In Germany rear-end collisions are still responsible for 22 percent of accidents involving injury or fatalities, and in the USA the figure is as high as 31 percent. For many decades Mercedes-Benz has worked on methods to prevent these accidents. Milestones in the company's safety developments include ABS (1978), Brake Assist BAS (1996), DISTRONIC proximity control (1998) and the further development stage DISTRONIC PLUS with BAS PLUS (2005). These new systems always celebrated their debut in the luxury class models, but in the interests of traffic safety it has always been a principle of Mercedes-Benz to make innovative technology available on a broad basis as rapidly as possible – also outside its own model range. As a result ABS and BAS, and incidentally also the Mercedes development ESP®, are nowadays standard equipment in practically all passenger cars.
New Brake Assist: a milestone in safety technology
The next milestone in the democratisation of automotive safety technology is due to follow this year: with the launch of the new-generation B-Class, followed a little later by the A-Class, Mercedes-Benz is making a radar-based collision warning system with adaptive Brake Assist available in compact class vehicles as a world first. The company expects this to make a significant, positive impression on accident statistics: "Our aim is to reduce the number of serious accidents even further, and on a broad basis. Following detailed analyses of accident data, we estimate that this radar-based technology will be able to prevent around 20 percent of all rear-end collisions, and mitigate the effects of the accident in a further 25 percent of cases," says Ulrich Mellinghoff, Head of Safety at Mercedes-Benz.
This estimate is backed up by test results: during tests with 110 car drivers in the driving simulator, the accident rate in three typical situations fell from 44 to eleven percent thanks to a combination of collision warning and adaptive Brake Assist.
BAS PLUS has a high level of acceptance among drivers
DISTRONIC PLUS and BAS PLUS already have a high level of acceptance amongst Mercedes customers. This is also confirmed by a 2010 survey of car drivers whose cars are equipped with these. 87 percent of the respondents gave a positive assessment of the proximity control function, and after six months of ownership 41 percent has already experienced an intervention by Brake Assist PLUS. Their comments speak for themselves:
- "It can easily happen of course, you are chatting away in the car, and if the system had not beeped I would have driven straight into the back of him."
- "You are not on your own, and on those occasions when you are not paying attention you get this useful warning."
- "There is a marked reduction in rear-end collisions. There is always the odd moment when you are not paying proper attention, and before you know it you have hit the car ahead. The warning sound immediately gets your attention, and you can still brake, there is enough time."
It is precisely this requirement profile that is met by the new assistance system, which will already be launched for the compact car segment before the end of this year: it gives a visual and acoustic warning to a possibly inattentive driver, and prepares Brake Assist for an absolutely precise braking response. This is initiated as soon as the driver emphatically operates the brake pedal.
Key functions of the coming generation
A radar-based collision warning system with adaptive Brake Assist
- recognises an inadequate distance from a vehicle ahead in the speed range between 30 and 250 km/h,
- recognises when the gap is decreasing. The driver is given a visual and acoustic warning if a collision threatens,
- is able to recognise stationary objects ahead of the vehicle and issue a corresponding warning,
- recognises specific driving situations such as bumper-to-bumper traffic, and adapts the activation threshold for the warning and adaptive Brake Assist to these parameters,
- calculates the precise braking force ideally needed to avoid the accident when the danger of a collision is detected, and makes best possible use of any distance remaining. This means that the driver behind in turn has better chances of preventing a rear-end collision.
- The brake pressure is adjusted if the situation changes – if the vehicle ahead accelerates, it is decreased to the level the driver requires; if the distance to moving and stopping vehicles decreases, the brake pressure is increased further.
- Preventive safety systems (PRE-SAFE®) can be activated if needed (e.g. belt tensioners).
- The new system meets the key "Forward Collision Warning" requirements of the NHTSA, the American road and vehicle safety authority.
More experience with assistance systems than any other manufacturer
Mercedes-Benz has the most extensive experience with assistance systems of all car manufacturers. Ulrich Mellinghoff, Head of Safety at Mercedes-Benz: "Fine coordination of these systems requires comprehensive know-how, and is decisive for customer acceptance and effectiveness. Systems are only accepted if they work reliably, and are only seldom operated or triggered in error."
In addition to preliminary studies covering a driver-oriented system configuration in the driving simulator, the systems are therefore verified by extensive, practical driving trials during the development stage. To this end vehicles are fitted with measuring equipment to register key dynamic values, as well as video cameras to record the traffic situation. An input terminal enables the drivers to provide feedback on the behaviour of the assistance systems, and assess whether the intervention was appropriate or not. To date the experiences of 608 drivers have been recorded and analysed using precisely 198,828 measurements over a total distance of 1,130,215 kilometres. These included more than 5000 proximity warnings which were taken into account to optimise the system.