Re: EU to force daytime use of headlights?



"Al C-F" <[email protected]> wrote in
message news:[email protected]...
> David Lloyd wrote:
>
> >
> > Before anyone thinks 'Oh no, here's a cycling nut/car hater trying to
start
> > a flame war', I'll tell you that I am a Design Engineer in the
automotive
> > industry and that I designed the bonnet and trunk hinges and the fuel
filler
> > flap an the Jaguar XK8, the bonnet and trunk hinges on the Aston Martin
DB7,
> > the fuel flap, bonnet and all tailgate hinges on the Range Rover P38A. I
was
> > the launch Engineer for the front seat slides in the original Ford Focus
and
> > I redesigned the Freelander rear seats to take isofix child seat
anchorages
> > for the North American market.
>
> But your qualifications / experience in lighting and perception?
>
> Just asking.

It should be lightly covered in all our pre-'O'-level / GCSE education, it
was in mine, together with the functioning of the ear, in terms of what can
be perceived. When you study design in higher education, it is not much use
designing warning systems that are not effective, so audio/visual perception
is covered quite substantially as part of ergonomics.

If we don't know that flashing rear lights are better, why do we as cyclist
buy flashing rear lights? Surely this is already known and accepted?

--
David Lloyd,
The pub is responsible for my opinions.
 
David Lloyd wrote:

> If we don't know that flashing rear lights are better, why do we as cyclist
> buy flashing rear lights? Surely this is already known and accepted?

Because we know that our eyes spot flashing lights more easily than
steady lights. But that doesn't make them *better*.

And because we see "flashing" advertised as a feature on the lights,
and assume that it's better.

--
Stevie D
\\\\\ ///// Bringing dating agencies to the
\\\\\\\__X__/////// common hedgehog since 2001 - "HedgeHugs"
___\\\\\\\'/ \'///////_____________________________________________
 
"Stevie D" <[email protected]> wrote in message
news:[email protected]...
> David Lloyd wrote:
>
> > If we don't know that flashing rear lights are better, why do we as
cyclist
> > buy flashing rear lights? Surely this is already known and accepted?
>
> Because we know that our eyes spot flashing lights more easily than
> steady lights. But that doesn't make them *better*.
>
> And because we see "flashing" advertised as a feature on the lights,
> and assume that it's better.
>
I don't assume anything. All else being equal, it has already been prooved
to my satisfaction that a rear flasher is better than a static light. To be
clear, my opinion is:-

Rear in the dark - flasher
Rear in dull conditions - flasher
Front - static only, flashers are not legal but there may be a case for
their use in dull conditions but not in the dark.

--
David Lloyd,
The pub is responsible for my opinions.
 
David Lloyd wrote on 15/10/2006 10:48 +0100:
>
> If we don't know that flashing rear lights are better, why do we as cyclist
> buy flashing rear lights? Surely this is already known and accepted?
>

Unfortunately there is not a lot of visual perception thought that goes
into either the design or purchasing decision. The lights should be
designed to flash at the optimum rate for triggering the "look at me"
response in the peripheral retina using scotopic (i.e. night) vision.
Most are designed and all are purchased looking at the brightness and
noticeability in daylight using the central retina and photopic
(daytime) vision. Scotopic and photopic vision and peripheral and
central retina are quite quite different in their visual perception.

An interesting aside is that the wavelength of a typical red LED has
very low visual sensitivity in scotopic vision - about 90 times less
sensitivity than in photopic vision. A green or yellow LED would be
much more suitable for getting attention and being visible.

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci
 
David Lloyd wrote on 15/10/2006 11:30 +0100:

> Front - static only, flashers are not legal but there may be a case for
> their use in dull conditions but not in the dark.
>

Is the wrong answer. Flashers are legal on the front provided they
exceed 4 candela and do not have a CW mode.

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci
 
"Tony Raven" <[email protected]> wrote in message
news:[email protected]...
> David Lloyd wrote on 15/10/2006 10:48 +0100:
> >
> > If we don't know that flashing rear lights are better, why do we as
cyclist
> > buy flashing rear lights? Surely this is already known and accepted?
> >
>
> Unfortunately there is not a lot of visual perception thought that goes
> into either the design or purchasing decision. The lights should be
> designed to flash at the optimum rate for triggering the "look at me"
> response in the peripheral retina using scotopic (i.e. night) vision.
> Most are designed and all are purchased looking at the brightness and
> noticeability in daylight using the central retina and photopic
> (daytime) vision. Scotopic and photopic vision and peripheral and
> central retina are quite quite different in their visual perception.
>
> An interesting aside is that the wavelength of a typical red LED has
> very low visual sensitivity in scotopic vision - about 90 times less
> sensitivity than in photopic vision. A green or yellow LED would be
> much more suitable for getting attention and being visible.
>
I think we're stuck with red on the rear. No point confusing the poor adled
drivers, they should know what red means.

--
David Lloyd,
The pub is responsible for my opinions.
 
David Lloyd wrote on 15/10/2006 11:42 +0100:
>
>> An interesting aside is that the wavelength of a typical red LED has
>> very low visual sensitivity in scotopic vision - about 90 times less
>> sensitivity than in photopic vision. A green or yellow LED would be
>> much more suitable for getting attention and being visible.
>>
> I think we're stuck with red on the rear. No point confusing the poor adled
> drivers, they should know what red means.
>

If they can see it away from where they are looking. It is absolutely
the wrong colour for being noticed.

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci
 
"Tony Raven" <[email protected]> wrote in message
news:[email protected]...
> David Lloyd wrote on 15/10/2006 11:30 +0100:
>
> > Front - static only, flashers are not legal but there may be a case
for
> > their use in dull conditions but not in the dark.
> >
>
> Is the wrong answer. Flashers are legal on the front provided they
> exceed 4 candela and do not have a CW mode.
>
I stand corrected. I personally don't have a method of measuring the light
output of a lamp.The restriction of output from a front flasher is prudent.
I think I'll get myself one to complement my 10w rechargable. What is a CW
mode?

--
David Lloyd,
The pub is responsible for my opinions.
 
In article <[email protected]>, Tony Raven wrote:
>David Lloyd wrote on 15/10/2006 11:30 +0100:
>
>> Front - static only, flashers are not legal but there may be a case for
>> their use in dull conditions but not in the dark.
>
>Is the wrong answer. Flashers are legal on the front provided they
>exceed 4 candela and do not have a CW mode.

Looking at http://www.opsi.gov.uk/si/si2005/20052559.htm flashers seem to
be legal if either they do not have a constant mode or they have a BS approval.
(The exemption to the no flashing lights rule says
"a front position lamp capable of emitting a flashing light (whether or not
it is also capable of emitting a steady light)", but the exemption to
the marking requirement says "unless the lamp is also capable of emitting
a steady light.")

I'm fairly sure I've seen the HL-EL500 advertised as now having BS approval,
but I'm not sure whether it has a flashing mode.
 
David Lloyd wrote on 15/10/2006 12:39 +0100:
>
> What is a CW
> mode?
>

Continuous. From Continuous Wave in radio and electromagnetics.

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci
 
Response to Tony Raven:
> > What is a CW
> > mode?
> >
>
> Continuous. From Continuous Wave in radio and electromagnetics.

Thank God for that - I was afraid it meant Country & Western.


--
Mark, UK
"Don't Give Me A Plastic Saddle 'Cuz I Want To Feel That Leather When I
Ride."
 
"Mark McNeill" <[email protected]> wrote in message
news:[email protected]...
> Response to Tony Raven:
> > > What is a CW
> > > mode?
> > >
> >
> > Continuous. From Continuous Wave in radio and electromagnetics.
>
> Thank God for that - I was afraid it meant Country & Western.
>
>
Think of the road safety implications when you grab your partners and
dozey-doe :)
 
Ian wrote:
>
> Any light on a cycle at night would be a step forward from the current
> typical situation of no lights at all.

I saw a classic example last night, not only unlit but wearing a
camouflage coat
 
POHB wrote:
> Ian wrote:
>>
>> Any light on a cycle at night would be a step forward from the
>> current typical situation of no lights at all.
>
> I saw a classic example last night, not only unlit but wearing a
> camouflage coat

SMIDSY and Darwin in Action at once, Result!
 
POHB wrote:
>
> I saw a classic example last night, not only unlit but wearing a
> camouflage coat

Not a very good camouflage coat then.

--
Don Whybrow

Sequi Bonum Non Time

"I've noticed that the press tends to be quite accurate, except when
they're writing on a subject I know something about." (Keith F. Lynch)
 
"POHB" <[email protected]> wrote
> Ian wrote:
>>
>> Any light on a cycle at night would be a step forward from the current
>> typical situation of no lights at all.
>
> I saw a classic example last night, not only unlit but wearing a
> camouflage coat

You *saw* that... so what's the problem?
 
On 17 Oct 2006 04:46:37 -0700 someone who may be "POHB"
<[email protected]> wrote this:-

>Ian wrote:
>>
>> Any light on a cycle at night would be a step forward from the current
>> typical situation of no lights at all.
>
>I saw a classic example last night, not only unlit but wearing a
>camouflage coat

The irony of the following sort of statement is usually lost on
those that make them. "These unlit cyclists are dangerous because
they can't be seen. I saw three of them last night."

I saw a cyclist without lights last night. I also saw far more with
lights.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54
 
In message <[email protected]>, David Hansen
<[email protected]> writes

>The irony of the following sort of statement is usually lost on
>those that make them. "These unlit cyclists are dangerous because
>they can't be seen. I saw three of them last night."

Unless they add "as they bounced off my bullbars".

The objection is usually that they were not visible early enough to plan
how best to deal with them for the benefit of both parties. If, as an
expert on cycling, you think that unnecessary, perhaps I am taking too
much care to pass cyclists safely and considerately?

--
Steve Walker
 
David Hansen wrote on 18/10/2006 08:44 +0100:
>
> The irony of the following sort of statement is usually lost on
> those that make them. "These unlit cyclists are dangerous because
> they can't be seen. I saw three of them last night."
>
> I saw a cyclist without lights last night. I also saw far more with
> lights.
>

You have it all wrong. Motorists _only_ see cyclists without lights.
For those with lights it's always SMIDSY. Which is why many cyclists
don't use lights ;-)


--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci
 
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