Writing an Infrastructure Delivery Plan (IDP) report: A practical guide

Introduction

In the Introduction section of your IDP report you can set the context and purpose of the IDP in relation to your Local Plan and spatial strategy. You can also use this section to provide evidence as to how it has been prepared in accordance with Planning Practice Guidance, how you have engaged stakeholders, and the methodology and evidence used to develop the IDP and Project Schedule.

We provide further guidance on some of these issues below but as a minimum your Introduction should include the following information. 

• A brief description of what an IDP is, and how it relates to the Local Plan (bear in mind this will be published as a public document so available for anyone to read, so a simple description of an IDP may be helpful for non-technical audiences).
• A brief overview of the national, local, and if relevant regional policy context that the IDP and Local Plan relates to.  This should include the relevant sections of the Planning Practice Guidance which will have informed your approach.
• How the IDP links to the Local Plan spatial strategy, and site allocations or strategic sites.
• The scope of the IDP, and which infrastructure categories and sub-categories are included.
• An overview of the methodology you followed in the production of your IDP
• An overview of the stakeholder engagement that informed the IDP
• And a section outlining the contents of the IDP and how it relates to the IDP project schedule, which may help signpost the reader to relevant sections of the IDP.

Link to the Local Plan

In the Introduction to your IDP report, it is helpful to explain how it supports and aligns with the Local Plan — particularly the spatial strategy, site allocations (or strategic sites), and relevant infrastructure policies. This reinforces that the IDP is not a standalone exercise, but an integral part of the plan’s evidence base. 

References can be provided to relevant policies on infrastructure provision or funding, to show how future infrastructure needs will be met. Where infrastructure requirements are embedded within specific site allocations, the IDP can help expand on those expectations — for example, by linking provision to the site’s delivery trajectory or the phasing of the wider spatial strategy.

This alignment demonstrates that infrastructure planning has been considered in a coordinated way, helping to support the soundness of the plan.

Scope

Stakeholder engagement

The IDP report should clearly document the stakeholder engagement undertaken during its preparation. This demonstrates how infrastructure planning has been informed by input from key delivery bodies — both within the council (e.g. education, highways, public health) and external partners such as utility companies, the NHS, National Highways, and other strategic infrastructure providers.

A summary of the engagement approach can be included in the Introduction section of the report, with a more detailed record of stakeholders, meetings, and correspondence provided in an Appendix. This may also include Statements of Common Ground or written agreements where relevant, to evidence alignment and shared understanding of delivery responsibilities.

Including this information not only supports compliance with the Duty to Cooperate (where relevant) but also reinforces the credibility and realism of the IDP. You may also wish to briefly outline how you plan to maintain engagement post-submission to keep the IDP live and responsive to changes.

Methodology

This section of the IDP report should provide a clear overview of the methodology used in its preparation. This helps demonstrate that the IDP follows a structured, evidence-led approach and fulfils its role as a robust and proportionate part of the Local Plan evidence base.

You can outline the key stages of production — including how the IDP was informed by engagement with infrastructure providers, a review of existing strategies, needs assessments, and other relevant datasets. Where applicable, include references to technical inputs such as population or housing growth projections, site capacities, or infrastructure modelling, along with their sources.

It is also good practice to identify any limitations or caveats in the evidence — for example, where costs are indicative, engagement is ongoing, or further studies are planned. Being transparent about assumptions, data sources, and uncertainties helps build confidence in the IDP and supports its use as a living document that can be updated over time.

Structure of the infrastructure assessment

The infrastructure needs assessment section of your IDP report can be structured in different ways. While many IDPs are organised by infrastructure category (e.g. transport, education, utilities), alternative approaches may also be appropriate depending on the Local Plan's structure, geography, and intended audiences.

One option is to structure the assessment spatially, with sections focused on defined areas such as strategic sites, growth areas, clusters of settlements, or administrative areas. This allows you to summarise infrastructure needs specific to each location, which can support place-based policy-making and help identify spatial dependencies. This format works well with maps and visual summaries, making it more accessible to non-technical audiences. However, it can be less effective for infrastructure that operates at a district-wide or cross-boundary scale and may require specialist tools (e.g. GIS or desktop publishing) to produce. Accessibility standards must also be considered.

Another option is to structure the assessment by delivery period, typically in five-year bands aligned with the Local Plan's phasing. This approach can help illustrate how infrastructure delivery supports the trajectory of site delivery over time and highlight when key investments are needed. It also recognises that detail is usually greater in the early years of the plan, while later phases may have broader assumptions or more uncertainty.

These structures can be used individually or in combination — for example, categorising infrastructure needs by type within each strategic site or phasing band. Whichever format is chosen, the assessment should clearly show what infrastructure is required, when and where it is needed, and how it relates to the plan's spatial strategy and delivery priorities.

Infrastructure assessment

Planning Practice Guidance states that Infrastructure Delivery Plans should “assess the quality and quantity of, and accessibility to ... infrastructure ... including expected future changes” and its ability to meet forecast demand. Where deficiencies are identified, Local Plan policies should set out how they will be addressed.

The infrastructure assessment section of your IDP should identify gaps and pressures in provision by analysing existing infrastructure, current capacity, and the impact of planned growth. This analysis should be based on engagement with infrastructure providers and relevant evidence.

It should consider both:

• New infrastructure required to support planned growth; and
• Renewal or upgrading of existing infrastructure, where assets are ageing, no longer fit for purpose, or where change is driven by policy (e.g. decarbonisation, digital infrastructure, or flood resilience).

For each infrastructure category, your assessment should set out what is needed to support delivery of the Local Plan. A clear and consistent structure can help, and you may wish to include the following:

• A summary of current provision, including capacity, quality, and accessibility;
• Any planned changes to provision and an assessment of whether these meet projected demand;
• Identified deficiencies and proposed responses;
• Planned or committed projects relevant to the Local Plan;
• Any additional infrastructure needed to meet demand arising from growth;
• Prioritisation of infrastructure projects or types (e.g. critical, essential, desirable), linked to site delivery and phasing;
• Known costs and funding sources, where available — noting where costs are indicative or uncertain.

Where full information is not available, the IDP should transparently set out assumptions, limitations, and delivery risks. Use this section to explain how the IDP is ‘managing uncertainty’, for example where evidence is being updated, funding is unconfirmed, or engagement is ongoing. This helps position the IDP as a living document that will be reviewed and refined over time.

Finally, ensure the narrative remains focused and relevant to the IDP’s purpose. Avoid repeating general background already covered in other planning documents. Where necessary, use signposting to refer to source reports, rather than duplicating content.

Site allocations or strategic sites 

If your Local Plan includes strategic sites or larger site allocations that require on-site infrastructure — or offer opportunities to accommodate new infrastructure — it is helpful to include a dedicated section in your IDP report. This strengthens the link between infrastructure planning and the spatial strategy, showing how site-specific needs have been considered and how infrastructure will be delivered alongside growth.

Where sites are phased over the plan period and generate significant infrastructure demand, the IDP can set out expected delivery 'triggers'. For example, you might specify that a primary school will be required once a certain number of homes are occupied, or that transport upgrades are needed before a later phase begins. This helps to coordinate infrastructure delivery with housing trajectories and provides clarity to infrastructure providers and developers.

You may also wish to:

• Identify on-site infrastructure responsibilities versus off-site infrastructure dependencies;
• Clarify where land is safeguarded for future infrastructure provision;
• Highlight any cost assumptions or delivery mechanisms, including Section 106 or CIL;
• Note whether infrastructure will be delivered by a single developer or requires coordination between multiple landowners or promoters;
• Link infrastructure requirements to site viability evidence, where relevant.

Including this detail helps to demonstrate that infrastructure provision has been planned realistically and proportionately and supports the overall deliverability of site allocations.

Monitoring and updating the IDP

It is essential that the IDP includes a clear and proportionate approach to monitoring and updating, to ensure it remains a live and credible document throughout the Local Plan period.

To reduce the risks associated with outdated or incomplete information, the IDP should set out:

• Who is responsible for monitoring and maintaining the IDP;
• How often updates will be made (e.g. annually, or alongside the Authority Monitoring Report);
• What triggers an update (e.g. changes in infrastructure funding, new infrastructure commitments, significant updates to site trajectories, or new evidence).
• Where possible, explain how the IDP aligns with existing governance and monitoring processes — for example, whether it will be reviewed as part of the Infrastructure Funding Statement (IFS) or your annual monitoring programme.

It is also good practice to outline any governance structures used to support updates, such as cross-department working groups, infrastructure boards, or joint arrangements with delivery bodies. This helps ensure regular engagement with providers and keeps the IDP grounded in the most up-to-date position.

Finally, emphasise how you intend to re-engage with stakeholders during future reviews, which will help maintain transparency and ensure continued alignment with infrastructure delivery programmes.

Appendices

Your IDP can include additional or more detailed information in appendices, helping to keep the main body of the report focused and accessible while ensuring key evidence is available. Appendices are a useful place to include:

• Full details of stakeholder engagement, including records of meetings, correspondence, and consultation responses;
• Data sources and technical references used to inform infrastructure assessments;
• Statements of Common Ground (SoCG) or other formal agreements with infrastructure providers;
• Supporting material produced or updated after the main IDP was published but before the Local Plan examination.

Using appendices in this way adds transparency and strengthens the robustness of the IDP as part of the evidence base for your Local Plan.