We undertake early junction capacity checks to understand how a proposed development may affect the surrounding highway network before detailed design or full modelling is undertaken. Our work provides an initial view on whether nearby junctions are likely to operate within capacity, where pressure points may arise, and whether mitigation is likely to be required.
Early capacity checks help inform feasibility, access strategy and planning risk at a stage where change is still possible.
What are early junction capacity checks
Early junction capacity checks are high-level assessments of how key junctions may perform once development traffic is introduced. They are typically undertaken before a full Transport Assessment and are used to test whether junction performance is likely to be acceptable in principle.
These checks are not a substitute for detailed modelling where that is required, but they provide valuable early insight into whether capacity is likely to be a constraint and where further work should be focused.
Our early junction capacity checks are proportionate and site-specific, and typically include:
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Identification of key junctions likely to be affected by a development
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Review of existing traffic conditions and baseline data
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Initial assessment of junction layout and form
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High-level capacity testing using appropriate tools (ARCADY, PICADY, TRANSYT and LinSig)
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Consideration of development traffic from early trip estimates
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Identification of potential operational issues
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Initial view on whether mitigation may be required
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Clear written commentary on likely performance and risk
The value of early junction capacity checks lies in providing informed, realistic insight before significant time and cost are committed to detailed modelling. By testing junction performance at an early stage, we help clients understand whether capacity is likely to be a fundamental constraint, a manageable issue, or unlikely to influence deliverability. This clarity supports better decisions on site layout, access strategy and assessment scope, and reduces the risk of late-stage objection or unexpected mitigation requirements. It also ensures that any future modelling is targeted and proportionate, focused on the junctions that genuinely matter rather than those assumed to be problematic.
When early junction capacity checks are needed
Early junction capacity checks are commonly undertaken:
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At feasibility or pre-purchase stage
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Prior to pre-application discussions
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When testing development scale or density
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For sites near known congestion points
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Where junction performance is likely to be scrutinised
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Before committing to detailed modelling or surveys
They are particularly valuable where development impact is uncertain or marginal.
Our approach
We take a clear, experience-led approach to early capacity assessment:
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Review the site and surrounding highway network
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Identify junctions likely to be sensitive to change
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Apply proportionate capacity checks using appropriate methods
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Interpret results using professional judgement
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Set out clear advice on risk, opportunity and next steps
Our focus is on helping clients understand what the evidence is telling them and how it should inform their wider planning strategy.
Who we support
undertake early junction capacity checks for:
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Residential developments
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Strategic land and site promotion
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Commercial and employment uses
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Retail and leisure schemes
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Education and healthcare projects
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Energy and infrastructure developments
Our experience across England, Scotland and Wales gives us strong insight into local highway authority expectations and common areas of scrutiny.
Need an early view on whether junction capacity could constrain your site?
Get in touch and we will provide clear, proportionate advice to inform your next steps.
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