Nationally Significant Infrastructure Projects: Advice on Good Design
Source: gov.uk (2025-04-16)

This advice explains why good design is important, what success might look like and how it might be delivered in applications for Nationally Significant Infrastructure Projects (NSIP).

The government has published guidance about national infrastructure planning which applicants and others should read. See the National Infrastructure Planning Guidance Portal (https://www.gov.uk/government/collections/national-infrastructure-planning-guidance-portal). The guidance should be read alongside the Planning Act 2008 (https://www.legislation.gov.uk/ukpga/2008/29/contents) (the Planning Act).

This advice is non-statutory. However, the Planning Inspectorate’s advice about running the infrastructure planning system and matters of process is drawn from good practice and applicants and others should follow our recommendations. It is intended to complement the legislation, regulations and guidance issued by government and is produced under section 51 of the Planning Act.

National Policy Statements (NPS) set out the requirement to deliver good design and the criteria by which it will be assessed.

The requirement for good design

The Secretary of State is under a duty in preparing NPSs to contribute to sustainable development, mitigating and adapting to climate change and achieving good design.

Good design is crucial for achieving excellent functionality, sustainability, positive place-making and resilience in NSIPs.

The NPSs set out criteria for achieving good design in projects, aligning functionality with sustainability principles and balancing environmental, economic, and social factors.

The NPSs and guidance also point to the importance of explaining decisions taken in the design process and the reasons for them. This includes how environmental impact assessment (EIA) and views from stakeholder engagement and consultation have informed the design process.

Definitions of good design

There are many sources for definitions of good design. The principles set out by the Roman architect and engineer Marcus Vitruvius (c70-15BC) for good architecture still apply equally to present day infrastructure and chime with the statements in the NPSs. He defined good architecture as “firmitas, utilitas, venustas” meaning firmness, commodity, and delight, emphasising the importance of functionality, durability, and aesthetic appeal in buildings and structures.

Planning Policy Wales (https://www.gov.wales/technical-advice-note-tan-12-design) also recognises good design as a process. It defines design as “the relationship between all elements of the natural and built environment”. It emphasises the need to go beyond aesthetics and include “the social, environmental and economic aspects of the development, including its construction, operation and management, and its relationship to its surroundings.”

Achieving good design

Achieving good design requires a holistic approach to deliver high quality, sustainable infrastructure that responds to place and takes account of often complex environments. Good design is not primarily about how infrastructure looks, although these considerations (the aesthetics) are important.

Achieving high quality, good design outcomes requires an effective, intentional, transparent, deliverable process to be planned, followed and secured. Success in good design comes from a combination of securing both good process and good outcomes.

Given the scale and impact of NSIP developments, achieving well-designed project outcomes addressing sustainability and climate change is essential.

The National Infrastructure Strategy

The National Infrastructure Strategy (https://assets.publishing.service.gov.uk/media/5fbf7591e90e077ee2eadc44/NIS_Report_Web_Accessible.pdf) commits government to embedding good design into all NSIPs. The National Infrastructure Commission (NIC) Design Group recommends that considering design properly in NSIPs supports the government’s ambition to speed up delivery and maximise value by addressing:
- a structured design process
- design principles
- multiple beneficial outcomes
Design principles, parameters and codes

The government has adopted four high-level principles of climate, people, place and value for infrastructure, published by the NIC in its Design Principles for National Infrastructure (https://nic.org.uk/app/uploads/NIC-Design-Principles.pdf).

In the government’s guidance on the Pre-application stage (https://www.gov.uk/guidance/planning-act-2008-pre-application-stage-for-nationally-significant-infrastructure-projects#key-considerations-in-preparing-an-application), paragraph 14, applicants are advised that they should involve a diverse range of people in developing their design and that they should explain how it responds to the NIC principles.

The NIC principles have been further underpinned with guidance on how to apply them within a project context Project Level Design Principles (https://nic.org.uk/app/uploads/NIC-Design-Principles-Handbook-Digital-PDF.pdf). This sets out a structured process for applying tailored design principles at every stage of a project life cycle. Building on the NIC high-level design principles the Project Level Design Principles provide applicants with issues to consider under each of the the four design principles.

For climate these include carbon impact, environmental enhancement including nature recovery and climate resilience. Truly inclusive and accessible design that is sympathetic to the social and community context is important for people. Places should cover boosting a local sense of identity and stewarding the local landscape. For value, it is important to look beyond the site boundary, working with partners to unlock additional value.

The purpose of the design principles at a project level includes having an overarching vision with a locally contextual design narrative, being informed by affected people and groups, being inclusive and identifying opportunities for wider benefits and outcomes beyond the project itself.

Future Wales (https://www.gov.wales/sites/default/files/publications/2021-02/future-wales-the-national-plan-2040.pdf), Planning Policy Wales (https://www.gov.wales/sites/default/files/publications/2024-07/planning-policy-wales-edition-12.pdf) and Technical Advice Notes (https://www.gov.wales/technical-advice-notes) set out the national planning policy to achieve good design in Wales. Applicants should determine the appropriate design principles for the project.

Approaches to design principles are set out in guidance, such as the Design Principles for National Infrastructure and Project Level Design Principles and the National Design Guide (https://assets.publishing.service.gov.uk/media/602cef1d8fa8f5038595091b/National_design_guide.pdf), as well as in local design policies and standards. Applicants should ensure that good design outcomes will be secured through use of such design principles, parameters and design codes.

The National Model Design Code (https://assets.publishing.service.gov.uk/media/611152f98fa8f506ca458925/NMDC_Part_1_The_Coding_Process.pdf) is a helpful tool for establishing design codes. These are most likely to be relevant post-consent in guiding the construction phase of the project. Design codes can be secured through requirements or the Design and Access Statement.

Good design process

A good design process is iterative within a structured approach which problem solves and secures good design outcomes.

A good design process includes the following components:
- an effective, intentional, transparent, and deliverable process
- a collaborative, multi-disciplinary approach including positive community and land rights engagement
- a succinct and ambitious vision for the project, underpinned by a clear analysis of the context for the place, its environment and the opportunities for creating social value, including for the local and wider economy
- a clear statement of design principles that will drive the project and deliver wider value and benefits beyond the core purpose of the scheme
- a narrative that explains how the approach to design has evolved, the reasons for the choices that have been, or will be, made, an explanation of the multiple beneficial outcomes the project will achieve and how they will be secured
- design leadership supported by an engaged design champion to ensure design governance is secured and the design principles drive a structured design process and hierarchy of design control
Good design outcomes

Achieving good design outcomes involves:
- securing a clearly understood, integrated design concept, consistent design language, and project-wide sustainability
- consistent design language where all components can be followed through in post-consent decisions
- clarity on achieving project-wide sustainability that goes beyond mitigating adverse effects to achieve economic, environmental and social net-gain
- design principles that respond positively to the four elements – climate, people, place and value - established by the NIC
- realistic assessments of the project’s durability and effectiveness during its operational phase, to underpin and secure a successful maintenance and monitoring regime
- sufficient flexibility for technical innovation balanced by sufficient detail and controls for post-consent approvals that will ensure good design outcomes are achieved
- particular attention on place-making to ensure the development’s positive effects on the character of a place and delivery of public benefits
- well thought out mechanisms to enable design outcomes to be scrutinised, assessed and developed during the post-consent design process. For example, parameter plans, design codes, management plans, independent design review and intentional community engagement which are secured in requirements or certified documents
Environmental Impact Assessment (EIA) and good design

Importance of EIA

EIA is an important decision-making tool and can help the achievement of good design outcomes by avoiding or reducing adverse effects and providing benefits through identifying ways to improve the environmental or cultural opportunities. The Planning Inspectorate’s Advice on the Environmental Impact Assessment Process provides further information on EIA.

The Levelling Up and Regeneration Act 2023 enables regulations requiring a developer to produce an ‘Environmental Outcomes Report’ to assess the impact on the delivery of ‘specified environmental outcomes’.

Maximising EIA effectiveness

Engagement and collaboration with technical experts and integrating the design team with the EIA team will maximise the effectiveness of the process. This collaboration should be used to inform the main design decisions and secure environmental gains.

Where a parameter-based approach is used, the assumptions and design principles which underpin parameters must be clearly set out.

EIA in the design process

EIA should inform the design process, and its influence on the design should be clearly articulated in the Environmental Statement. This is particularly relevant to identification of site and infrastructure appraisal and selection in the consideration of alternatives.

Establishing good design

Challenges in NSIP design

Design is a way of dealing with the complexities and challenges associated with NSIPs. These can include lengthy timescales, changing technologies and micro-siting which can influence design outcomes and changing market conditions.

The details of the NSIP considered during examination are often not the final as built infrastructure because further design input is required for the reasons set out above. The Examining Authority (ExA) therefore needs to be satisfied that there is evidence that applicants have engaged in and are committed to a process that can deliver good design outcomes, which are specific and proportionate to the type of infrastructure proposed. These need to be secured by the Development Consent Order (DCO) through requirements, conditions, management plans or other certified documents.

A good design process diagram

The diagram below is a graphic description of the elements within the overall design process of which the Planning Inspectorate will expect to see evidence during pre-application and examination stages.

A flow diagram showing the design process through four stages: 'assemble, research, co-ordinate and secure'.

The following elements should be considered during the pre-application process and addressed within an NSIP application. The extent to which they need to be covered will depend on the nature of the infrastructure proposed and the site. Pre-application advice can be sought from the Planning Inspectorate in this regard.

Assemble

This stage requires a brief setting out the project’s purpose, a budget, a proposed timeline, a multi-disciplinary team with design skills and gathering of baseline information which can inform consideration of alternatives and eventual site selection.

The multi-disciplinary project team must use the information that it has assembled to develop a vision. The vision should have a compelling narrative, which goes beyond solving technical problems and policy compliance and considers construction as well as operation. It should define an ambition which goes beyond the Order limits in line with outcomes that are wider than the project limits. It must include the development of design principles.

Research

This stage needs to be iterative. It should analyse the constraints and opportunities of technology and location with a narrative of how the design evolved from the brief. It will need to mitigate adverse effects assessed as part of the EIA process and show how the proposed development will deliver positive outcomes and create a new and distinctive place. During this stage, engagement and consultation with statutory parties, affected persons, local communities and independent design panels should inform the project’s design evolution. This should be explained.

Co-ordinate

Further iteration must be undertaken to refine choices for details and parameters. This should incorporate consultation responses, independent design input and ensure that design principles are being met. There may be choices to be made. Decisions need to be taken using strong design leadership, driven by the vision. This stage must set out the process by which future post-consent decision-making will be made.

Secure

The essential output of this stage must be to set out how the project’s good design is secured and will be delivered, including ongoing design advice and community engagement. It is important that applicants are clear about the influence procurement decisions could have and that any differences with future consenting authorities are aired. ExAs will expect designs to be progressed to a detailed level where the outcomes of the applicant’s analysis, program and vision are defined. Clarity over how design elements that have less certainty at application stage will be decided and secured post-consent must be provided.

Main factors for applicants

Considerations for good design

Annex A below sets out the considerations relating to good design which applicants should consider before applying for acceptance under section 55 of the Planning Act.

Pre-application process

Applicants can seek advice from the Planning Inspectorate under section 51 of the Planning Act to address good design considerations. Applicants are encouraged to engage on matters relating to good design at an early stage during the development of the project. The aim is to ensure that the emphasis given to good design in the NPSs or local design documents is taken on board from the outset. This should enable the production of well-prepared, sufficiently detailed applications, which can then proceed through an efficient examination.

It is recognised that applicants may require different levels of support during pre-application through the tiers of offer which are available, set out in the Pre-application Prospectus (https://www.gov.uk/guidance/nationally-significant-infrastructure-projects-2024-pre-application-prospectus#Component4). One such component is a Design Approach Document (DAD). DADs will assist ExAs and Interested Parties understand the preparation and evolution of the design case from project inception to that presented in the application. DADs are supported under the Tier 3 offer. They are appropriate for any NSIP as a way of communicating the design case and supporting efficient examination.

Acceptance criteria

The Secretary of State must ensure that the application and supporting documents are of a satisfactory standard, including the extent to which the applicant has had regard to any guidance issued under section 50 of the Planning Act.

Examination, Recommendation and Decision

Demonstrating a clear approach to good design, which has been consulted upon and has responded to comments is necessary to support an efficient examination of the NSIP. An appropriate level of design detail together with clarity over how future post-consent approvals will be assessed and are secured is also necessary. This is because it will result in efficiencies for examination time (written questions and hearings, where necessary), reduce the need for Secretaries of State to consult further and in the time needed for post-consent approvals.

Good design is one factor which ExAs need to consider when reporting on the planning balance and making any recommended changes to an applicant’s final DCO. ExAs need to consider how successfully good design has been achieved in the recommendation on the project. If design matters are left unresolved, or without secured methods for future approvals (which may also include further independent design input and community consultation), ExAs will need to explore ways of ensuring that this does happen in their recommendations.

Conclusion

Good design is essential for achieving sustainable, well-designed, and inclusive infrastructure projects, and applicants should follow the recommendations and considerations outlined in the advice.

Annex A – Good design issues to consider

Annex A sets out good design issues applicants should consider before submitting a NSIP application for examination.