General information about ESC

Description

ESC stabilises the vehicle and prevent skidding under all driving conditions and driving situation within the physical limits by active brake intervention on one ore more wheels and by intelligent engine torque management.

As soon as ESC identifies a critical driving situation it intervenes by applying specific brake pressure to one or more wheels, as required. If necessary, the engine torque is also adjusted automatically. In this way, ESC helps the driver stabilise the vehicle - although the extent to which it can do so is of course limited by the physical laws governing the dynamic behaviour of the vehicle.

A yaw-rate sensor and a lateral acceleration sensor continuously monitor the movement of the vehicle about its vertical axis and compare the actual value with the target value calculated on the basis of the driver's steering input and the vehicle speed. The moment the car deviates from this ideal line, ESC intervenes to counteract any incipient tendency to skid by applying a precisely metered braking force to one or more wheels. ESC systems combine the functions of ABS and TCS traction control and complement them with directional stability assistance.

Variants of ESC are sold under several brand names such as: ASC (Automotive Stability Control); ASR (Automatic Stability Regulation); AH (Active Handling System); ASMS (Automotive Stability Management System); CBC (Cornering Brake Control); DSC (Dynamic Stability Control); EDS (Electronic Differential-lock System); DSTC (Dynamic Stability and Traction Control); ESC (Electronic Stability Control); ESP (Electronic Stability Program); ICCS (Integrated Chassis Control System); IVD (Integrated Vehicle Dynamics); PCS (Precision Control System); PSM (Porsche Stability Management); SCS (Stability Control System); StabiliTrac; STC (Stability and Traction Control System); Traxxar; VDC (Vehicle Dynamics Control); VSA (Vehicle Stability Assist); VSC (Vehicle Stability Control); VSES (Vehicle Stability Enhancement System); and YCS (Yaw Control Stability).

Impacts

• Mercedes data indicates that the installation of ESC as standard equipment on all of its vehicles has resulted in a 29 percent reduction in single-vehicle crashes and 15 percent fewer crashes overall. Based on these figures, the widespread installation of ESC in the United States could save as many as 5,000 lives and nearly $35 billion in economic losses annually. This study, which implements German government data, is especially significant because all new Mercedes vehicles are equipped with ESC as standard equipment.
• DEKRA Automotive Research in Germany indicates a 27 percent reduction in serious loss-of-control crashes. It also reports that 37 percent of corner accidents are definitively influenced by ESC, confirming the Mercedes findings.
• The European Accident Causation survey, conducted throughout Europe, shows that ESC had a positive influence on the total number of loss-of- control accidents. 
• The Swedish National Road Administration study shows that ESC was found to reduce accidents with personal injuries. It goes on to recommend the implementation of ESC in new cars as quickly as possible and also advises consumers to choose vehicles with ESC, especially in countries with wet and icy roads. 
• A study by Toyota in Japan reports that vehicles with ESC showed a 35 percent reduction of single-vehicle crashes, which could save an estimated 6,000 lives annually in the United States, and a 30 percent reduction of head-on crashes, saving another 2,500 lives. The study also confirms Mercedes' conclusion that ESC is more effective in higher speed ranges when vehicle dynamics play a greater role and when the crashes that occur are more severe.

Studies

Overall the cars with ESC are involved in 3% fewer crashes although the effectiveness is substantially higher under conditions of adverse road friction i.e. 25% reduction on snowy and icy roads. ESC equipped cars are involved in 15% fewer fatal crashes although this reduction represents the combined effect of ESC and passive safety improvements.	The study used the national accident statistics of Great Britain. The crash experience of 8951 cars was analysed and compared to a closely matching set of non-ESC cars using case-control methods.	Thomas, P.	2006	pdf (79 KB). Proceedings, 13th ITS World Congress and Exhibition, 8-12 October 2006, London, UK.
ESC reduces the risk of fatal multiple-vehicle crashes by 32 percent amd the risk of all single-vehicle crashes by more than 40 percent — fatal ones by 56 percent.  While both cars and SUVs benefit from ESC, the reduction in the risk of single-vehicle crashes was significantly greater for SUVs — 49 percent versus 33 percent for cars. The reduction in fatal single-vehicle crashes wasn't significantly different for SUVs (59 percent) than for cars (53 percent). ESC reduces the risk of fatal single-vehicle rollovers of SUVs by 80 percent, 77 percent for cars. ESC was found to reduce the risk of all kinds of fatal crashes by 43 percent. Losses under collision coverage are about 15 percent lower for vehicles with ESC than for predecessor models without it. However, ESC doesn't have much effect on property damage liability claims or the frequency of injury claims. These findings track police-reported crashes, which show little effect of ESC on the risk of low-severity multiple-vehicle crashes.	Statistical analysis of road accidents and fatalities as well as traffic insurance claims.	IIHS	2006	pdf (313 KB). Insurance Institute for Highway Safety, Status Report, Vol. 41, No. 5 and News Release, June 13, 2006.
ESC decreased the accident rate of single-car accidents by about 44% and that of head-on collisions by about 24%; the decrease was higher for more severe accidents; the decrease of single accidents and head-on collisions was higher on wet road conditions (58%) than on dry conditions (20%).	Comparison of data of 1,471 single-car accidents or head-on collisions not caused by drunk driving or drowsy driving involving ten models that were originally designed and shipped without ESC but subsequently became to be equipped with ESC were chosen from the accident data held by the Institute for Traffic Accident Research and Data Analysis (ITARDA) in Japan. Accident numbers were related to the number of such cars in use.	Ohono & Shimura	2005	pdf (83 KB). Press release. National Agency for Automotive Safety & Victims' Aid (NASVA) 2005/02/18.
The overall effectiveness of ESC on all injury crashes except for rear end crashes was 16.7 +/- 9.3%, while for serious and fatal crashes the effectiveness was 21.6 +/- 12.8%. The effectiveness for serious and fatal crashes on wet roads was 56.2 +/- 23.5 %. On roads covered with ice and snow, the corresponding effectiveness was 49.2 +/- 30.2 %.	The estimates are based on the assumption that rear end crashes on dry road surfaces are not affected at all by ESC.	Lie, A., Tingvall, C., Krafft, M. & Kullgren, A.	2005	pdf (82 KB) 19th International Technical Conference on the Enhanced Safety of Vehicles Conference (ESV), June 2005.
In Australia, ESC is estimated to reduce road fatalities in light vehicles by 29%. Assuming that ESC can prevent 50% of loss-of-control accidents and that an ESC units costs $1,000, ESC is estimated to have a benefit cost ratio of 0.51.	Compilation of ESC safety evaluation results throughout the world.	Paine, M	2005	pdf (848 KB) Vehicle Design and Research Pty Limited for Roads and Traffic Authority of NSW. June 2005.
In Germany, 100 per cent equipment of all cars with ESP is estimated to reduce the number of accidents with car occupant injuries by about 7 -11 %. The reduction in the car occupant fatalities would be approximately 15 -20 %	The study compiled all available accident studies on ESP effectiveness	Langwieder, K.	2005	Wissenschaftlicher Erkenntnisstand zu ESP. 10 Jahre ESP, Berlin, 23. Februar 2005.
Single vehicle crashes were reduced by 35% in passenger cars and by 67 % in SUV crashes. The study also showed significant or borderline-significant reductions in the multi-vehicle crash rates per 100,000 vehicle years with ESC.	As multi-vehicle crashes we used as the control group and it is possible that multi-vehicle crashes are being reduced by ESC, this means that the true effectiveness of ESC could be higher than estimated for single vehicle crashes.	Dang, J.	2004	pdf (61 KB) National Highway Traffic Safety Agency, USA.
ESC reduced single-vehicle crash involvement risk by approximately 41 % and single-vehicle injury crash involvement risk by 41 %. This translates to an estimated 7 % reduction in overall crash involvement risk and a 9 % reduction in overall injury crash involvement risk. Based on all fatal crashes in the United States over 3 years, ESC was found to have reduced single-vehicle fatal crash involvement risk by 56 percent. This translates to an estimated 34 percent reduction in overall fatal crash involvement risk.	The study compared crash involvement rates for otherwise identical vehicle models with and without ESC systems.	Farmer, C	2004	pdf (79 KB) Insurance Institute for Highway Safety, Arlington, Virginia, USA.