Road safety decisions are made nationally, regionally and locally. But many of the questions behind those decisions are shared across borders.
How do we define a road fatality or serious injury? How complete is collision registration? How do we measure exposure to risk? And when we compare two countries, are we actually comparing the same thing?
These questions are fundamental to working with road safety data. They are also central to the work of the International Traffic Safety Data and Analysis Group, IRTAD.
The same number does not always mean the same thing
International road safety comparisons can appear simple. One country reports a certain number of road fatalities, while another reports fewer. But the figures behind those comparisons are not always constructed in the same way.
Countries differ in how collisions are registered, which organisations contribute to registration and how fatalities and injuries are defined. Even when similar terminology is used, the underlying methodology may differ. That directly affects how figures should be interpreted.
One of IRTAD’s key roles is therefore to improve the harmonisation and comparability of road safety data. The objective is not to make every national dataset identical, but to understand methodological differences well enough to make meaningful comparisons.
Why exposure matters
Absolute numbers are only part of the picture.
A country with more inhabitants, more vehicles or considerably more kilometres travelled cannot simply be compared with a smaller country on the basis of casualty numbers alone. This is where exposure data becomes important.
By combining collision data with variables such as population, vehicle fleet, traffic volumes and vehicle kilometres travelled, it becomes possible to look beyond the number of collisions.
Instead of only asking:
How many people were killed or injured?
we can also ask:
How does risk develop in relation to the amount of traffic? Which road users are most affected? And how does that development compare with countries facing similar circumstances?
That provides a much stronger basis for interpretation.
A common foundation for learning
The value of an international database is not simply that it contains more figures. Its real value lies in creating a shared basis for understanding those figures.
Consistent definitions, long-term data series and information about exposure make it possible to study developments over time and compare them across countries more responsibly.
That matters because road safety is influenced by many factors at once: infrastructure, mobility, legislation, vehicle technology, enforcement and road-user behaviour. Looking across borders can help reveal patterns that are harder to see when focusing on one country alone.
International comparison therefore is not about creating a ranking. It is about understanding why developments differ and what can be learned from those differences.
