1. Analysis of accidents due to inadequate maintenance constituting a legal violation by the driver
1-1. Statistics and legal violations in vehicle first party accidents due to inadequate maintenance
  Since 1991, when there were 620,000 vehicle first party accidents, the trend has been on the increase. Although the rate of increase slowed after 1999, there were still 820,000 such accidents in the year 2000 (Fig. 1).
  The number of accidents due to inadequate maintenance peaked at 272 in 1993, decreased thereafter, but turned around again in 1999 and totaled 202 in the year 2000 (0.02% of the total 820,000 vehicle first party accidents).


1-2 Percentage of Accidents Involving Violations of Maintenance Laws by Accident Party Type (in 2000)
  Of the 202 accidents in 2000 where the first party was an inadequately maintained vehicle, 95, or approximately 50%, involved private passenger vehicles, 41, or 20%, involved motorcycle, and 25, or 10%, involved commercial-use trucks. (Fig. 2)


1-3  Changes in the Number of Fatal Accidents Involving Violations of Maintenance Laws
  Of the 35 fatal accidents in the ten years from 1991 to 2000 involving violations of maintenance laws, 19, or 50% of the total, were caused by inadequately maintained transport vehicles.(Fig. 3)


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2. Analysis of vehicle first party accidents by types of inadequate maintenance
2-1  Numbers of vehicle first party accidents by types of inadequate maintenance (1996 - 2000)
  The number of accidents due to inadequate maintenance peaked at 1,146 in 1996, decreased over the past 5 years, but turned around in 1999 and totaled 1,020 in the year 2000 (Fig. 4).   No changes were registered during the five years with regard to accidents caused by tire inadequacy and brake equipment inadequacy, the former causing 70% and the latter causing 10% of the total accidents.


2-2  Numbers of accidents by types of inadequate maintenance and accident type (2000)
  In the year 2000, 69.0%, or 704, of the accidents were between vehicles and 24.0%, or 250, accidents were single-vehicle accidents. (Table 1) Tire inadequacy was the cause of 674, or 70% of the 1,020 accidents.
  Of the 674 accidents due to tire inadequacy, 80%, or 429, were caused by using summer tires on snowy roads, and 85 were caused by tread wear. In all incidents, the drivers had accidents because they could not maintain control on icy or slippery roads.
Chart 1 Numbers of Accidents Involving Inadequate Maintenance (2000)
 Person/VehicleVehicle/VehicleSingle-VehicleRR CrossingTotal
Inadequate brake equipment9115210145
Inadequate steering equipment33410047
Inadequate tires254521970674
Inadequate wheels3160019
Inadequate lamps4101015
Engine breakdown16108
Inadequate or broken transmission02103
Inadequate fuel, oil equipment01102
Inadequate windshield and other window glass10160026
Inadequate adjustment, breakage, or loss of mirror25209
Inappropriate remodeling (fenders, etc.)06118
Other inadequate structure, equipment adjustments 84115064
Total6570425011,020
2-3  Numbers of Accidents by Types of Vehicles and Maintenance Inadequacy (2000)
  Looking at the accidents by the types of vehicles involved, we see that 620 (60.8%) involved ordinary passenger vehicles, 159 (15.6%) involved ordinary transport vehicles, 74 (7.2%) involved light transport vehicles, and 73 (7.2%) involved light passenger vehicles. (Fig. 5)


  Looking at Figure 6, we see that tire inadequacy of ordinary passenger vehicles accounted for 446, or 43.7% of the total accidents, while 104, or 10.2% were caused by tire inadequacy of ordinary transport vehicles. In both cases, tire inadequacy was the outstanding factor.


  Of the 446 accidents caused by tire inadequacy of ordinary passenger vehicles, 294, or 70%, were brought about by the use of summer tires on snowy roads.(Fig. 7)


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Institute for Traffic Accident Research and Data Analysis (ITARDA)