Guide to contributory factors (and road safety factors) for reported road casualty statistics
A guide to use of the contributory factors data which form part of the Department for Transport's reported road casualty statistics, and the new road safety factors which replace them.
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Details
Contributory factors apply to collisions recorded under the pre‑2024 STATS19 specification. Road Safety Factors (RSFs) are collected under the 2024 specification. Users should exercise caution when comparing results across specifications.
This guidance provides an overview of the contributory factors (CFs) and road safety factors (RSFs) recorded as part of the STATS19 road collision data collection. It explains how these data are collected and published, how the transition from CFs to RSFs affects the interpretation of the statistics, and factors users should consider when carrying out analysis.
Road safety factors are replacing contributory factors following recommendations from the 2018 STATS19 review. As police forces have adopted the new STATS19 specification at different times, recent statistics contain a mixture of collisions recorded using both systems. Initial analysis suggests that this transition has affected the factors recorded by police officers, meaning that direct comparisons between CF-based and RSF-based data should be made with caution.
This guide covers:
- an overview of contributory factors and road safety factors
- strengths and limitations of the data
- the transition from contributory factors to road safety factors, including implications for analysis and interpretation
- data confidentiality, access arrangements and published outputs
- coverage and completeness of factor reporting
- analysis of reporting patterns by police force, road type and road user type
- future developments and planned improvements to the statistics
Further information relating to contributory factors or road safety factors can be obtained from the road safety statistics team using the contact details below.
Contact us
Road safety statistics
Email roadacc.stats@dft.gov.uk
Updates to this page
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Updated with 2025 data
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Updated with details of road safety factors based on 2024 data.
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Updated with 2023 data
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2022 reported road casualties Great Britain report published.
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First published.