Congestion and reliability
This series presents information about road congestion and journey time reliability on motorways and ‘A’ roads in England.
A brief introduction into these statistics, including what they measure, how they are published and how they are used is available below:
Browse statistical releases within this series
Browse individual statistical tables within this series
Raw data available for download
National Statistics
Statistics about congestion and reliability were assessed during 2011 by the UK Statistics Authority. An assessment report was published in March 2012.
- Assessment of compliance with the Code of Practice for Official Statistics: Statistics on Road Reliability and Congestion
- Letter of confirmation as National Statistics (PDF – 49 KB)
Pre-release access lists
These lists detail the post holders that are given pre-release access for up to 24 hours prior to release.
- Pre-release access list: Reliability of journeys on Highways Agency’s motorway and ‘A’ road network (PDF – 11 KB)
- Pre-release access list: Congestion on local authority managed ‘A’ roads (PDF – 11 KB)
Technical information
- Methodology for calculation of reliability on Highways Agency’s motorway and ‘A’ road network (PDF – 200 KB)
- Data quality table for reliability statistics: percent of imputation required for monthly figures (XLS – 18 KB)
- Statement of administrative sources: journey time database, Highways Agency managed roads (PDF – 36 KB)
- Methodology for calculation of flow-weighted vehicle speeds on locally managed ‘A’ roads (PDF – 560 KB)
- Exploration of differences between flow-weighted and unweighted estimates of vehicle speed on locally managed ‘A’ roads (PDF – 129 KB)
- Data quality table for flow-weighted speed statistics: percent of imputation required for monthly figures (XLS – 27 KB)
- Data quality table for flow-weighted speed statistics: percent of imputation required for quarterly figures (XLS – 422 KB)
- Data quality table for flow-weighted speed statistics: percent of imputation required for annual figures (XLS – 106 KB)
- Difference between provisional and final versions of flow-weighted speed statistics (XLS – 50 KB)
- Statement of administrative sources: journey time database, local authority managed roads (PDF – 29 KB)
Statistical research and development
- Public attitudes towards road congestion, November 2009 to February 2010 (PDF – 113 KB)
- Annex A – Public attitudes towards road congestion, November 2009 to February 2010 (PDF – 46 KB)
This report discusses the combined results for questions included in the Office for National Statistics’ Opinions Omnibus Survey, and covers patterns and frequency of road use, attitudes towards road congestion and effectiveness and fairness of alternative road charging schemes.
Archived statistics
External websites
Contact us
- congestion.stats@dft.gsi.gov.uk
- Phone: 020 7944 6579
