options. Locations with heritage designations, however, should not be subject to poor connectivity simply because locating equipment there may require non-standard equipment and creativity in deployment approaches. Appropriate archaeological mitigation strategies may be required to address impacts on some sites. Information and advice should be sought from the relevant local authority, and Historic Environment Scotland where appropriate, at the outset.

4.47 It is an offence to carry out works to listed buildings or scheduled monuments without first obtaining the necessary consents. Any impacts on their setting must also be considered as part of the site selection and design process. Further information on these consents is available from Historic Environment Scotland: Applying for Consents | Historic Environment Scotland | History.

Public Roads

4.48 As statutory undertakers, operators benefit from rights within The New Roads and Street Works Act, as amended by the Transport (Scotland) Act 2005, supported by relevant Regulations and Codes of Practice for all ‘works in roads’ in Scotland. They can install and maintain equipment on public roads. In areas where there are no suitable buildings or land available for the installation of communications infrastructure e.g., suburban and residential areas, the option of installing equipment on the public road is often pursued. Engagement with the roads authority will allow for safety issues to be considered.

4.49 A standard ‘street works’ style installation would generally comprise a slimline mono-street pole with antennas and associated ground-based equipment cabinets. All streetworks equipment installed on the public road should comply with the necessary visibility splays and ensure that sufficient footway width remains to allow safe movement by the public.

4.50 Operators must comply with any conditions on planning permission or on PDR requiring the removal of redundant equipment, and in any event should ensure that apparatus which is no longer in use is removed as quickly as possible after it ceases use. The land should be restored to its condition before the development took place, or such other condition as is agreed between the operator and the planning authority. This helps to avoid the proliferation of unnecessary clutter in the street scene.