Nationally Significant Infrastructure Projects: Advice on Transboundary Impacts and Process
Source: gov.uk (2025-03-25)

This advice summarises the required notification and consultation procedures governing Nationally Significant Infrastructure Projects (NSIPs) that may have transboundary impacts.

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

This advice is non-statutory. The Planning Inspectorate’s advice about running the infrastructure planning regime and matters of process is from good practice, 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.

It should be read together with the Planning Inspectorate’s Advice on the Environmental Impact Assessment Process and Advice on Habitats Assessments (https://www.gov.uk/government/collections/national-infrastructure-planning-advice-notes) as well as government guidance on the Planning Act process (https://www.gov.uk/government/collections/national-infrastructure-planning-guidance-portal).

Legislation

Transboundary impacts referred to in this advice are impacts on the environment of European Economic Area Member States (EEA States). Transboundary procedures are managed by the Planning Inspectorate on behalf of the Secretary of State as part of the Planning Act 2008 process for examining NSIP applications.

The United Kingdom (UK) is a signatory to:
- the United Nations Economic Commission for Europe (UNECE) Convention on Environmental Impact Assessment in a Transboundary context, known as the ‘Espoo Convention’
- the Convention on Access to Information, Public Participation in Decision-Making and Access to Justice in Environmental Matters, known as the ‘Aarhus Convention’
The European Union (EU) Directive 2011/92/EU (as amended) (the EIA Directive) implements the Espoo and Aarhus Conventions in the EU. The Infrastructure Planning (Environmental Impact Assessment) Regulations 2017 (the EIA Regulations) and the European Union (Withdrawal) Act (2018 and 2020) transposed into UK law the requirements of the EIA Directive governing statutory notification and consultation in respect of transboundary effects of development on EEA States.

The UK consists of England, Scotland, Wales and Northern Ireland (and excludes the Isle of Man, Jersey and Guernsey). EEA States comprise all Member States of the EU as well as Iceland, Liechtenstein and Norway. Switzerland and the UK are not EEA Member States.

The signatory states to the Espoo and Aarhus Conventions number more than the EEA States. The UK therefore has obligations to engage, where relevant, with other signatory states and their public.

Regulation 32 of EIA Regulations establishes certain duties where Secretary of State (or an EEA State) considers that NSIP may have significant effects on the environment in an EEA State. It outlines obligations on the Secretary of State to notify and consult EEA States where needed and within the timeframes set by the Planning Act 2008.

The duties set out in Regulation 32 apply until a decision on the NSIP application is made.

For proposed NSIP development needing an Environmental Statement, Schedule 4 of the EIA Regulations requires that the description of likely significant effects should include transboundary.

Under Regulation 32, the Secretary of State must notify and consult EEA States in any of the following circumstances:
- the development is likely to have significant effects on the environment in an EEA State and the Secretary of State is notified that an Environmental Statement will be provided, or adopts a screening opinion, or makes a direction that development is EIA development
- or it is otherwise made aware that the development is EIA development and considers it is likely to have significant effects on the environment in an EEA State
- or it is requested by an EEA State likely to be significantly affected by such development
The Conservation of Habitats and Species Regulations 2017 (the Habitats Regulations) and the Conservation of Offshore Marine Habitats and Species Regulations 2017 (the Offshore Marine Conservation Regulations) transposed Council Directive 92/43/EEC on the conservation of natural habitats and of wild fauna and flora (the Habitats Directive) into UK law.

Following the UK’s departure from the EU on 31 December 2020, the Habitats Regulations and Offshore Marine Conservation Regulations were amended by the Conservation of Habitats and Species (Amendment) (EU Exit) Regulations 2019.

The Habitats Regulations and the Offshore Marine Conservation Regulations require (where applicable) competent authorities to carry out an appropriate assessment before granting consent for a plan where likely to have a significant effect on a European site or a European Marine site (alone or in combination with other plans or projects).

The Department of Business, Energy and Industrial Strategy (BEIS) has issued guidelines which specify that Secretary of State, when considering whether to consent energy projects, will apply the principles of the Habitats Directive. This is where significant effects on the national site network, European or candidate sites in EEA States are likely. This will typically apply to offshore windfarm developments.

Transboundary Process under Regulation 32

During the pre-application stage and before recommendation is made to the Secretary of State, relevant Regulation 32 requirements are carried out by the Planning Inspectorate.

Where a proposed NSIP is EIA development the Inspectorate must determine whether it is likely to have significant effects on the environment in an EEA State, as part of a transboundary screening process.

For other NSIP developments, Regulation 32 applies if an EEA State which is likely significantly affected by the development makes a request for provisions to be applied.

Where the likelihood of transboundary effects is very low, the transboundary screening decision will be included in the scoping opinion or as a separate short form document where a scoping opinion is not requested. Otherwise, the transboundary screening decision will be provided in a separate, long form document. The opinion may subsequently change subject to any new or materially different information being received.

Annex 1 (https://assets.publishing.service.gov.uk/media/66ea7fe4f8082e9740881cb8/Transboundary_Annex_1_-_The_Inspectorates_Long_Form_Transboundary_Screening_Proforma__1_.odt) (ODT, 40.1 KB) and Annex 2 (https://assets.publishing.service.gov.uk/media/66ea806224c4f1826d81bcc8/Transboundary_Annex_2_-_The_Inspectorates_Short_Form_Transboundary_Screening_Proforma__1_.odt) (ODT, 35 KB) contain the Planning Inspectorate’s transboundary screening templates and relevant criteria.

These duties under Regulation 32 continue through the stages of the Planning Act 2008 process. This may result in further transboundary screenings and consultation with EEA States where new or updated information occurs.

Notifying EEA States

Where the Planning Inspectorate identifies a likely significant effect on the environment in an EEA State, it will notify the relevant EEA States. The EEA States to be notified are identified based on the type of NSIP development, its location, the nature of the receiving environment and material provided by the Applicant. See Annex 1 (https://assets.publishing.service.gov.uk/media/66ea7fe4f8082e9740881cb8/Transboundary_Annex_1_-_The_Inspectorates_Long_Form_Transboundary_Screening_Proforma__1_.odt) (ODT, 40.1 KB) for further information.

Reasonable discretion is used by the Planning Inspectorate based on these factors when identifying if an NSIP is likely to have significant effects on the environment in any EEA State. It adopts a precautionary approach when deciding on the possibility of a development having such effect. It therefore does not state that a development will have an effect.

The Planning Inspectorate uses the contacts on the UNECE website for making notifications to EEA States. For relevant NSIP applications, the Planning Inspectorate must send to the EEA States as soon as possible (Regulation 32(3)):
- a description of the development, together with any available information on its possible significant effects on the environment in their State
- information on the nature of the decision which may be taken
The Planning Inspectorate must publish a notice in the London Gazette, and Edinburgh Gazette if the development is in Scotland, with the information about the development. The Planning Inspectorate may also send information to the EEA States about the Planning Act 2008 process.

EEA States can then indicate if they wish to participate in this process. Six weeks is given for EEA States to respond. Unless an extension is agreed, where an EEA State does not reply within this timescale, it will be assumed that they do not wish to participate in the transboundary process (Article 3.4 of the Espoo Convention).

The proposed development is re-screened for transboundary impacts following the acceptance stage and/or if relevant new information becomes available.

If necessary, the Planning Inspectorate will renotify relevant EEA States, and notify additional States should new effect pathways be identified, informing that the development has been re-screened for transboundary effects, including those States that did not previously express a wish to be involved. In these circumstances, such EEA States can request again or newly to participate in the procedure.

Where an EEA State wishes to be updated only on the development of the NSIP application, they are given a link to the relevant project page from the national infrastructure planning website.

Consulting EEA States

Consultation with EEA States cannot begin until the Planning Inspectorate has received the required information to meet its consultation duty. This only occurs once the NSIP application has been accepted for examination.

Any EEA State taking part in the transboundary procedure must be consulted to ensure that they have an opportunity, before development consent is granted, to seek the opinion of its public and relevant authorities about the application and its transboundary impacts.

Where an EEA State has indicated that it wishes to participate in the Regulation 32 procedure, the Planning Inspectorate must:
- consult with the EEA States regarding the potential significant effects of the development on the environment in that State and the measures envisaged to reduce or eliminate such effects
- agree a reasonable time period for the duration of the consultation
- inform the consulted EEA States of the decision
The Planning Inspectorate must send them, as soon as possible (Regulation 32(4):
- a copy of the application
- a copy of the Environmental Statement in respect of the proposed development
- details of the authority responsible for deciding the application
- any relevant information on the Regulation 32 procedure
These documents are made available through the national infrastructure planning website. Links will be provided in the consultation correspondence to signpost the EEA States to the relevant parts of the website.

Information is provided in English unless a translation is requested and justified by the EEA State.

Translating documents

To support an efficient examination, Applicants should ensure that any affected EEA States, other relevant bodies and their public, understand the details of the proposed development including any safeguards and mitigation measures. Though English is the default language, translated information will depend on the needs of EEA States and others.

It is good practice for Applicants to organise and meet the costs of translating their documents if reasonable and justified requests are made.

The applicant’s role

The applicant has no formal role under the Regulation 32 process. However, the Planning Inspectorate uses the information provided by the applicant to assist in determining the potential for likely significant effects on the environment in EEA States.

Information about potential for transboundary effects should be provided by the applicant as part of:
- its scoping request under Regulation 8 of the EIA Regulations (if one is made)
- the suite of documents submitted with the NSIP application
Where sufficient information is not provided voluntarily, the Planning Inspectorate may ask for further information on the likelihood of significant effects on the environment in an EEA State.

Where NSIPs may cause likely transboundary impacts, applicants may wish to undertake their own consultation with governmental divisions, appropriate bodies and interest groups within relevant EEA States, or other relevant states that are parties to the Espoo or Aarhus Conventions.

Any engagement may form part of the applicant’s statutory or non-statutory consultation under the NSIP pre-application stage and should be evidenced in the consultation report that is required under section 37(3)(c) of the Planning Act 2008.

The applicant is advised to undertake such consultation to ensure that potential transboundary issues and concerns are addressed, where possible, before the NSIP application is submitted.

EEA States’ role

Notification

EEA, Espoo and Aarhus states should respond to the notification request issued from the Planning Inspectorate within the timescale given and using the contact details provided. An acknowledgment of receipt will then be issued. The response should state whether or not they wish to participate in the process under Regulation 32.

The same applies in relation to Espoo / Aarhus states who have been informed about a proposed NSIP. Responses are requested within the timeframe stated in the notification letter and should be sent marked for the attention of the Environmental Services Team at the Planning Inspectorate using the contact details provided in the notification letter.

If a notified EEA State confirms that they do not wish to participate in the Regulation 32 process, the Planning Inspectorate will acknowledge this response and will not contact the EEA State again unless new relevant information relating to likely significant effects on the environment in their State becomes available.

Consultation

If a notified EEA State confirms that they wish to participate in the Regulation 32 process, the Secretary of State will acknowledge this response and if the Development Consent Order (DCO) application is accepted, will consult the EEA State on the proposed NSIP.

Participating EEA States should provide comments on the following:
- the potential effects of the proposed development on the environment in their State
- the measures proposed to reduce or eliminate such effects
Regulation 32 requires that the EEA State should be given ‘reasonable time’ to provide the opinions of its public and of the authorities referred to in Article 6 (1) of the EIA Directive (Regulation 32(5)).

Unless the relevant EEA States provides reasonable representations that a longer period should be allowed, the time period for responding to the notification and consultation requests will be six weeks. This is not a statutory deadline and EEA States can request a reasonable extension.

Public Participation

The Espoo and Aarhus Conventions set out provisions for public participation in the EIA procedure. The Planning Inspectorate will, where relevant, invite EEA States and any other Convention States to become involved in the Planning Act 2008 process and consult with their public. Public participation will occur:
- where the proposed development is considered likely to have a significant effect on the environment in other specific EEA States
- where the proposed development is a nuclear NSIP
A press release will be published, alongside any relevant translations, on the gov.uk website and linked from the British Embassy websites in any relevant states.

The press release will include:
- information on the transboundary screening assessment
- links to the national infrastructure planning website
- details of how their public can express their views on the NSIP application
- how they can participate in the examination process
Applicants will be asked to publish a press notice in the print media of each EEA state where a significant effect on their environment is identified. For nuclear NSIPs, the applicant will also be asked to publish a press notice in all neighbouring states of the UK.

An EEA State, other relevant state and any person or group may participate and express their views on the NSIP application during the examination. Doing this by registering as an ‘interested party’. They may also be invited to participate in the examination at the discretion of the Examining Authority as an ‘other person’.

EEA States or other relevant states registered as ‘interested parties’, may be asked questions by the Examining Authority regarding the transboundary effects, to inform their recommendation to the Secretary of State on whether the development should be granted consent.

The Planning Inspectorate’s Advice for Members of the Public (https://www.gov.uk/government/collections/national-infrastructure-planning-advice-notes) provides general information on the Planning Act 2008 process, including on how to register and become an ‘interested party’.

Where the Examining Authority is not satisfied before the close of examination that measures have been provided to avoid, reduce and if possible, offset any significant adverse transboundary effects of the NSIP, it may have to recommend refusal of development consent. The Secretary of State must not grant development consent if to do so would lead to the UK being in breach of its international obligations under section 104(4) of the Planning Act 2008.

Special Arrangements for Nuclear NSIPS

Special arrangements are applied to the transboundary impacts process for nuclear electricity generating station NSIPs (nuclear NSIPs). These NSIPs are defined under section 15 of the Planning Act 2008 and Schedule 1 of the EIA Regulations. The special arrangements take account of the specific features of a nuclear NSIP and the provisions of the Espoo and Aarhus Conventions.

Each nuclear NSIP will be screened using the long form template in Annex 1 (https://assets.publishing.service.gov.uk/media/66ea7fe4f8082e9740881cb8/Transboundary_Annex_1_-_The_Inspectorates_Long_Form_Transboundary_Screening_Proforma__1_.odt) (ODT, 40.1 KB).

Where the Planning Inspectorate considers that a proposed nuclear NSIP is likely to have a significant effect on the environment in an EEA State, the Planning Inspectorate will notify and (if necessary) consult that EEA State specifically in accordance with Regulation 32.

As standard practice, the Planning Inspectorate will inform all relevant states which are party to the Espoo and Aarhus Conventions of a proposed nuclear NSIP, which will include non-EEA States. This is the same information given to EEA State being notified or consulted under Regulation 32, with the same ability to participate in the process should they wish.

In addition, the Planning Inspectorate will also inform the Crown Dependencies of the Isle of Man, Jersey and Guernsey of its view that a proposed nuclear NSIP is likely to have significant transboundary effects.

Decisions

Following determination of the NSIP application, the Secretary of State will inform consulted EEA States of the decision and forward a copy of the decision notice. The Secretary of State also has a duty to inform all ‘interested parties’ of the decision.

In accordance with Regulation 31(2), a summary of how the results of consultation, particularly those received from EEA States, have been incorporated or addressed in respect of the NSIP application will be made available on the national infrastructure planning website.