Abstract
Keywords: ESC, Active safety, Fatal car accident, Traffic safety, Loss of control
Active safety systems have become common equipment in all size categories of cars. However, the advantage of active safety systems are easily hidden behind the passive safety systems, which only mitigate the consequences of the crash. Active safety systems primarily prevent accidents and secondary mitigate the consequences.
Vehicle manufactures and vehicle systems suppliers have many differently named stability control systems, which are all based on the same principle. The best known is ESP (Electronic Stability Programme) by Bosch, but ESC (Electronic Stability Control) has been agreed on as the common name for all stability controls.
Vehicle behavior is found to be non-linear during extreme driving maneuvers, which typically occur when the driver has lost the control of his car. The driver adapts himself for a certain response of the car during normal driving. In extreme maneuver, the driver still controls the car based on this earlier routine, but the vehicle does not respond as predicted. The ESC regulates this difference between nominal and actual behavior of the car.
In theory, ESC could prevent all the crashes due to the loss of control. By contrast, it cannot prevent any crashes caused by drift off the lane or if the turn is entered extremely fast.
The research covers fatal car accidents in Finland in 2000-2006 for cars, whose commissioning date fall between these years. The benefit of ESC is clearly visible in the data. The results are similar to the studies made in Sweden and Germany. However, in Finland the number of relevant accidents is smaller than in other western countries, because of the old age of the vehicle fleet.
The ESC would have saved 31 human lives during the seven years (2000-2006), which is only 4-5 per year. However, due to the old age of Finnish fleet, the control group included only 171 fatal car accidents. Thus, the relative effectiveness of ECS was found to be 18 %.
An interesting comparison could be made between an ESC and a median barrier, which both can reduce head-on collisions effectively. The median barrier is an expensive investment for the road keeper, but ESC is paid directly by the road end-users, who in addition pay the car-tax and VAT for ESC.