The UK’s infrastructure planning system has been misfiring for years. Neil Chester and Simon Rawlinson of Arcadis look at latest efforts to speed up crucial planning decisions for major infrastructure projects

01 / Introduction

It’s not often that infrastructure planning rises to the top of the political agenda but, ahead of the 2024 general election, both Labour and the Conservatives are promoting their own reform agenda. Ambitious and far-reaching changes to the system are already in the works, highlighted by a raft of announcements in the 2023 autumn statement.

Whereas most development planning in the UK is delegated to local authorities, large infrastructure projects including transport, energy, water and waste are managed nationally, with ministers having the final say on whether a development consent order (DCO) should be awarded. After a successful launch in 2010, the performance of the centralised nationally significant infrastructure project (NSIP) planning process in England and Wales has been deteriorating since around 2015. Typical overall planning durations, from pre-examination to award, have extended to four years, the number of judicial reviews challenging awards has increased by 60% and costs have ballooned.

In the midst of a rapid expansion of infrastructure investment, the performance of the current system is unsustainable. Consenting major infrastructure projects is always difficult on a crowded island like Britain. Schemes have complex impacts, many stakeholders, and quite often the locals who are directly affected see little benefit. For linear schemes such as roads or transmission lines, a large number of affected planning authorities will be involved, adding to the complexity. The NSIP model was designed to rationalise the debate by assessing schemes at a national level against agreed policy criteria.  

In principle, schemes are consented when they meet an infrastructure need required by policy and when the solution is shown to provide an optimum and acceptable mitigation of negative scheme impacts such as loss of habitat. Proposals must also demonstrate acceptable levels of consultation. Recent DCOs awarded on major schemes such as the A303 Stonehenge Tunnel have, however, been successfully challenged through judicial review.


There have been plans to put the A303 trunk road, which runs past Stonehenge, in a tunnel for nearly 20 years. Planning was given for the latest iteration in 2020, overturned by the High Court in 2021 and granted by the secretary of sate for transport earlier this year. This decision has since been challenged by campaigners

One reason for successful legal challenge – either directly or indirectly – is that the policy backbone of NSIP has not been able to keep up with new developments, including those associated with climate change, net zero, environmental impacts and biodiversity. The consequence is a system that is less efficient and less certain, requiring ever more investment in pre-application development to build a consensus between promoters and consultees.  

Planning delay was one of the main targets of Project Speed, the long-forgotten Boris Johnson initiative from June 2020 designed to “build better, faster, greener”. However, the complexity of the update and the parallel impact of the Environment Act mean that much of the detail has only come together in the past year – ranging from updated national policy statements (NPSs) formally issued in November 2023 to some substantial proposed changes to process such as environmental outcome reports (EORs). A review by the National Infrastructure Commission (NIC) has identified further opportunities for improvement that have broadly been accepted by the government.

The latest update to planning reform, snappily entitled Getting Great Britain Building Again, anticipates significant progress by summer 2024. In practice there is little significant difference between the main political parties in their approach to reform.  This should mean that project teams and stakeholders can focus on responding to new challenges including biodiversity net gain (BNG) rather than second-guessing further changes to the process.

02 / Outline of the NSIP planning process

This section examines the six steps of the NSIP planning process, current problems and potential solutions, including many that have been set out in recent planning reform proposals.

As highlighted, the Planning Act process is intended to be a time-bound test of the suitability of a proposal against well-defined and nationally agreed policy criteria. The aim is to resolve differences early in the process, clearly identifying the key issues to be the focus of the examination.

In practice it is becoming harder to secure consensus at pre-examination stage, meaning that decisions on project scope are being delegated upwards to the examining authority and, in some cases, the secretary of state who determines the DCO. This increases the risk of delay and challenge to decisions.

The table below lists the most likely sources of problems, and the potential solutions to them, at each of the main stages of the process.

 Key activitiesSources of problemsOpportunities to improve the process
Pre-application (open timescale) * Early scheme development based on options
* Scheme design of the preferred option together with documented consideration of alternatives
* Non-statutory consultation with stakeholders and statutory consultees on the options
* Development of all supporting documentation
* Policy basis of the development out of date, so scheme open to challenge
* Failure to demonstrate that all reasonable options have been considered through scheme development
* Quality and extent of engagement with stakeholders and ability to reconcile needs – issues not resolved before examination
* Complexity of documentation produced to pre-empt challenge in examination
* Maintaining updated national policy statements (NPSs)
* Adoption of modular structure to facilitate regular updating
* Adoption of structured approach to consideration of alternatives against all aspects of the scheme where mitigation is required
* Front-loaded scheme development and engagement including statements of common ground and principal areas of disagreement
* Enhanced resourcing for Planning Inspectorate and statutory consultees to be implemented in 2024
* Process reforms such as environmental outcomes report
Acceptance (28 days) * Process and compliance review by Planning Inspectorate, including adequacy of consultation test * Proposals delayed due to quality or compliance issues, including those related to statutory consultation * Planning Inspectorate advice on process
* Fast-track process for schemes meeting enhanced quality threshold (spring 2024)
* Enhanced paid-for advisory services from Planning Inspectorate to be implemented in 2024
Pre-examination (typically, three to five months) * Appointment of examining authority
* Registration of members of the public and other interested parties
* Engagement with widest group of stakeholders through registration * Wider use of digital tools
Examination (six months) * Inquisitorial review by the examining authority of scheme proposals
* Consideration of proposals against policy and process compliance
* Review of proposals where no policy is in place
* Detailed proposals – limited flexibility for change post-consent
* Detailed proposals and evidence – difficult to understand and assess in timescales
* Risk of potential changes to the scheme
* Challenges on basis of policy compliance – such as net zero by 2050
* Challenges due to process compliance – such as reasonable alternatives
* Adoption of managed flexibility mechanisms and new post-award change process
* Process reforms to limit the required scope of content – EOR
* Maintenance of updated NPSs and other guidance
* Regular updates to NPSs
* Planning processes to demonstrate reasoned consideration of mitigation options
Recommendation and decision (six months total) * Examining authority’s recommendation
* Secretary of state’s final decision on DCO
 * Additional mitigation required in response to changes
* Issues not resolved and referred to secretary of state
* Recommendation does not adequately address material considerations, leading to secretary of state taking more time to consider decision
* Clearer standards and more effective pre‑examination engagement
* Better resourcing for Planning Inspectorate and statutory consultees
* Fast-track process for non-contentious applications
Post decision (six weeks or more) * Opportunity to launch judicial review * Identification of process and policy shortfalls  

03 / Proposed reforms

The government announced a five-point plan for the updating of the NSIP programme in February 2023, and has also published a review by the National Infrastructure Commission (NIC). A raft of announcements in the autumn statement signalled further progress, although the real changes will be implemented in 2024. The key components can be summarised as follows:

Get Great Britain Building Again 

Issued after the autumn statement, this action plan combines immediate actions focused on planning reform with new longer-term initiatives on spatial planning and a plan to build a “big projects skillset”. Other initiatives include a proposal to consider 24/7 working on major programmes to speed up delivery, together with a ministerial “star chamber” to strengthen cross-government co-ordination.

Updated National Policy Statements 

Fully updated energy and water resource NPSs are now published. The 2023 update has been a colossal effort revising 12-year-old documents, which took at least three years. Looking forward, the government has broadly accepted an NIC recommendation for a maximum five-year updating cycle and the adoption of a modular structure to accommodate major changes.  Unfortunately, these suggestions were made after the development of the latest NPS updates, so implementation of a modular approach might take several years.

Improved pre-application proposals 

We highlighted above the critical pre-examination stage as a source of single points of failure. Recently consulted reforms are intended to improve not only the quality of submissions but also the efficiency of the process. Key elements include:

  • Enhanced, paid-for pre‑application support from the Planning Inspectorate and statutory consultees set at three levels. The highest level includes paid-for statutory consultee engagement and a review of the submission. This will be operational by summer 2024.
  • More support on procedure, including an expanded role for the Planning Inspectorate to provide “merits advice” related to examination issues as well as updated guidance on requirements for an acceptable application.
  • Guidance on the scope and adequacy of consultation, including a new proportionality test.

The aim of these changes is to increase certainty by ensuring all key issues have been properly addressed. By tracking main areas of disagreement at pre-application stage, the examination itself should be made more efficient.

Faster and more proportional examination approaches

These will include proposed solutions that focus on a more proactive, front-loaded approach. For example, the planning inspector will be involved earlier in the process, ensuring greater familiarity with the issues at examination. Under the updated process, principal areas of disagreement will be favoured over statements of common ground, providing a greater focus on key considerations at examination. Examination will also be enabled by enhanced digital processes.

Proposals to update the examination process also include a fast track for projects that meet tight criteria with respect to a maximum number of disputed areas, demonstrated policy compliance and an agreed plan for design development. Qualifying projects will benefit from an accelerated, four-month examination period.

Environmental outcomes reports 

The EOR is the planned replacement for the environmental impact assessment (EIA) and was finally enacted in the Levelling Up and Regeneration Act. The EIA model has received a lot of criticism. Bulky EIAs developed using a holistic but risk-averse approach to impact assessment have ended up covering a huge range of issues, just in case they are raised during examination. The detailed EOR proposals, which are still in development, will focus exclusively on environmental issues, narrowing the scope of examination to a defined range of desired environmental outcomes.

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Latest consultations on the NPSs have highlighted that agreeing and enforcing appropriate mitigation will still be difficult, even with a simpler reporting process. The NIC proposes further reforms, advocating a strategic environmental approach whereby a portfolio of schemes located within the same area can share data and potentially propose a joined-up mitigation plan.

Work updating various aspects of the NSIP planning process has been under way for several years and, assuming latest timescales are met, performance will start to improve from 2024 onwards. However, there are also further opportunities for substantial change in connection with both spatial planning and strategic approaches to data-sharing and mitigation development.

Case study: Silvertown Tunnel

Silvertown Tunnel is a strategically important road link promoted by Transport for London (TfL). When complete, the tunnel will provide additional cross-river access to east London. By providing an alternative route for the Blackwall Tunnel, the scheme will also improve the resilience of the London strategic road network.

The project is an example of a successful NSIP process that demonstrated the mitigation of significant environmental concerns, particularly in connection with air quality. For the DCO, the process focused on the issues that really mattered rather than attempting to cover all potential sources of challenge.

Arcadis undertook the air-quality modelling in support of the application, developing a highly robust approach to modelling of air-quality effects by combining an analysis of traffic flow forecasts, traffic type modelling and the different levels of exposure of receptors of varying sensitivity. The analysis demonstrated that the introduction of a user charge on both the Blackwall and Silvertown tunnels would help to manage traffic levels, in part by encouraging road users onto new public transport using the tunnels. This is turn would help manage air quality. Ironically, many objectors were concerned that a user charge would incentivise TfL to increase traffic levels. To build upon the findings of the EIA process, TfL also undertook an equalities and health impact assessment that sought to quantify the effects on local communities in relation to both noise and air quality.

The Silvertown DCO was also innovative in submitting a monitoring and mitigation strategy as part of the application process, covering road traffic, air quality and the socio-economic effects of the scheme, which has subsequently been implemented as part of project development.

Air-quality work on the Silvertown DCO also highlights that some procedural delays are not simply due to the NSIP process but are influenced by related policy and processes. The Department for Environment, Food & Rural Affairs’ air-quality metrics were updated twice during the design, assessment and decision-making processes, necessitating further analysis and delaying the project significantly while modelling was verified. This experience suggests that promoters will continue to face many challenges even with a streamlined DCO process.

04 / Practical steps to improve certainty of outcome

The procedural processes now being introduced should deliver a step change to NSIP planning effectiveness. There are also actions clients and their teams can take to improve their performance and impact, including the following:

Setting up for success 

An obvious step but one often overlooked by either first-time promoters or organisations delivering one-of-a-kind projects. Key aspects include the organisational structure and in particular the relationship between the consenting team and the design team, which should encourage planning process considerations to be included within design development.

Other considerations include access to DCO expertise, a responsive governance structure and commercial arrangements that provide flexibility to deal with a wide range of unknowns.

Successful NSIP consent processes need to balance design development to meet the precautionary principle of eliminating areas of uncertainty while providing enough flexibility for the delivery team to develop an optimum solution. Delivery teams will find it hard to deliver an outcome-based proposal if their hands are partly tied by the DCO.

One solution suggested by the Public Sector Playbook is that the wider delivery team should be appointed during the planning process. Using the “Rochdale envelope” principles of developing mitigation proposals based on a cautious worst-case scenario can help make proposals more flexible. However, the latest updates to NPSs provide only limited guidance on flexibility. Further work on the post-consent change processes is part of the long-term reform programme.

Technology-enabled stakeholder engagement  

Achievement of adequate consultation adds to the certainty of the process, and technology has a key role to play in this. Digital techniques including visualisation and interactive story-telling platforms improve engagement by making proposals easier to understand and communication more targeted at the specific consultee audience. Two-way communication platforms can also be an effective way of generating feedback and participatory engagement. However sophisticated, digital tools cannot be relied upon to assure adequate consultation, and traditional techniques such as exhibitions and open days are still needed to enable full inclusion.

Digital optimisation of the consideration of alternatives 

Corridor modelling for linear infrastructure such as overhead power lines can be digitally enabled within geographical information systems (GIS) based on preset criteria and weightings. Criteria typically focus on social and environmental factors such as proximity to housing, heritage assets and environmental impacts.

AI-based tools are also available, although a balance is needed as “black-box” processing can make it harder to demonstrate the basis for the selection.

Early-stage corridor modelling is focused on the identification of pinch-points that create either technical or consenting challenges. Consideration of issues such as community impacts and mitigation design still require expert input.

05 / Conclusion

As the pressure to invest in new infrastructure for growth and net zero increases, the role of the national planning system in legitimising, mitigating and compensating for the effects of development will only become more important.

However, a step change in planning durations for complex schemes like transmission lines is now needed to meet pressing net zero target.

Forthcoming updates to the NSIP planning process should make it more effective, although experience highlights the importance of careful, consistent policy drafting as well as deliberate, well-structured management of the planning process by the promoter and its team.

Even as more changes are brought forward related to biodiversity net gain, community benefits and process improvements around shared data and digital process, one constant will remain – the need to maintain the proportionality of the system, balancing fairness and representation on the one hand and social benefit on the other.


The authors would like to thank Alison Powell and Sarah Venn for their contributions to this article.