Accredited official statistics

Travel time measures for the Strategic Road Network: January to December 2023 report

Updated 3 October 2024

Applies to England

About this release

This statistical release presents information about travel times on the Strategic Road Network (SRN) - the roads managed by National Highways. The measures in this release are estimated using in-vehicle Global Positioning Systems (GPS) observations.

An accompanying release covers data on the local ‘A’ roads. Due to methodological differences between the local ‘A’ Road and SRN data these are not directly comparable, see the methodology and technical details section for further details.

These are accredited official statistics ^{[footnote 1]} and were independently reviewed by the Office for Statistics Regulation in 2012. For more information, see the About these statistics section.

Definitions of key terminology can be found in the glossary.

Notes on the methodology and sample

These travel time measures are based on data matched to National Highways’ National Traffic Information Service (NTIS) network in England.

The SRN covers ‘A’ roads and motorways that are operated by National Highways.

1. Headline Statistics

On the SRN in 2023, the average speed was 57.0 miles per hour (mph). This is down 1.9% from 58.1 mph in 2022 and down 1.7% from 58.0 mph in 2019.

The average delay on the SRN in 2023 was 10.5 seconds per vehicle per mile (spvpm). This is up 12.9% from 9.3 spvpm in 2022 and up 10.5% from 9.5 spvpm in 2019.

Table 1: Average annual speed and annual delay on the SRN per year (Tables CGN0404a and CGN0405a)

Year	2019	2020	2021	2022	2023
Average speed (mph)	58.0	60.0	58.9	58.1	57.0
Average delay (spvpm)	9.5	7.3	8.5	9.3	10.5

2. National Overview

This section contains annual average speed and delay values for all of England for the year ending December 2023.

2.1 Speed

The average speed on the SRN in 2023 was estimated to be 57.0 mph, a 1.9% decrease from 58.1 mph in 2022 and a 1.7% decrease from 58.0 mph in 2019.

Prior to March 2020, average speed had remained relatively stable at between 58 mph and 59 mph. Since late 2022, average speeds have been declining to below pre-pandemic levels.

Chart 1: Average speed on the SRN (Table CGN0404a)

Graph showing average speed (miles per hour) on the SRN for each month from 2019 to 2023. This figure shows that average speed in 2023 has decreased below pre-COVID-19 levels. See Table CGN0404a for full data.

2.2 Delay

The average delay on the SRN across in 2023 was estimated to be 10.5 spvpm, a 12.9% increase from 9.3 spvpm in 2022 and a 10.5% increase from 9.5 spvpm in 2019.

Prior to March 2020, average delay had remained relatively stable between 8.6 spvpm and 9.0 spvpm. Since late-2022, average delay has been increasing to above pre-pandemic levels.

Chart 2: Average delay on the SRN (Table CGN0405a)

Graph showing average delay (seconds per vehicle per mile) on the SRN for each month from 2019 to 2023. This figure shows that average delay in 2023 has increased above pre-COVID-19 levels. See Table CGN0405a for full data.

3. Sub-national Transport Bodies (STBs) Breakdown

This section contains average speed and delay values on the SRN for the year ending December 2023, split by sub-national transport body (STB). Map 1 displays the geographic coverage and delay values of the STBs.

What are STBs?

The Sub-national Transport Bodies are transport bodies formed of multiple local highways authorities to provide large-scale strategic governance. STBs are given statutory power through secondary legislation.

Travel time measures for sub-national transport bodies on the SRN are available from January 2019 onwards. The annual average speed and average delay for SRN roads within STBs can be found in Tables CGN0404b and CGN0405b.

3.1 Speed

Annual average speeds for the STBs for the year ending December 2023 are given in Chart 3. Values for the year ending December 2022 are given for comparison.

Chart 3: Average speed on the SRN by Sub-national Transport Bodies (Table CGN0404b)

STB	2022 Average Speed (mph)	2023 Average Speed (mph)
Transport for the North	58.3	57.2
Midlands Connect	57.5	56.7
England’s Economic Heartland	59.1	58.6
Transport East	56.5	55.4
Greater London Authority	52.4	51.4
Transport for the South East	58.2	57.4
Western Gateway	58.3	57.0
Peninsula Transport	60.9	60.4

A map displaying average speed on the SRN split by Sub-national Transport Body is published on ArcGIS Online.

3.2 Delay

Annual average delay values for the STBs for the year ending December 2023 are given in Chart 4 Values for the year ending December 2022 are given for comparison.

Chart 4: Average delay on the SRN by Sub-national Transport Bodies (Table CGN0405b)

STB	2022 Average Delay (spvpm)	2023 Average Delay (spvpm)
Transport for the North	9.1	10.3
Midlands Connect	9.7	10.6
England’s Economic Heartland	8.9	9.5
Transport East	10.5	11.8
Greater London Authority	14.7	15.9
Transport for the South East	9.5	10.3
Western Gateway	8.1	9.5
Peninsula Transport	6.0	6.6

Map 1: Average delay on the SRN by Sub-national Transport Body in England, 2023 (Table CGN0405b)

Map showing average delay (seconds per vehicle per mile) on the SRN in England split by Sub-national Transport Body. Transport for the North (10.3), Midlands Connect (10.6), England’s Economic Heartland (9.5), Transport East (11.8), Transport for South East (10.3), Western Gateway (9.5), Peninsula Transport (6.6), Greater London Authority (15.9).

4. Further Geographic Breakdowns

Further geographic breakdown of speed and delay on Local ‘A’ Roads are included in the data tables as described below. Interactive maps visualising these breakdowns as well as those presented above are published on ArcGIS Online.

4.1 Combined Authorities

Data is available for combined authorities within the data tables CGN0404c and CGN0405c.

4.2 Road Level

Data available at road level from 2021 and average speed and average delay figures can be found in: CGN0404e and CGN0405e.

4.3 Junction Level

Several roads saw significant increases to travel times due to major upgrades and maintenance projects in 2023 which appear to impacted the level of delay in these areas. These roadworks may have taken place within or on motorways adjacent to the affected junctions. A number of these are road resurfacing programs through 2023, such as the A12 in Essex and the A4 near Wiltshire. Similarly the M621 in Leeds continues into 2024 to undergo a resurfacing program, as well as adjacent lane and junction closures.

Travel time measures for individual junctions on the SRN are available from 2021. The annual average speed and average delay figures for individual junctions can be found in CGN0404d and CGN0405d.

A map displaying average speed on the SRN at junction level is published on ArcGIS Online.

Map 2: Average delay on the SRN at a junction level in England, 2023 (Table CGN0405d)

Map showing average delay (seconds per vehicle per mile) on the SRN in England at junction level. Average delay on the SRN is highest (over 20 spvpm) closest to most major cities, and lowest around the border counties, East and South West coasts where it is less than 5 spvpm. See Table CGN0405d for full data.

While junction level changes in speed and delay between years may appear large in some cases, the variations should be interpreted with caution. When travel time figures are based on data from a single road, they are more sensitive to disturbances such as road works and other local events. Therefore, road level speed and delay are expected to have greater variation from year to year than national figures.

5. 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 for 2020 to estimate the impact of the coronavirus pandemic on congestion and can be found at the storymap included with the 2020 annual publication. 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 to March 2022.

As with previous years, most road traffic has trended back towards levels seen before the pandemic.

6. Context and user feedback

Measures for the SRN were developed as part of the first Road Investment Strategy (RIS1), which sets out a long-term programme for England’s 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 using ArcGIS Online for the SRN and local ‘A’ roads. We will continue to review the content and presentation of these statistics, which we expect to develop further over time. Please contact us with any feedback you have, or if you would like further information.

7. Methodology and technical details

Average speed and delay are calculated from in-vehicle GPS units and weighted by road traffic flows to better represent the volume of traffic at different locations and times of day. For the SRN data, the sample includes all vehicle types.

It is important to note that although figures are produced for average speed and average delay on both the Local ‘A’ and SRN networks, they are not directly comparable. The methodological differences between the Local ‘A’ road and SRN data prevents comparison between the 2 road types. 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. Data throughout this release is compared on an annual basis, rather than quarterly within year, due to seasonality.

8. Glossary

The glossary below contains some key terms utilised in this statistical release and how these are defined.

Term	Definition
Average Speed	Speed is measured in miles per hour and is an estimate of the physical level of congestion across the entire day (24-hour period). The metric weights speed observations from a sample of vehicles so that it is representative of traffic volumes. The weighting for the SRN accounts for associated profile flows by time period.
Average Delay	Delay is measured in seconds per vehicle per mile and is the difference between free flow travel times and recorded average journey times across the entire day (24-hour period). This metric is indicative of the relative congestion on the network. Road users do not typically expect free flow conditions and will perceive delay relative to their expected conditions.
Free Flow Speed	Free Flow on the SRN is taken as the speed limit for each individual road section, as though there was no congestion.
SRN	Strategic Road Network. The SRN covers ‘A’ roads and motorways that are operated by National Highways.
STB	Sub-national Transport Body. 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.

9. About these statistics

These official statistics were independently reviewed by the Office for Statistics Regulation in 2012. They comply with the standards of trustworthiness, quality and value in the Code of Practice for Statistics and should be labelled  ‘accredited official statistics’.

10. Next update

The next quarterly table update in this series is expected to be published in June 2024. This will contain monthly, and annual (year ending) figures, for the period April 2023 to March 2024. This will include new figures for the period January 2024 to March 2024.

The next annual written report is expected to be published in February 2025 and will contain annual figures for 2024.

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13. Contact us

Road congestion and travel times

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1. Accredited official statistics are called National Statistics in the Statistics and Registration Service Act 2007. Accredited Official Statistics Policy – Office for Statistics Regulation ↩