Scottish Government

G6 Materials, adoption and maintenance

CHAPTER AIMS

• Encourage authorities to adopt a palette of materials which allow for more creative design.
• Show how planting can be included in a street environment.
• Advise on foul water and surface water drainage systems, including the use of sustainable urban drainage systems ( SUDS).
• Provide guidance on accommodating utilities, etc. and planning for maintenance in the long term.

Advise on highway adoption procedures and requirements.

G6.1 INTRODUCTION

G6.1.1 The quality of the environment created by new development needs to be sustained long after the last property has been occupied. This requires good design and high-quality construction, followed by good management and maintenance.

G6.1.2 The latter tasks are commonly the responsibility of the local roads authority, although other public and private-sector bodies can also be involved. It is therefore important that the roads engineers responsible for adoption should be included in all key decisions from the pre-planning stage through to detailed design, as part of a continuous team approach. An overall approach to collaborative working is included within Chapter 3 which discusses the importance of pre-application discussion.

G6.1.3 Details of how planning approval and the adoption process should be better integrated are described in Section G6.7 below.

G6.2 MATERIALS AND CONSTRUCTION

G6.2.1 Developers and local authorities are encouraged to consider the imaginative use of materials, processes or techniques including the use of sustainable/recycled materials where it is appropriate. However there is a need to be mindful of longer term maintenance issues and material availability and therefore early discussion with Local Authorities about adoption of such materials is recommended. This could be supported by Local Authorities adopting as wide as practical palette of suitable local and natural materials, bearing whole-life costs in mind and considering stores of salvaged materials.

G6.2.2 The inflexible application of standard construction details and materials may not be appropriate in new housing layouts. Local authorities should be prepared to allow the use of alternative materials, landscaping treatment and features (Fig. G6.1). However, it is recommended that all materials meet the following requirements:

• easy to maintain;
• safe for purpose;
• durable;
• sustainable (including the manufacturing process and energy use); and
• appropriate to the context

Figure G6.1 The use of good-quality materials achieves a sense of place without leading to excessive maintenance costs.

G6.3 PLANTING

G6.3.1 Planting should be integrated into street designs wherever possible. Planting, particularly street trees, helps to soften the street scene while creating visual interest, improving microclimate and providing valuable habitats for wildlife (Fig. G6.2). Care needs to be taken to preserve existing trees, particularly when changes to a street are planned (Fig. G6.3).

Figure G6.2 Good quality planting softens the street scene (Scottish Government).

Figure G6.3 Existing trees preserved in new development.

G6.3.2 Where trees are to be used, careful consideration needs to be given to appropriate tree selection, their location and how they are planted. Trench planting, irrigation pipes and urban tree soils will increase the chance of trees establishing themselves successfully, thereby minimising maintenance and replacement costs.

G6.3.3 Consideration should also be given to the potential impact of planting on adjacent buildings, footway construction and buried services. Concerns have been expressed by roads authorities regarding the impact that tree roots can have on road drainage - this can be reduced with tree pits (see Fig. G6.4). Detailed advice on this issue is contained in Tree Roots in the Built Environment ¹.

Figure G6.4 Typical tree pit detail.

G6.3.4 Trees and shrubs should not obstruct pedestrian sightlines. In general, driver sightlines also need to be maintained, although vegetation can be used to limit excessive forward visibility to limit traffic speeds. Slow growing species with narrow trunks and canopies above 2 m should be considered. Vegetation should not encroach onto the carriageways or footways.

G6.3.5 Maintenance arrangements for all planted areas need to be established at an early stage, as they affect the design, including the choice of species and their locations. The approval and maintenance of proposed planting within the street boundary will be required to comply with sections 50 and 51 of the Roads (Scotland) Act 1984 ².

G6.3.6 Generally, any planting intended for adoption by a public body should match standards set locally and be capable of regeneration or easy renewal if vandalised. Planting needs to be designed for minimal maintenance. Evidence that buildings and walls have been built with foundations to allow for tree growth may be required.

G6.3.7 The planting of less robust species which require specialist skilled maintenance, or more frequent maintenance visits than usual, are unlikely to be accepted for adoption by the local or road authority and should be avoided.

G6.3.8 Alternatives to formal adoption may require innovative arrangements to secure long-term landscape management. These may include the careful design of ownership boundaries, the use of covenants and annual service charges on new properties.

G6.3.9 Funding for initial set-up costs and an endowment to generate income for maintenance (e.g. executive staff, gardening staff, site offices, equipment, machinery, stores, compost/leaf litter-bins) and community and resident facilities capable of generating regular income, may be appropriate.

G6.3.10 Guidance on planting in street environments includes:

• Roots and Routes: Guidelines on Highways Works and Trees - consultation paper ³;
• Tree Roots in the Built Environment;
• BS 5837: 2005 Trees in Relation to Construction ⁴; and
• National Joint Utilities Group ( NJUG), Guidelines for the Planning, Installation and Maintenance of Utility Services in Proximity to Trees ⁵.

G6.3.11 Further advice on planting considerations is set out in Chapter G.2.

G6.4 RAINAGE

INTRODUCTION

G6.4.1 One of the functions of a street is to provide a route for foul water and surface water drainage (Fig. G6.5).

Figure G6.5 Sustainable drainage systems can form an integral and attractive part of the street ( WSP).

FOUL WATER DRAINAGE

G6.4.2 The majority of streets are designed to accommodate the disposal of foul water from buildings. This will normally take the form of drains around the curtilage of buildings which come under Building (Scotland) Regulations 2004 ⁶ and sewers located in the street where the relevant guidance is found within Sewers for Scotland⁷.

G6.4.3 The adoption process for sewers is set by Section 16 of the Sewerage (Scotland) Act 1968 ⁸. Sewers for Scotland acts as a guide to facilitate the procurement, design, maintenance and adoption of sewers by Scottish Water.

G6.4.4 An important consideration when designing sewers is their siting within the street and the impact they may have on detailed design issues. Advice on these matters is given in Sewers for Scotland.

SURFACE WATER DRAINAGE

G6.4.5 The street provides a conduit for the storage or disposal of rainwater and, by its nature and its impact on the environment, the management of surface water runoff is a more complex matter than dealing with foul water. Forms of sustainable drainage solutions suitable for both private systems or systems adoptable by Local Authority and those adoptable by Scottish Water are set out in The SUDS Manual 2007 ⁹, with the emphasis on the sustainable management of surface water, whereby conveyance is maintained between SUDS features in the traditional sense using pipework and open channels with SUDS features enhancing water quality, amenity and biodiversity, whilst controlling run-off quantity.

G6.4.6 When considering the management of surface water, designers, developers and authorities need to take account of the Planning Advice Note 61: Planning and Sustainable Urban Drainage ( PAN 61)¹⁰ ; Scottish Planning Policy 7: Planning and Flooding ( SPP7) ¹¹ and the Water Environment and Water Services (Scotland) Act 2003 ( WEWS Act 2003) ¹². WEWS Act 2003 transposes the Water Framework Directive to assess, protect and enhance water environments in Scotland, into national law. The Water Environment (Controlled Activities) (Scotland) Regulations 2005 ( CAR) ¹³ have been introduced under WEWS Act 2003 to allow regulatory controls on this matter.

G6.4.7 The planning and management of surface water discharge from buildings and roads requires a co-ordinated approach to evaluating flood risk and developing an integrated urban drainage strategy.

G6.4.8 A Flood Risk Assessment ( FRA) will demonstrate how flood risk from all sources of flooding to the development itself and flood risk to others will be managed at time of design and taking climate change into account. FRA is required for planning applications where flood risk is an issue, depending on their location and size, as set out in sections 33-37 of SPP7, which advocates a risk-based planning approach.

G6.4.9 The responsibility for undertaking an FRA rests with the developer. However, SPP7 advocates a partnership approach, consulting with the relevant stakeholders to compile the FRA. This will involve the Local Authority as flood authority, SEPA and Scottish Water.

G6.4.10 In addition to a Flood Risk Assessment, Sewers for Scotland recommends and some Local Authorities require, that drainage criteria for new development comply with the drainage assessment requirements set out in Drainage Assessment - A Guide for Scotland ¹⁴.

SUSTAINABLE DRAINAGE SYSTEMS

G6.4.11 The term Sustainable Drainage Systems ( SUDS) covers the whole range of sustainable approaches to surface water drainage management. SUDS aim to mimic natural drainage processes and remove pollutants from urban run-off at source. SUDS comprise a wide range of techniques, including permeable paving, swales, detention basins, filter strips, filter drains, ponds and wetlands. To realise the greatest improvement in water quality amenity and biodiversity and flood risk management, these components should be used in combination, sometimes referred to as the SUDS Management Train, as described in The SUDS Manual.

G6.4.12 SUDS are more sustainable than conventional drainage methods because they:

• manage runoff flow rates, using infiltration and the retention of storm water;
• protect or enhance the water quality;
• are sympathetic to the environmental setting and the needs of the local community;
• provide a habitat for wildlife in urban watercourses; and
• encourage natural groundwater recharge (where appropriate)
• can assist in reduction or removal of drainage network constraints.

They do this by:

• dealing with run-off close to where the rain falls;
• managing potential pollution at its source; and
• protecting water resources from pollution created by accidental spills or other sources.

G6.4.13 The use of SUDS is seen as a primary objective by the Government and should be applied wherever practical, and technically feasible. Granting of Planning Consent will be dependent on agreement between the local planning authority and SEPA, as statutory consultees. It will be a SEPA requirement that sufficient levels of SUDS are provided.

G6.4.14 Detailed guidance on SUDS is contained in The SUDS Manual and Sewers for Scotland. All stakeholders need to be aware of the importance of the application of SUDS as part of an integrated urban drainage strategy for a development.

G6.4.15 Adoption issues will need to be clarified at an early stage in the design process, with the likely adopting authorities; Scottish Water, Local Authority and potential private bodies. The draft amendments to Section 7 of the Sewerage (Scotland) Act 1968 have been published for consultation to Local Authorities, focusing on adoption of SUDS at a regional level by encouraging a collaborative approach to shared systems between Local Authorities and Scottish Water. It is important for a continuous team based approach to this matter.

G6.4.16 New guidance is currently being developed by the SUDS Working Party, including representatives of SEPA, Scottish Water and Local Authorities regarding acceptable forms of SUDS to be applied to roads. The new " SUDS for Streets" guidance is due for publication in mid 2009 and until its introduction it is important that early discussion is held with those bodies on SUDS requirements.

G6.5 UTILITIES

G6.5.1 Most residential streets provide routes for statutory undertakers and other services. Detailed advice on providing for utilities in new developments can be found in NJUG Guidance ¹⁵ and Local Authority Guidelines.

G6.5.2 It is best to liaise with the utility companies when the layouts of the buildings and streets are being designed. In nearly all cases this should be prior to making the planning application. Where streets are to be adopted, it will be necessary to ensure that any legal documentation required by the utility companies is completed as soon as is possible.

G6.5.3 Similar principles apply to streets that are to remain private. It is important that the rights of access to the development by utility companies are set out in the factor/ management company's obligations. Residents will need to be made aware of these rights.

G6.5.4 The availability and location of existing services should be identified at the outset. The requirements for new apparatus should be taken into account in the layout and design of the streets and a balance should be struck between the requirements of the utility companies and other objectives. The locations of any existing trees or shrubs and proposals for new planting, will require special consideration.

G6.5.5 Where possible, all utility apparatus should be laid in 'corridors' throughout the site. This will facilitate the installation of the services and any future connections as the development proceeds. Consideration should be given to the use of trenches and ducts to facilitate this.

G6.5.6 In designing for utilities, there are advantages in developing streets along reasonably straight lines rather than introducing gratuitous bends and curves (see Section G4.4 regarding the control of traffic speeds). This practice will assist in simplifying utility runs, with a corresponding improvement in the efficient use of land and a reduced need for inspection chambers.

G6.5.7 There have been problems with service strips where residents have not been aware of them. In addition, service strips can be unsightly and limit opportunities for planting. As an alternative, placing apparatus in the road may be acceptable on well-connected networks, as traffic can be routed around a point closure if it is necessary to excavate the carriageway for maintenance ( Please note discussions are continuing with SJUG and RAUCS on this matter - the results of these may be known in time for final draft).

G6.5.8 In shared surface areas, such as in some Home Zones, the routing of services will require careful consultation between designers, utility companies and the roads authority. Guidance on this can be found in RAUCS Advice Note 10. ¹⁶ This consultation should take place at an early stage in the planning and design process. Although it may be necessary to route services in the vehicle track in some places, as noted above this may not be a significant problem on well-connected networks.

G6.6 ARRANGEMENTS FOR FUTURE MAINTENANCE

G6.6.1 It is important that the future maintenance arrangements of the streets and public spaces in a development are decided early in the design process. If the streets are to be adopted by the local roads authority, the layout and material choices need to be acceptable to the authority.

G6.6.2 It is possible for streets to remain private but a properly-constituted body with defined legal responsibilities will need to be established to maintain the streets to the common benefit of residents. Further guidance on factor/management companies is given in Section G6.9.

G6.6.3 A road authority will require legal certainty that the streets are going to be properly maintained in perpetuity by these private arrangements. Approval for construction of new private streets will be required under sections 17 and/or 21 of the Roads (Scotland) Act 1984 ¹⁷,and under Section 13 of this Act The Local Roads Authority has powers to require a private road is maintained at a reasonable standard (as set by them).

G6.6.4 A roads authority may be unwilling to adopt items such as planting and street furniture (e.g. play equipment and public art) which are not considered to relate to the movement functions of the street. If there is no private management company, arrangements can be made for such features to be maintained by another Local Authority department.

G6.6.5 In these circumstances the developer must ensure that there is agreement between the adopting party as to:

• which authority is best able in practice to take day-to-day responsibility for each element of planting and/or non-street-related furniture;
• the future maintenance responsibilities, obligations and liabilities arising from such planting, street furniture etc.; and
• the apportionment of these contributions among the authorities concerned in the light of the apportioned responsibilities/ liabilities.

G6.7 ROADS ADOPTION - LEGAL FRAMEWORK

G6.7.1 Provision of roads for new developments is controlled and consented by the local roads authority through the Roads Construction Consent ( RCC) process, governed by Section 21 of the Roads (Scotland) Act 1984.

G6.7.2 Under the terms of the RCC, the developer is obliged to construct the streets, over which there is a public right of passage, to an agreed standard, having first secured technical approval of the designs from the roads authority. Expenses will be payable by the developer to the roads authority to cover its reasonable costs in inspecting the construction of the works and associated testing.

G6.7.3 The Roads Scotland Act sets out the obligations of the developer to construct the streets and maintain them for a set period normally 12 months. Following the satisfactory discharge of these obligations, the new streets can be offered to the roads authority for adoption. If the road is adopted it will in the future be maintainable by the roads authority.

ROAD BOND SECURITY

G6.7.4 Where Roads Construction Consent is granted relative to roads associated with housing development the granting of the consent will require the deposit of sum or surety (Roads Bond) sufficient to meet the cost of constructing the road ¹⁸. The purpose of this bond is to enable the roads authority to meet the cost of constructing or completing the construction of the roads, should the developer fail in his responsibility to do so under the terms of the granted RCC.

G6.7.5 Before any roads works commence on such a housing development the developer will normally be required to have both the Roads Construction Consent and the Roads Bond in place. However under the provisions of Section 17(3) of the Act it is permitted to exclude particular classes of dwelling house from the requirement to provide in Roads Bond and it may be that local roads authorities would apply this exclusion to social housing projects.

G6.7.6 Thus, before any construction begins, the developer will normally be required either:

• to secure the payment of the estimated cost of the road works under the requirements of the Roads (Scotland) Act.
• to make an agreement with the road authority under terms of the Act and provide a Bond of Surety.

PRIVATE STREETS

G6.7.7 Where a developer wishes the streets to remain private, some roads authorities have incorporated conditions into the planning approval to require the developer to design, construct and to make arrangements for the future maintenance of the new streets to a standard acceptable to the authority. This agreement may still require the submission and approval of an RCC under the terms of Section 21 of the Act.

G6.7.8 Such a planning obligation will still require the developer to provide a road bond, or other security, under Section 17 of the Act, to the council to guarantee that provision is in place to ensure satisfactory completion of the new streets.

WHAT IS ADOPTABLE?

G6.7.9 The roads authority has considerable discretion in exercising its powers as to whether to grant a roads construction consent under Section 21 of the Act. There are other mechanisms contained in the Act which help to define the legal routes to approval and adoption.

G6.7.10 Section 21 of the Act allows applicants to appeal local roads authority decisions on refusal of or application of conditions to RCC decisions.

G6.7.11 A roads authority can be required to adopt a street constructed in accordance with an RCC. The streets put forward for adoption must be constructed to the agreed standard and will be subject to a 12 month period of use as a road whilst being maintained to the agreed standard by the developer.

G6.7.12 The Local Roads Authority may, under the terms of Sections 13 to 16 of the Act, either require the frontagers of a private road to make up and maintain the road to a set reasonable standard, or on application by, or with the agreement of, the requisite number of frontagers add (or delete) a road to (from) their "List of Public Roads", again subject to the road being made up and maintained to a set reasonable standard.

G6.7.13 Roads authorities have also tended to only adopt streets that serve more than a particular number of individual dwellings or more than one commercial premises. Two to three dwellings is often set as the lower limit, but some authorities have set figures above this.

G6.7.14 There is no statutory basis for the lower limit on the number of dwellings justifying adoption. The use of two to three dwellings as a criterion may have come from the notional capacity of private service supplies (gas, water, etc.) and public servicing of the dwellings by delivery agencies etc. It is not desirable for this number to be set too high, as this would deny residents of small infill developments the benefit of being served by an adopted street. It is recommended that roads authorities set a clear local policy on this issue.

G6.7.15 In exceptional circumstances where it is not intended that the street will be constructed as a road then the roads authority still has a role for ensuring appropriate design in accordance with its role as a consultee in the planning process.

G6.8 DESIGN STANDARDS FOR ROAD CONSTRUCTION CONSENT

G6.8.1 The roads authority has considerable discretion in setting technical and other requirements for a new street. Concerns have been raised over the rigid adherence to these requirements, leading to refusal to adopt new streets. This issue was explored in England in the report Better Streets, Better Places¹⁹ and in Scotland in the research work underpinning PAN76: Residential Streets²⁰.

G6.8.2 Roads authorities are now encouraged to take a more flexible approach to road adoption in order to allow greater scope for designs that respond to their surroundings and create a sense of place. It is recognised, however, that roads authorities will need to ensure that any future maintenance liability is kept within acceptable limits.

G6.8.3 One way of enabling designers to achieve local distinctiveness without causing excessive maintenance costs will be for roads authorities to develop a limited palette of special materials and street furniture. Such materials and components, and their typical application, could, for example, be set out in local design guidance and be adopted as a Planning Policy, or within a Local or Structure Plan.

G6.8.4 Developers should produce well-reasoned design arguments, and articulate these in a Design Statement (where required), particularly if they seek the adoption of designs that differ substantially from those envisaged in a local authority's design guide or Designing Streets. However, provided it can be demonstrated that the design will enhance the environment and the living experience of the residents, and that it will not lead to an undue increase in maintenance costs, then roads authorities should consider responding favourably.

G6.8.5 Drawings should indicate which parts of the layout the developer expects to be adopted and how the adoption limits are to be differentiated on the ground. Widths and other key carriageway dimensions, and the location and dimensions of parking spaces, should also be shown, together with full details of all planting.

G6.8.6 Roads authorities would be expected to approve street layouts complying with their Design Guide which have been constructed in accordance with the roads authority's specification of works. They would normally be expected to adopt:

• residential streets, combined footways and cycle tracks;
• footways adjacent to carriageways and main footpaths serving residential areas;
• Home Zones and shared-surface streets;
• land within visibility splays at junctions and on bends (in some cases);
• trees, shrubs and other features that are an integral part of vehicle speed restraints;
• any verges and planted areas adjacent to the carriageway;
• structures, i.e. retaining walls and embankments, which support the road or any other adoptable area;
• street lighting;
• gullies, gully connections and road drains and other road drainage features;
• on-street parking spaces adjacent to carriageways; and
• service strips adjacent to shared surface streets.

G6.9 PRIVATE MANAGEMENT COMPANIES/FACTORS

G6.9.1 Any unadopted communal areas will need to be managed and maintained through private arrangements. Typical areas maintained in this way include communal gardens, shared off-street car parking, shared cycle storage, communal refuse storage and composting facilities and sustainable energy infrastructure.

G6.9.2 Where a private management company is established, it is desirable for residents to have a strong input into its organisation and running in order to foster community involvement in the upkeep of the local environment.

G6.10 APPROVAL PROCESSES FOR NEW STREETS

G6.10.1 The design and approval of new streets is governed by both planning and roads legislation. The design process must therefore recognise both sets of requirements. The Roads (Scotland) Act 1984 is the primary legislation for new roads, and all new roads must receive RCC under Section 21 of that Act prior to construction. Previous practice applied by most Local Authorities dictates that the formal RCC approval process only starts with the granting of detailed planning consent, or at least with the agreement of the final planning layout. The process thus results in a 2-stage (planning and roads) approval process that not only significantly extends the overall statutory approval process and delays commencement of development construction, but by more rigid application of engineering requirements at this 2nd stage can lead to a dilution of overall design quality.

G6.10.2 Designing Streets requires an integrated approach to approval, involving collaboration between planning officers and RCC engineers. In this way, roads colleagues will be satisfied with the fundamentals of the development proposal, and can approve it in principle concurrent with the granting of planning permission. RCC engineers will have an important role to play as a consultee in the planning application process. It is as a consultee that the roads authority can ensure that an appropriate 2-stage approach is adopted. The roads authority should be satisfied that sufficient information has been provided with the planning application to ensure that a subsequent RCC reflecting the design will not alter the details approved under the planning permission.

G6.10.3 Streets perform several functions and many agencies have a role to play in their design, approval and maintenance. It is vital that there is an early and continued, dialogue between the principal stakeholders i.e. developers, their consultants, planners, road engineers and a range of others including public transport operators, utility companies, the emergency services, drainage and waste authorities. These discussions should take place as early as possible - before a layout is worked up and a planning application submitted.

G6.10.4 Some Local Authorities operate a development team approach whereby all of the departments with an interest in street design work together during the design and approval process. This has clear advantages and is to be strongly encouraged.

G6.10.5 Planners and engineers should take a consistent approach to street design throughout all stages of the design process. A collective decision at the earliest opportunity provides certainty. The principles agreed could then be written into a development brief. This can then be used as a tool to help initial consultations with developers in guiding layout design, obtaining planning consent, receiving RCC, checking construction and finally achieving adoption. It is important that any principles that have been agreed at a point in the design process are not revisited later, unless there has been a significant change in circumstances.

G6.10.6 Planning policies should set the overall benchmark for the design quality of any new development, which includes the new streets as a key part of the public realm. This is why Local Authorities should have specific planning policies on street design ideally within the development plan, or as Supplementary Planning Guidance (See the Case Study on the East Lothian Council guidance). Planners and road engineers should work together to ensure policies are up to date and allow for the most appropriate street patterns.

G6.10.7 The flow chart contained in Chapter 3 shows how a more integrated system should operate, and the key design decisions which would need to be taken, and signed off, at each stage.