THE EFFECTIVENESS OF ESC (ELECTRONIC STABILITY CONTROL) IN REDUCING REAL LIFE CRASHES AND INJURIES Anders Lie Swedish Road Administration Claes Tingvall Swedish Road Administration, Monash University Accident Research Centre Maria Krafft Anders Kullgren Folksam Research Sweden Paper number 05-0135 19th International Technical Conference on the Enhanced Safety of Vehicles Conference (ESV) June 2005 ABSTRACT ESC (Electronic Stability Control) was introduced on the mass market in 1998. Since then, several studies showing the positive effects of ESC has been presented. In this study, data from crashes occurring in Sweden during 1998 to 2004 were used to evaluate the effectiveness of ESC on real life crashes. To control for exposure, induced exposure methods were used, where ESC-sensitive to ESC-insensitive crashes and road conditions were matched in relation to cars equipped with and without ESC. Cars of similar or in some cases identical make and model were used to isolate the role of ESC. The study shows that the positive and consistent effects of ESC overall and in circumstances where the road has low friction. The overall effectiveness on all injury crash types except rear end crashes was 16.7 +/- 9.3 %, while for serious and fatal crashes; the effectiveness was 21.6 +/- 12.8 %. The corresponding estimates for crashes with injured car occupants were 23.0+/-9.2% and 26.9+/-13.9%. For serious and fatal loss-of control type crashes on wet roads the effectiveness was 56.2 +/- 23.5 % and for roads covered with ice or snow the effectiveness was 49.2+/-30.2%. It was estimated that for Sweden, with a total of 500 vehicle related deaths annually, that 80-100 fatalities could be saved annually if all cars had ESC. On the basis of the results, it is recommended that all new cars sold should have ESC as standard equipment. BACKGROUND The Electronic Stability Control, ESC or ESP, is an on-board car safety system, which enables the stability of a car to be maintained during critical manoeuvring and to correct potential under steering or over steering (1). In a general sense the equipment should eliminate loss of control. Since 1998, when the first mass-produced car with ESC standard equipment was launched, the market for cars with ESC has grown quickly. In Sweden, the proportion of new car sales equipped with ESC has grown from 15% in March 2003, to 69% in Dec 2004. ESC operates normally with both brakes and engine management. If the car loses control, defined as when one wheel or more is moving faster or more slowly than calculated from the steering input and turning angle, braking is applied to one or more of the wheels, and the engine power might be reduced. It has been expected, that the ESC will have a significant effect on loss of control type crashes. This effect is expected to have an influence both on the number and the severity of impacts (1), and might also change the orientation of the vehicle prior to impact (2, 3, 4). A projection of the effects based on in-depth data suggests that in 67% of the fatal and 42% of injury only crashes where the driver lost control, ESC would have a probable or definite influence (1). For all injury crashes, the estimated proportion of crashes addressed is 18%, for fatal crashes 34%. Several studies have been presented, demonstrating the effectiveness of ESC in real life crashes. A Swedish study (5) presented in May 2003 showed that there was a positive influence of ESC, especially in crashes on wet surface or surface covered by ice or snow. The effectiveness ranged between 20% and 40%, all being significant.