Trees in Hard Landscapes: A Guide for Delivery


Trees in Hard Landscapes: A Guide for Delivery is the companion document to Trees in the Townscape: A Guide for Decision Makers. It explores the practical challenges and solutions for integrating trees in 21st century streets, civic spaces and surface car parks. These are arguably the most challenging environments for growing trees, but are also the areas that can derive great benefits from their inclusion.

The report was developed by  the Tree and Design Action Group (TDAG) who have joined forces with the Chartered Institution of Building Services Engineers (CIBSE), the Chartered Institution of Highways and Transportation (CIHT), the Institution of Civil Engineers (ICE), and the Institute of Chartered Foresters (ICF).  Trees in Hard Landscapes: A Guide for Delivery has benefited from the input of over 100 built environments professionals and organisations from wide ranging disciplines and sectors who have taken part interviews, contributed case study materials and/or offered feedback on earlier drafts.

To download the report:


Starting from the point where the policy decision to retain or plant trees has been made, this guide explores the key building blocks to success through:

  • Collaborative Process – From project initiation to maintenance and monitoring, when, how and with whom joined-up working needs to happen.  Weaving natural resources, especially trees, into the built environment requires a cross-disciplinary collaborative approach from project initiation through to design, implementation, maintenance and monitoring. This guide looks at when, how and with whom joined-up working needs to happen.
  • Designing with Trees – Practical strategies to ensure trees best contribute to the delivery of the design objectives of a project.  Achieving long-term benefits from trees requires a concerted strategy. This guide explores current evidence on the enabling factors for trees to bring value to the hard landscapes in which they grow.
  • Technical Design Solutions  – The available technical below-ground solutions to achieve lasting overall success.  Design of the below-ground environment is key to achieving long-term compatibility between trees and the built infrastructure that surrounds them in towns and cities. This guide examines innovative and available technical solutions to help build lasting success from investing in trees.
  • Species Selection Criteria  – The frame of reference to use as a basis for tree selection.  While tree species selection alone cannot make up for a poor design strategy or inadequate underground growing conditions, choosing the right tree for the right place is an essential final ingredient for success. This guide offers a five-step process for making the best shortlist of available options and achieving resilient and successful tree choices.
  • integrating

Audience for the report – Highway engineers, civil and structural engineers, highway contractors, construction site managers, project managers, designers and tree specialists are the primary audience for this guide. It will also be of value to developers, planners, elected members, local communities and all involved in hard urban landscapes and their design and management.

The need for a sustainable integrated infrastructure – Two themes are expressed throughout the guide. Firstly, the importance of innovation, an element of experimentation, so that improvements can be made in response to changes in available techniques as well as in constraints and expectations for the public realm. Secondly, the mindset to achieve multiple benefits. Both are essential for successfully integrating trees in high-performance hard landscapes in a 21st century context.

There is much evidence on the wide range of benefits that can be gained by integrating trees with other infrastructure. However research also shows that, while trees need to reach a degree of maturity to fulfil their potential and deliver returns on investment and benefits to their communities, many urban trees in hard landscapes are not living as long as they should.

The context in which trees can thrive in hard landscapes is in a state of flux, with new challenges and opportunities for success. Many urban trees, especially the larger growing trees, were planted from the mid-19th to mid-20th century when there was less crowding, complexity and compaction beneath our highways and public spaces.


There are now new uses and quality expectations for the public realm. Streets are increasingly regarded as ‘places’, not just as vehicular movement corridors. The same ‘space’ needs to accommodate cycles and a public transport system as well as private vehicles and better conditions for pedestrians to encourage walking. These challenges will need creative solutions.

Climate change and increasingly erratic weather patterns including heatwaves and extreme localised rainfall also put new pressures on the infrastructure of our towns and cities. Urban trees have a lot to offer towards urban cooling and surface water management. Modelling conducted for Manchester has shown that increasing the canopy cover by 10% would keep summer peak temperatures at their current level until the 2080s. In terms of Manchester this would mean an increase in average canopy cover from about 15% to 25% but it is important that canopy cover is as evenly distributed as possible across the urban area.

Images: Tree and Design Action group (TDAG)


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