• Stability programme most important element in traffic safety
• Share of driver-related accidents involving Mercedes passenger cars down 42 per cent
• Improved occupant protection in passenger cars thanks to Mercedes innovations
• Passenger car development in a conflict of goals between Euro NCAP and practical experience with accidents
• PRE-SAFE® to be equipped in the future with a radar sensor to help prevent accidents

The Electronic Stability Programme (ESP®) developed by Mercedes-Benz, which reduces the risk of skidding and helps drivers to better deal with critical driving situations, has led to greater safety on German roads and motorways. After five years of having the system included as standard equipment in Mercedes vehicles, the Stuttgart-based brand has registered a significant decrease in so-called driver-related accidents in which drivers lose control of their vehicles, skid and drive off the road. "If all automobiles were equipped with the stability system, more than 20,000 such serious accidents, which claim over 27,000 victims each year, could be prevented in Germany," says Dr. Thomas Weber, DaimlerChrysler Board of Management member for Research and Technology and head of Development at the Mercedes Car Group.

Since being fitted with ESP® as standard equipment, Mercedes passenger cars have been involved in serious driver-related accidents far less frequently than vehicles from other brands. The average share of newly registered Mercedes models involved in such accidents in 1998/1999 was 20.7 percent. ESP® helped to reduce this figure by more than 42 percent in 2002/2003. At the same time, the share of passenger car models from other brands involved in these types of traffic accident fell by only about 13 percent.

Driver-related accidents are one of the most severe types of accident that can occur: In 2003, 43 percent of all traffic fatalities and 20 percent of all injuries were due to driver-related accidents.

"Along with seatbelts, airbags and ABS, ESP® is by far the most important safety system in today’s passenger cars," says Weber. "The invention of ESP® and the inclusion of this technology as standard equipment have enabled Mercedes-Benz to set an important trend in improving traffic safety."

The system does in fact offer tremendous potential for preventing serious accidents. Moreover, ESP® also helps to reduce the extent of injuries to vehicle occupants in an accident. For example, because the system stabilizes vehicles in a skid, the risk of dangerous side collisions with trees, poles or other objects at roadsides is reduced. Following the installation of the stability programme as standard equipment in Mercedes-Benz passenger cars, the proportion of collisions resulting in the most severe injuries fell from 15 to five per cent.

The results of Mercedes-Benz accident studies also show that passenger cars equipped with ESP® roll over less frequently than vehicles not equipped with this safety system. Thanks to ESP®, the proportion of Mercedes-Benz vehicles involved in rollover accidents has decreased by around 12 percentage points.

Studies conducted in the USA and Sweden also confirm the positive impact the system has had in reducing accidents or mitigating their consequences. The American Insurance Institute for Highway Safety has determined, for example, that ESP® can reduce the number of fatal traffic accidents by more than one-third (34 percent).

ESP® celebrated its world premiere at Mercedes-Benz in 1995 and has been included as standard equipment in all the brand’s passenger car models since the summer of 1999. Half of all newly registered vehicles in Germany are currently fitted with the system, with the proportion of small cars so equipped at under ten percent. Approximately one-third of all new passenger cars in the European Union are fitted with the safety system.

Statistics show that Mercedes innovations help reduce the number of accidents

The Electronic Stability Programme is the result of safety developments at Mercedes-Benz that are based on analyses of real situations and the knowledge gained from accident research. Other technological milestones that benefit the occupants of all passenger cars, such as the crumple zone, airbags, seat belt tensioners, offset layouts, and side and window bags, are also based on this development principle.

As such, Mercedes-Benz has been a trendsetter in passenger car safety for exactly 65 years. The brand has also made a major contribution to the continual reduction of the number of injured vehicle occupants that has been registered in Germany, with a decrease of more than 41 percent recorded in the period between 1993 and 2003 alone. The number of drivers and vehicle passengers killed in traffic accidents fell by more than 38 percent to a record low during the same period.

Having developed a series of pioneering inventions that have been proven to enhance occupant safety, Mercedes-Benz has spent the last few years focusing on accident prevention. Technological milestones such as ESP®, the ABS anti-lock braking system (ABS), the ASR acceleration skid control system, Brake Assist (BAS) and Active Body Control (ABC) have made Mercedes a pioneer and trendsetter in the field of accident prevention as well. The ultimate goal of Mercedes engineers is the “vision of accident-free driving."

As was the case with airbags, seatbelt tensioners, ABS and ESP®, the development of future Mercedes safety systems will also be primarily based on analyses of actual accidents and extensive practical tests.

Safety system development: Contradictory goals as a result of laboratory tests and data from actual accidents

Safety-system development at Mercedes-Benz thus differs from other goals that focus mainly on the demands of laboratory tests such as the Euro NCAP procedures, rather than the knowledge gained from research into actual accidents. "Using standard crash tests like the Euro NCAP procedures as the sole testing and assessment criteria for judging safety in new automobiles is not the right path to follow, as it does not allow us to take into account the way accidents actually occur," says Weber.

Mercedes considers the "European New Car Assessment Programme," which awards the well-known safety stars as a certificate, to be quite helpful in terms of informing car buyers about occupant protection in new models. However, the crash tests stipulated by NCAP cover only approximately one-third of the actual circumstances surrounding accidents. Moreover, this proportion falls significantly when one additionally takes into consideration the exact severity of various accidents. For this reason, Mercedes believes that NCAP harbours a risk in that vehicles could be designed primarily in a manner that ensures they fulfil the test requirements, and might therefore not offer sufficient occupant protection in many types of accidents.

Mercedes experts point to head-on collisions as an example, whereby it is often the case that vehicles of differing sizes and weights crash into one another. In such situations, an extremely rigid front structure does not always offer the best occupant protection, despite the fact that it leads to the best results in the Euro NCAP head-on collision test.

"Many safety innovations over the last few years have not had any influence on the results of the Euro NCAP tests, and their protective functions have not been awarded with safety stars," says Weber. “In practice, however, these systems are important in ensuring the best possible protection for vehicle occupants in all types of accidents."

PRE-SAFE®: Preventative safety system to include short-distance radar in future

The PRE-SAFE® preventative occupant protection system, which was also developed on the basis of knowledge gained through accident research, makes it possible for the first time to prepare the vehicle and its occupants for an impending accident just seconds before it occurs. In such a situation, the system automatically tightens the front seatbelts and places the front passenger and separate rear seats into an optimum position. It also closes the sunroof if it senses that the vehicle is about to roll over. "PRE-SAFE® heralds a new era of vehicle safety," says Weber.

In future, Mercedes-Benz will further develop PRE-SAFE® into an even more versatile system and create a direct link between active and passive safety — in other words, between accident prevention and occupant protection. For example, Mercedes engineers are now working on a radar-assisted sensor system that will monitor the immediate area in front of and on the side of the vehicle up to a distance of approximately 30 metres. This future PRE-SAFE® technology will be able to autonomously sense danger and then act in a pre-emptive manner. If, for example, it appears that the vehicle is about to collide into the car in front of it, the system will not only tighten the seatbelts but also prepare the brakes for engagement. This means that as soon as the driver hits the brake pedal, the brake pressure needed for the situation at hand will be made available. This can significantly reduce braking distance.

In further development stages, the short-distance radar will serve as the basis for an autonomous PRE-SAFE® braking system that will automatically engage in situations when the only way to prevent an accident or mitigate its consequences for occupants is by making an emergency stop.

Brake lights: Blinking lights as an effective warning signal to prevent rear collision

For some time now, Mercedes safety engineers have been focusing on the high number of rear-end collisions that occur, which is why they have developed a technology alongside PRE-SAFE®’s sensor system that can be quickly implemented in all vehicles and thus help to counteract the trend: Blinking brake lights, which in the form of a red, blinking warning signal instead of conventional stop lights can reduce a driver’s braking reaction time by up to 0.2 seconds, according to tests conducted by Mercedes engineers. This translates, for example, into an approximately 4.4-metre reduction of the braking distance for a car travelling at 80 kilometres per hour — something which would lead to much greater safety in dense traffic. The study conducted by the Mercedes engineers also revealed that switching on the warning signal in dangerous situations has only a minor effect on a driver’s reaction time.

Brake Assist: Technology that helps prevent accidents involving pedestrians

Brake Assist, which Mercedes-Benz was the first carmaker to introduce in 1996, has also proven to be an effective instrument for accident prevention. The system supports drivers who engage the brakes quickly enough but not hard enough in dangerous situations by ensuring maximum braking deceleration at lightning speed.

A recent study conducted by Mercedes engineers shows that Brake Assist also makes an effective contribution towards preventing accidents involving pedestrians. This study had 55 drivers take part in a test at a driving simulator in Berlin. While driving through a town at a speed of 50 kilometres per hour, the test subjects would suddenly see a child run in front of the car from the left side. An emergency stop was the only way to avoid an accident here. The results of the test showed that drivers whose cars were equipped with Brake Assist caused significantly fewer accidents than drivers without the system, with the accident rate dropping by 26 percentage points.

Electronic Stability Programme (ESP®)

In the summer of 1999, Mercedes-Benz became the first auto maker to fit all of its passenger car models with the Electronic Stability Programme as standard, thereby making an important contribution to the improvement of road safety.

ESP® works according to the principle of a "permanent monitor", whereby sensors observe the driver’s and the vehicle’s behaviour and then send their data to a high-performance control unit loaded with a mathematical model. As a result, the actual condition of the vehicle is continuously compared to a reference value provided by the driver. The system is thus able to sense when the vehicle is in danger of skidding.

When the ESP® computer registers a discrepancy between the two values, it engages at lightning speed according to a specially developed logic system on the basis of which it applies precise dosages of braking power to the front or rear wheels, and also adjusts the engine torque. If, for example, the vehicle’s rear axle swings too far outwards when taking a curve, ESP® will lower the drive torque, thereby increasing the lateral guidance force of the rear wheels. If this action fails to produce the desired result, the system will apply precise brake pressure to the front wheel on the outside of the curve in order to stabilise the vehicle. The braking impulses counteract the critical rotary movement, while the simultaneous deceleration provides an additional safety effect.

Unlike the acceleration skid control system, which assists the driver when he or she accelerates the vehicle, ESP® is available to go into action at any time — during braking, acceleration, or cruising along. ESP® immediately adapts to the vehicle’s movements and continues to engage until there is no longer any danger of skidding.

Brake Assist

During tests conducted with a driving simulator, Mercedes engineers discovered that although drivers may implement emergency stops quickly, they often do not step on the brake pedal hard enough. This discovery led to the development of Brake Assist, which Mercedes-Benz was the first to include as standard equipment in its vehicles, and which is now standard in all Mercedes passenger car models.

Brake Assist interprets the brake pedal being engaged at a specific speed as indicative of an emergency situation. It then automatically generates maximum brake boosting power within a fraction of a second, thereby reducing braking distance significantly.

Brake Assist is integrated into the ESP® system in today’s Mercedes passenger cars. It uses ESP® technology to regulate braking pressure, making additional components unnecessary. A sensor continually registers the speed at which the brake pedal is engaged and sends this data to the electronic control unit.

If the speed at which the pedal is engaged should suddenly exceed the norm, the system will conclude that there is an emergency braking situation. It will then assist the driver in the emergency stop and automatically raise the braking pressure in the wheel brake cylinders.

There is no danger of the wheels locking during this automatic hard stop, as ABS continues to apply precise braking power dosages up to the slip limit and the vehicle thus remains steerable. If the driver removes his or her foot from the brake pedal, the automatic power reinforcement deactivates immediately.

PRE-SAFE®

The PRE-SAFE® pre-emptive occupant protection system that premiered in the S-Class in 2002 marked the beginning of a new era in vehicle safety at Mercedes-Benz. PRE-SAFE® is a preventative system that recognises critical driving situations that could lead to an accident, and goes into action immediately to prepare both occupants and the vehicle for a possible collision by:

• Tightening the driver and front passenger seatbelts as a preventative measure.
• Putting the front passenger seat into a better position if it should be disadvantageously situated, and improving the angle of the backrest and seat cushion.
• Activating the electrically adjustable individual rear seats to improve the angle of the seat cushions.
• Automatically closing the sunroof if the vehicle is in danger of rolling over.

Thanks to the preventative protective measures undertaken by PRE-SAFE®, vehicle occupants are placed into a better sitting position that ensures that seatbelts and airbags will work more effectively. If the accident is avoided, the preventative tensioning of the seatbelts is automatically deactivated, allowing the occupants to return the seats and the sunroof to their original positions.

PRE-SAFE® is able to prepare for an accident by combining elements of active and passive safety to create a synergy that is unique in the world to date: PRE-SAFE® is networked to the ABS anti-lock braking system, Brake Assist and the Electronic Stability Programme (ESPÒ), all of whose sensors can recognise dangerous driving manoeuvres and send the corresponding data within seconds to the control units for these standard safety systems. Mercedes-Benz uses this sensor data for its preventative occupant protection system. In future, PRE-SAFE® will be outfitted with additional features for preventing accidents, including a system for autonomous or semi-autonomous braking in critical situations.