First Accident Avoidance System Reduces Rear Collisions by 75 Percent
When the next-generation Mercedes-Benz S-Class goes on sale in Europe this fall, the flagship sedan will be the first to feature a new version of PRE-SAFE, a revolutionary new safety system that can reduce rear collisions by 75 percent. The next evolution of Mercedes-Benz accident avoidance, PRE-SAFE uses two complementary radar frequencies to detect vehicles up ahead, warn of a likely impact and prime the braking system for faster response when the driver brakes the car.
In addition, the front seat belts are tightened during the valuable time just before a possible impact, and seats move to positions that provide better protection -- two measures that have been part of the current S-Class PRE-SAFE system since its debut in 2002. The latest version also closes the side windows to provide better support for the curtain air bags, and can inflate special seat cushions that provide greater lateral support for occupants and help the side air bags provide even greater protection.
Testing Shows New PRE-SAFE Reduces Rear Collisions by 75 Percent
The new PRE-SAFE uses an enhanced version of the Mercedes-Benz Brake Assist system that can not only supply full-power braking assist in emergencies as soon as the driver applies the brake pedal, but also continuously measures the distance to the vehicle ahead and adjusts brake pressure if the driver doesn't brake hard enough. In extensive tests conducted by Mercedes researchers using 300 drivers, PRE-SAFE reduced rear collisions in heavy city traffic by 75 percent.
Two Radar Beams Stay on the Alert
The newest PRE-SAFE system uses two very different radar beams to scan traffic in front of the car. Newly developed short-range radar with a frequency of 24 gigahertz sweeps the first 33 yards in a fan-shaped 80-degree pattern, working in tandem with a narrower nine-degree beam of longer-range 77-gigahertz radar (already used for the car's optional Distronic cruise control feature). The two radar frequencies complement each other to provide a full range of more than 160 yards - more than one and a half football fields. The system can identify when the car is gaining too quickly on vehicles ahead to intervene with the Distronic system, and it decides whether to sound a warning, ready Brake Assist and trigger other PRE-SAFE measures.