no63 2006
Traffic Accidents in the Dusk

  The number of traffic accident deaths dropped by almost 40% from 11,451 people in 1992 to 6,871 people in 2005. The figure consistently decreased over this 14-year period due to various reasons, including: stronger clampdown on drunk driving and speeding, higher percentage of drivers and passengers wearing seatbelts, and improved road safety measures, such as pedestrian safety areas, sidewalks, road lighting where accidents occur frequently, and line-of-sight guidance markings on roads. Moreover, the safety of automobiles themselves has been enhanced.

  This issue of ITARDA Information shows how cars have become safer in the event of an auto crash, examining actual accident case studies.
1. Improved Car Safety in Crashes: Case Study

1-1 Accidents Involving Cars Designed Under the New Concept (Recent cases)

1-2 Accidents Involving Cars Designed Under the Old Concept (Cases from about 10 years ago)

2. Car Safety Viewed from Macrostatistics

3. Safety and Seatbelts (Macrostatistics)


  Improved crash safety of new cars, brought about by social demand and the efforts of those involved in car manufacturing, has been confirmed through case analysis and macrostatistic data analysis. The following commentary is from the engineering viewpoint.

  A car is designed and manufactured to absorb the impact of collision by crushing the body. It is this deforming of the auto body that softens the shock and protects the car's occupants in the event of a crash. In a collision involving ordinary-size or light passenger cars, as studied here, the degree of deformation depends on the pre-collision energy of each vehicle.

  Compared to autos that have recently rolled off the production line, those manufactured two decades ago undergo a greater degree of body deformation in a collision. This is because, back then, priority was placed on reducing the impact of a collision. However, if a car crashes against a large (thus, heavy) vehicle or an auto traveling at a high speed, the car is often unable to absorb the energy of the collision by deforming its front part alone, resulting in significant deformation of the passenger compartment and reduction of survival space for car occupants, whose injuries may thus end up more serious.

  In new car design, the passenger compartment is made more stiff to secure survival space in the event of a collision, while absorbing a greater part of the impact by crushing the front part only. Since the front part is more stiff, the impact of a collision on the car's occupants increases somewhat. Cars are designed to soften this increased shock by restraining the occupants with seatbelts and airbag deployment.

  As seen in the macrostatistic analysis in Section 3, the newer the cars are, the smaller the number of driver fatalities per 1,000 drivers wearing seatbelts. Among drivers who were not wearing seatbelts, this figure is on the rise. It can therefore be concluded that the crash safety of new cars cannot be ensured unless the occupants fasten their seatbelts and the airbags are deployed. So, fasten your seatbelts even when driving in a brand-new car. Never assume that new cars are safe without them.

Institute for Traffic Accident Research and Data Analysis (ITARDA)