PRE-SAFE 360° improves safety in rear-end collisions
While the Traffic Jam Assistant heightens active safety, simply because the driver is able to stay alert longer, the innovative protective system known as PRE-SAFE 360° further improves passive safety. PRE-SAFE 360° was realized for the first time in the ESF 2009 experimental safety vehicle from Mercedes-Benz, which was a world first, and it is also being used in the F 800 Style. It is based on the well-known PRE SAFE® system presented by Mercedes-Benz in 2002. If PRE SAFE® recognizes a critical driving situation, the system activates occupant protection measures in advance.
The enhanced PRE-SAFE 360° monitors not only what is on either side of the vehicle, but also the area behind the vehicle. The system uses short-range and multimode sensors to monitor the area of up to 60 meters behind the vehicle. If the system for early recognition of accidents determines that a collision is unavoidable, the brakes are activated about 600 milliseconds before the impact.
Braking a stationary vehicle that is hit in the rear helps prevent secondary accidents such as those that result when such a vehicle is hit and catapulted in an uncontrolled manner into an intersection or a pedestrian crossing. This application of the brakes can also reduce the severity of possible injuries to the passengers’ cervical vertebrae because the vehicle, and therefore the occupants’ bodies, are subjected to a lower acceleration. The driver always retains control in a vehicle fitted with PRE-SAFE 360°, however. For example, the brake is immediately released if the driver hits the gas pedal knowing that there is sufficient space in front of his or her own vehicle to avoid the rear impact.
The protective effect of PRE-SAFE 360° supports that of the NECK-PRO crash-responsive head restraints. As soon as the sensors detect a rear-end impact of a predefined severity, the system releases pre-tensioned springs inside the head restraints. These move the padded surface of the head restraints slightly forward and upward within milliseconds, thus supporting the driver’s and front passenger’s heads sooner than conventional head restraints.