How common is aggression?
Limited registration, unclear definitions
Little is known about how often aggressive traffic behaviour occurs. Aggressive incidents that have no further, visible consequences are seldom registered. The available data is mainly based on incidents registered by the police. These are mainly incidents involving injury or damage and are recorded as 'traffic violence'. In any case, if the violence took place after those involved had left their vehicles, any casualties are not registered as traffic casualties. Such incidents are often labelled as 'street violence between unknown persons resulting from a traffic situation'. There is no systematic registration of such traffic violence incidents and there are no good definitions of damage, injury, etc. The police data reported below and the estimates of national numbers must, therefore, be treated with some reserve.
During one year in the Amsterdam-Amstelland police district there were about 830 files in which a confrontation in traffic was mentioned and which ended up with verbal abuse or physical violence (Bookelman et al. 2000). In 1998 there were 365 reports of violent street incidents in the IJsselland police district. In the Rotterdam Rijnmond police district this number of incidents was 603. 36% of them referred to street violence between persons unknown. A quarter of these, i.e. 9%, took place in traffic (Terlouw et al., 2000). If the available data is extrapolated to national figures, there were reports of 4 – 5,000 incidents of violence against persons unknown in traffic (Terlouw et al., 2000).
As already stated, only a small fraction of traffic aggression is reported. In police files there is mostly fysical violence involved. However, in casualty research, swearing is also registered and this leads to much larger numbers. A survey among casualties in