Guidance: Road congestion and travel time statistics information

Tables displaying the level of imputation for historic data tables CGN01, CGN02, CGN09 and select CGN04 and CGN05 are no longer available, as the relevant tables are no longer produced.

Road congestion and travel time statistics notes and definitions and other source documents.

Published 11 August 2016 Last updated 27 June 2024 + show all updates 27 June 2024 Data up to March 2024 has been added to the Local A data quality table.

7 March 2024 Over 2023 the congestion statistics processing was transferred to a new software enabling greater precision and accuracy in calculations and imputation of the production of statistical values. This has led to minor revisions for 'Percentage of data imputed for travel time statistics on the local 'A' road network, by month'

13 December 2023 Data table for the percentage of data imputed for travel time statistics on the local 'A' road network, by month has been updated.

27 September 2023 Data table for the percentage of data imputed for travel time statistics on the local 'A' road network, by month updated with the latest data.

14 June 2023 The percentage of data imputed for travel time statistics on the local 'A' road network, by month' table has been updated to include data from April 2022 to March 2023.

9 March 2023 The 'Percentage of data imputed for travel time statistics on the local 'A' road network, by month' table has been updated to include data from January 2019 to December 2022

14 December 2022 The local A road imputation table has been updated to included data to September 2022.

8 September 2022 The 'Percentage of data imputed for travel time statistics on the local 'A' road network, by month' has been updated to include data to June 2022.

29 June 2022 A new HTML document discussing the impact of the coronavirus (COVID-19) pandemic on flow weighting has been added.

16 March 2022 A new background quality report has been produced to reflect the change in data suppliers and data processes.

2 March 2022 Percentage of data imputed for travel time statistics on the local 'A' road network, by month data table updated.

14 December 2021 New methodology added.

8 July 2021 SRN and local 'A' roads imputation tables updated for the year ending March 2021. Pre-release access document updated.

25 February 2021 SRN and local 'A' roads imputation tables updated for the year ending December 2020 and pre-release access document updated.

3 December 2020 SRN and local 'A' roads imputation tables updated for the year ending September 2020.

16 September 2020 Pre-release access page added, SRN and local 'A' roads imputation tables updated for the year ending June 2020.

18 June 2020 SRN and local 'A' roads imputation tables updated for the year ending March 2020.

5 March 2020 National Statistics designation page for road reliability and congestion added. Data tables for the Strategic Road Network and local 'A' roads updated for the 2019 travel time measures report.

19 September 2019 Updated imputation tables for 'Travel time measures for the Strategic Road Network and local ‘A’ roads: July 2018 to June 2019'.

13 June 2019 SRN and local 'A' roads imputation tables updated for the year ending March 2019.

28 February 2019 SRN and local 'A' roads imputation tables updated for the 2018 report.

13 December 2018 Local roads and SRN monthly data tables updated for the year ending September 2018.