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Polnoon Masterplan: Idea to Design - Residential Streets Project

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6. Lessons

  • Home truths: How easy was this to do?
  • Timing: How long did it take?
  • Team perspective: How was it for you?
  • Bottom line: Cost and construction?
  • Future: What are the recommendations?

red amber green graphicHome Truths

How easy was this to do?

In order to succinctly capture what was hard to achieve, caused most debate or was relatively easy, during the course of the project. A simple red, amber and green 'traffic light' approach has been used but the whole process has been about learning and all 6 rules which were established at the start of this process have been achieved.

red graphicHard to achieve

Planning

Materials

When selecting the materials for the houses, a team meeting was held and a range of materials were exhibited. Whilst most of the team were in agreement, a difference of opinion between the planners became apparent. The crux of the issue highlighted a key difference between the previous and the proposed development. With the previous application, the standard house types located in the Conservation Area of the site had been conditioned with natural materials (such as natural slate, natural stone, wet dash render, timber sliding sash and casement windows), with the remainder of the site in artificial materials (such as concrete tiles, PVC and casement look-a-like windows and artificial stone). In contrast, the proposed development, rather than distinguishing between those houses within the Conservation Area, and those outwith, raised the quality of materials across the whole site. After significant discussions, it was agreed that the new solution offered a better quality environment rather than creating a 'front' and 'back' to the development.

Role of councillors

With this project, at the pre-committee meeting, some councillors did require more explanation about the masterplan. As a result, the application was pulled from the forthcoming committee, further plans were provided, together with a meeting with the Head of Roads, Planning and Transportation, but thereafter some minor amendments were made and the application then went forward to the following committee meeting.

Road Construction Consent

Road Design levels

An iterative step-by-step approach was required to ensure that road design levels had suitable gradients in light of the challenging ground profiles. In addition, it was necessary to ensure road levels tied up to challenging house levels to provide acceptable access for homeowners and to meet the streetscape longitudinal profiles. These factors, along with consideration of the extent of earthworks, in terms of value engineering and road specifications provided for a challenging but achievable project.

Road safety considerations post the planning and RCC submission

Although safety issues were considered throughout the pre-application stage however, during determination and independent safety audit issues were raised. The level of scrutiny applied ensured all safety concerns were highlighted and addressed which inevitably required additional work and negotiation.

Drainage infrastructure

All drainage was designed in accordance with Sewers for Scotland (2nd Edition). However, as the development was based on the ethos of shared surfaces with integrated landscaping such as trees in roads, it was necessary to indicate the exact position of sewers and their dimensions away from trees, services and building foundations. In terms of the sewers sizes, it was also necessary to ensure that the system did not flood for a 1 in 30 year storm duration and that adequate flood routing for a 1 in 200 year storm was achievable. This was undertaken by ensuring the sewers had sufficient capacity. These issues, however, did require lengthy negotiations which mainly took place during the determination period and, ideally, could have been dealt with prior to submitting the application.

Sustainable urban drainage

It was difficult to achieve an optimum sustainable urban drainage solution. The main contributing factor for this was the central green space available against the extent of surface water storage required. Discussions on locating a smaller pond at the entrance of the site was investigated but deemed as unsuitable in terms of drainage and overall development aspirations. However, as an alternative solution, an integrated approach was developed to ensure that the development accorded with SEPA, East Renfrewshire Council and Scottish Water policies.

The added challenge, however was that with recent changes in legislation, tighter scrutiny by SEPA and Scottish Water was required, compared to the previous application. The requirement was to provide a two-phase treatment for all road trafficked areas (this policy does not exist in England). After lengthy discussions, and the use of new drainage solutions such as bio-retention-retention areas, 65% of trafficked areas received a two-phase treatment process to remove pollutants at source, from road drainage. The use of bio-retention cells in this situation is a first in Scotland (and possibly the UK) and the design team are to be commended in including their use.

Permeable paving

Whilst the project achieved permeable paving in the private courtyards and car parks, it was unable to achieve permeable paving in adopted areas. The reason is that with all the other engineering achievements made on the site, this was an additional issue which was considered to be too difficult at the time. However, with recent changes in policy, combined with the proposed construction period, this is an issue which may re-investigated in the future.

amber graphicMost debate

Planning

The transition from the rural edge to the Conservation Area

With the development not being on an 'infill' site but rather located on the edge of the village, a lot of thought was put into getting the main elevation right, which fronted Moor Road. This marked the transitional route to and from the village and the moors. The previous application created a very strong suburban edge by continuing Polnoon Street right up to the moors. In contrast, the proposed development, took its building alignment from Polnoon Street, but created a landscape connection with the Orry, and then gradually graded the houses up towards the moors, as well as creating a small 'landmark' gatehouse at the end of the development. Also, in order to maintain a rural connection to the moors, the proposed development retained the existing roadside hedge and used this as a feature to create a pathway behind it, as well as setting the houses back from the main road. This is something which had been requested by the local residents who lived opposite. Whilst this was a very sensitive approach, it took some time to change the mindset of what would have been a more standard, and yet, inappropriate solution.

Getting the location of the architectural details right

The location of key architectural details required a lot of attention to create the right impact at street level. For example, the houses have not just been 'plonked' down in any location, key primary and secondary 'marker' homes have been strategically placed to either provide views or to close vistas etc.

Road Construction Consent

Surface materials

Agreeing the palette of materials on the hierarchy of road surfaces took some debate. The aim was to achieve something that was functional, durable and matched the building styles and aspirations of the masterplan. Two design concepts were considered. One took the form of a single block colour (pennant grey) but using different sizes and patterns to distinguish street hierarchies whilst the other used different colour blocks to distinguish the hierarchy, but by using standard patterns. The latter was considered to be a more readable code to help people identify the street hierarchy, as well as being easier to build-out during construction, along with consideration in terms of buildability.

Hedges

There was considerable deliberation between the traffic safety engineer and the landscape architect over the purpose and height of the hedges along with tree positions. The auditor considered that the hedges (which were where designed to be over 1 metre in height and located in areas to hide parked cars) were considered to be a safety risk and contravened national guidance. The solution therefore was to maintain the hedge positions but to reduce the heights to 600 millimetres.

Vehicle tracking

There was considerable dialogue between the road engineer, East Renfrewshire Council and the landscape architect on tracking of high side vehicles such as refuse vehicles in relation to tree positions, taking account of their anticipated canopy spread and height. Underground service requirements added a further level of complexity to the introduction of street trees. Ultimately, a landscape strategy which ensures functional tracking with a consistent landscape proposal was achieved.

Permeability on Bonnyton Drive

During the design development stages, it emerged that there were differences of opinion, between those of the local authority engineer and the community, compared to the views of A+DS, as to whether there should be a vehicle or pedestrian access at Bonnyton Drive. The decision, however, was taken in favour of the community, together with the engineer, to create a walking and cycling connection only.

Bio-retention

Detailed discussions where required in respect to location of bio-retention areas and their adoption. This was ultimately resolved and agreed by East Renfrewshire and SEPA.

This is the first time that bio-retention cells will be used in Scotland (and possibly the UK) in a residential aspect and it is felt by SEPA that integrating landscaping into the road infrastructure is a major step forward in sustainable drainage.

green graphicEasy to achieve

Planning

Community engagement

The community consultation was well planned and attended. It also took place during the early stages of the design development which allowed for sufficient material to be shown to the community to help them visualise the proposed development as well as allowing plenty of time to be able to take on board their views and amend the plans accordingly.

Changing the facade of the proposed standard house type

By taking Mactaggart & Mickel Ltd's standard house type, and researching some key architectural and rural vernacular details from Eaglesham, it was relatively easy to transform the standard house type into something which related more to its context.

New standard house types

After reviewing Mactaggart & Mickel Ltd's range of house types, it was easy for the architect to identify a gap in their portfolio. The solution was to create a new L-shaped house design. This proved to be an important new addition which allowed for a much improved, and connected, streetscape. This is something which is often lacking in many standard design solution layouts.

Planning policies

Applying most of East Renfrewshire's development plan planning policies proved to be fairly straight forward. For example, those which carried some form of clear requirement or measure such as garden sizes, parking standards, play spaces whereas, those which were open to interpretation did require debate.

Design statement

The development of the masterplan was a very visual process, and so once the designs had been completed, it was relatively easy to pull the design statement together. This then acted as a key document with the planning application.

Road Construction Consent

Joint planning and Road Construction Consent

It was relatively straightforward to work on both the planning and engineering issues, in parallel, and to eventually achieve joint planning and RCC. Further lessons have, however, been learnt during this process which have enabled an improved methodology for future developments of this nature.

Layout revision

The layout amendments and negotiations with East Renfrewshire were relatively easy and all associated visibility and vehicle tracking checks were undertaken quickly to move the layout forward.

Culture of engineers

The Council engineers who worked on the project were open minded throughout the process. This always helped to develop and discuss the design as a team.