Emergency Brake Assist -safety feature or serious hazard?

[monoloco]

yep -I've had mine kick in due to long grass/cowparsley etc in the verge -particularly if its wet and bending over into the road slightly. It trips the proximity sensors and the buzzer goes off but if you just happen to touch the brake at the same time the emergency braking kicks in for a second or so until you've gone past the offending tuft of grass..

[Dog Star]

The only issue I've had with MB assist is on the M621 and I had a scruffy Clio sat right on my back bumper. The car in front braked quite hard. I had a good safety margin so was braking at a much lesser rate (and eating into my safety gap) so that the banger behind didn't run into me, I was trying to brake not as hard initially and then brake really hard. However this just made the collision avoidance think I wasn't braking hard enough so it took over and nearly caused the incident I was trying to avoid.

[FiF]

Now if manufacturers want to get all smart and come up with devices scanning around you, lane markings and so on, how about a system to tell MLMs to move the hell over.

[Debaser]

I can't believe we still have faults with features as simple as emergency brake assist. Aren't fully autonomous cars just around the corner?

[liner33]

I had EBA in my old E class , it kicked in twice in 8 years , once when a car pulled out on me on a roundabout and secondly when a child on a bicycle shot out in front of me with no warning , I was amazed how quick that car stopped and would have almost certainly hit him had I not had it

[Toaster Pilot]

Debaser said:

I can't believe we still have faults with features as simple as emergency brake assist. Aren't fully autonomous cars just around the corner?

Most of these "faults" are caused by tailgating drivers who stab at the brakes - surely working as designed

Much like with autonomous cars, until every vehicle on the road has the same features, accidents will happen. The example above of the Galaxy piling into the Merc for example - if both had EBA....

[RobM77]

Personally I'd rather have control. Since I started driving 23 years ago I've been in a couple of situations where I've had to brake hard unexpectedly, but have been followed too close by another vehicle at the same time, so had to look forwards and backwards as best I could and judge the level of braking correctly to stay safe. In both situations I stopped in good time to avoid the unexpected hazard up ahead (because I always drive so I can stop in the distance I can see), but perhaps at 70-80% of my car's capability rather than 100% in order to avoid being rear-ended. In fact, you could say that the chances of being tailgated are higher in areas with potential hazards up ahead, because that's where careful drivers slow down and reckless drivers want to speed on ahead and tailgate out of frustration. I'll obviously retract my comment if the system is capable of making this judgement, but from what's said so far, I doubt it is. The notion of it picking up long grass on verges as described above is very alarming and another reason to avoid it!!!

[Mr.Jimbo]

I had this happen on a rental Ford in the company multi-storey, we've got a barrier that senses your approach and lifts up - occasionally if you're not nose to tail it starts to come down, then senses you and lifts up - no problem.

In this Ford, it sensed the barrier coming down and full on slammed the brakes, and seeing as it was a manual and I wasn't expecting it, stalled and put the electric park brake on. Very abrupt and pretty uncomfortable (because the inertia reel locked and pinned me to the seat) but scared the st out of the guy behind.

Have to say though, I have EBA in my Jaguar and never noticed it, it doesn't get phased by the same barrier either.

[MajorMantra]

Dog Star said:

The only issue I've had with MB assist is on the M621 and I had a scruffy Clio sat right on my back bumper. The car in front braked quite hard. I had a good safety margin so was braking at a much lesser rate (and eating into my safety gap) so that the banger behind didn't run into me, I was trying to brake not as hard initially and then brake really hard. However this just made the collision avoidance think I wasn't braking hard enough so it took over and nearly caused the incident I was trying to avoid.

It seems to me that for these systems to be an improvement over not having EBA, the car should monitor what's happening behind as well as in front.

[Mr2Mike]

Toaster Pilot said:

Most of these "faults" are caused by tailgating drivers who stab at the brakes - surely working as designed

Well, except for the instances where is has nothing to do with tailgating as described just above.

Any "safety" system that can reduce the possibility of avoiding a collision is inherently faulty IMO.

[rxe]

albert100 said:

Interesting topic:

I'm aware that these systems can seem overly intrusive, on occasion. But I'm generally glad my car has them:

I have EBA along with collision warning and braking, etc. on my V70 D5. Earlier this year, I had just joined the M1, lane 3, doing 70 on a pretty busy but flowing road. I had just clicked on the adaptive cruise and all was OK, until the car noticed the traffic slowing rapidly in front of me slightly more quickly than I did. Indeed, unlike most motorway 'heavy traffic' slow downs (i.e. often from 70 to 20-30), this was clearly from 70 to a standstill.

Car immediately braked, I braked (but probably not heavily enough), whereas the system knew that I had to do a lot better than that, and really piled it on, triggering the ABS and sounding a claxon and lighting up the HUD.

Even more cleverly, it automatically engaged the hazard lights. Came safely to a total halt, and pulled into lane 2 which was slowing but still going; a few cars up in Lane 3 there was a nearly new Mercedes E-Cabrio, wanged hard into the back of a supermini, which had stopped behind a van for some reason. (no serious injury on any side as far as i could see - the airbag didn't go off on the Benz which I guess was a good sign)

IMO the problem here begins with "switching on adaptive cruise". Adaptive cruise is a simple beast which makes sure you don't get too close to the guy in front. I don't think I'm particularly good at motorways, but I'm generally observing the brake lights of the cars 6 ahead of the car in front. You see brake lights in the distance, you back off, open the gap. Some time later, the guy in front of you reacts, and you have all the time in the world to not hit him. I would consider the need to brake hard as a complete emergency - sudden accident in front or whatever, not a conventional "the motorway is standing on its nose".

[RobM77]

Mr2Mike said:

Toaster Pilot said:

Most of these "faults" are caused by tailgating drivers who stab at the brakes - surely working as designed

Well, except for the instances where is has nothing to do with tailgating as described just above.

Any "safety" system that can reduce the possibility of avoiding a collision is inherently faulty IMO.

There's no doubt I'd have had a crash in one of those situations I described above, and it would have been very close and uncomfortable in the other one, potentially a crash. The fact is that a normal modern family car can do 60mph-0 in under 3 seconds, which is often more dangerous than safe in plenty of situations. It's very simplistic to just assume any driver braking heavily wants to brake maximally and come to a complete halt, just as it would be simplistic to detect full throttle from a standstill and automatically engage launch control to hit 60mph in the smallest time possible

[johnaerial]

Same problem….I was doing 70mph in outside lane of two lane dual carriageway with a car about 30 yards in front of me in the left hand lane doing about 65mph. He indicated to pull off into exit road and quickly slowed down. As I was about to draw level with him, my Golf sharply braked for no reason. Slight screech of tyres and I continued. Unnerving to say the least. My wife has already experienced this twice. My only mitigating circumstance (on behalf of the car) might be that when I checked the sensor below the front bumper, I found the plastic surround had come adrift and could possibly have deflected the sensor signal.

Edited by johnaerial on Monday 26th February 08:52

[RobM77]

This week I had another incident where I wouldn't have wanted EBA. I was following a large artic down a lane near our house when it struck a tree and the trailer was destroyed with a loud bang - I came to a halt immediately, but the girl behind me very nearly didn't manage to. I think if EBA had taken over I would have been rear ended; the artic dragged the trailer remains with it, so I could have continued, but I thought it best to stop in case the tree or part of it fell down - I'd have happily driven on though in preference to having a Fiat Panda squashed into my bootlid - for her sake as well as mine!

Edited by RobM77 on Sunday 25th February 22:58

[Alucidnation]

johnaerial said:

Same problem….I was doing 70mph in outside lane of two lane dual carriageway with a car about 30 yards in front of me doing about 65mph. He indicated to pull off into exit road and quickly slowed down. As I was about to draw level with him, my Golf sharply braked for no reason. Slight screech of tyres and I continued. Unnerving to say the least. My wife has already experienced this twice. My only mitigating circumstance (on behalf of the car) might be that when I checked the sensor below the front bumper, I found the plastic surround had come adrift and could possibly have deflected the sensor signal.

I doubt it was the plastic trim.

The other driver was still within the radar coverage and was doing what it is supposed to.

Not sure how old your car is but they did tweak the software quite recently i believe.

[cptsideways]

camshafted said:

Bumping this thread after reading a very interesting story on Cornwall Live - http://www.cornwalllive.com/news/cornwall-news/vw-...

Ex-traffic plod has a new Tiguan and the brake assist seems to kick in when it isn't needed, prompting fears it will cause an accident.

He seems to put it down to the Cornish roads and hedgerows. The video, from around 1m30s or so, shows it in action.

Anyone recently had this issue? It's a bit worrying TBH!

The Tiguan is rather well known for this! & yes its dangerous.

Accidental EBA trigger activations are almost always caused by a "fast but light" panic brake application. You can actually set off EBA on most cars by reaching down & prodding the pedal with one finger (On a test road of course)

Edited by cptsideways on Sunday 25th February 22:30

[Alucidnation]

I think some people are getting confused between vws front assist and brake assist systems, which differ in opertaion.

[Monty Python]

So strictly speaking, the title should be "Collision avoidance systems" rather than "Emergency brake assist". From what I understand, EBA only monitors how the brakes are applied and nothing else.

[tejr]

Our CR-V has CMBS (collision mitigation braking system) which brakes for you and pre-tensions your seat belts..

I liked the idea, but have switched it off permanently. There are situations where you are approaching a car that my have stopped to turn right and plan to manouvre around it, or it has begun to move off so you can continue, but the car detects a (near) stationary object and begins to brake for you and sts you up by tugging hard on your seat belt.. annoying..

[rxe]

Max_Torque said:

The things is,modern cars are now so easy to drive, the vast majority of drivers don't make any effort to familarise themselves with a new (to them) vehicle. They just get in, stick it in "D" and zoom off. If the first time you have to use the brakes hard is a genuine emergency, then you have pretty much failed as a driver imo.

Day in, Day out, drivers are surprised by things their car does, and in an unfortunate few cases, that surprise leads to accidents, injury and even death. No one would pick up a hand gun and just mess around with it without any instruction, and yet that is exactly what happens with our cars........

What are you suggesting he does?

If I get in a car, I tend to work out pretty quickly if the brakes don't work - I tend to brake slightly more aggressively than I need to on the first few stops to familiarise myself with the sensitivity of the system. Mostly works, other than in Seats which have two brake settings "on" or "off".

This sort of thing is fine. What you seem to be advocating is some sort of system test in moving traffic - that the driver should experiment with their car's features in situations where it might be dangerous. By its very definition, Emergency Brake Assist is all about emergencies - I'm not going to create an emergency to test it.

I have no doubt these things prevent accidents when the driver is not paying attention or on their phone. When I'm driving (and paying attention) they are a PITA. I was in a car with collision warning a few months ago, and it was a nightmare of bonging and flashing. It appeared to fail completely to identify cars in the adjacent lanes that were completing manoeuvres, and had trouble with sharp bends.