So far we have looked at the shift in traffic accident deaths, difference in accident types, and rate of fatality and serious injuries. Next, we will analyze what types of accidents occur most often, and whether there are any characteristic traits in riders' ages and the time of day, based on actual circumstances of accidents that occurred in 2003.
Figure 8 shows the breakdown of traffic accident deaths by mode of travel. Of those who died, motorcycle/moped riders accounted for 18%. This means approximately one in five people who died in traffic accidents were riding two-wheeled vehicles.   Figure 9 shows the breakdown of those who died in such accidents: motorcycle riders accounted for 54%, moped riders for 46%.
- Composition of Accident Types -   In what types of accidents do motorcycle riders most frequently die? Figure 10 breaks down the causes of death by percentage.
(1)Single-vehicle accidents (31%): an accident in which a two-wheeled vehicle rolls over or crashes into a guardrail     or other protective fence, building, wall or other fixed structure without involving other vehicles or pedestrians. (2)Right-turn/straight-ahead collisions (20%): a collision between a vehicle turning right and a vehicle moving     straight ahead. Usually, it is a crash between a motorcycle moving forward and a car making a right turn. (3)Crossing collisions (20%): a crash between a two-wheeled vehicle and a four-wheel vehicle at an intersection.
In the following analysis, typical accidents are examined.
(1)Single-vehicle accidents   In 2003, deaths of motorcycle riders in single-vehicle accidents totaled 229. Figure 11 shows that about 30% of these accidents were motorcycle rollovers that did not crash into fixed objects. Crashes into guardrails, buildings, fences, bridges, central dividers, telephone poles, signposts and other fixed structures accounted for 54% of the total.
The primary cause of rollovers and skidding off the road is inappropriate speed for negotiating road curves: i.e. speeding. Figure 12 shows how fast the motorcyclist was driving upon meeting a single-vehicle accident. As many as 66 victims were speeding at 80 km/h or more, accounting for about 50% of the total. Fatality rises sharply when the speed exceeds 50 km/h at the time of crash. The faster the vehicle is moving, the greater the damage to the human body, with fatal consequences.
Figure 13 indicates that the number of deaths is greatest in the 16-39 age groups, showing the tendency for young people to meet this type of accident. For those below the age of 24, riders tend to meet accidents more frequently at night than during the daytime. The ratio of motorcyclists aged 65 and above meeting single-vehicle accidents is small.
(2)Right-Turn/Straight-Ahead Collisions   The second most frequent type of accident for motorcycles is right-turn/straight-ahead crashes, with the number of deaths totaling 142 riders and accounting for 20% of the total. Figure 14 shows that the younger the motorcyclist, the greater the fatal accidents, with the fatality of those under the age of 39 particularly large. Comparing accidents at daytime and night, nighttime accident deaths numbered 90 riders, accounting for 60% of this type of accident. Various combinations of vehicles are possible, but the most frequent is a motorcycle going straight in an intersection and crashing with an automobile making a right turn. Often the cause is that the car driver is unaware of the approaching motorcycle until it is too late to avoid a collision.
(3)Crossing Collisions   Deaths by crossing collisions totaled 142 motorcyclists, the same as right-turn/straight-ahead collisions, accounting for 20%.   In this type of accident, a motorcycle rider assumes that a car driver stopping at an intersection is aware of him/her and proceeds ahead, whereas the driver does not notice the approaching motorcycle. Figure 15 shows that the deaths of those aged 29 and below accounted for the greatest portion, totaling 72 riders and accounting for 50% of the total. What was remarkable was that 35% of the daytime corner collision fatalities were old people (there were no fatal corner collisions of aged motorcyclists at night in 2003), while fatal motorcycle accidents of other types are infrequent among the aged. Corner collisions accounted for 54% of all motorcycle accident deaths among the aged during the daytime. There could be some factor contributing to the fact that old people are likely to meet or cause corner collisions.
UP

Institute for Traffic Accident Research and Data Analysis (ITARDA)