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Has anyone noticed the new indicator and brake lights fitted to Range Rovers and London buses. They are so instantaneous and suddenly bright that you don't notice them. The more normal bulbs with a filament are much easier to see. Another triumph of form over substance?
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>>They are so instantaneous and suddenly bright that you don't notice them.
Eh???? If they are so bright that you don't notice them (!), perhaps you need an eye test?! ;-)
They are LEDs and, IMHO they are much easier to see than conventional bulbs. Plus the fact that they last much longer than filaments.
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I have to agree with Rob on this. My Merc has LED brake lights and people comment on how bright, fast and easy to see they are.
If they are quicker then they will give you that little bit more time to brake earlier and if they are brighter how on earth can you not notice them.
Maybe I'm going mad!
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I, too can't follow this "suddenly bright that you don't notice them" comment. LED brake lights have been used as original and aftermarket centre brake lights for ages, and are accepted as being easier to see and longer lasting than filament lamps. I and thousands of others have LED rear lights on the push-bike in the hope that I'm more visible.
Care to expand Richard?
H.
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I believe there was a study in Italy (Rome or Turin?) where they have a very high number of rear end shunts. They fitted cars with LED style brake lights, but also a gizmo that put the lights on when it *thought* a driver was about to brake suddenly (by measuring the rate of lift off the throttle IIRC). This brought the brake lights on, on average, 0.5s earlier (again IIRC). The result was a marked drop in rear end shunts on the equipped vehicles.
Richard
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"They are so instantaneous and suddenly bright that you don't notice them."
I, also, do not understand.
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Can't comment on the London bus, but what I've noticed on the new Range Rover, is that the indicator lights are concentric with the brake lights.
So if the vehicle is signalling or braking then there is no problem, but braking and signalling then the turn signal is not so visible being a single circle of amber leds around a round matrix of red leds.
Hope that explains.
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My previous Vectra GSi Estate and current V70 2.4T both had/have conventional brake lights supplemented by LED repeaters at the top of the rear window. In both cases, when reversed against a building window, looking in the rear view mirror, and applying the foot brake, the LEDs become visible a small but noticeable length of time before the bulbs, so I can indeed see how they help safety on this aspect alone, as well as from other benefits like service life.
On the subject of brightness, having sat in a queue of traffic behind many cars with a similar setup to what I have just described, whilst the driver blinds me with his brake lights, I wonder how long before one of the manufacturers with a bent for gizmos introduces a sensor that measures ambient light and proximity of an object (ie another vehicle) behind, and adjusts brightness accordingly?
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SjB
The adjustable light level for differing ambients is allowed for in the lighting regs and I think the New XJ has it.
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I believe there was a study in Italy (Rome or Turin?) where they have a very high number of rear end shunts. They fitted cars with LED style brake lights, but also a gizmo that put the lights on when it *thought* a driver was about to brake suddenly (by measuring the rate of lift off the throttle IIRC). This brought the brake lights on, on average, 0.5s earlier (again IIRC). The result was a marked drop in rear end shunts on the equipped vehicles. Richard
The only problem with this is the new Mercedes system which does just that.
Unfortunately you see a new Merc going down the road with the brake light constantly flashing as they are pushing the accelerator and lifting off to maintain their speed rather than setting their pedal position and keeping it there.
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I believe the high incidence or rear end shunts in Italy has its cause partly in the preoccupation of male drivers with rear ends other than those of the vehicle in front :-)
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LED brake lights should be standard as this is a cheap safety measure. Travelling at 70 mph the decreased time in lighting the brakes is the equivalent of something like 30ft.
Also reminds me of a study that was done in Israel a few years back where they attached a sensor to the brake peddle. If you took your foot of the accelerator quickly and moved it over to the brake peddle (as in an emergency stop) the sensor would work this out and illuminate your brake lights those few milliseconds before your foot could.
Post amended. It\'s brake lights, not break lights. DD.
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Why don\'t you lot of grumblers just go back to your whiny comments about Toad and leave us to tidy spellings, grammar, format up as we feel appropriate.
And Dave corrected it, and then commented, as a form of courtesy. Look it up.
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Mark, are you expecting too much in the way of literacy on a motoring forum?
And I deny ever making comments about Toad, whiny, whiney or otherwise.
So there!
H.
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I have observed before that brake lights only operate once the manoeuvre has already commenced, unlike other signals which indicate merely an intention to do something. Therefore it seems to me that anything that reduces the time before the lights show can only be a good thing.
If there are clever devices which can actually anticipate a driver's intention to brake then they a good idea, if they work reliably.
But why not have the switch arranged so that it is possible to signal "I am going to brake soon", rather than waiting until the brakes are actually applied?
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I believe there are such devices available from (insert well known motor factor here) near the shelf with the crystal balls!
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How about brake lights that gradually come on, depending on the pressure on the pedal?
Actually thinking about it that would be a ****(censored by me) idea; you'd hardly see the brake light in strong sunlight when braking gently. :-(
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How about brake lights that gradually come on, depending on the pressure on the pedal?
I have thought about this break/brake light idea before and think that it is a good idea. I think that it would work if you used the high level brake light as the "pressure snesitive" one
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Much of the technology to do this exists in modern cars.
www.honestjohn.co.uk/forum/post/index.htm?f=4&t=13...4
describes the multiplex and PWM technology for variable brightness rear lights. The rate of decrease in speed must be measured in some of the optional handling (anti skid etc) electronics. Throttle is often fly by wire so ECU has all the info. Just a matter of some clever additional programming. Marginal cost zero, just some developement budget.
Opportunity for another highly priced, zero manufacturer cost optional extra.
However if there is too much processing going on, (or the programmer gets it wrong?) the delay in illuminating the rear brake lights may increase.
I am intrigued about the human eyes ability to percieve the delay time in a filament heating up vs LED display. I feel a lttle experiment coming on....
pmh (was peter)
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I have seen some of the new London buses with them. I think the problem is that they aren't a particularly bright orange on an orange background. With the sun shining on one the other day, it was difficult to see it flashing.
I'm certainly not against LEDs as most red ones are very bright and noticeable. It's just that the yellow-orange bus ones don't always stand out.
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I am very impressed with the LED set of tailights/indicators I bought in the US for my Harley. The set-up is very bright and attention-commanding given all the other competing lights at night (bill-boards, other vehicles, etc). Further, when the brake is applies the stop light flashes 1-2-3 then stays on, which is hopefully a bit more attention-getting. Anything which might avert a rear-ender on a motorcycle on a fast freeway has to be worthwhile. Of course all this only works when not everyone has LED's. When they do we're all back to square one.
But I do wonder why the flashing slow-down warning on stoplights is not adopted more widely.
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Of course all this only works when not everyone has LED's. When they do we're all back to square one.
But I do wonder why the flashing slow-down warning on stoplights is not adopted more widely.
Actually, there is another advantage to LEDs as well as being more noticeable. One of the reasons LEDs are being used is because they light up quicker than normal bulbs. I forget the exact amounts, but say it's 0.2s for filaments and 0.1s for LEDs. At 70mph that's an extra 10 feet or so.
I guess this reaction time could also be the reason why normal bulbs don't flash.
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On the face of it LEDs are virtually instantaneous.
< 200 nSec according to
www.augusttech.com/products/LEDlights/led.pdf
unless I've misread it.
Anyway the important figure is the difference between LED and bulb.
If I get the chance in the next day or two I'll try and run incandescent and LED in parallel, and record the result on something which can jog through frame by frame.
It should be possible to see how many 25ths of a second behind the LED the bulb is in getting to, say 80% of it's maximum brightness.
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Now here's an idea. How about semaphore arms that fly out of the side of the car? Just between the doors would be about right......
Wot? been done before? Aw shucks!
:-)
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Now here's an idea. How about semaphore arms that fly out of the side of the car? Just between the doors would be about right...... Wot? been done before? Aw shucks! :-)
Better than that. A semaphore arm that pops out the side only after you operate the switch on the steering wheel AND bang the side pillar of the car with your fist
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...and which it is the job of your rear passengers to wind down their window and manually push the arm back into its slot when the turn has been completed. Used to keep us kids occupied on a run.
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Electric semaphore arms were a backward step in terms of reliability. The originals were large wooden flaps connected by rods to a big 'switch' in the middle of the dashboard. Heaving the switch left or right raised the relevant flap.
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Managed to compare a generic red LED and incandescent bulb fed in parallel - it's a fairly crude measurement, as I don't run to a high speed camera, but in terms of 25th of a second the bulb is 2/25ths behind to [u]virtually[/u] full brightness.
But, it was significantly illuminated by the first 25th after the LED - perhaps 20-30%.
So at 60 mph you cover 88 feet in a second.
88 x 0.08 = 7.04 feet.
Worth having.
However there's probably the issue of visual perception to consider on something which is instantly there, which might be what the OP was hinting at.
Whole can of worms...
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