Emergency Brake Assist -safety feature or serious hazard?
Discussion
TurboHatchback said:
If you're needing to brake heavily close behind another car on a motorway then your observations were poor and/or you were dangerously close to begin with.
I do agree that space must be left on the motorway, however many years of bitter experience tells me that the second you leave a nice gap some t**t pulls into it........If anyone can tell me how you can stick to 4 seconds gap or so on the motorway or more without an Audi/BMW/Range Rover undertaking and then pulling into your nice gap, I would be grateful.
As for EBA - I don't like these kinds of things that I suspect will make some drivers a bit complacent and pay even less attention to the road ahead, thinking that the computer will save them...
I've got this system on my XC60. I've never been aware of it kicking it.
If you really were a sensible distance back from the car in front, then it might be worth taking it to the dealer to have them check it over. Although you might well just get a "computer says no" response from them.
If you really were a sensible distance back from the car in front, then it might be worth taking it to the dealer to have them check it over. Although you might well just get a "computer says no" response from them.
Tje said:
I have it on a VW golf. We have a one way system that goes to two (barely) lanes before a junction. If I'm in the left and cars queued to turn right it beeps warning me, and if j touch the brakes like I need to to reduce speed for the junction it hammers them on.
That sounds ridiculous - does it depend how fast you're going?I have an older Merc which has brake assist but not the collision warning - however I'm certainly aware that more and more cars have it and it's made me more wary in fast moving motorway traffic as I know if the car in front slams on I probably won't be able to react as fast.
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)
Would I have crashed without EBA and the rest? Perhaps, I don't know. I knew little about EBA until I read the manual later on; the system not only does all the above but, perhaps usefully, it 'airbursts' my rear LEDs to the car behind making it abundantly clear that I am slowing rapidly, so they'd better do the same. So for all I know, the system stopped the guy behind me faster too...
I am also aware that the one thing all road safety people say WRT accidents is that "people never brake hard enough." Perhaps this is especially truer of older people, who subliminally remember the dangers of lock-up etc. With modern cars with ABS and ESP, if you want to stop you need to brake as hard as you can. (wet conditions I know is somewhat more complicated, as perhaps is dodgy surfaces). And if my car can do it quicker and harder and better than me, it gets my vote.
(off topic: I'm looking forward to getting into a V90 in 2-3 years; I'm sure Volvo's systems will be great on that car, and judging by the 2-door shooting brake concept, will look amazing)
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)
Would I have crashed without EBA and the rest? Perhaps, I don't know. I knew little about EBA until I read the manual later on; the system not only does all the above but, perhaps usefully, it 'airbursts' my rear LEDs to the car behind making it abundantly clear that I am slowing rapidly, so they'd better do the same. So for all I know, the system stopped the guy behind me faster too...
I am also aware that the one thing all road safety people say WRT accidents is that "people never brake hard enough." Perhaps this is especially truer of older people, who subliminally remember the dangers of lock-up etc. With modern cars with ABS and ESP, if you want to stop you need to brake as hard as you can. (wet conditions I know is somewhat more complicated, as perhaps is dodgy surfaces). And if my car can do it quicker and harder and better than me, it gets my vote.
(off topic: I'm looking forward to getting into a V90 in 2-3 years; I'm sure Volvo's systems will be great on that car, and judging by the 2-door shooting brake concept, will look amazing)
Tje said:
I have it on a VW golf. We have a one way system that goes to two (barely) lanes before a junction. If I'm in the left and cars queued to turn right it beeps warning me, and if j touch the brakes like I need to to reduce speed for the junction it hammers them on.
I was given a Skoda loaner and I didn't even know it had this fitted. Exactly the same as above, however I have no idea how the system works and the manual was as clear as mud.
If I could master how it all works and it's quirks then I could adjust my driving for the systems operation.
I still think it's much better with it than without.
Think I may have seen this in action this morning. Outside lane of M62 around 9.30am, rubber necking at a broken down HGV on the opposite carriage way, white Merc slams on far harder than it needs to, lighting up the hazard lights. A Galaxy (not a whole solar system, the big car thing) goes in to the back of the Merc, and another car in to the back of the Galaxy.
No need to brake that hard, but I wonder if it was the Merc drivers choice or the cars decision.
No need to brake that hard, but I wonder if it was the Merc drivers choice or the cars decision.
Edited by IanCress on Thursday 17th September 12:05
IanCress said:
Think I may have seen this in action this morning. Outside lane of M62 around 9.30am, rubber necking at a broken down HGV on the opposite carriage way, white Merc slams on far harder than it needs to, lighting up the hazard lights. A Galaxy (not a whole solar system, the big car thing) goes in to the back of the Merc, and another car in to the back of the Galaxy.
No need to break that hard, but I wonder if it was the Merc drivers choice or the cars decision.
Scary! I must admit that I now always give the car in front of me plenty of space, as I don't even have ABS in the TVR.No need to break that hard, but I wonder if it was the Merc drivers choice or the cars decision.
Are some of these modules faulty, some seem to be very 'all or nothing', and I wonder how these cars will fare 5-10 years down the line if some are this bad from relatively new.
chris watton said:
Are some of these modules faulty, some seem to be very 'all or nothing',
That's the point of them, they're designed to fully apply the brakes. Most ordinary drivers press them nothing like hard enough, even in an emergency - you're supposed to absolutely bury the brake pedal and let the ABS do its stuff.
IanCress said:
Think I may have seen this in action this morning. Outside lane of M62 around 9.30am, rubber necking at a broken down HGV on the opposite carriage way, white Merc slams on far harder than it needs to, lighting up the hazard lights. A Galaxy (not a whole solar system, the big car thing) goes in to the back of the Merc, and another car in to the back of the Galaxy.
No need to brake that hard, but I wonder if it was the Merc drivers choice or the cars decision.
Sounds very much like it -particularly the hazard lights coming on which I seem to recall is part of it. No need to brake that hard, but I wonder if it was the Merc drivers choice or the cars decision.
Edited by IanCress on Thursday 17th September 12:05
In the week since I made the original posting I'm starting to think I might have a fault on the system as the collision warning buzzer/light has activated twice more when it wasn't required -once as I was passing an HGV in the lane along side me and the second time in heavy rain but no other vehicle or obstacle in sight. A trip to the dealer required I think.
However, possible faults in the triggering system aside, I think I've concluded the system basically a good idea but it is currently under-developed and needs to be more selective about when and how it kicks in. When it activated on me it really wasn't necessary -there categorically wasn't an emergency and everything was under control -whether this was down to a over-zealous sensor or not is uncertain of course but it does highlight Chris Watton's comment above about future reliability! However, triggering aside and given the way everything else on the car is 'adaptive' -eg dynamic dip-beam range on headlights depending on distance to the next vehicle, dynamic cruise control etc, it must be feasible to vary the braking force it applies dependent on the distance/speed/etc in order to bring you to a controlled halt in the space available rather than slamming everything on in a panic and ending up with the guy behind slamming into the back of you.
I would also add to all the 'doubters' -wait until it happens to you when it's unnecessary and you're not expecting it -its terrifying!
Sheepshanks said:
Tje said:
I have it on a VW golf. We have a one way system that goes to two (barely) lanes before a junction. If I'm in the left and cars queued to turn right it beeps warning me, and if j touch the brakes like I need to to reduce speed for the junction it hammers them on.
That sounds ridiculous - does it depend how fast you're going?I have an older Merc which has brake assist but not the collision warning - however I'm certainly aware that more and more cars have it and it's made me more wary in fast moving motorway traffic as I know if the car in front slams on I probably won't be able to react as fast.
I've found the easiest way to get round the problem is to turn the traction control off, doing this deactivates the front assist so I do this out of habit every time I get in the car now.
I have something similar on my Mazda 6, called City Emergency Brake or something like that. Up to 20mph it'll monitor for you crashing into anything in front and automatically apply brakes if it thinks you're going to crash. This can be particularly annoying if you try and pull into a narrow garage, brakes come on. On the road though its only applied the brakes once, I was doing maybe 10mph approaching a car waiting to turn right, the car was turning and there was plenty of room for me to continue on the left, however the car thought otherwise. Brakes slammed on bringing me to a complete halt, for no apparent reason.
Luckily with the Mazda, within the computer is an option to turn it off, permanently.
Luckily with the Mazda, within the computer is an option to turn it off, permanently.
Never had this problem in my merc with brake assist and i've done a couple of track days in it so have been much closer to cars in front than i would be on the road.
I have seen on video that the rear brake lights flash under heavy braking with a car in front and the pedal does feel more responsive but it never locks on/enables the abs.
I have seen on video that the rear brake lights flash under heavy braking with a car in front and the pedal does feel more responsive but it never locks on/enables the abs.
ORD said:
I agree that the OP was following too closely. You should aim to almost never use your brakes on a motorway, let alone having to use them with force. If you cannot brake very gently or, even better, just ease off, you are too close.
While I agree in principle and as you say try to leave sufficient room so I can attempt to avoid using my brakes on a motorway (or in any other heavy traffic), this is far too simplistic especially in a heavy car which like most modern Mercs has an autobox (and also proves you haven't read the rest of the thread). Just to make the point, while I was out at lunch a few minutes ago I tried to test how long it would take to slow naturally from 50mph. So, doing exactly 50mph on a flat, straight (and empty!) road, I took my foot off the throttle. By the time I got to the end of the 300metre+ straight and had to apply the brakes I was still doing 40mph. How long it would take to scrub off the other 40mph is anyone's guess -another half mile? More? Would it ever actually stop without applying the brakes? Apply your your holier-than-thou theory would mean leaving a gap between you and the car in front of at least half a mile.Gassing Station | General Gassing | Top of Page | What's New | My Stuff