Emergency braking - eh?

Emergency braking - eh?

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Pica-Pica

Original Poster:

13,621 posts

83 months

Monday 18th June 2018
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Driving on a dual carriageway, absolutely clear, a pelican crossing light goes amber. Nothing in front, and I knew nothing was behind, so clear all round. I could have legitimately gone through, but decided to stop (as I said, clear all round).

So a sharpish stop. Then I can hear the indicators clicking. I then realised that the sharp stop had triggered the hazards. I know this happens (and brake lights flash), I was just somewhat surprised that it occurred at what felt a sharp but not fierce stop. It could be that the car was actually stopping sharply, but felt very secure and safe doing so, and therefore seemed slower than the stop really was. I feel I want to practise a few quick stops to check it out at various levels of deceleration.

Anyone experienced this? This was a 335d.

codenamecueball

529 posts

88 months

Monday 18th June 2018
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Pica-Pica said:
Driving on a dual carriageway, absolutely clear, a pelican crossing light goes amber. Nothing in front, and I knew nothing was behind, so clear all round. I could have legitimately gone through, but decided to stop (as I said, clear all round).

So a sharpish stop. Then I can hear the indicators clicking. I then realised that the sharp stop had triggered the hazards. I know this happens (and brake lights flash), I was just somewhat surprised that it occurred at what felt a sharp but not fierce stop. It could be that the car was actually stopping sharply, but felt very secure and safe doing so, and therefore seemed slower than the stop really was. I feel I want to practise a few quick stops to check it out at various levels of deceleration.

Anyone experienced this? This was a 335d.
Never had it as my car isn't equipped, but much more helpful on a motorway than the situation you were in. I'd be a very grateful for it, it could make the difference between someone stopping short or finishing inside your spare wheel.

joshleb

1,544 posts

143 months

Monday 18th June 2018
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Anything to make it more visible to people behind is surely a good thing...?

Prefer it to come on when braking too softly...!

CoolHands

18,496 posts

194 months

Monday 18th June 2018
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The nanny state in action. Or in this case bmw

EmmaJ

4,525 posts

145 months

Monday 18th June 2018
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I’ve had the same trigger on my S3, I find it’s not so much how hard you’re braking but how abruptly the initial application of brakes are which results in the hazards flashing. YMMV......

StanleyT

1,994 posts

78 months

Monday 18th June 2018
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Sneezing whilst just about to do the final park in my Other German Marque to BM causing a very jerky stop put the hazards on. As did a child letting go a of a helium ballon at a crossing which drifted in front of me (me at 15 mph in traffic) to get the proximity front warning beepy braky system to kick in and the hazards come on.

In a fairly chavy estate in the dark bowels of the Nor'n town I currently work there is a "thing" of chavs to slap gaffer tape over front bumper sensors of slow moving cars in traffic to cause automatic braking to come on. I don't know if this is then a ruse to get the occupant out the vehicle so said chavs can steal it / bum them / grab handbags or just typical high jinks?

ecsrobin

17,019 posts

164 months

Tuesday 19th June 2018
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My car the manufacturer left the setting on as per the normal cars and decided to add Brembos to the car without adjusting the sensitivity so my hazards come on everytime I hit some B roads or on a trackday.

essayer

9,010 posts

193 months

Tuesday 19th June 2018
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This is emergency brake assist isn’t it? The car detects a rapid brake application, and assumes full braking is required.
Apparently people don’t realise how hard they can press the brake pedal in an emergency, so the car compensates.

EmmaJ

4,525 posts

145 months

Tuesday 19th June 2018
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essayer said:
This is emergency brake assist isn’t it? The car detects a rapid brake application, and assumes full braking is required.
Apparently people don’t realise how hard they can press the brake pedal in an emergency, so the car compensates.
Not on my S3, you can have the hazards activate (to warn of heavy braking) but not trigger EBA.

cobra kid

4,906 posts

239 months

Tuesday 19th June 2018
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CoolHands said:
The nanny state in action. Or in this case bmw
Like airbags and ABS?

motco

15,919 posts

245 months

Tuesday 19th June 2018
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essayer said:
This is emergency brake assist isn’t it? The car detects a rapid brake application, and assumes full braking is required.
Apparently people don’t realise how hard they can press the brake pedal in an emergency, so the car compensates.
My sixteen year old BMW Z3 has this panic girly brake feature. It means that if I brake firmly and quickly (but not a full-on emergency) to compensate for a sudden hazard it locks up, activates the ABS, and makes me look daft and risks a rear ender from anyone following.

nickfrog

20,871 posts

216 months

Tuesday 19th June 2018
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CoolHands said:
The nanny state in action. Or in this case bmw
So what has this got to do with the state if it's BMW ?

CoolHands

18,496 posts

194 months

Tuesday 19th June 2018
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It’s a state of mind, dear

anonymous-user

53 months

Tuesday 19th June 2018
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Pica-Pica said:
Driving on a dual carriageway, absolutely clear, a pelican crossing light goes amber. Nothing in front, and I knew nothing was behind, so clear all round. I could have legitimately gone through, but decided to stop (as I said, clear all round).

So a sharpish stop. Then I can hear the indicators clicking. I then realised that the sharp stop had triggered the hazards. I know this happens (and brake lights flash), I was just somewhat surprised that it occurred at what felt a sharp but not fierce stop. It could be that the car was actually stopping sharply, but felt very secure and safe doing so, and therefore seemed slower than the stop really was. I feel I want to practise a few quick stops to check it out at various levels of deceleration.

Anyone experienced this? This was a 335d.
What triggers the system is not just the rate of deccel, but the speed at which you stop braking! If that is bellow about 20mph, the system triggers at a lower deccel threshold, because you have become a 'stationary Hazard' in the road. You can do a full threshold brake (1g) and as long as you stay about roughly 20mph the brake lights wont' come on (so the systems doesn't generally trigger on track etc)

Pica-Pica

Original Poster:

13,621 posts

83 months

Tuesday 19th June 2018
quotequote all
Max_Torque said:
Pica-Pica said:
Driving on a dual carriageway, absolutely clear, a pelican crossing light goes amber. Nothing in front, and I knew nothing was behind, so clear all round. I could have legitimately gone through, but decided to stop (as I said, clear all round).

So a sharpish stop. Then I can hear the indicators clicking. I then realised that the sharp stop had triggered the hazards. I know this happens (and brake lights flash), I was just somewhat surprised that it occurred at what felt a sharp but not fierce stop. It could be that the car was actually stopping sharply, but felt very secure and safe doing so, and therefore seemed slower than the stop really was. I feel I want to practise a few quick stops to check it out at various levels of deceleration.

Anyone experienced this? This was a 335d.
What triggers the system is not just the rate of deccel, but the speed at which you stop braking! If that is bellow about 20mph, the system triggers at a lower deccel threshold, because you have become a 'stationary Hazard' in the road. You can do a full threshold brake (1g) and as long as you stay about roughly 20mph the brake lights wont' come on (so the systems doesn't generally trigger on track etc)
Hmmm. I shall have to experiment on a clear road. As I said it was not an uncomfortable stop, I stopped firmly because it was safe to do so. I don’t recall feeling a harsh stop at the end, as I eased off the pedal. I will experiment some more!

jonwm

2,504 posts

113 months

Wednesday 20th June 2018
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Happened to me yesterday in my 330e. ABS wasn’t activated as it wasn’t overly sharp but hazard warning lights were on, wife has a new 5008 Peugeot and that’s even worse.

I believe it is more the change in speed not just the sharpness of braking.

30mph to 0 smashing the pedal may not activate it but 65 to 0 heavily braking will put them on

motco

15,919 posts

245 months

Wednesday 20th June 2018
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I have tracked my Z3 and it certainly did not panic brake from 100mph, or thereabouts, into a bend. Hit the pedal in a country lane as a tractor appears and it does.

Lazadude

1,732 posts

160 months

Wednesday 20th June 2018
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From what I remember, its to do with the amount of brake force applied (something along the lines of 60+%) within something like a second of coming off the throttle.

There is also EBA, which is annoying if it triggers. Such as approaching some traffic lights at the end of a NSL which start to turn so hit the brakes knowing I'll stop at the line. EBA activates and makes the car stop 100m short of where you meant to stop...

Byker28i

58,826 posts

216 months

Wednesday 20th June 2018
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It was your BMW running a systems check to see if the indicators were working as they hadn't been used for a while. It ensured noone was around before it performed this test so as not to embarrass you.

biggrin

Pica-Pica

Original Poster:

13,621 posts

83 months

Wednesday 20th June 2018
quotequote all
Byker28i said:
It was your BMW running a systems check to see if the indicators were working as they hadn't been used for a while. It ensured noone was around before it performed this test so as not to embarrass you.

biggrin
I assure you, I make all necessary signals (and no unnecessary ones), unlike many police cars whose drivers seem to have forgotten to think about the need for informing other road users of their intentions. Sorry to spoil your ‘joke’.