Travel time measures for local 'A' roads: January to December 2021 report
Published 2 March 2022
Applies to England
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About this release
This statistical release presents information about travel times on Local Highway Authority managed ‘A’ roads in England. The measures in this release are estimated using in-vehicle Global Positioning Systems (GPS) observations.
Changes to data provider
The Department for Transport (DfT) went through an open procurement exercise and have changed GPS data providers to Ctrack and Inrix. The data is provided on the same monthly basis and to the same specification to ease the transition, however this data is not comparable to the previous datasets. These changes are discussed in the methodology notes.
1. Local ‘A’ roads, in 2021
Definitions
Average speed is in miles per hour and is an estimate of the physical level of congestion.
Free flow speed is the estimated speed of the traffic if there was no congestion. This is calculated differently for the Strategic Road Network (SRN) and Local ‘A’ roads.
Average delay is in seconds per vehicle per mile and is the difference between free flow travel times and recorded average journey times.
Notes on the Methodology and sample
These travel-time measures are based on data matched to the Ordnance Survey Highways Network representation of the Local ‘A’ road network in England.
2. Local ‘A’ roads: average speed
2.1 National overview of average speed
The average speed on Local ‘A’ roads in England across 24 hours in 2021 was estimated to be 24.1 mph. Due to changes in the provider for Local ‘A’ roads data, there has been a step change in average speeds from 2021 onwards. Therefore, it is not possible to compare average speeds from 2021 to those prior.
Figure 1: Average speed on Local ‘A’ roads in England (Table CGN0503a)
2.2 Average speed at peak times
Average speed on Local ‘A’ roads during the weekday morning peak (7am to 10am) was 23.4 mph in 2021. For the weekday evening peak (4pm to 7pm), the average speed in 2021 was 22.4 mph. The average speed in 2021 for weekday inter peak (10am to 4pm) is 23.2mph, meanwhile the weekday off peak (7pm to 7am) average speed was 28.0 mph.
Further information on average speed on Local ‘A’ roads
This measure reflects the average speed of vehicles on Local ‘A’ roads across the entire day (24-hour period). The measure weights speed observations from a sample of vehicles by associated traffic flows so that it is representative of traffic volumes on the roads in different locations and at different times of day (as for average delay). The weighting for Local ‘A’ roads also weights by hour, day type, month, urban and rural classification, and local authority.
2.3 Average speed on urban and rural roads
On urban classified Local ‘A’ roads, average speed was 17.4 mph in 2021. On rural classified Local ‘A’ roads, the average speed was 34.3 mph in 2021. Despite the differences in speed between the two road types, drivers on urban and rural Local ‘A’ roads may perceive changes in speed levels differently.
Definition:
For statistical purposes, DfT defines ‘urban’ roads to be those within a settlement of 10,000 people or more. This is consistent with the Rural and Urban Area Classification 2011. All other roads are defined as ‘rural’.
3. Local ‘A’ roads: average delay
3.1 National overview of average delay
The average delay on Local ‘A’ roads in England across 24 hours in 2021 was estimated to be 46.1 spvpm compared to free flow. Due to changes in the provider for Local ‘A’ roads data, there has been a step change in the average delay from January 2021. Therefore, a comparison to the years prior to 2021 is not possible.
Figure 2: Average delay on Local ‘A’ roads Table CGN0504a
Free flow on Local ‘A’ roads:
Free flow travel times (used to calculate the average delay measure) are currently calculated using the 85th percentile speed observation, for each individual road section. These are ‘capped’ at national speed limits.
3.2 Average delay at peak times
In 2021, average delay on Local ‘A’ roads during the weekday morning peak (7am to 10am) was 50.1 spvpm. The average delay in 2021 on Local ‘A’ roads during weekday evening peak (4pm to 7pm) was 57.5 spvpm compared to free flow. Outside of peak hours, in 2021, the average delay in the inter peak period (10am to 4pm) was estimated to be 51.8 spvpm, while the weekday off peak period (7pm to 7am) was 26.1 spvpm.
3.3 Average delay on urban and rural roads
On urban classified Local ‘A’ roads, average delay was 76.9 spvpm in 2021, compared to 22.6 spvpm on rural classified Local ‘A’ roads.
Example: Average delay on urban and rural Local ‘A’ roads
It is important to note that urban roads generally have lower free flow speeds than rural roads. As a result, a fixed absolute decrease in observed speeds will generally translate into a higher level of delay on urban roads relative to rural roads. An example of this is illustrated in Figure 3.
Figure 3: Illustrative example of average delay on urban and rural Local ‘A’ Roads
4. Local ‘A’ roads: Sub-national Transport Bodies (STBs)
4.1 STBs
The STBs are transport bodies formed of multiple local highways authorities to provide large-scale strategic governance. STBs are given statutory power through secondary legislation, with Transport for the North being the first. The monthly average speed and average delay for Local ‘A’ roads within STBs can be found in Tables CGN0503b and CGN0504b.
4.2 Average speed
In 2021, the Greater London Authority recorded the lowest average speed, with a figure of 14.7mph being recorded for 2021, whereas the Transport East STB recorded the highest average speed, with a figure of 30.0mph being recorded for 2021.
Figure 4: Average speed on Local ‘A’ roads in England for Sub-national Transport Bodies, 2021 (Table CGN0503b).
4.3 Average delay
Figure 5 shows the average delay in each STB in 2021. In 2021, the average delay in the Peninsula Transport and Transport East STBs have been the lowest, with figures of 29.0 and 29.1 spvpm being recorded respectively, whereas the average delay has been highest for the Greater London Authority, which recorded a value of 99.2 spvpm in 2021.
Figure 5: Average delay compared to free flow on Local ‘A’ roads in England for Sub-national Transport Bodies, 2021 (Table CGN0504b).
Data is available for combined authorities within the data tables CGN503c and CGN0504c, however data is not for the entire country so this has not been mapped.
5. Local ‘A’ roads: Local Authority
5.1 Average speed
The lowest average speeds were recorded by London boroughs, with Camden recording the lowest average speed in 2021 at 8.3mph. The highest average speeds were recorded in more rural Local Authorities, with Rutland recording the highest average speed in 2021 at 39.0mph.
Figure 6: Average speed on Local ‘A’ roads by Local Highway Authority in England, 2021 (Table CGN0503d)
5.2 Average Delay
The average delay in each local authority for 2021 is shown in Figure 7. The lowest average delay values were recorded by more rural Local Authorities, with Rutland recording the lowest average delay in 2021 at 15.6 spvpm. The highest delay values were recorded by London boroughs, with Camden recording the highest average delay in 2021 at 201.1 spvpm.
Figure 7: Average delay on Local ‘A’ roads by Local Highway Authority in England, 2021 (Table CGN0504d)
Regional and Local Highway Authority figures
The annual average speed and delays for each region and Local Highway Authority can be found in Tables CGN0503d and CGN0504d.
6. Local ‘A’ roads: road level speed and delay
6.1 Average speed
Average speeds were the lowest on roads in London and other large cities such as Manchester, Leeds, Liverpool and Birmingham and highest in more rural areas.
Figure 8: Average speed on Local ‘A’ roads in England, 2021 (Table CGN0503e)
6.2 Average delay
On the Local ‘A’ roads network the average delay is highest on roads in London and other large cities such as Manchester, Leeds, Liverpool and Birmingham and lowest in more rural areas. Figure 9 shows the average delay on the Local ‘A’ road network.
Figure 9: Average delay on Local ‘A’ roads in England, 2021 (Table CGN0504e)
Road level speed and delay
Travel time measures for individual Local ‘A’ roads are available from 2021 onwards. The annual average speed and average delay for individual roads can be found in Tables CGN0503e and CGN0504e.
7. Coronavirus (COVID-19) effect on congestion
The coronavirus (COVID-19) pandemic has had a marked impact on everyday life, including on congestion on the road network. Exploratory analysis was conducted last year to estimate the impact of the coronavirus pandemic on congestion. A fall in the number of vehicles on the roads could be seen from when the national lockdown was announced in March 2020. Therefore data has been considered as “affected by the pandemic” from 12 March 2020. While the coronavirus pandemic continues to have an effect, most road traffic has trended back towards levels seen before the pandemic.
8. Context and user feedback
The Local ‘A’ road measures presented in this release were developed to provide a more complete picture of travel times on Local ‘A’ roads and to align with measures introduced for the SRN.
Following user feedback this release has developed the statistics to include Subnational Transport Body level data for the SRN and Local ‘A’ roads. Interactive maps have also been developed for the SRN and local ‘A’ roads using ArcGIS Online. We will continue to review the content and presentation of these statistics, which we expect to develop further over time. Please contact us using the details at the bottom of the front page with any feedback you have, or if you would like further information.
9. National Statistics
Statistics on Road Reliability and Congestion were designated as national statistics in 2012 signifying that they are produced to the high professional standards set out in the Code of Practice for Statistics. They undergo regular quality assurance reviews to ensure they meet customer needs. Details of ministers and officials who receive pre-release access to these statistics up to 24 hours before release are available.
10. Methodology and technical details
It is important to note that although there are figures for average speed and average delay on both networks, they are not directly comparable. A full explanation and further information on the data used, methodology, quality assurance and other sources of data can be found in the Background Quality Report. Due to methodological changes in the underlying traffic flow data used to weight the Local ‘A’ road data, a break in the time series has been introduced to the 2019 estimates of average speed and delay. The 2018 data was calculated for quality assurance purposes, to calculate the 12-month rolling average, and the percentage change. Further information on this change, including a comparison of the 2018 data, can be found in the methodology note.
| What do congestion statistics tell us? | Understanding the data | Important considerations |
|---|---|---|
| What comparisons can be made? | Due to a step change in 2019 the Local ‘A’ roads data can only be compared on a rolling year basis from December 2018 onwards. | Methodological differences prevent comparisons between road types, while seasonality makes quarter on quarter comparisons inadvisable. Details are available in the Background Quality Report |
| Interpreting average delay | Delay is recorded across all 24 hours of a day on a seconds per vehicle per mile (spvpm) basis. Delay here is compared to free flow conditions or the maximum speed limit journey time. This can be an indication of the relative congestion on the network. | Road users do not expect free flow conditions so consciously build in additional time for journeys. Delay may therefore be perceived as relative to expected conditions. |
| Interpreting average speed data | Average Speeds are weighted by road traffic flows to represent the volume of traffic at different locations and times of day. This can indicate the level of physical congestion on the network. | SRN average speeds only include cars. The Local ‘A’ Roads include cars and vans and additionally weight by day type, urban/rural and Local Authority distinctions. |
| Interpreting reliability measures | The reliability measures provide the additional journey time required to travel across one link compared to free-flowing conditions. | Reliability measures are calculated for the daytime hours (6am to 8pm). |
11. Request for feedback
We are keen to receive feedback from users of transport statistics. If you have any comments about how the statistics in this release are presented or analysed, please contact us using the details listed on the front page of this release.
12. Next update
The next tables in this series are expected to be published in June 2022. This will contain monthly, and annual (year ending) figures, for the period April 2021 to March 2022. This will include new figures for the period January 2022 to March 2022. The next written report is expected to be published in February 2023 and will contain annual figures for 2022.
13. Department for Transport (DfT) statistics Twitter feed
To hear more about DfT statistics publications as they are released, please follow us on Twitter via our @DfTstats account. TWITTER, TWEET, RETWEET and the Twitter logo are trademarks of Twitter, Inc. or its affiliates.
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16. Contact details
Road congestion and travel times
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