(1)Rear-end collisions between passenger cars account for 66% of all accidents.   Figure 3 numerically expresses the frequency of rear-end collisions in 2001 for different combinations of vehicle types as rear-ending vehicle and rear-ended vehicle. Rear-end collisions involving buses have been omitted since such cases are scarce. In 2001 there were 204,324 rear-end collisions. The combination of two passenger cars accounted for the bulk of these accidents, occupying almost 66% of the total. This was followed by the combination of passenger car and small-sized truck, which accounted for approximately 24%, while accidents involving large-sized trucks occupied a low 6% of the total. This does not mean that passenger cars are more likely to be rear-ended or to rear-end other vehicles; rather, it reflects the fact that passenger cars occupy a high percentage of the registered vehicles. (2)In most cases the driver of the rear-ending vehicle is uninjured and that of the rear-ended vehicle is slightly injured.   The small pie graphs in Figure 3 show the corresponding ratio of accidents resulting in death, injury or no injury to the drivers of the rear-ending vehicle and the rear-ended vehicle. Mostly we see a familiar pattern in which the driver of the rear-ending vehicle is uninjured and that of the rear-ended vehicle is slightly injured. In cases where a large-sized truck is rear-ended, however, there is a marked tendency for the injuries of the rear-ending vehicle driver to be more severe. This is thought to be due to the fact that the rear-ended vehicle is much bigger and heavier than the rear-ending vehicle.

The following describes rear-end collisions between passenger cars, with emphasis on collisions in which the driver of the rear-ended vehicle suffers slight injuries. (3)The majority of rear-ending vehicle drivers are older people and young people.   Figure 4 shows the ratio of rear-ending and rear-ended vehicle drivers by age group. As the drivers of rear-ending vehicles, two age groups stand out from the rest: the 65 and over group and the 24 and under group. Presumably, the reason for this is that, on the one hand, young people tend to have so-called reckless driving habits, and, on the other hand, older people are more likely to present careless driving behaviors due to the deterioration of physical function. The same tendencies can be also observed in accidents other than rear-end collisions.

(4)More than half of rear-end collisions occur at non-intersection locations without traffic signals (2002 accidents).   Contrary to what people might think, almost 60% of rear-end collisions occur at locations other than intersections, and most of locations have no traffic signals. The remaining 40% occur at or near intersections, and two-thirds of those occur at intersections with traffic signals (Figure 5). In other words, most rear-end collisions occur at non-intersection locations where there are no traffic signals and the flow of traffic should be relatively smooth. We will explain this in greater detail below with the results of the analysis of in-depth investigation of traffic accidents.

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Institute for Traffic Accident Research and Data Analysis (ITARDA)