The International Road Assessment Programme
International Transport Statistics Database

Safety: Data Definitions and Caveats

Table of Contents

This section of the database provides information on the number of accidents reported to the police and the number of road users killed. It also includes data on the number of road users injured, but this should be treated with caution.

Casualties of road accidents are classified by severity as killed, seriously injured and slightly injured. These are often grouped as KSI (killed and seriously injured) and all casualties (killed, severely injured and slightly injured), or all injuries (excluding fatalities).

Comparisons between countries are difficult because of differing definitions and reporting systems. Accidents are normally only reported to the police if someone is injured, and it is known that many accidents involving minor injuries do not get reported. Countries are moving towards a standard definition of a road traffic fatality as someone who dies within 30 days of an accident, but in the past different definitions have been used in many countries; France used a 6 day criterion for fatalities until 2005. Any data on non-fatal casualties should be treated with considerable suspicion.

Injuries, although recorded in United Nations Economic Commission for Europe (UNECE) Road Traffic Accidents databases, are not comparable between countries because of widely differing definitions. This can be demonstrated by calculating the ratios of injuries to deaths in different countries. Furthermore, several countries do not classify injuries into serious and slight, as is done in UK. Finally, in some countries fatalities are seriously under-reported, as has been shown by the World Health Organization. Examples are China, India and Brazil.

Road users are classified as pedestrians, pedal cyclists, users of powered 2-wheelers (which may be further separated into mopeds and motor cycles), car drivers, car passengers, bus drivers and passengers, goods vehicle drivers and passengers, and others (horse riders, drivers of farm tractors, etc).

Data are the number of accidents with various outcomes, the number of casualties by severity, casualties by type of road user, and casualty rates such as casualties per population, casualties per passenger kilometre travelled and casualties per vehicle kilometre of traffic.

By following the Links provided for Safety, it is possible to obtain more detailed information for individual countries than it is possible to include in this database.


In Great Britain this is defined as an incident which 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 becomes known to the police within 30 days of its occurrence.

The US DoT uses the term 'crash' instead of accident in its highway safety data, defined as an event that produces injury and/or property damage, involves a motor vehicle in transport, and occurs on a trafficway or while the vehicle is still in motion after running off the trafficway. Highway crashes often involve more than one motor vehicle, hence "total highway crashes" is smaller than the sum of the components.


Defined is Great Britain as human casualties who sustain injuries which cause death in less than 30 days (before 1954, about two months) after the accident. Confirmed suicides are excluded.

Defined in the USA (Fatality Analysis Reporting System) as a death due to injuries in a transportation crash, accident or incident that occurs within 30 days of that occurrence. A fatal crash is one that involves a motor vehicle on a trafficway that results in the death of a vehicle occupant or non-motorist within 30 days of the crash.

Defined in France as a person who dies in the 6 days (pre 2005) after the accident; in the 30 days (post 2005) after the accident.


Defined in Great Britain as an accident involving human injury or death. Serious injury is an injury for which a person is detained in hospital as an "in-patient", or various defined injuries whether or not detained in hospital, and slight injury as an injury of a minor character such as a sprain, bruise or cut which are not judged to be severe. This includes injuries not requiring medical treatment.

In the USA an Incapacitating injury is defined as any injury, other than a fatal injury, that prevents the injured person from walking, driving, or normally continuing the activities the person was capable of performing before the injury occurred. A Non-incapacitating evident injury is any injury, other than a fatal or an incapacitating injury, evident to observers at the scene of the accident. A Possible injury is any injury that is reported or claimed that is not evident.

In France a Light injury (Blesse leger) is defined as one requiring hospitalisation of 6 days or less, while a serious injury (Blesse grave) is one requiring hospitalisation of more than 6 days.

A general issue in databases is whether injured casualties include fatalities or are additional to them. This is often not made clear, but can sometimes be checked by comparing with other sources of data.

Published Date: 13 April 2008

iRAP Ltd is registered in England and Wales under company no. 05476000. Registered office: 60 Trafalgar Square, London, WC2N 5DS, UK.

Funded by the FIA Foundation for the Automobile and Society