Brake Assist Plus Can Reduce Rear Collisions by 75 Percent
Making its debut on the new S-Class, an optional enhanced version of Mercedes-Benz Brake Assist not only supplies full-power braking in emergency braking situations as soon as the driver applies the brake pedal, but also monitors the distance to the vehicle ahead and adjusts brake pressure if the driver doesnt brake hard enough.
While conventional Brake Assist is only triggered by the drivers reflex reaction on the brake pedal, Brake Assist Plus also considers the closing speed of the vehicle ahead based on radar signals from Distronic Plus.
In tests conducted by Mercedes researchers using 300 drivers, the new integrated system reduced rear collisions in heavy traffic by 75 percent.
Actively mastering difficult situations with the vehicle
PRE-SAFE® -Brake and BAS+: Automatic emergency braking
Mercedes-Benz has continued to further develop the PRE-SAFE® Brake, which was first unveiled in 2006.
From spring 2009, a version of the system that activates the maximum braking power automatically if there is an acute risk of an unavoidable accident will be available for the new E-Class and the S-Class.
The PRE-SAFE® Brake therefore acts as an electronic crumple zone and can greatly reduce the severity of an impact.
What’s more, it does this in two stages: around 1.6 seconds before the calculated impact point – after three audible warning signals – the system initiates partial braking autonomously and decelerates the car with around 40 percent of the maximum braking power.
Designed to supplement the visual and audible warnings, autonomous partial braking gives the driver a further, perceptible signal to act.
If the driver then brakes immediately, the maximum braking force is made available or, if the driver swerves, the accident can be avoided at the last moment, depending on the driving situation.
Mercedes will be offering a further enhanced version of this safety system from spring 2009.
If the driver fails to react, even after automatic partial braking, the PRE-SAFE® Brake activates the maximum braking power around 0.6 seconds before the now unavoidable collision.
This emergency braking can greatly reduce the severity of the impact. The system therefore acts like an “electronic crumple zone”, offering the car occupants even greater protection.
Radar sensors for early accident detection
• Accident rate reduced from 44 to 11 percent in simulator tests
situation ahead of the vehicle: a newly developed close-range radar based on 24-Gigahertz technology works together with the 77-Gigahertz radar of the DISTRONIC PLUS proximity control system.
- 100 male and female drivers took part in a series of tests in the driving simulator. They each completed a 40-minute journey with several critical situations on motorways and country roads. It was only possible to avoid accidents by hard braking. Thanks to the new Brake Assist PLUS system, the accident rate during this test series fell by three quarters compared to the average of 44 percent with conventional brake technology. The new technology demonstrated its advantages particularly well when driving in a line of traffic at 80 km/h on a country road: when the vehicle ahead was suddenly braked, the radar-based Brake Assist system prevented an accident in 93 percent of cases – while more than one in two test drives ended in a rear-end collision without the system. Even in situations where a collision was unavoidable owing to a late response by the driver, the new system helped to reduce the severity of the impact. This was confirmed by the measured impact speed, which was reduced from an average of 47 to 26 km/h thanks to Brake Assist PLUS.
- More than 200 male and female drivers took part in practical trials in Europe and the USA, covering a total of more than 450,000 kilometres in 24 test cars. These journeys were recorded with the help of the latest measuring and video technology. Evaluation of the data and video sequences showed that Brake Assist PLUS also makes a major contribution to safety under real conditions. Accident research: focus of attention on rear-end collisions With Brake Assist PLUS Mercedes-Benz has once again confirmed its role as the trendsetter in the field of road safety. As in the case of the airbag, belt tensioner, ESP® and other pioneering safety systems, the development focus for the preventive Brake Assist system was on the real accident situation, or more precisely the high number of rear-end collisions, which account for more than 17 percent of accidents involving fatalities or injuries in Germany.
Statistics compiled by the road safety authority NHTSA in the USA show that around 31 percent of all accidents with fatalities or injuries are rear-end collisions.