1.3. Comparison of Accident Situations
  Comparing accident situations between older drivers and the others, the most numerous accident configurations are rear-end collisions which account for about half of total accidents in both age groups (Figure 4). The second most numerous are crossing collisions which account for about one fourth in both groups. Consequently, it can be said that both groups are involved in similar types of accidents.

  Furthermore, regarding the danger perception speed*1 in Fig. 5, we can’t see much difference between the two. After all, it can be stated that the situations in which drivers become involved in accidents are similar between both groups.

Fig. 4  Types of accidents resulting in injury

Fig. 5  Cumulative ratio of danger perceiving drivers

Note 1: "Danger perception speed" is the vehicle speed at which the driver perceives danger of a possible collision with a vehicle, a person or a structure appearing in front.


1.4. High Risks of Fatality and Serious Injury
  The drivers who experienced an accident while protected by a seat belt are isolated in the Macro Data. The damage done to vehicles in accidents is graded in three levels - major damage, medium damage, and minor damage*2. Assuming that these vehicle damage levels are proportional to the levels of physical impact on drivers, the injury proneness of older and the others is compared at each of the vehicle damage level.

  The fatality rate*3 of drivers according to age is determined for each vehicle damage level (Figure 6.1). Similarly, the serious injury rate*3 is also derived according to the age of drivers and the level of vehicle damage (Figure 6.2).

  The results indicate that the fatality rate is the lowest among the drivers aged around 30 in both major and medium vehicle damage cases. The fatality rate goes up as the age of drivers increases from about 30. A similar trend is observed for the serious injury rate of drivers. These results suggest that older drivers are prone to sustain more serious injuries than are the others, when the impact levels are equivalent.

Fig. 6.1  Fatality rate by age of driver

Fig. 6.2  Serious injury rate by age of driver

Note 2: "Major damage" makes the vehicle totally unfunctional and unrecoverable. "Medium damage" renders the vehicle incapable or nearly incapable of running by its own power while the repair of its body components is extremely difficult. With "minor damage", the vehicle remains able to run by its own power while its body components and attachments are deformed slightly so that their repair is possible.
Note 3: Fatality rate = (No. of fatalities) / (No. of fatalities + serious injuries + slight injuries)
Serious injury rate = (No. of serious injuries) / (No. of fatalities + serious injuries + slight injuries)
Note 4: A "fatality" is defined as a death within 24 hours as a result of accident. A "serious injury" means the injury that needs medical treatment for a month (30 days) or more. A "slight injury" on the other hand requires medical treatment for less than a month(30 days).

Institute for Traffic Accident Research and Data Analysis (ITARDA)