Definitions Used In Road Accident Statistics
1. The definition of "severity" used in the Road Accident statistics
The classification of the severity of an accident (as "fatal", "serious" or "slight") is determined by the severity of the injury to the most severely injured casualty. The police usually record this information soon after the accident occurs. However, if further information becomes available which would alter the classification (for example, if a person dies within 30 days of the accident, as a result of the injuries sustained in the accident) the police change the initial classification of the severity.
For the purposes of the Road Accidents statistical returns:
a fatal injury is one which causes death less than 30 days after the accident;
a fatal accident is an accident in which at least one person is fatally injured;
a serious injury is one which does not cause death less than 30 days after the accident, and which is in one (or more) of the following categories:
(a) an injury for which a person is detained in hospital as an in-patient
or (b) any of the following injuries (whether or not the person is detained in hospital): fractures, concussion, internal injuries, crushings, severe cuts and lacerations, severe general shock requiring treatment
or (c) any injury causing death 30 or more days after the accident;
a serious accident is one in which at least one person is seriously injured, but no-one suffers a fatal injury;
a "slight" injury is any injury which is neither "fatal" nor "serious" - for example, a sprain, bruise or cut which is not judged to be severe, or slight shock requiring roadside attention;
a "slight" accident is one in which at least one person suffers "slight" injuries, but no-one is seriously injured, or fatally injured.
Over the years, improvements in vehicle design, and the provision and use of additional safety features, together with changes in the law (eg on the fitting and wearing of seat belts), will all have helped to reduce the severity of the injuries suffered in some accidents. Road safety measures should also have reduced the levels of injuries sustained. For example, if traffic calming schemes reduce average speeds, people may suffer only "slight injury" in collisions that previously would have taken place at higher speeds and so might previously have resulted in "serious injury".
However, it is also possible that some of the changes shown in the statistics of "serious injuries" and "slight injuries" may be due to changes in administrative practices, which may have altered the proportion of accidents which is categorised as "serious". For example, the distinction between "serious" and "slight" injuries could be affected by factors such as changes in hospitals' admission policies. All else being equal, the number of "serious injury" cases would rise, and the number of "slight injury" cases would fall, if it became standard procedure for a hospital to keep in overnight, for precautionary reasons, casualties with a particular type of injury. The increase in the number of "serious" injury accidents in 1994 was partly attributed to a change in the health boards' policies in admitting more child casualties for overnight observation, which in turn changed the classification of many injuries from "slight" to "serious". The number of child casualties recorded as having serious injuries in 1994 was 35% higher than in the previous year. There could also be changes in hospitals' procedures that would reduce the numbers of "serious injury" cases. In addition, there is anecdotal evidence that changes in procedures for assigning severity codes may affect the categorisation of injuries. For example, different severity codes might be assigned by a police officer who was at the scene of an accident and by a clerk who bases the code on a police officer's written description of the accident.
2. Other definitions
Accident: The statistical returns include only those accidents which result in personal injury, which occur on roads (including footways), in which a vehicle is concerned, and which become known to the police. The vehicle need not be moving and it need not be in collision. The statistics are therefore of "injury road accidents" only: "damage-only accidents" are not included in the figures.
Adults: People aged 16 and over.
Built-up roads: accidents which occur on "built-up" roads are those which occur on roads which have speed limits of up to 40 miles per hour ( ignoring temporary speed limits on roads for which the normal speed limit is over 40mph). Therefore, an accident on a motorway in an urban area would not be counted as occurring on a "built-up" road, because the speed limit on the motorway is 70mph. An accident on a stretch of motorway with a temporary speed limit of 30mph would not be counted as occurring on a "built-up" road, because the normal speed limit is 70mph.
Buses and coaches: Include works' buses and (in past years) trams and trolley buses. Vehicles are coded according to their construction, irrespective of their use at the time of the accident. Thus, vehicles of bus construction which are privately licensed are included under 'buses and coaches', while Public Service Vehicle licensed minibuses are included under minibuses.
Cars: Include estate cars and three-wheeled cars.
Casualty: A person killed or injured in an accident. One accident may give rise to several casualties.
Children: People under 16 years old.
Darkness: From half an hour after sunset to half an hour before sunrise, ie 'lighting-up time'.
Drivers: Persons in control of vehicles other than pedal cycles and two-wheeled motor vehicles.
Goods vehicles: Vans, lorries, tankers, milk floats, tractor units travelling without their trailer units.
Heavy goods vehicles: From 1994, "heavy goods vehicles" have been defined as goods vehicles with a maximum permissible gross vehicle weight of more than 3.5 tonnes. Prior to 1994, they were defined as those with an unladen weight of more than 1.5 tons (1.52 tonnes).
Junction: A place at which two or more roads meet, whatever the angle of the axes of the roads (including roundabouts), or within 20 metres of such a place.
Killed: Sustained injuries which caused death less than 30 days after the accident.
Light goods vehicles: From 1994, "light goods vehicles" have been defined as goods vehicles with a maximum permissible gross vehicle weight of up to 3.5 tonnes. Prior to 1994, they were defined as those with an unladen weight of 1.5 tons (1.52 tonnes) or less.
Major roads: Motorways and A roads.
Minor roads: B roads, C roads and unclassified roads.
Motor cycles: Includes all two wheeled motor vehicles.
Motorists: The drivers or riders of motor vehicles (including, for example, motorcyclists).
Motorways: Include A(M) roads.
Non built-up roads: Roads for which the normal speed limit ( ignoring any temporary speed limits) is more than 40mph.
Other vehicles: Include ambulances, fire engines, pedestrian-controlled vehicles with motors, railway trains or engines, refuse vehicles, road rollers, tractors, excavators, mobile cranes, tower wagons, army tanks, etc - and from 1999, motor caravans. Other non-motor vehicles include those drawn by an animal, ridden horses, invalid carriages without motor, street barrows, etc.
Passengers: Occupants of vehicles, other than the person in control, including pillion passengers.
Pedal cycles: Including toy cycles ridden on the carriageway, tandems and tricycles. Pedal cyclists includes any passengers of pedal cycles.
Pedestrians: Includes people riding toy cycles on the footway, people pushing bicycles, people pushing or pulling other vehicles or operating pedestrian-controlled vehicles, those leading or herding animals, occupants of prams or wheelchairs, and people who alight safely from vehicles and are subsequently injured.
Riders: People in control of pedal cycles or two-wheeled motor vehicles.
Road users: Pedestrians and vehicle riders, drivers and passengers.
Trunk roads: Roads for whose upkeep Scottish Executive Ministers are responsible.
Users of a vehicle: All occupants, ie driver (or rider) and passengers, including persons injured while boarding or alighting from the vehicle.
Vehicles involved in accidents: Any vehicle directly involved in an accident where at least one injury is sustained by a pedestrian or vehicle driver, rider or passenger. Vehicles which collide after the initial accident which caused injury are not included, unless they aggravate the degree of injury or lead to further casualties.