Near miss on busy road - plea for good lights!!

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drossall
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Re: Near miss on busy road - plea for good lights!!

Postby drossall » 11 Dec 2017, 11:56pm

Lesaid wrote:Bike lights are not going to contribute to the 'arms race' I think, because the upper end of car headlamps will surely always outshine the majority of even the brighter cycle lamps!

Someone more expert will be along in a while. However, "brightness" is a rather imprecise quantity. Some bike lights are heading towards very narrow beams, which can be quite "bright". Car lights by contrast tend to be much larger of course, so would need far more light emission to be equally "bright". This makes it possible for bike lights to have nuisance value.

That's deliberately imprecise; try here for the various measures.

Also, some bike lights are really designed for night-time mountain biking, and so project light high to help you avoid branches and the like. Such lights are not suited to road use, as they are anything but dipped.

Lesaid
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Re: Near miss on busy road - plea for good lights!!

Postby Lesaid » 12 Dec 2017, 12:07am

gaz wrote:Unless you have some quite sophisticated measuring equipment you'll gather some anecdote, not evidence.


well - I'm not equipped for lab-style optical measurements, but I can for example, vary the power provided to a light pretty accurately, and I can probably set up to calibrate the output of a light on trial against known references, and to look at the geometry of the beam produced.

On the detection end - what matters is whether a human can perceive it. That bit doesn't need electronics or lab equipment - just two or three people to look and record what they see.

Perhaps could also check how visible the light is to peripheral vision as well.

To do all that will some time to prepare for and set up - but it would be interesting to try. This won't happen tomorrow! Happy to take suggestions and ideas.

Though a very informal first trial with some off-the-shelf lights (I've got a selection) would give a first idea of whether it is worth going deeper into this or whether the results are obvious.

I won't get results sufficient for an academic paper!! But I should be able to get enough to give some idea of what it takes to be visible in the kind of situation we've been discussing. And perhaps settle some of the arguments, one way or the other.

Lesaid
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Re: Near miss on busy road - plea for good lights!!

Postby Lesaid » 12 Dec 2017, 12:21am

drossall wrote:Someone more expert will be along in a while. However, "brightness" is a rather imprecise quantity. Some bike lights are heading towards very narrow beams, which can be quite "bright". Car lights by contrast tend to be much larger of course, so would need far more light emission to be equally "bright". This makes it possible for bike lights to have nuisance value.


Think our posts crossed!

For a first pass, I would be inclined simply to check out each of the lights that I have in my bike box - which vary from a claimed 1200 lumen down to an old, 4.5 battery powered filament lamp from 20+ years ago. I also have no idea what the legal minimum requirement equates to in practical terms, so I would want to find that out as well.

If all of these are clearly visible, then there is little point in going further, though I doubt if that will be the case.

I'll also do a bit of hunting in case someone has already done something like this already.

I should thank "mjr" for, maybe unintentionally, pushing me into looking at this more carefully and getting something more solid than speculation to settle the arguments :)

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Paulatic
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Re: Near miss on busy road - plea for good lights!!

Postby Paulatic » 12 Dec 2017, 9:04am

Lesaid wrote:
For a first pass, I would be inclined simply to check out each of the lights that I have in my bike box - which vary from a claimed 1200 lumen down to an old, 4.5 battery powered filament lamp from 20+ years ago. [color=#FFFF40]I also have no idea what the legal minimum requirement equates to in practical terms[/color], so I would want to find that out as well.

If all of these are clearly visible, then there is little point in going further, though I doubt if that will be the case.

I'll also do a bit of hunting in case someone has already done something like this already.

I should thank "mjr" for, maybe unintentionally, pushing me into looking at this more carefully and getting something more solid than speculation to settle the arguments :)


I think this is a lot of the reason we see people riding with poor lights. Users of this forum take an interest in their bike and it’s equipment. Personally if it’s good enough for Germany then I’ll use it. Your average Joe walks into a shop and buys a package saying cycle lights. Takes them home, fits to his bike and thinks everything is fine and dandy.
I regularly see a guy Cycling Home from his work at a sawmill. By this time of year his batteries have become so weak his hi-viz work jacket outshines his lights. Even when he’s on an adjacent cycle track I always see him mind you. That I believe is because I’m always looking out for cyclists in case I ken them :D
UK standards, or lack of, on cycle lights are further evidence of the UKs race to the bottom. 1 in 5 school buses found not fit for use revealed yesterday. Woman run over by 4vehicles and no one stops. Where will it all end? I doubt stopping the sales of rubbish lights is top of any governments agenda.
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pwa
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Re: Near miss on busy road - plea for good lights!!

Postby pwa » 12 Dec 2017, 9:24am

For being seen and noticed lights need to be bright enough. Not too bright, just bright enough. And with a wide enough beam to be noticed from angles other than simply straight ahead.

Lights also need to be reliable. They need to stay on when you go over a bump in the road, or when they get rained on. There are still a lot of lights on sale in places like Halfords that fail on that.

The beam requirements for lighting up the road are not quite the same as the beam requirements for being seen, so I go for two front lights. One is chosen because it throws out a widespread bright enough but not-too-bright beam for being seen. And the other will be a brighter beam angled so as to light up the road without dazzling other road users. If either fails, the other will get me home.

Lesaid
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Re: Near miss on busy road - plea for good lights!!

Postby Lesaid » 12 Dec 2017, 9:47am

pwa wrote:For being seen and noticed lights need to be bright enough. Not too bright, just bright enough. And with a wide enough beam to be noticed from angles other than simply straight ahead.


Sure - but, can anyone, even in a specialist forum like this one, give advice on just how bright 'enough' is, based on some kind of evidence rather than guesswork? To be honest - I have no idea how visible I actually am on the road to others - I believe I am as visible as I can reasonably be for the kind of cycling I do, but is that good enough?

I go for a light which can go really bright, and can be run at a reduced brightness when I think that is appropriate. Perhaps even that is too much - but I don't know, and I don't know of anyone that can tell me definitively. Not that I've thought until now of searching for that information (i.e. what range of brightness is thought safe - what is too dim and what is too bright - for different kinds of situations).

So - a key question - what real evidence is there that would tell us how bright really does pose a genuine safety hazard on the roads through dazzling other road users (if properly adjusted)? If we had that, then a sensible strategy might be to formulate some rules of thumb aimed at using lighting a somewhat below that level but not too much below since we don't know how dim is sufficiently visible either!

pwa
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Re: Near miss on busy road - plea for good lights!!

Postby pwa » 12 Dec 2017, 10:02am

Lesaid wrote:
pwa wrote:For being seen and noticed lights need to be bright enough. Not too bright, just bright enough. And with a wide enough beam to be noticed from angles other than simply straight ahead.


Sure - but, can anyone, even in a specialist forum like this one, give advice on just how bright 'enough' is, based on some kind of evidence rather than guesswork? To be honest - I have no idea how visible I actually am on the road to others - I believe I am as visible as I can reasonably be for the kind of cycling I do, but is that good enough?

I go for a light which can go really bright, and can be run at a reduced brightness when I think that is appropriate. Perhaps even that is too much - but I don't know, and I don't know of anyone that can tell me definitively. Not that I've thought until now of searching for that information (i.e. what range of brightness is thought safe - what is too dim and what is too bright - for different kinds of situations).

So - a key question - what real evidence is there that would tell us how bright really does pose a genuine safety hazard on the roads through dazzling other road users (if properly adjusted)? If we had that, then a sensible strategy might be to formulate some rules of thumb aimed at using lighting a somewhat below that level but not too much below since we don't know how dim is sufficiently visible either!


The best I've come up with is to do my own tests in the street outside my home with any lights I install. I lean the bike against something, with the lights on, then walk away from it and view it from a distance and from different angles. I'm looking to have it really visible but not dazzling. It's not scientific but it is the best I've got.

Lesaid
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Re: Near miss on busy road - plea for good lights!!

Postby Lesaid » 12 Dec 2017, 10:27am

pwa wrote:The best I've come up with is to do my own tests in the street outside my home with any lights I install. I lean the bike against something, with the lights on, then walk away from it and view it from a distance and from different angles. I'm looking to have it really visible but not dazzling. It's not scientific but it is the best I've got.


similar to me - only difference is I do mine with the bike in front of my car with the headlights on - I want to be able to see the bike clearly against the headlights. I find that my (bright) light is adequate for that, and much less dazzling than the dipped headlights, so long as it isn't pointed up directly at the oncoming drivers' line of sight! Angle it slightly downward (as it has to be for cycling on unlit roads/tracks) and it doesn't dazzle at all (alongside headlights) but is still clearly visible. At 20-30 yards anyway. I've never experimented to see how 'dim' a light will still be clearly visible though.

But as you say, not very scientific!

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[XAP]Bob
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Re: Near miss on busy road - plea for good lights!!

Postby [XAP]Bob » 12 Dec 2017, 10:41am

Lesaid wrote:Sure - but, can anyone, even in a specialist forum like this one, give advice on just how bright 'enough' is, based on some kind of evidence rather than guesswork?!


Since there are vehicles on the road where the requirement is 'a white light to be visible from a reasonable distance' there is clearly no numerical option here.

You could see a candle from a few miles away (which I would consider to be at least a reasonable distance) but you couldn't possibly see it amongst the ridiculous shouty 'look at me' powered by hundreds of watts of 'waste' energy from infernal combustion engines.

I run a single German dynamo light up front, a pair of German dynamo rear lights and a little battery powered blinky on occasion.
I have two German standard rear reflectors as well as a couple of strips of red retroreflective tape up my mudguards.

AFAICT the only people who claim they can't see me are those who are stationary, and therefore assume that nothing else can move.
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

Lesaid
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Re: Near miss on busy road - plea for good lights!!

Postby Lesaid » 12 Dec 2017, 11:19am

[XAP]Bob wrote:You could see a candle from a few miles away (which I would consider to be at least a reasonable distance) but you couldn't possibly see it amongst the ridiculous shouty 'look at me' powered by hundreds of watts of 'waste' energy from infernal combustion engines.


Perhaps that problem will be of limited lifetime. The Scottish government have announced their intention to ban all-petrol/diesel cars from some city centres by 2032 (I think) - and I'm sure that will only be a stepping stone to requiring all vehicles to be electric (will be fun for the National Grid!). Once that happens, energy spent on lighting will detract from available range. Then there may be an incentive in the motor industry not to provide lights that are brighter than necessary!

But until then, no point in moaning about it - we are where we are and I can't see any amount of lobbying/complaining to anybody causing regulation change that will have any effect in the coming decade, if ever. So - we need to do whatever we need to do to be seen and not rely on car headlights changing for our benefit! Lobbying for strategic cycle routes away from major roads might sometimes get further in specific places - get the bikes and headlights separated from each other?

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[XAP]Bob
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Re: Near miss on busy road - plea for good lights!!

Postby [XAP]Bob » 12 Dec 2017, 4:13pm

Yep - but I am not campaigning for stuff that will be watered down to the point of being useless...

And the people here aren't exactly likely to be those with sub par lighting...
You're preaching to the choir, and being told why the message isn't the right one, we have had the discussions a few times...
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

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gaz
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Re: Near miss on busy road - plea for good lights!!

Postby gaz » 12 Dec 2017, 9:22pm

Lesaid wrote:Sure - but, can anyone, even in a specialist forum like this one, give advice on just how bright 'enough' is, based on some kind of evidence rather than guesswork?

The legal minimum required to be roadworthy under RVLR perhaps? (I feel like a stuck record :wink: ). In setting the standard the governement is telling other road users it's bright enough for a cyclist to be seen by. It is undeniably an evidenced definition and I don't doubt that it was arrived at through research.

I fully respect the right of any cyclist to choose something better than that minimum, I'd even recommend it subject to the maximum. It is refreshing when another road user accepts it is their responsibility to see a cyclist equipped with just the minimum, recent (short) thread here.

Lesaid wrote:So - a key question - what real evidence is there that would tell us how bright really does pose a genuine safety hazard on the roads through dazzling other road users (if properly adjusted)? If we had that, then a sensible strategy might be to formulate some rules of thumb aimed at using lighting a somewhat below that level but not too much below since we don't know how dim is sufficiently visible either!

Have a read here, you'll get a few pointers: https://www.cyclinguk.org/blog/chris-ju ... y-dazzlers
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MikeF
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Re: Near miss on busy road - plea for good lights!!

Postby MikeF » 12 Dec 2017, 10:18pm

The problem with flashing lights is they are off for a period of time. If they are off the instant a motorist looks the cyclist may not be seen. :wink:
Also brightness does not equate to visibility. As I've posted before a laser is extremely bright (literally blindingly so), but if used as a bicycle headlight would not be very "visible". Visibility depends on brightness, area of light source, and, for vehicles, height, as well as other factors.
"It takes a genius to spot the obvious" - my old physics master

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661-Pete
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Re: Near miss on busy road - plea for good lights!!

Postby 661-Pete » 13 Dec 2017, 1:55pm

gaz wrote:Problem two.

I've seen that famous video before - so it wasn't a 'problem' to me any more!

It's probably an unfair test, but it illustrates an important point. Where you have a scene in which "there's a lot going on", you need to train yourself to pick out the elements of the scene that matter. For the case of a road user, that means, spotting those features which might pose a threat to you, and spotting those features that you might pose a threat to. In practice, that includes anything that you might collide with. There's no need to 'notice' pedestrians walking safely on the pavement (unless you suspect they might step out into your path). There's no need to admire Xmas lighting on the houses you pass (a particularly pertinent point at this time of year). No need to stare at the moon as it emerges from behind clouds. No - you need to filter all these things out, and concentrate on what's on the road ahead of you.

Why did I say, the video is an 'unfair test'? Because the objective is to make you notice something that is totally unexpected, but in fact is totally irrelevant. {spoiler alert]. The man in the bear-suit is not participating in the game in any way. He doesn't pose a threat to anyone, nor is he threatened by anyone (now, if a real bear had walked onto the set, everyone would have noticed it, because bears are recognised as dangerous animals). This video may be of help in refreshing memories of witnesses at the scene of a crime - but I don't see how it helps in persuading motorists to notice cyclists. Motorists should be thinking "there may be a cyclist there" all the time - except when on motorways!
Pete

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Lesaid
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Re: Near miss on busy road - plea for good lights!!

Postby Lesaid » 13 Dec 2017, 3:01pm

gaz wrote:The legal minimum required to be roadworthy under RVLR perhaps? (I feel like a stuck record :wink: ). In setting the standard the governement is telling other road users it's bright enough for a cyclist to be seen by. It is undeniably an evidenced definition and I don't doubt that it was arrived at through research.


I'm sorry, but I don't accept that any such legal minimum standard for lighting or anything else is necessarily sufficient in all circumstances. I think it is foolhardy to trust your life to the principle "because I'm required to have 'that' lamp, that's what I'm going to have and it will be enough no matter what, because the government says it is!". (and based on your next comment, I suspect you might agree with me on that). I'm sure that research contributed towards the setting of the standard - possibly was the main consideration. But I highly doubt if the mandate was to produce a standard that would be fine in ALL circumstances, especially if lighting from other road users has become brighter since the standard was set. I also notice that the standard appears to have been set in 1989, and perhaps, what lights were practicable for cyclists given the technology of the day may have played a role in the decision making. If the standard were reviewed today, would the same levels be set?

gaz wrote:I fully respect the right of any cyclist to choose something better than that minimum, I'd even recommend it subject to the maximum. It is refreshing when another road user accepts it is their responsibility to see a cyclist equipped with just the minimum, recent (short) thread here.


It was an interesting thread. Morally, I agree with you about responsibility to see any road hazard. And I think any of us, if we ran down, say, a pedestrian dressed all in black, on an winding unlit road at night, in the face of oncoming dazzling headlights - we'd all feel guilty and morally responsible. This would be in spite of the fact that there would possibly have been nothing we could have done to avoid that accident, other than drive everywhere at 5 mph, or stay off the roads altogether after dark. So while such a motorist would probably feel responsible, I think it is quite wrong to blame them for such an accident. The pedestrian in that circumstance has to take some responsibility for being visible! Similar with an unlit or poorly lit cyclist wearing dark clothes and no hi vis. Where you draw the line between 'victim fault' and 'driver fault' however seems to me to be an almost impossible moral question!

Lesaid wrote:So - a key question - what real evidence is there that would tell us how bright really does pose a genuine safety hazard on the roads through dazzling other road users (if properly adjusted)? If we had that, then a sensible strategy might be to formulate some rules of thumb aimed at using lighting a somewhat below that level but not too much below since we don't know how dim is sufficiently visible either!

Have a read here, you'll get a few pointers: https://www.cyclinguk.org/blog/chris-ju ... y-dazzlers[/quote]

thanks - I read that closely.

You guys have gotten me interested in this topic now, thanks to all the contributions on this thread (thank you :) ). I'm having a go at analysing the performance of my own front light, to see how it compares with some of the numbers out there - both in lighting pattern, and brightness. Will take a little time though - doing those measurements without purpose-designed and calibrated equipment needs some careful preparation and analysis.

I will also (for my own interest) try to find a lamp of a similar power to the minimum standard, and see how visible it is against car headlights. If it proves clearly visible, I'll eat my words and re-think !! If it isn't, I'll try to find out what it does take to be visible, so far as I can without a specialist lab!