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PostPosted: Mon Mar 07, 2005 12:32 
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Not sure about these. I they are used on motorcycles as an aftermarket item. I find them very distracting!

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Stuttgart, March 2005; Future Mercedes-Benz will make a further contribution towards a reduction in rear-end collisions by means of flashing brake lights. The EU licensing authority has recently approved this technology, and it will now enter series production in the S-Class for the first time.
Research by Mercedes engineers has shown that driver reaction times are shortened by up to 0.2 seconds if a flashing red warning signal is given instead of the conventional brake light during emergency braking. At a speed of 80 km/h this reduces the stopping distance by approx. 4.40 metres, and at 100 km/h by no less than 5.50 metres or so. This means that flashing brake lights are an effective and easily implemented way to reduce rear-end collisions. The Mercedes-Benz S Class is now the first car to feature this innovative, adaptive brake light. It will shortly be followed by the CL-Class Coupés.
Specialists at Mercedes tested various warning light systems during their study. Brake lights which light up four times as quickly as the amber hazard warning flashers during emergency braking proved particularly effective in alerting following drivers to the danger of a rear-end collision. The Mercedes study also revealed that switching on the hazard warning system in a dangerous situation has no significant effect on the reaction times of other drivers.

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PostPosted: Mon Mar 07, 2005 12:47 
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Up to 0.2 seconds? Sounds like a very small amount; unless the sample size is enormous then it is probably of no significance at all.

On the other hand, even if the two-phase lights don't improve reaction times they at least give extra information about what the other car is doing, so I guess I'm tentatively in favour anyway.


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PostPosted: Mon Mar 07, 2005 13:41 
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Wait till you see one.

The problem is if you are in slow moving trafic you keep getting the brake lights blinking at you continuously as the other driver keeps tapping the brake pedal.

It is works like it does on bikes you get about 5 short pulses then it stays on.

It can only work with LED brake lights.

In poor visiblity It may also get confused with bikes that use those daft blinking tail lights.

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PostPosted: Mon Mar 07, 2005 14:11 
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The back of every car should have rearward facing spikes at eye level that are long enough to penetrate the driver driving behind-I think that may put the tailgating phenomenon to bed :D

Is it not time for some SERIOUS action on tailgating-maybe combined with not wearing seatbelt and inattention as well? how about this for an advert:

Man with wife in front, she's not got belt on, he's the usual matcho 3 feet from the car in front show off, meanwhile every 2 seconds he turns to her with an admiring glance or a cheesy line about his driving etc. then you see an outside scene of cars all making emergency stops up in front, he subsequently looks round and has no time to brake because of his short stopping distance and stoves the car in front, which has a kid in the back meanwhile his wife takes a trip through the front screen, she's pan bread and the kid in the front car is injured and he is left standing thinking 'it should have been me through that screen'...!





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PostPosted: Mon Mar 07, 2005 14:23 
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Gizmo wrote:
Wait till you see one.

The problem is if you are in slow moving trafic you keep getting the brake lights blinking at you continuously as the other driver keeps tapping the brake pedal.


Oh, the impression I got was that it is a normal solid light under normal braking but flashes under hard emergency braking. If it flashed all the time that would be very annoying.


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PostPosted: Mon Mar 07, 2005 14:50 
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Something to give an idea of rate of deceleration would be very useful. FWIW, I'd thought of an LED lightbar across the back of the vehicle with an accelerometer controlling the number of lights to illuminate. The harder the braking, the closer the left and right light clusters got to meeting in the middle.

However, there is a downside to something like this. When "reactive brake lights" become the norm, I suspect that "non-reactive" brake lights would be interpreted as gentle braking no matter how hard the braking actually was.

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PostPosted: Mon Mar 07, 2005 22:20 
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Brake Force Display is standard for the first time on 3 Series Saloon models, offering two stage brake lights. Brake lights illuminate normally in average driving conditions but during an emergency stop or when the ABS braking cuts in, the area of brake light illumination increases to warn those travelling behind of the situation ahead.

BMW have had this feature as an option for some time and will be standard on the new E90 3 series.

Any improvement in reaction times, no matter how small, has to be a good thing...

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PostPosted: Mon Mar 07, 2005 23:17 
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I saw something similar to this on the back of a foriegn registered truck, normally positioned brake lights, but a third light in the middle of the rear underrun bar that flashed when the brakes were used.
Thought it was a good idea at the time, and still do.

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PostPosted: Thu Mar 10, 2005 10:31 
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What happens when the car behind hasn't got brakes as good as a Merc.

Another clever idea.
Use the rear parking sensors to measure the distance of the car behind, then if the car was too close, flash a different rear red light saying "Too close" . To stop false alarms it could be disabled at slower speeds.

Could also have front sensors that warn when you are too close to the car in front.


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PostPosted: Thu Mar 10, 2005 12:56 
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Gordon68 wrote:
What happens when the car behind hasn't got brakes as good as a Merc.

Another clever idea.
Use the rear parking sensors to measure the distance of the car behind, then if the car was too close, flash a different rear red light saying "Too close" . To stop false alarms it could be disabled at slower speeds.

Could also have front sensors that warn when you are too close to the car in front.

Hello Gordon.

Yes, a clever idea, and when used as a lead car for learners, novices and occasional drivers, it could help them decide what is a reasonable distance at a given speed. However, I foresee a few problems with it (that may not readily be apparent).

  • People will come to rely on it to an extent - or "play" with it (hover on the brink).
  • Unless the software takes into account road surface (possible in a few years perhaps), it will actually give a false sense of security on greasy roads.
  • It may be a distract as one closes to the "safe overtaking" position in less powerful cars. As and when one gets used to it, it is possible a genuine braking or brake-pedal-covering may be "parked" as one of these "too close" indicators.
    ands for me the showstopper, it will actually dumb down drivers still further. This is a bit like the needle-watching dumbing down effect that cameras are having now. Cameras encourage drivers to target numerical speeds; this "too close" sign will effectively enocourage drivers to concentrate on the mechanistic distance rather than instinctively establishing by feel what safe distances are for given situations.

I'd welcome others' views on this too.


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PostPosted: Thu Mar 10, 2005 13:59 
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Zamzara wrote:
Up to 0.2 seconds? Sounds like a very small amount.


Well, at 60mph 0.2s = 17 feet, or thereabouts.

Would you rather have the front of your vehicle (or the one behind you), 17 feet further forward or backwards after an e-stop? ;)


The US equiv. to this, the Cyberlite, has been around in the US for decades, I understood they were illegal over here.

July 1982 advertisement in Cycle magazine:

"More than a Brake Light. Cyberlite. The Ultimate Brake Light"

"This modulated light works in parallel with your standard brake light. The harder you brake (1) the faster Cyberlite pulses, (2) the shorter the on-time of each light pulse, and (3) the more brilliant each light pulse becomes."

"Effectiveness verified by 19.5 million miles of testing.
In a controlled, eleven-month, 19.5 million split-sample test on 500 Yellow Cabs in San Francisco... found that the rear-end collision rate was reduced by 60% for Cyberlite-equipped cabs..."

List $125, advertised for motorcycles.

Mind you, can't find them now . . . :(

However, there are:
http://www.sampson-sporttouring.com/hyp ... ersal.html
http://www.sampson-sporttouring.com/hyper-lite.html



I use a more 'DIY' approach, and - apart from e-stops when I'll be more concerned with what's in front - I try to release and re-apply the brakes after 3-4 seconds, and will do so when stopped if there's traffic approaching.


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PostPosted: Thu Mar 10, 2005 14:12 
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Never discount the simple ideas...

BMW now fit rear lights to many of their cars that comprise a cluster of LEDs rather than a traditional bulb. Quite apart from the obvious benefit of eradicating blown bulbs, these deliver the simple benefit that they light up about a quarter of a second quicker when you put power to them.

Thus any car behind you that is reacting based on seeing your brake lights now gains an extra bit of braking time, and with no trade-off that I can think of.

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PostPosted: Thu Mar 10, 2005 15:27 
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Gordon68 wrote:
What happens when the car behind hasn't got brakes as good as a Merc.


The Mercedes system merely alters the way their brake lights operate when a heavy brake application is made, it doesn't alter the effectiveness of the brakes in any way.


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PostPosted: Thu Mar 10, 2005 15:42 
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Twister wrote:
Gordon68 wrote:
What happens when the car behind hasn't got brakes as good as a Merc.


The Mercedes system merely alters the way their brake lights operate when a heavy brake application is made, it doesn't alter the effectiveness of the brakes in any way.


Gordon may be referring to the Mercedes "Brake Assist System" that increases braking effort automatically at a given threshold of driver initiated braking effort?


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PostPosted: Thu Mar 10, 2005 20:33 
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Quote:
Thus any car behind you that is reacting based on seeing your brake lights now gains an extra bit of braking time, and with no trade-off that I can think of.

I believe the 0.2 seconds is significant and potentially very worthwhile. however, one trade off - the "attack" phase is now sub-microsecond as opposed to tens of miliseconds. this might, just might, have some effect on epileptics.


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PostPosted: Fri Mar 11, 2005 11:25 
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I think innovation is very important. 0.2 seconds probably will be significant within a proportion of potential accidents. But is Mercedes developing any technology to alert drivers of their cars when they are too close to the car in front? On the outside lane of a motorway for example when a Merc driver experiences the displeasure of having to wait 2 minutes in a queue of busy traffic on their motorway. :wink:


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PostPosted: Fri Mar 11, 2005 12:44 
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Sam Dentten wrote:
On the outside lane of a motorway for example when a Merc driver experiences the displeasure of having to wait 2 minutes in a queue of busy traffic on their motorway.


Yeah!

I was heading along the M4 last year, this matey in a silver Merc. zooming along lane 3, flashing his lights at all and sundry to get out of his way. Eventually he got stuck behind someone 'dawdling' at 80, for half a mile or more before the 'blocker' moved over to lane 2 and Merc man could carry on.

What amazed me, tho', was how you could only hear the Merc's wailer as it went past - although the blues & flashing headlamps had been visible for some distance. :wink:


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PostPosted: Fri Mar 11, 2005 16:31 
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What I meant by 0.2 seconds not being significant is that it might not be statistically significant, unless the sample size is very large and the study otherwise flawless. If it's a real improvement, it is certainly useful.


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PostPosted: Fri Mar 11, 2005 17:12 
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Zamzara wrote:
What I meant by 0.2 seconds not being significant is that it might not be statistically significant, unless the sample size is very large and the study otherwise flawless. If it's a real improvement, it is certainly useful.


Fair point. The fact that this is basically marketing casts some doubt over its scientific validity too.


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PostPosted: Fri Mar 11, 2005 20:44 
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Zamzara wrote:
What I meant by 0.2 seconds not being significant is that it might not be statistically significant, unless the sample size is very large and the study otherwise flawless. If it's a real improvement, it is certainly useful.


It ought to be a real improvement, given that the 0.2s is delivered via the quicker turn-on time of LED brake lights compared to existing filament brake lights, and should be independent of how long it takes individual drivers to react to a brake light appearing in their field of vision. In effect, it's as if the driver in front of you has hit their brake pedal 0.2s earlier than they actually did, thus bringing your own reaction forwards by that same 0.2s.


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