In our latest blog, Head of OSR Ed Humpherson discusses how data sharing and linkage can provide vital insight into the problems and potential solutions when looking at road traffic collision data.
At the start of 2025, OSR published a rather optimistic piece on the potential for data sharing and linkage. Data sharing and linkage can yield new insights, identify previously hidden problems, and highlight what works and what doesn’t. It has huge potential to serve the public good.
But it’s also difficult to achieve, and there are still lots of frustrated researchers who have not been able to progress their work because they can’t access the data that they need.
So why are we optimistic? Partly, it’s a top-down perspective: we’ve seen progress through the increasing maturity of the UK-wide facilitation of data sharing and linkage provided by the excellent Administrative Data Research UK, reflected in programmes like the Ministry of Justice’s Data First.
But it’s also because, in some specific policy areas, there is a growing bottom-up drive to make better use of datasets by linking them to others, and enhancing the insight that they can provide.
Developments in data on road traffic collisions provide the best grounds for my optimism. The Department for Transport (DfT) publishes a long-standing data set on road traffic fatalities. The statistics show that the UK does well in international comparisons of road traffic fatalities per capita. They are based on a consistent set of categories for recording traffic collisions by police forces in England, Wales and Scotland, using a system called STATS19. They are well presented and clearly explained.
But the STAT19 data set has some limitations. The data series does not capture all traffic collisions, nor does it record all injuries. And as with all data based on police recording, the incidents recorded are those that come to the police’s attention – and not all do. To its credit, DfT is clear about these limitations in its annual statistical release.
Moreover, the picture painted by the traffic fatalities statistics can hardly be described as positive. Every fatality is a personal tragedy, impacting the families and friends of those involved in a deep and difficult way. And the long-term declines in fatalities seem to have stalled over the last decade, as shown in Chart 1 in the annual report here:
Figure 1: All road users killed in traffic collisions in Great Britain, 1979 to 2023
The chart shows a decline in road users killed in traffic collisions in Great Britain from 1979, with the decline slowing from 2013 – 2023. The chart was originally published on the Department for Transport website. The data can be found here.
So, we should welcome anything that can give us more insight into the problems and potential solutions. This is where linked data comes in. By linking STATS19 data to ambulance data and hospital records, we can get a much richer picture of collisions – where they happen; who is affected and, just as importantly, the full extent of their injuries; how the victims are treated by the health care system; and the outcomes of their treatment. And this information can in turn help answer important questions, like why it is that the reductions in fatalities appear to have stalled, and whether there are practices and interventions that can reduce collisions and increase people’s survival chances.
The potential for the linkage of STATS19, ambulance and hospital data is the basis of an excellent paper by Seema Yalamanchili of Imperial College (PDF download), which in turn was the starting point for a round table I attended in January. The meeting was convened by the RAC Foundation and took place at the Royal Automobile Club. Seema presented her paper, setting out the case for this data linkage, the barriers to linking the STATS19 data – technical, legal and cultural barriers alike – and crucially, laid out a clear plan for addressing these barriers.
The meeting at the RAC Foundation was one of the most constructive, positive meetings that I’ve attended on data sharing and linkage. It was chaired by the RAC Foundation, and included people who produce the official statistics for the Department for Transport and the Department of Health and Social Care; NHS England; policy and scientific leaders from those departments; surgeons who work in trauma care; transport and health researchers; and data governance experts.
A lot of the meetings I’ve attended on data sharing and linkage focused on setting out all the barriers and constraints. And there are indeed a number of challenges. First of all, in any endeavour of this kind, the project should test whether what it is proposing is publicly acceptable. This needs to be done through a process of public involvement that listens to how people feel about linking sensitive pieces of information.
Then there is the legal authorisation – is what is proposed lawful, and who needs to approve it? This element can be complex and time-consuming, as any researcher who has proposed working with healthcare data can attest.
And beyond these ethico-legal considerations, how technically feasible is the linkage? Do the datasets have enough common identifiers for records to be linked with a reasonable degree of confidence? How easy is it to link a record of a road traffic injury to the trauma centre where the patient is treated?
All these issues – public perception, legal context, technical data quality and linkability – are complex in their own right. It can take a lot of time to work through each of them. But underlying these substantive issues lurks a deeper issue: it seems as though the culture of data-owning organisations is not always conducive to data linking. This could be for a range of reasons, including risk aversion or a lack of incentives. Whatever the cause, the result is that organisations are less supportive of data linking than their leaders claim to be.
The RAC Foundation meeting was different from many others I’ve attended on linkage. Led by Seema’s presentation, and drawing on her paper, it focused less on the barriers themselves, and more on what attendees can do collectively to address them. We all focused on what can be done, not what can’t be done. For example, the DfT lead statistician said that, if the linkage took place, he would be keen to include insights from the linked dataset in the annual publication.
The meeting ended with a clear commitment to take the work forward: to enrich the official statistics on road traffic collisions; to link data for more insight into trauma care; and to make a difference to a societal problem that continues to devastate victims and loved ones. Within a couple of weeks of the RAC meeting, a working group involving all the key players has sprung up. All this points to a building momentum for change.
Of course, it may be that there are further challenges ahead. But this project shows that, with creativity, ambition and focus, progress is possible – and that cultural barriers to data linkage are by no means fixed. I hope this approach becomes the norm when people seek to use data to serve the public good.
So, why am I optimistic? Because of initiatives like this.