Potential Effects of Electronic Stability Control (esc) on Accidents

The aim of this study is to investigate the effects of Electronic Stability Control (ESC) on the frequency and severity of accidents. ESC is an active safety device for motor vehicles which enhances controllability by preventing skidding in cases of oversteering or understeering. Skidding occurs when speed, steering input, possibly also braking, are in excess of what is possible under the current friction conditions. It may be caused by too high speed in curves, collision avoidance manoeuvres, or icy roads. Skidding can result in road departure and collisions with objects or other vehicles. These collisions are relatively likey to be side collisions, because skidding involves rotation. Side collisions usually have quite severe consequences because vehicles provide less protection than in front collisions. The avoidance of skidding may not always avoid collisions, but if a side collision is replaced by a head-on collision, the severity of the consequences may be reduced. According to Zobel et al. (2000), the probability of at least one very severely injured (MAIS 5+) in accidents which (without ESC) would be side collisions, would be reduced by 50%. Front collisions can also have severe consequences, especially when occurring at high speeds. Under extreme dynamic conditions, skidding can result in roll-over. Accidents which involve skidding can be prevented by ESC, or the severity of such accidents may be reduced due to reduced probability of side collisions and roll-overs, increased probability for succesful evasive manoeuvres, and reduced speed in collisions. Collisions in junctions and overtaking accidents are less likely to be prevented by ESC. Accidents which involve skidding, but in which the driver was driving extremely fast, very sleepy, or driving under the influence of alcohol or drugs, also are less likely to be affected by ESC.