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New BMW 5 Series passes first crash test using brake intervention
28 May 2010
Up until now, verification of vehicle safety has been obtained by means of crash tests in which structural integrity and restraint systems were tested in a non-braked situation. However, as a result of modern electronics such as those also featured in the new BMW 5 Series and 7 Series, protective systems that warn the driver in advance of an accident and prepare the driver and the vehicle for impact in the event of an unavoidable collision are becoming more and more widely accepted.

Future testing procedures will have to make allowances for the effect of preventive protection systems. In a recent world premiere, the BMW 530d successfully passed a crash test involving brake intervention at the DEKRA facility in Neumünster near Hamburg.

It’s a familiar situation for many motorists. The end of a tailback suddenly appears behind a motorway bend, and if a motorist is inattentive or visibility is impaired, a rear-end collision could be highly likely – after all, this is the cause of around 40% of all motorway accidents involving injured persons. In order to defuse this kind of hazardous situation, some premium segment vehicles such as the BMW 5 Series are already equipped with anticipatory assistance systems that help reduce the risk of such accidents. BMW’s successful upper mid-range model, which was just recently brought to market, features – combined with Active Cruise Control – an optional rear-end collision warning system incorporating a braking function that activates an alarm scenario in two stages.

In the event of a potential collision with the vehicle in front, the driver is first given a preliminary warning by means of an illuminated red vehicle symbol on the instrument panel and on the Head-up Display. At the same time, the braking system is prefilled and the minimum triggering level of the hydraulic brake assistant lowered. This ensures that in an emergency brake pressure is built up faster when the driver applies the brakes, therefore significantly reducing the stopping distance.

If the danger of collision is acutely imminent, the second stage of the collision warning commences. In situations demanding particularly rapid intervention by the driver, the system activates an acoustic signal in addition to the visual warning. Should the driver still not react to the request to apply the brakes, a time-limited delay procedure is activated: The car brakes for 1.2 seconds with reduced deceleration, whereby speed is already reduced before the driver can apply the pre-tensioned brakes.

Based on the information supplied by the radar sensor of the Active Cruise Control system (ACC Stop &Go) featured in the new BMW 5 Series, the system detects when a collision can no longer be avoided by the driver’s reaction. In this case, an automatically activated emergency brake application function ensures that collision speed is, nevertheless, significantly reduced.

Based on a conventional EuroNCAP test with the car approaching an offset obstacle at 64km/h, a so-called offset crash, the vehicle used in the DEKRA test incorporating advanced brake intervention likewise initially accelerated to 64km/h. However, immediately before impact the BMW 530d braked hard – as stipulated by the system – and collided with the offset block at a reduced speed of just 40km/h.

Due to full brake application immediately prior to impact and the car’s pitching movement resulting from this, the vehicle changes its position, particularly when the front bumper hits the block. The vehicle collides with the obstacle in a slightly ‘lower’ position than in the case of a crash occurring without prior application of the brakes.

Concerning the deceleration, occupants also assume a position further forward. More importantly, though, in the event of a crash incorporating prior brake application, the severity of impact is reduced considerably, thereby significantly lessening the strain on all occupants.

Previous testing facilities have not permitted verification of the effect of anticipatory occupant protection systems in crash tests. The demonstrative test implemented by BMW in collaboration with DEKRA is the first step in testing future pre-crash scenarios, as in the years ahead innovations in active safety will be found in an increasing number of vehicles, with BMW playing a leading role.

Seeing as volvo just totalled one of their press cars with such an avoidance system I certainly wouldn't rely on it...

If abs led to some risk compensation behaviour I dread to think what automatic brakes would do to driver awareness. And what would happen if someone was used to a car with the system then drove a car without it?

...In the event of a potential collision with the vehicle in front, the driver is first given a preliminary warning by means of an illuminated red vehicle symbol on the instrument panel and on the Head-up Display....

...If the danger of collision is acutely imminent, the second stage of the collision warning commences. In situations demanding particularly rapid intervention by the driver, the system activates an acoustic signal in addition to the visual warning....

...And what would happen if someone was used to a car with the system then drove a car without it?

...Does one benefit from therefor 'always' driving a variety of cars so 'one' is 'always' thinking about what is what on 'this car, or is it better to drive one 'type' and become totally familiar with that ? I wonder if there is any research on that ?

I sure as hell wouldn't like to be following one in a "lesser" car and

That said, I don't think I've ever seen anyone driving on a busy motorway whilst leaving a gap such that they could stop in the distance they can see to be clear.

That said, I don't think I've ever seen anyone driving on a busy motorway whilst leaving a gap such that they could stop in the distance they can see to be clear. Pretty much everyone that I see tends to assume that a concrete block isn't suddenly going to appear in front of them at precisely the point that the previous car's back bumper is!

I'm not sure how people will become reliant on it, are people reliant on ABS?

An experienced driver obviously knows what to do in this situation but would an new driver?...very unlikely!

Graball, are you saying that your usual braking force is enough to engage ABS? You need to seriously consider driving more smoothly mate!

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