Police recorded road collisions and casualties: quality report

Police recorded road collision and casualty statistics provide information about road collisions in Wales which resulted in personal injury. Police forces are required by law to collect information about such incidents, including details about casualties, vehicles, locations and factors that led to the collision. 

Provisional headline statistics, StatsWales data on roads and an interactive dashboard are updated on a quarterly basis, and detailed final analysis and commentary are published in annual reports. 

These statistics only include road collisions which resulted in personal injury and for which information was reported by the police. It is known that there is an element of under-recording of such incidents, particularly for less severe incidents where police officers may not have been in attendance. 

These statistics do not include collisions:

• that were not reported to the police 
• that occurred on private land i.e. car parks or fields
• where no personal injury was recorded
• where the collision was later confirmed by a medical professional or coroner to be a suicide or medical episode

These statistics feed into the Department for Transport’s (DfT) statistics on reported road collisions and casualties in Great Britain.

Road safety is devolved to the Welsh Government and Welsh Ministers are the Highways Authority for motorways and trunk roads in Wales. These statistics are essential to support analysis and policy development on road safety in Wales. A Road safety partnership plan was published by the previous Government in March 2026. This included the creation of targets to reduce the number of people killed and seriously injured on Welsh roads by 2040.

The data are used by the Welsh Government to assess the effectiveness of current policy, develop and assess the impact of new policies and road safety interventions and monitor trends of the number of people killed and seriously injured on Welsh roads. As the Highways Authority for the trunk roads, Welsh Ministers must analyse the data to help promote road safety in Wales. Much of the data is important in understanding the operation of the road network and driver behaviour.

In addition, a variety of other organisations use these data to support road safety assessments and identify and address collision hotspots. They include police forces, road safety groups, local authorities, transport planners and highway authorities. The statistics are also frequently covered by national and local media in reporting the latest picture and trends in road safety.

The statistics included in this release do not cover any of the national indicators, however they may be relevant in the context of some indicators, and they may be used by public services boards in relation to their local well-being assessments and plans.

The data are the most comprehensive and reliable source of information on road collisions and casualties in Wales.

Strengths

• The information is processed and published on a quarterly basis to enable users to identify and act on emerging road safety issues. 
• The statistical outputs have been developed to meet user needs and cover a wide range of topics relevant to users. 
• The road collisions dashboard enables users to manipulate the underlying data by a range of geographical and demographic variables to create bespoke analyses to supplement those in the statistical bulletins. 
• The statistics are derived from existing administrative systems operated by police forces.

Limitations

There are long-standing issues around under-coverage, particularly with less serious collisions, affecting the statistics in Wales and across Great Britain. For example, hospital, survey and compensation claims data indicate that many non-fatal collisions are not reported to or recorded by the police. This is further discussed in the coverage section

Interpreting short-term trends can be problematic because of changes in police recording practices and road users’ reporting of incidents. 

Quarterly updates are regarded as provisional because they are often under-estimates compared with final year’s data. 

Prior to 2016, majority of data on severity of injuries and factors contributing to incidents were based on police officers’ judgement of injury severity. Since 2016, the coding of injury severity in many police forces changed, as forces have adopted injury-based reporting systems (IBRS). This is where police officers record a casualty’s injuries from a defined list and the overall severity is determined from the most severe injury recorded. This removes an element of judgement from the coding of severity, but care needs to be taken when comparing over time.  The IBRS was not adopted by any of the four police forces in Wales until Dyfed-Powys police force became the first Welsh force to move in May 2023. Since then, South Wales police force moved to IBRS in November 2025, and Gwent and North Wales police forces are yet to move to an injury-based reporting system. Further information on injury-based reporting system can be found in the coverage section.

Delays in data provision have occasionally resulted in postponements to statistical releases. 

In the latest specification for the STATS19 data collection (DfT) is the 2024 specification a new vehicle category “Personal Powered Transport (PPT)” has been included. For example, prior to this “E-scooters” would be classed as “other” and can only be identified using a free text field. 

Additional validation carried out in 2023 identified some inconsistencies between the speed limit of the road where the collisions occurred recorded by the police officer in attendance, compared with data held by local authorities. This is further discussed in the accuracy section.

The longstanding issues with under-coverage of collisions is one of the most significant quality concerns with these statistics. Under-coverage falls into two categories.

1. Collisions resulting in personal injury not reported to the police

Research by DfT through their National Travel Survey (Summarised under ‘National Travel Survey (NTS)’ in Other sources of information on road casualties (DfT)) [primary source of data on personal travel patterns by residents of England within Great Britain] indicates a moderate increase from 48% in 2017 to 2019 to 55% in 2020 of respondents not reporting injuries sustained in a road collision in the 3 years to the police. One explanation for this increase may be that casualties with minor injuries were less inclined to make an additional journey to report a collision to police in 2020 than previous years. Another explanation may be that increased cycle traffic in 2020 led to a higher than usual fraction of single vehicle pedal cycle accidents on the roads. Previous analyses of STATS19 and Hospital Episode Statistics data have shown that these types of accidents are less likely to be reported to police. However, additional data and further analyses are needed to firmly understand the reasons for this increase.

2. Collisions reported to the police but not recorded by the police

We have identified some instances of this through our quality assurance processes, which flag significant changes in the data which we then query with police. In these scenarios police forces have usually, but not always, been able to retrospectively collate and supply the missing information. But by their nature, these occurrences are only identifiable if there are relatively large discrepancies compared with previous years’ data. It is not known to what extent there is under recording on a small scale or on an ongoing basis. Improving awareness around the need to record collisions through the STATS19 system has been a feature of our work with police forces. As with non-reported collisions, most non-recorded cases are likely to be ‘slight’ injury collisions.

Overall, the available sources show that collisions reported to and recorded by police forces represent only a subset of all personal injury road collisions, but that coverage of serious injuries and fatalities is good. 

In addition to under coverage of collisions, there is a known under recording of serious injuries in the non injury-based reporting systems.

Injury severity and severity adjustments

The DfT and the Welsh Government publish road collisions and casualty statistics based on the STATS19 data collection system. This well-established system sets out the variables and data standards to which each of the police forces in Great Britain submit data relating to vehicle accidents in which an injury has occurred. 

Within STATS19, injured casualties are classified as seriously or slightly injured. Historically, this has been based on the judgement of recording police officers, using an agreed definition of serious injury. However, since 2015, the coding of injury severity in many police forces has changed, as forces have adopted injury-based reporting systems (IBRS), where police officers record a casualty’s injuries from a defined list and the overall severity is determined from the most severe injury recorded. This removes an element of judgement from the coding of severity. 

Following the 2018 STATS19 review, it was recommended that all forces move to this approach. However, the new approach has impacts on the level and trend in the number of serious casualties, so that a means of adjusting data for forces not using injury-based reporting was required to estimate figures comparable over areas and over time for use in the published statistics. This adjustment is particularly required when comparing or grouping data from systems using both injury-based and non injury-based systems.

In 2019, the Office for National Statistics (ONS) conducted an analysis on behalf of DfT to develop a methodology to quantify the effect of the introduction of injury-based reporting systems on the number of slight and serious injuries reported to the police, and to estimate the level of slight and serious injuries as if all police forces were using injury-based reporting systems. The final report can be found at Reported road casualties Great Britain (DfT). Further information is also published in the Guide to severity adjustments for reported road casualties Great Britain (DfT).

DfT publish both adjusted and unadjusted figures in their data tables. The unadjusted figures are comparable with the figures we publish. We do not currently apply any adjustments to our collision or casualty figures, meaning there will be an underreporting of serious injuries and therefore serious collisions. 

As stated above since 2016 onwards, figures for Great Britain on the severity of injury have been affected by a large number of police forces moving to IBRS. Approximately half of English police forces moved to IBRS for recording reported road collisions at the end of 2015 or the first part of 2016. The introduction of IBRS in England led to a change in the reported severity of road casualties (with a higher proportion of injures recorded as serious). As a result, a means of adjusting data for forces not using injury-based reporting is required to estimate what the numbers would be if all police forces were using injury-based reporting systems. 

In May 2023, Dyfed-Powys police force became the first Welsh force to move to an injury-based reporting system. South Wales police force moved to IBRS in November 2025. We are continuing to work with both Gwent police force and North Wales police force that have not adopted the injury-based reporting system and with DfT to establish timeframes for when they will move to an injury-based reporting system.

The move to an injury-based reporting system does not affect the total number of collisions, or the total number of fatalities. However, the move to injury-based reporting means it’s likely that there will have been an increase in the number of seriously injured casualties reported from the point when they moved to IBRS, and therefore an increase in the number of serious collisions.

Given that two police forces have now moved to injury-based reporting system, we intend to adjust data not based on injury-based reporting from the next quarterly publication in July. In advance of the quarterly publication, we will publish a Chief Statistician’s blog providing further information on severity adjustments, the methodology, a timeline of how we got here and our plans for future publications to help users understand these changes. Further information on IBRS from the DfT can be found at Road safety data and statistics: STATS19 review update and future plans (DfT).

Data collection

The Annual Data Requirement (ADR) (Home Office) confers a statutory duty on police forces in England and Wales to collect information about road traffic collisions which result in personal injury. There are two different ways of collecting this information.

1. Police officers record this data on a ‘STATS19’ form (DfT).
2. Police forces that are using an IBRS can input the data into a standardised reporting tool (e.g. CRaSH – Collision Recording and Sharing) whilst those that are not using IBRS compile the data using their own IT IBRS system, for example, South Wales police force. To note, all police forces have a legal obligation to move to an IBRS.

Data are collated at a police force level onto administrative systems and transferred to the Welsh Government on a routine basis. Most of the information is recorded at the scene of the incident by attending officers, however, the STATS19 forms may be completed or updated subsequently when more information is available. 

Dyfed-Powys police force moved to CRaSH in May2023 whilst South Wales police force moved to its IBRS in November 2025. The other two police forces remain on the non injury-based reporting system.

Validation and verification

The Welsh Government runs a suite of automatic validations on the raw data provided by police forces. These checks are intended to identify records containing unusual, invalid or missing data and these are flagged for validation with police forces. Some examples of the types of checks are:

• age of drivers within expected range 
• invalid collision geographical locations 
• checks for duplicate records 
• internal consistency of records 
• confirming which local authority the collision occurred in when along police force boundaries

When these validation checks are resolved Welsh Government compiles a near-final dataset and runs comparisons against previous years’ aggregates. This is done on a quarterly and annual basis for Wales as a whole and for the police force areas. This helps to identify unusual trends in the statistics which can indicate missing data, which can be queried again with the police.

We also compare against other sources of information, for example intelligence from meetings with police forces, information reported to the Road Safety Wales group coordinated by  Royal Society for the Prevention of Collisions (ROSPA), and fatal collision reports supplied to Welsh Government. 

The data are provided to the DfT to feed into their statistical releases. DfT also run a suite of automatic validations which can flag up additional quality issues such as duplicate records, but these are typically on a very small scale. 

The final data are shared with police forces for final quality assurance and sign off before publication.

Publication

Once the data has been finalised the statistical bulletin, dashboard and StatsWales tables are compiled. All elements of the release are independently checked, and a final sense check is carried out by the responsible statistician prior to publication on the website. 

The final data also feed into the Department for Transport’s statistical releases at Road safety statistics (DfT).

A full list of notes and definitions relating to these statistics is published by DfT at Road safety statistics: coverage and definitions (DfT), though the following are particularly important.

STATS19 data

The core set of statistical data which the police have agreed to provide about personal-injury road traffic collisions.

Collision

Involves personal injury occurring on the public highway (including footways) in which at least one road vehicle or a vehicle in collision with a pedestrian is involved and which becomes known to the police within 30 days of its occurrence. Damage-only collisions, with no human casualties or collisions on private roads or car parks are not included.

Collision severity

The severity of a collision is based on the severity of the most severely injured casualty, as outlined below.

Casualty

A person killed or injured in a collision. Casualties are sub-divided into killed, seriously injured and slightly injured.

Killed (fatal)

Human casualties who sustained injuries which caused death less than 30 days after the collision. Confirmed suicides are excluded. 

Seriously injured

Injured casualties are classified as seriously or slightly injured based on the type of injury sustained, as recorded by the police on the basis of information available within a short time of the collision. This generally will not reflect the results of a medical examination but may be influenced according to whether the casualty is hospitalised or not. Injuries classed as serious include fractures, concussion, internal injuries, crushings, burns (excluding friction burns), severe cuts, severe general shock requiring medical treatment and injuries causing death 30 or more days after the collision.

Slightly injured

An injured casualty that is not classified as seriously injured, having an injury of a minor character such as a sprain (including neck whiplash injury), bruise or cut which are not judged to be severe, or slight shock requiring roadside attention. This definition includes injuries not requiring medical treatment.

Injury-based reporting system (IBRS)

A system of recording road collisions (e.g. CRASH). In these systems, casualty injury severity is coded from a list of injuries, rather than being based on the judgement of the reporting officer. In some forces, officers complete the information required on a mobile device.

All official statistics should show the standards of the Code of Practice for Statistics (UK Statistics Authority). The Code of Practice sets out common standards that should be followed by all UK organisations that produce official Code of Practice statistics.

These are accredited official statistics. The designation of these statistics was confirmed in July 2013. They comply with the standards of trustworthiness, quality and value in the Code of Practice for Statistics. 

It is Welsh Government’s responsibility to maintain compliance with the standards expected of accreditation. If we become concerned about whether these statistics are still meeting the appropriate standards, we will discuss any concerns with Office for Statistics Regulation (OSR) promptly. Accreditation can be cancelled or suspended at any point when the highest standards are not maintained, and reinstated when standards are restored.

Accredited official statistics are called National Statistics in the Statistics and Registration Service Act 2007.

Statement of compliance with the Code of Practice for Statistics

Our statistical practice is regulated by the Office for Statistics Regulation (OSR). OSR sets the standards of trustworthiness, quality and value in the Code of Practice for Statistics that all producers of official statistics should adhere to. 

All of our statistics are produced and published in accordance with a number of statements and protocols to enhance trustworthiness, quality and value. These are set out in the Welsh Government’s Statement of Compliance. 

These accredited official statistics (OSR) demonstrate the standards expected around trustworthiness, quality and public value in the following ways.

Trustworthiness

These statistics use data collected by Welsh Police Forces via the STATS19 system. The UK-level data, together with a full description of the sources and methods used to compile these data can be found on the GOV.UK website (Road Safety Statistics (DfT)). 

These statistics are pre-announced on the Statistics and Research area of the Welsh Government website. Access to the data during processing is restricted to those involved in the production of the statistics, quality assurance and for operational purposes. Pre-release access is restricted to eligible recipients in line with the Code of Practice (UK Statistics Authority).

Quality

The published figures provided are compiled by professional analysts using the latest available data and applying methods using their professional judgement and analytical skillset. Statistics published by Welsh Government adhere to the Statistical Quality Management Strategy which supplements the Quality pillar of the Code of Practice for Statistics (UK Statistics Authority) and the European Statistical System principles of quality for statistical outputs.

The statistical release is then drafted, signed off by senior statisticians and published in line with the Welsh Government’s statement on confidentiality and data access.

Value

The purposes of this statistical release and the accompanying data published on StatsWales are to provide evidence for policy development and to inform the media and wider public about the changes to the police recorded road collisions in Wales.

You are welcome to contact us directly with any comments about how we meet these standards. Alternatively, you can contact OSR by emailing regulation@statistics.gov.uk or via the OSR website.

This release has been scored against the UK Statistics Authority’s Administrative Data Quality Assurance matrix. The matrix is the UK Statistics Authority regulatory standard for the quality assurance of administrative data. The Standard recognises the increasing role that administrative data play in the production of official statistics and clarifies what producers of official statistics should do to assure themselves of the quality of these data. The toolkit that supports it provides helpful guidance to statistical producers about the practices they can adopt to assure the quality of the data they receive and sets out the standards for assessing statistics against the Code of Practice for Statistics.

The criteria against which statistics are scored are: 

• operational context and administrative data collection 
• communication with data supply partners 
• quality assurance principles, standards and checks applied by data suppliers 
• producer’s quality assurance investigations and documentation 

The matrix enables us to make an assessment about the risk profile of our statistics based on public interest and quality concerns. We have assessed these statistics as ‘A2/A3’ because we consider the statistics to be of medium/high data quality concern and of medium public interest. This implies that our assurance practices should be either ‘Enhanced’ (A2) or ‘Comprehensive’ (A3) depending on the relevance of the particular practices to our work.

Our initial assessment was that our existing processes met or exceed the requirements at the A2 and A3 levels of assurance in most cases, though there were also areas of the framework requiring improvement. Existing processes were strong in areas such as communication with suppliers, our internal quality assurance and our understanding of the operational context of the data collection. We identified some areas of relative weakness, for example providing information around sources of bias and error and understanding suppliers’ quality assurance processes.

Steps taken to improve our practices

• Met with individual police forces to develop better understanding of their data collection and quality assurance processes. Helped forces to improve their processes and established more collaborative approaches to quality assurance by increasing the frequency and efficiency of data validations. 
• Formalised agreements around roles and responsibilities in data collection, quality assurance and supply. 
• Use a wider range of information to help verify data, including fatality reports, local authorities’ intelligence and information presented to the Road Safety Wales group. 
• Provide more detailed information about the sources of error in the data, with comparisons against related data sources and discussion around the likely scale of under-coverage. 

Our work across these and other areas of the Quality Assurance of Administrative Data (QAAD) (OSR) framework is ongoing and we continue to work with police forces and stakeholders to identify where improvements to data quality and statistical dissemination can be made.

The published statistics on road collisions do not include any personally or commercially sensitive information requiring action around disclosure control or protection of confidentiality. However, the source data do contain some personal sensitive fields, for example post codes, registration numbers and breath test results. All such data are held and transferred securely, and they are not available in published outputs. Sensitive data are made available to external users in some circumstances, for example to support local authorities’ road safety initiatives. In these cases, users conform through signed UK GDPR data access agreements that they will meet the necessary data security requirements and destroy the data at a specified time in the future. 

A privacy notice on the police recorded personal injury road collision data (STATS19) has been produced and published.

Police recorded road collision and casualty statistics adhere to the Welsh Government’s Statistical Quality Management Strategy, and this is in line with the European Statistical System’s dimensions of quality. Details of the dimensions, and how we adhere to them, are provided below.

Relevance

The degree to which the statistical product meets user needs for both coverage and content. 

A variety of organisations use the Welsh road collision and casualty data. The Welsh Government uses road collision and casualty data to help set road safety policy. It is also used for performance indicators, both for the Welsh Government’s Transport Strategy and for some Health Performance indicators. 

Other users include Highway Authorities, including the Welsh Government which is responsible for the motorway and trunk road network, and local authorities, which are responsible for other roads in Wales. Other bodies involved in road safety include Go Safe, Trunk Road Agents, Police & Community Safety Partnerships, Road Safety Wales and the Royal Society for the Prevention of Collisions (ROSPA). Welsh Government also provides data to transport planning organisations to support road safety assessments. 

There is some demand for information on non-injury road collisions, but these are not covered by the STATS19 process.

Accuracy

The closeness between an estimated result and the (unknown) true value. 

As discussed in the administrative data quality assurance section, there are number of known issues relating to accuracy, such as an incomplete record of all incidents, and an underreporting in serious collisions. In addition, changes in police recording practices may mean that the statistics are not directly comparable over time. 

The figures are based on information available to the Welsh Government around 4 months (17 weeks) after the end of the latest quarter. Published figures are subject to revisions if additional data subsequently become available. There are likely to be some errors with collision details and geographical and demographic information, though these are minimised by the validations carried out by the Welsh Government, local authorities and police forces. 

Ahead of the 2023 police recorded road collisions release, we undertook additional validation of the road speed limit data as recorded by police officers at the scene of the collision. This additional validation was undertaken due to the change in the default speed limit on unrestricted roads on 17 September 2023 and wanting to ensure that the speed limit data had been correctly recorded. We continue to monitor and quality assure all the data we receive from the police forces including the road speed limit data. This is presented under the Data Quality Issues section in the Police recorded road collisions: 2023 publication. 

As a result of additional validation, we have highlighted some historical inconsistencies together with potential reasons for the inconsistencies. These will not be amended but limitations will be communicated within publications. Findings based on a small unrepresentative sample of cases suggest that the road speed limit recorded at the time of the collision is consistent with local authority held information in roughly two-thirds of cases. For cases where the information is inconsistent, this is likely to be due to: 

• police officers recording the observed speed limit as it was at the time of the collision rather than the permanent speed limit (which may differ due to temporary orders, roadworks, diversions or other causes)
• inconsistencies between LA records and road limit signs ‘on the ground’
• errors in recalling the road speed limit (based on own knowledge) when completing STATS19 forms back in an office environment

Based on the small sample, the road speed limit information is more likely to be consistent with LA data for 20, 30 and 60mph roads (where over 80% of collisions take place) than for 40, 50 and 70mph roads. 

This issue affects the distribution of road collisions and casualties by speed limit. It does not affect the total number of collisions or casualties at a Wales, police force or local authority area. It does not affect the overall data on collision and casualty severity. 

We do not propose to amend any other historic data, due to uncertainty about the quality of historic speed limit data and the scale of manual validation required. In addition, the speed limits where most collisions occur are typically more likely to be consistent with the speed limit recorded by LAs. We will communicate the quality limitations within our publications.

Timeliness and punctuality

Timeliness refers to the lapse of time between the reference period and the publication of the statistics. Punctuality refers to the time lag between the actual and planned dates of publication. 

There is a clear public interest in road collisions and road casualty data and statistics being put into the public domain. This allows people to make informed decisions on road safety issues based on the up-to-date data. However, it is also important that official statistics are released in compliance with the relevant legislation (the Statistics and Registration Service Act 2007) and in an orderly manner that promotes public confidence in their objectivity and integrity. The release of pre-announced official statistics is fully consistent with the legislation and promotes objectivity and integrity by making the figures available to all users in the same format at the same time. 

Final detailed road collision and casualty statistics are reported on a calendar year basis and are usually published around 5 to 6 months following the year to which the data relate. This release includes the statistical bulletin, interactive dashboard, and StatsWales tables. 

Provisional updates for quarters 1, 2 and 3 are also published through a written summary of the data, dashboard and StatsWales. This is normally with a lag of 4 months after the end of the reference period. 

Delays with data provision and quality assurance have, on occasion, resulted in the postponement of the main statistical release. 

Department for Transport publish annual results for Great Britain sometimes at provisional and final as well as final only. Provisional annual road safety statistics in the May following the year to which the data relate with detailed final data in the following September.  Their annual and provisional publications can be found at reported road casualties Great Britain, annual report (DfT) and reported road casualties Great Britain, provisional (DfT) respectively.

Accessibility and clarity

Accessibility is the ease with which users are able to access the data, also reflecting the format(s) in which the data are available and the availability of supporting information. Clarity refers to the quality and sufficiency of the metadata, illustrations and accompanying advice. 

Statistical releases are pre-announced and published on the Welsh Government’s Statistics & Research website. Data are available on StatsWales and users are able to download and export bespoke cuts of data in open data formats. 

There are a range of options for accessing road safety data.

• We publish around 13 data tables on StatsWales.
• Our interactive data tools provides access to collision and casualty data.
• Road safety data with details on each collision reported (except sensitive variables) is also made available in an open dataset.

This includes collision coordinates, severity, and vehicles and casualties involved in each collision.

We aim to inform known users about developments with the statistical outputs. For example, we developed a user-friendly interactive dashboard with which users can explore a range of location and demographic features of the data. We update and promote the dashboard on a quarterly basis. In our outputs, we aim to provide a balance of commentary, summary tables, charts and maps where relevant. The intention is to ‘tell the story’ in plain English, with a focus on certain topics of known interest to users. 

Since the introduction of the 20mph default speed limit on restricted roads on 17 September 2023 there has been considerable interest in collisions data. To provide clarity and to provide users a better understanding of the data we published a Chief Statistician’s update on ‘understanding road collisions and casualty statistics’ on 24 May 2024.

Our statistical headlines and tweets are published in Welsh and English. All of our outputs adhere to the Welsh Government accessibility policy, and they are subject to internal peer review. 

Further information regarding the statistics can be obtained by contacting Transport Statistics via stats.transport@gov.wales.

Comparability and coherence

The degree to which data can be compared over time and domain and the degree to which data that are derived from different sources or methods, but which refer to the same phenomenon, are similar. 

Changes in police recording practices and our quality assurance procedures may mean that the statistics are not directly comparable over time. These can come about through changes to systems, protocols, software or personnel. When we are aware of such cases we try to establish and describe the likely impact on the statistics. There may also be other more gradual recording or behavioural changes which we do not become aware of. An initial feasibility study linking police and health data on road collisions was published by DfT in November 2025. One of the main findings from the study was “around 70% of casualties in the ambulance service dataset that appear to be in scope of the police collection were linked to STATS19, suggesting police data understates the number of road traffic casualties, even for what are likely to be relatively more serious collisions”.

Conceptually, road collision statistics are fully comparable across Great Britain. However, there are some known differences in reporting systems used by police forces which are likely to result in variation in the comparability of certain information. For example, police forces in England and Wales that have moved to injury-based reporting systems where the IBRS system automatically assigns severity. These systems are known to result in higher numbers of severe injuries compared with non-injury-based reporting systems, which are based on police officers’ judgements. As with the differences between forces in Wales mentioned above, there may also be other procedural differences between police forces across Great Britain which would mean differences in coverage and quality of data. 

As discussed, evidence from other sources indicates that the police recorded road collisions data are only a subset of all personal injury collisions, with potentially large numbers of less serious incidents not being reported to, or recorded by, the police. This, and the fact that the STATS19 process excludes certain collisions (for example deliberate acts and collisions not on public highways) means that the STATS19 statistics are not coherent with estimates of road collisions or casualties from sources such as hospital episode statistics and insurance claims data. 

Evidence indicates the inconsistencies between STATS19 data and other data sources covering road collisions mainly affect less serious incidents. For example, there is broad coherence, both in terms of levels and in terms of trends, between the STATS19 statistics on fatalities and the ONS’ cause of death statistics for land transport collisions.

The DfT led STATS19 review will investigate whether it is possible to quantify the overall scale of under-reporting and what further work can be done to provide a better assessment of the coherence in trends from these statistics and other sources. An update of the STATS19 review and future plans can be found at Road safety data and statistics: STATS19 review update and future plans (DfT).

We welcome feedback on any of our statistics. If you wish to contact us, please do so via: stats.transport@gov.wales

Produced by Knowledge and Analytical Services, Welsh Government