We define Transport Assessment scenarios to test how a development may perform under different future conditions. Our work focuses on establishing a clear baseline, understanding the network following a status quo apporach, and defining realistic with development and future year scenarios informed by evidence and professional judgement.
Well-defined scenarios ensure that transport assessment is focused, proportionate and genuinely informative, rather than speculative or over-engineered.
What are Transport Assessment scenarios?
Transport Assessment scenarios are structured tests used to assess how a transport network may operate under different conditions. These typically include a baseline scenario based on existing conditions and surveys, a future year or assessment year scenario, and scenarios that account for committed development and proposed changes to the network.
Scenarios may include do minimum and do something tests, reflecting different levels of intervention or mitigation, and are used to understand how a network performs with and without development traffic and associated schemes.
Our Transport Assessment scenario work is tailored to the site, proposal and planning context and typically includes:
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Definition of baseline conditions using survey data
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Establishment of future year and assessment year scenarios
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Consideration of committed development and background growth
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Reference case and with development scenarios
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Do minimum and do something tests where appropriate
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Testing of alternative access, layout or mitigation options
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Sensitivity testing of alternative inputs such as distribution or trip rates
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Clear documentation of assumptions and scenario logic
The value of well-judged Transport Assessment scenarios lies in ensuring that assessment reflects how development is likely to come forward in reality. By grounding scenarios in baseline surveys, committed development and realistic future assumptions, we help avoid artificial outcomes driven by extreme or abstract testing. Our approach supports a shift away from purely predict and provide thinking towards a decide and provide, vision-led assessment framework. This ensures scenarios align with the development vision, policy objectives and practical delivery, providing decision makers with evidence that is both robust and relevant.
When Transport Assessment scenarios are needed
Transport Assessment scenarios are commonly defined:
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At the outset of Transport Assessment preparation
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During pre-application scoping discussions
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When agreeing survey requirements and assessment scope
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For phased or strategic developments
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Where future infrastructure or growth is uncertain
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To test mitigation or alternative proposals
Early agreement on scenarios reduces the risk of rework, delay or dispute later in the process.
Our approach
We take a clear, proportionate approach to scenario definition:
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Understand the development vision and objectives
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Establish a robust baseline using survey data
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Define future year and assessment year assumptions
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Incorporate committed development and policy context
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Apply do minimum and do something scenarios where relevant
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Clearly explain and justify all scenarios used
Our focus is on scenarios that inform decisions rather than obscure them.
Who we support
We define Transport Assessment scenarios for:
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Residential and mixed-use developments
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Commercial and employment sites
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Education and healthcare projects
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Strategic land and phased schemes
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Infrastructure and energy developments
Our experience across England, Scotland and Wales ensures scenarios align with local authority expectations and national guidance.
Need help defining clear, proportionate Transport Assessment scenarios
Get in touch and we will help set out scenarios that support robust, vision-led and defensible assessment.
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