Official Statistics

COVID-19 domestic transport data: methodology note

Updated 11 December 2024

For each day, the Department for Transport (DfT) produces statistics on the following, published on the second Wednesday of each month at 9.30am:

1. Road traffic in Great Britain
2. Rail passenger journeys in Great Britain
3. Transport for London (TfL) tube and bus routes
4. Bus travel in Great Britain (excluding London)
5. Cycling in England

This document sets out information on the data sources and methodology used to generate each of these headline measures.

These statistics are official statistics and have been produced quickly in response to developing world events. The Office for Statistics Regulation, on behalf of the UK Statistics Authority, has reviewed them against several key aspects of the Code of Practice for Statistics and regards them as compliant with the Code of Practice for Statistics.

Reminder on days of the week differences

Although daily data is being reported, direct comparisons of change should not be made between weekdays and weekends/bank holidays. For public transport there are typically different levels of service/timetable in place on weekends and bank holidays than on weekdays; and for road traffic, there is a different profile on weekend days compared to weekdays.

1. Road traffic

Coverage

The National Road traffic estimates include change in traffic on all road types in Great Britain at GB level. These estimates are provided split into selected vehicle types (cars, light commercial vehicles, heavy goods vehicles) and a total for all motor vehicles.

All motor vehicles	All vehicles except pedal cycles
Cars and taxis	Includes passenger vehicles with nine or fewer seats, three-wheeled cars and four-wheel-drive ‘sports utility vehicles’ (SUVs). Cars towing caravans or trailers are counted as one vehicle.
Light commercial vehicles (LCV) (also: light goods vehicles)	Goods vehicles not exceeding 3.5 tonnes gross vehicle weight. Includes all car-based vans and those of the next largest carrying capacity such as transit vans. Also included are ambulances, pickups and milk floats.
Heavy goods vehicles (HGV)	Includes all rigid and articulated goods vehicles over 3.5 tonnes gross vehicle weight.

Data source

The analysis is based on around 275 automatic traffic count sites across Great Britain. These sites are used for DfT’s Quarterly Road Traffic National Statistics series to estimate traffic change and as such the samples of automatic traffic counters are stratified by area, road classification, and road management and have been designed to be representative of national traffic.

Methodology

The daily road traffic estimates are suitable as an indication of traffic change rather than actual traffic volumes. The data provided is indexed to the first week of February 2020 and the comparison is to the same day of the week. Therefore, 100 would mean that traffic is the same as the equivalent day in the first week of February 2020. Over the course of the year, normal traffic can vary by +/– 20%.

Quality

In order to achieve a daily estimate of traffic change, lower levels of validation have been applied compared to normal statistical outputs. However, the data series is being verified against other sources and similar trends have been seen.

Further statistics

More information about DfT’s statistics on road traffic can be found on our road traffic statistics pages.

2. Rail passenger journeys

The National Rail (including Elizabeth Line) timeseries was temporarily withdrawn from the published data tables in the November 2023 and December 2023 releases, due to a data quality issue. The timeseries was reinstated in the January 2024 release, using a new methodology, which mitigates the effects of this issue. 

The ‘National Rail Excluding Elizabeth Line’ time series, not affected by this issue nor by the methodology change.  

More information about this issue can be found in this section.

Coverage

Passenger journeys across the rail network of Great Britain.

Data source

Information on journeys comes from the Latest Earnings Networked Nationally Over Night (LENNON) data source. LENNON is the revenue settlement service for the train operating companies for GB passenger rail ticket sales and is the main source of data for GB rail fares revenue. The system processes information from the majority of GB train ticket sales, it then allocates daily revenue to each of the train operators within 24 hours of the ticket being purchased.

Methodology

Data labelled ‘National Rail’ is calculated by summing the number of journeys over a seven-day period and expressing this as a percentage of the equivalent pre-COVID-19 week in 2019 or 2020. 

The number of journeys is calculated from LENNON by taking earnings and estimating the likely number of journeys that would have been taken, using an industry-agreed methodology. For season products of more than a week’s duration, journeys are apportioned out across the duration of the product’s validity. 

On Wednesday 23 November 2022, the National Rail data was revised, with changes backdated to the start of the series.  This revision involved switching from using pre-allocation (sales) data to using post-allocation (earnings) data, and including refunds and Transport for London (TfL) sold products. This revision reflects changes to passenger purchasing behaviour as demand has recovered from COVID-19. The Office of Rail and Road (ORR) carried out a review of this revised methodology and concluded that it is appropriate for DfT to switch to make these changes. 

From the January 2024 release, the methodology to calculate the number of journeys on the Elizabeth line changed. More information can be found in the Elizabeth line and the overestimation of journeys.

Quality

Whilst considered fit for purpose for monitoring overall change in usage trends, there are several features of LENNON journey data which should be borne in mind when using it for this purpose. These are mitigated to some extent by reporting the data as a percentage of 2019 (or 2020) rather than reporting journey numbers themselves. 

Adjustments have been made for bank holidays in England and Wales where an equivalent comparator date is available to use. On some occasions, such as over the Christmas and New Year period, when bank holidays have been moved, or when new bank holidays have been added, data have been suppressed because there is a lack of equivalent comparator date available to use. Because the published data is a 7-day rolling average, data for the days following a date which has been suppressed can be based on a rolling average with fewer than 7 days of data. 

The impact of industrial action or other unexpected events which affect rail usage are not adjusted for. This means caution should be made when interpreting figures for specific days. Such cases are flagged in the notes of the publication table. 

The latest daily data covers journeys up to 10 days before the date of publication. After 7 days the data is about 95% complete for a given date.  Journeys using monthly or annual season tickets are apportioned out over the duration of the product’s validity. The actual number of journeys made on each day might differ to how they are apportioned using this method, and therefore there could be an over or underestimate of usage. Therefore, we recommend looking at trends rather than interpreting the exact figures. 

LENNON does not cover some Passenger Transport Executives, local government bodies responsible for public transport in their areas. 

LENNON daily passenger journey estimates and ticket sales are sensitive to occasional lump sum adjustments. For example, TfL issue zonal season tickets which allow travel on National Rail. Earnings from these journeys are passed between TfL and train operating companies via LENNON. When these earnings are reported and dropped into LENNON, this could look like a considerable change in journeys or sales on a given day. Again, this supports looking at rolling weekly totals and comparing to the equivalent week in 2019.

Inclusion of Elizabeth line data

After services in the central section of Crossrail started running in May 2022, there was a significant uplift in National Rail journeys counted in the LENNON database. Before May 2022, Crossrail services were operated under ‘TfL Rail’ branding, which ran between Paddington and Reading or Heathrow Airport, and between Liverpool Street and Shenfield. These journeys were direct replacements for previous National Rail services and were counted in LENNON. Following the opening of the central section, when Crossrail services began operating under ‘Elizabeth line’ branding, these journeys started being recorded in LENNON, replacing some journeys that would have previously been taken on other modes such as London Underground and Docklands Light Railway (DLR). 

From September 2023 onwards, the ‘Daily domestic transport use by mode’ statistics include a second rail usage time series which excludes Elizabeth Line services (and other relevant services that have been replaced by the Elizabeth Line) from both the travel week and its equivalent baseline week in 2019, where appropriate. 

Before May 2022, services which would correspond to the current western Elizabeth Line services were operated by TfL Rail and Great Western Railway (GWR). Therefore, journeys allocated to the Elizabeth line in the current travel week, and journeys allocated to the relevant TfL Rail/GWR services in the equivalent baseline week are removed. This allows for a more meaningful like-for-like comparison of rail demand across the period because the effects of the Elizabeth line on rail demand are removed. 

This time series excluding Elizabeth line services presents a lower recovery than the time series which includes the effect of Elizabeth line services. 

From September 2023, the ‘Daily domestic transport use by mode’ statistics bulletin exclusively refers to the time series excluding Elizabeth Line services.

Elizabeth line and the overestimation of journeys

In November 2023, the rail usage time series which includes Elizabeth line services was temporarily withdrawn, until January 2024, due to a data quality issue with how Elizabeth line passenger journeys were counted. 

Due to system constraints in how the data is ingested into the LENNON system, there was an overestimation of the number of Elizabeth line passenger journeys since the Elizabeth line opened in May 2022. 

From analysis using data provided by TfL (which is unaffected), the impact of the issue had worsened over the 2023 calendar year, as more services were introduced on the Elizabeth line, with an overestimate of up to 25% for the first half of the 2023 and up to 40% for the second half. 

DfT worked with ORR to develop a new methodology to adjust the industry-wide ‘National Rail including Elizabeth line’ series. 

In January 2024, the ‘National Rail including Elizabeth line’ time series was reinstated, with a new methodology which mitigates the effects of the LENNON system constraints.

In this new methodology, Elizabeth line journeys are calculated by adjusting the LENNON counts, using a monthly adjustment factor.  

This adjustment factor is calculated by comparing LENNON monthly counts and TfL monthly counts for the Elizabeth line. The monthly adjustment factors are then applied to the daily LENNON counts for the relevant month.  

The adjusted Elizabeth line journey counts are then added to the non-Elizabeth line LENNON passenger journey counts (which are unaffected), to produce the rail usage time series which includes Elizabeth line services. 

Due to the unavailability of daily TfL counts, we are not able to apply daily adjustment factors to daily LENNON counts and are constrained to applying monthly adjustment factors. 

TfL monthly counts for the Elizabeth line are not always available for the most recent month. As a result, when an adjustment factor for a given month cannot be calculated, the adjustment factor from the previous month is carried forward. Any figures using estimated adjustment factors will be flagged as ‘provisional’ and revised and flagged as such in the following iteration of the publication. 

The ‘National Rail excluding Elizabeth line’ timeseries, however, was not affected by this issue and therefore did not undergo any methodology change.

Further statistics

More information about DfT’s rail passenger statistics can be found on our rail statistics pages.

3. Transport for London (TfL) tube and bus routes

Coverage

Transport for London bus and tube usage, including the number of tube entries during the peak 15-minute period for the previous day.

Data source

Operational data from Transport for London. TfL tube reductions compared to the equivalent day last year. Bus journey data is based off tap ins on the bus – there is a gap in the data series during the period where tap in was not being done.

Methodology

Usage is measured by entry/exit data from tube stations and bus boarding taps. This is then compared to equivalent data from 1 year ago and to other trends to gauge the extent to which travel has been reduced. Where a bank holiday occurs, this year or last year, then the comparison is to the nearest similar day (so a bank holiday is not compared to a non bank holiday).

The TfL data (tube and London buses) published in June 2023 is not directly comparable to the data published in previous months, and the back series has been revised. This is due to the implementation of full automation for the generation of the data and a number of changes in the TfL data processing methodology which came into place mid-May 2023. These methodology changes resulted in some small improvements to the quality of the data provided, which lead to a small change in the total tap counts which are used to calculate the TfL transport usage as a proportion of pre-COVID-19 levels. The effect on transport usage as a proportion of pre-COVID-19 levels is minimal.

The changes include:

The addition of paper ticket counts: tube usage data now includes both contactless and paper ticket entries and exists. Up to May 2023, publication timeliness requirements meant that tube usage data only included contactless taps. This change affects the data, though paper tickets are used in only a small proportion of journeys.

The addition of validation taps resulting in entry/exit: a more complex analysis process can now identify validation taps resulting in entry/exits and relabel them accordingly. This change increases the accuracy of the data at a number of stations.

The addition of late-arriving tap data: some tap data for the previous month can be received after the date of publication. Previously, these were subsequently excluded from the counts. Under the new process the back series is revised each month to account for late data arrival.

The use of an automated and more robust process to assign a pre-covid date for comparison with the post-covid travel date: this process was previously done manually. As a result, the pre-covid baseline comparison date under the new method might sometimes differ from the pre-covid baseline comparison date previously assigned to a date of travel

They also include a small number of changes in the way London Underground stations are identified and classified.

Quality

This is operational data, based on contactless card use, considered fit for purpose for reporting changes in trends in usage. Tube and bus data is deemed to be of high quality. Due to middle door bus boarding policy earlier in the pandemic, there is a period for which we did not receive the same high quality data.

Since May 2022, figures for TfL tube will include some Elizabeth Line journeys. Both Tube and Elizabeth line share ticket halls in central section stations such as Tottenham Court Road, Bond Street, Farringdon and Whitechapel – therefore either service can count as a single entry/exit against that station.

To ensure completeness of the data, the latest daily data covers journeys up to 3 days before the date of publication.

4. Bus travel in Great Britain (excluding London)

Coverage

Passenger boardings on around half of bus services in Great Britain outside London.

Data source

This data has been provided by Ticketer, based on operators which were using Ticketer in the January reference week (third week of January 2020). Data from other sources (including non-Ticketer operators) has been used to validate these figures and are generally consistent with the trends presented.

Methodology

A figure of 100 means the same level as that seen on the same day in the third week of January 2020. A figure higher than 100 shows an increase. A figure less than 100 shows a decrease.

Passenger boardings will include physical ticket sales, where money changes hands, as well as smart cards (commercial or concessionary), QR tickets, and where the driver counts passengers (such as school runs).

As a measure of comparability to “business as usual”, data for Easter and other bank holidays were adjusted in 2020 and much of 2021 to compare against typical usage for those dates. This is because it is known that operators offer a different service level for those dates when compared with the typical service levels for those days of the week. Data has been omitted for the bank holiday on Friday 8 May 2020 as a suitable comparative adjustment could not be identified. Since late 2021, data have not been adjusted, and therefore data for bank holidays have been excluded.

Quality

This is operational data considered fit for purpose for reporting changes in trends in usage, and has proved to be broadly comparable to the published Accredited Official Statistics on bus usage. However, it does not meet the same quality standards and coverage as the existing Accredited Official Statistics.

Further statistics

More information about non-TfL bus travel can be found on our Bus Statistics pages.

5. Cycling

From 11 April 2023, the cycling timeseries is no longer updated in this table. This is because DfT now publishes a new monthly cycling index, showing the change in cycling levels in England as part of the active travel statistics collection. This new publication was first published on 27 April 2023 and is available on the walking and cycling statistics page. The information in this section refers to data between 1 March 2020 and 7 April 2023 only.

Coverage

Estimated change in cycling usage in England.

Data source

This is an estimated percentage change in cycling derived from:

• telecommunications data – anonymised and aggregated data from O2, as a measure of total trip numbers
• National Travel Survey (NTS) results, as a pre-COVID-19 baseline modal split
• DfT Roads automatic traffic count (ATC) index data, as an indication of changes to road users
• LENNON rail data, as an indication of changes to rail users
• sources of cycling use data including automatic cycling counters and camera-based estimates

Methodology

Overall active travel (cycling and walking combined) is estimated as a proportion of total trips seen in telecommunications data. In this, a trip indicates when an individual moves from one cell tower to another and is then stationary for at least 30 minutes. Short trips of less than 1 kilometre in urban areas and 5 kilometres in rural areas will be excluded. This disproportionately affects walking trips, as a greater proportion of walking trips will be missed compared to other modes.

Using the 2018 NTS results, we estimated the breakdown in total trips by mode (road, rail and active) for a pre-COVID-19 baseline and added road freight (which is not included in the NTS). We applied this baseline split to the total trips in the telecommunications data for the first week of March. By calculating percentage changes in road and rail users relative to the same week, we have then been able to adjust this number of trips by mode over time.

We then have the total trips for each day (from telecommunications data) and the total trips for road and rail users (calculated). The difference between these two gives an estimate of the number of active travel trips.

Using the active travel estimate, we then apply the same NTS baseline for cycling to the total trips. We then follow the same process as above by calculating percentage changes in observed cycle counts from ATC data relative to the same week, which allows us to adjust this number of trips over time. Walking is therefore a residual of a residual, and as we know that the telecommunications data does not capture short walks, we do not think the walking estimate in isolation is a useful indicator.

Quality

This is a best-efforts estimate of national cycling utilising multiple data sources and is considered fit for purpose for reporting large changes in trends in usage. The methodology will be updated if or when additional information becomes available.

Analysis applies to England only due to the available geographies in the individual data sets.

Daily data is volatile based on both the relationship cycling has with the weather, but also volatility in the underlying data sources and methodology. Some of the increases noted will also reflect the seasonal pattern of cycling as comparisons are to a base week in March 2020.

As we consider further sources, we may update the methodology and therefore revise the results.

As of September, the timeliness of the source data has moved to a lag of 3 days rather than 1 reflecting the collection and processing of the mobile telecoms data.

Further statistics

More information about cycling,along with the monthly cycling Index, can be found on our walking and cycling statistics pages.

Annex: data periodicity and baseline by mode

Mode	Periodicity	Baseline
Roads	Daily figure	Equivalent day from first week of February 2020
Rail: passenger journeys	Rolling weekly total for week ending today	Equivalent week in 2019
TfL: tube and bus	Daily figure	Equivalent day in 2019
Bus travel (excluding London)	Daily figure	Equivalent day from third week of January 2020
Cycling	Daily figure	Equivalent day from first week of March 2020