visibility of DRL

wrote:
On Thu, 4 Apr 2019 10:55:46 -0400, Frank Krygowski
wrote:

On 4/3/2019 9:58 PM, David Scheidt wrote:
David Scheidt wrote:
:From time to time, we have discussed the visibility of daytime running
:lights. I commute on a bike with B&M Cyo, which I leave on all the
:time, because I can't tell the difference if it's on or off. I found
:myself on google street view on my ride home last fall. I got passed
:by the car, and then passed it, and got passed again. So I, and the
:bike, are in a bunch of pictures, from the front and behind, over
:several blocks. This one gives a good view of the headlight. It's
:more visible than I'd have expected. This was about an hour before
:dark, and overcast November day.

:https://goo.gl/maps/NQURJ9dps3p

And one that will make Frank happy:
https://goo.gl/maps/S1QRDrdpBhz

I used your Street Views to track you along the street for quite a
while. Looks to me like in most photos, the light is visible only as a
white dot. (I suspect the photos where it looks brighter happened to
capture a moment when your handlebars twitched a big more toward the
Google car.) Overall, I doubt very much that it will make any more
difference than, say, if you painted a white circle on the middle of
your chest.

Which is not to say your light - or a white circle - has zero value in
daylight. There's data out there showing that motorcyclists who choose
white helmets get hit a bit less than motorcyclists who choose dark
helmets. However, that doesn't justify forcing all motorcyclists to wear
only white hats.

Some here will say that the problem is your Busch & Mueller headlight,
which is designed for lighting the road but not glaring in the eyes of
other road users. They have called for super-bright lights with
unsophisticated round beams, the kind that can irritate or even blind
others.


I've read you and others going on about lights that blind oncoming
riders but frankly I don't see how that happens if the light is aimed
to illuminate the road. I use a regular single cell (3.7 VDC)
flashlight with the normal "unsophisticated" round beam and if I aim
it to illuminate the road it does not shine in the eyes of oncoming
riders, in fact after reading your various posts about blinding lights
I tested my lights.

I tested this, in full darkness, by parking the bike and walking a
distance in front of the bike and then turning and walking back toward
the bike. If the flashlight is aimed to illuminate the road it doesn't
shine in my eyes.

At other times I have observed where the light shines on autos that I
overtake in traffic and the beam seems to hit a car at about the level
of the tail lights.

Thus it would appear that blinding bicycle lights are simply aimed to
shine in approaching traffic's eyes. I might point out also that a
normal bicyclist's eyes are at a height above the roof level of the
average modern automobile.

This is not to say that it can't happen rather that it appears to be
just one of the usual short comings of the bicyclist.

A couple weeks ago, my wife and I were on vacation in a city south of
here. On a riverside bike path at night, we were assaulted by one of
those glaring beams used by a rider coming the opposite direction. We
had to stop by the side of the bike path and shield our eyes until he
rode by. But I'm sure he felt very virtuous as well as safe.

We were passed by only one other cyclist. She had no lights at all.

So much for the Golden Mean.
--
cheers,

John B.



I see fairly regularly, folks with the light angled up, now I’m not sure if
this choice or slipped? My personal bug bear is folks in the Royal Parks
that are large and unlit so dark who have there lights on flash, the
temptation to return with interest the favour and boot the light to full is
high, I don’t but it gives me a warm glow just thinking about it!

Roger Merriman

wrote:
On Sat, 6 Apr 2019 07:27:25 -0700, sms
wrote:

On 4/6/2019 4:22 AM, Roger Merriman wrote:

I was getting the occasional car pulling out when I just had a fairly
normal cheap light (day time) which clearly folks just hadn’t
noticed/looked, for other reasons I bought a nice front light, so I don’t
have to run two since it has a remote so can easily go from full to dip or
close enough.

But I have noticed that running it on low/dip during the day seems to have
stopped folks absent minded pulling out.

I do cross some fairly major roads so something to cut though is handy and
is zero cost essentially I also have some rear lights though blinding folks
is less of a issue with rear lights.

Exactly. The biggest change in driver behavior I've seen when using
adequate lights, both day and night, is a reduction in vehicles exiting
parking lots in front of me, or making right on red turns in front of
me. And as most of us that drive have also experienced, the "I just
didn't see you" excuse that vehicle drivers use, actually does have some
validity--you are MUCH more visible when you use an adequate light, both
day and night.

Since multiple studies have come to this conclusion regarding DRLs it
should not surprise anyone (well unless they abhor statistically
significant studies and research, and judging from the number of
climate-change deniers there are still some of these individuals around).

Yes the often mentioned Odense study (of some 1,845 users and some
2,000 non users over a 12 month period) showed permanent running
lights reduced accidents by 19%.

The study was initiated and funded by the company that made the
permanent running lights.

Which would seem to underwrite your argument until one discovers that
the "running lights" used in the study were tiny little lights powered
by two magnets attached to the wheel spokes which generated a short
flash as they passed the light which was attached to the forks. The
lights were manufactured by Reelight.

By the way, the study showed that the incident of solo accidents were
also reduced in the group equipped with lights.

Note: Both the entire study and Reelight's company advert are
available on the Web.
--
cheers,

John B.


"We'll give you this free light if you participate in our bicycling safety
study."

"OK. (Gee, it sure would be embarrassing to have to report an accident
while I'm in a safety study. Maybe I should do less stupid things...)"

They probably could have handed out St Christopher medals and gotten
similar results.

On Sat, 6 Apr 2019 23:21:59 -0000 (UTC), Roger Merriman
wrote:

I see fairly regularly, folks with the light angled up, now I’m not sure if
this choice or slipped? My personal bug bear is folks in the Royal Parks
that are large and unlit so dark who have there lights on flash, the
temptation to return with interest the favour and boot the light to full is
high, I don’t but it gives me a warm glow just thinking about it!
Roger Merriman

Well, if you change your mind and decide to do something about the
flasher in the face problem, I suggest you look into weaponizing your
bicycle headlight.

"The Incapacitating Flashlight. An LED flashlight makes culprits
vomit"
https://www.technologyreview.com/s/408360/the-incapacitating-flashlight/

"LED Incapacitator"
https://en.wikipedia.org/wiki/LED_Incapacitator
http://www.intopsys.com/technologies/featured-technologies/led-incapacitator-2/

"Flicker vertigo"
https://en.wikipedia.org/wiki/Flicker_vertigo

"Incapacitating flashing light apparatus and method"
https://patents.google.com/patent/US7180426B2/
https://patentimages.storage.googleapis.com/c6/43/13/d9e822141911a8/US7180426.pdf

"Can Strobe Weapons Really Make You Puke"?
https://www.wired.com/2008/05/strobe-weapons-2/
"I don’t think we've had anyone actually be sick",
says Bob Lieberman, CEO of Intelligent Optics, which
makes the LED Incapacitator.
Oh well. I was hoping it would make the view vomit.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Sat, 6 Apr 2019 11:59:39 -0400, Frank Krygowski
wrote:

On 4/6/2019 10:20 AM, sms wrote:


Since multiple studies have shown a big benefit for DRLs, for cyclists
and motorcyclists more than for cars, it would be pretty foolish not to
use them...

That's an excellent example of the hand wringer's Safety Inflation
Creed. "Someone claimed a big benefit, so it's foolish not to use it!"

No specifics are given on the "multiple studies" (at least one of which
is known to be crap). And in the general Safety Inflation case, no
studies are really needed. As long as someone's tried it and _believed_
it helped, it's foolish not to use it. No skepticism allowed!

In the famous Odense study it was found that even solo accidents were
decreased by the use of tiny little "flea watt" lights.
(Thanks to Jay for the definition "flea watts")

One can only assume that there is something akin to magic in the tiny
little magnet powered Reelights used in the study, if they even
decrease the numbers of solo accidents. Akin to a St. Christopher
Medal one supposes.

See:
http://vbn.aau.dk/files/274548813/Sa...bic ycles.pdf
for the complete study report.
--
cheers,

John B.

On Sat, 6 Apr 2019 23:22:06 +0000 (UTC), Ralph Barone
wrote:

wrote:
On Sat, 6 Apr 2019 07:27:25 -0700, sms
wrote:

On 4/6/2019 4:22 AM, Roger Merriman wrote:

I was getting the occasional car pulling out when I just had a fairly
normal cheap light (day time) which clearly folks just hadn’t
noticed/looked, for other reasons I bought a nice front light, so I don’t
have to run two since it has a remote so can easily go from full to dip or
close enough.

But I have noticed that running it on low/dip during the day seems to have
stopped folks absent minded pulling out.

I do cross some fairly major roads so something to cut though is handy and
is zero cost essentially I also have some rear lights though blinding folks
is less of a issue with rear lights.

Exactly. The biggest change in driver behavior I've seen when using
adequate lights, both day and night, is a reduction in vehicles exiting
parking lots in front of me, or making right on red turns in front of
me. And as most of us that drive have also experienced, the "I just
didn't see you" excuse that vehicle drivers use, actually does have some
validity--you are MUCH more visible when you use an adequate light, both
day and night.

Since multiple studies have come to this conclusion regarding DRLs it
should not surprise anyone (well unless they abhor statistically
significant studies and research, and judging from the number of
climate-change deniers there are still some of these individuals around).

Yes the often mentioned Odense study (of some 1,845 users and some
2,000 non users over a 12 month period) showed permanent running
lights reduced accidents by 19%.

The study was initiated and funded by the company that made the
permanent running lights.

Which would seem to underwrite your argument until one discovers that
the "running lights" used in the study were tiny little lights powered
by two magnets attached to the wheel spokes which generated a short
flash as they passed the light which was attached to the forks. The
lights were manufactured by Reelight.

By the way, the study showed that the incident of solo accidents were
also reduced in the group equipped with lights.

Note: Both the entire study and Reelight's company advert are
available on the Web.
--
cheers,

John B.


"We'll give you this free light if you participate in our bicycling safety
study."

"OK. (Gee, it sure would be embarrassing to have to report an accident
while I'm in a safety study. Maybe I should do less stupid things...)"

They probably could have handed out St Christopher medals and gotten
similar results.

The study seemed to be set up and run as a Internet based study.
Apparently you registered and when accepted got a set of the little
Reelights and installed them. Then you posted periodic reports listing
any and (one assumes) all accidents.

The accidents reported were both with injury and without injury and
seem pretty comprehensive as they are listed for All, Winter, Summer,
Daylight, Twilight and Night Time. The rates for solo accidents show
that the rate (for All) is about 24% lower for the light equipped
group as than for the control group.
--
cheers,

John B.

On Sun, 07 Apr 2019 09:39:15 +0700, wrote:

In the famous Odense study it was found that even solo accidents were
decreased by the use of tiny little "flea watt" lights.
(Thanks to Jay for the definition "flea watts")

One can only assume that there is something akin to magic in the tiny
little magnet powered Reelights used in the study, if they even
decrease the numbers of solo accidents. Akin to a St. Christopher
Medal one supposes.

See:
http://vbn.aau.dk/files/274548813/Sa...bic ycles.pdf
for the complete study report.

See Table 8 which indicates:
Incidence rate ratios for solo accidents reflecting
the likely systematic underreporting of accidents in
the treatment group.

See Table 10 which indicates:
multiparty accidents with personal injury only.
Correction made in order to control for the apparent
underreporting of bicycle accidents in the treatment group.

On Pg 8, it describes the statistical tweaks, using a 0.73 correction
factor, to tweak the treatment group numbers, in order to produce
usable results. The report then declares:
The downscaling in the number of accidents reported
by the control group, which is a result of the applied
correction for likely underreporting by the treatment
group, however has the effect that none of the estimated
differences in the incidence rates are significant...

Huh? Now the control group is accused of also underreporting
accidents. Yet, the -28% fudge factor is applied only to the
treatment group, after which the study declares that there are no
significant differences between groups. This -28% tweak is much
larger than the 19% improvement in overall safety by the treatment
group.

If the study had assumed that both groups underreported equally, the
results would have shown about a 9% improvement in safety in favor of
the control group. That would have been rather unacceptable, so the
numbers were tweaked to make the treatment group look good. And this
thing was apparently peer reviewed.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Sat, 06 Apr 2019 20:13:35 -0700, Jeff Liebermann
wrote:

On Sun, 07 Apr 2019 09:39:15 +0700, wrote:

In the famous Odense study it was found that even solo accidents were
decreased by the use of tiny little "flea watt" lights.
(Thanks to Jay for the definition "flea watts")

One can only assume that there is something akin to magic in the tiny
little magnet powered Reelights used in the study, if they even
decrease the numbers of solo accidents. Akin to a St. Christopher
Medal one supposes.

See:
http://vbn.aau.dk/files/274548813/Sa...bic ycles.pdf
for the complete study report.

See Table 8 which indicates:
Incidence rate ratios for solo accidents reflecting
the likely systematic underreporting of accidents in
the treatment group.

See Table 10 which indicates:
multiparty accidents with personal injury only.
Correction made in order to control for the apparent
underreporting of bicycle accidents in the treatment group.

On Pg 8, it describes the statistical tweaks, using a 0.73 correction
factor, to tweak the treatment group numbers, in order to produce
usable results. The report then declares:
The downscaling in the number of accidents reported
by the control group, which is a result of the applied
correction for likely underreporting by the treatment
group, however has the effect that none of the estimated
differences in the incidence rates are significant...

Huh? Now the control group is accused of also underreporting
accidents. Yet, the -28% fudge factor is applied only to the
treatment group, after which the study declares that there are no
significant differences between groups. This -28% tweak is much
larger than the 19% improvement in overall safety by the treatment
group.

If the study had assumed that both groups underreported equally, the
results would have shown about a 9% improvement in safety in favor of
the control group. That would have been rather unacceptable, so the
numbers were tweaked to make the treatment group look good. And this
thing was apparently peer reviewed.


You need to do some more research.

Reelight, the maker of the little magnet powered lights that were used
in the study, seems to have provided the lights used in the study
free. Now THINK! Someone just gave you almost 2,000 lights so that you
can make your study...
--
cheers,

John B.

On Sun, 07 Apr 2019 10:31:41 +0700, wrote:

You need to do some more research.

I need to go back to working on my income taxes.

Reelight, the maker of the little magnet powered lights that were used
in the study, seems to have provided the lights used in the study
free. Now THINK! Someone just gave you almost 2,000 lights so that you
can make your study...

Yep. The way it works is the researchers own the content of the
paper, while the driving force behind the project owns the conclusion.
Since most readers will never read beyond the initial summary, this is
sufficient. I've read research papers where the conclusions have
little or no connection to the data in the body of the report.

However, we have a new contender in the bicycle safety study business.
Flashing headlights are out, and bright yellow jackets are in:
https://ars.els-cdn.com/content/image/1-s2.0-S0925753517313528-gr1_lrg.jpg
"The effect of a yellow bicycle jacket on cyclist accidents"
https://www.sciencedirect.com/science/article/pii/S0925753517313528
The accident rate (AR) (accidents per person month) for
personal injury accidents (PIAs) for the test group was
47% lower than that of the control group. For accidents
involving cyclists and motor vehicles, it was 55% lower.
I wonder if Denmark will also make wearing bright yellow bicycle
jackets manditory, just like the daylight running lights? Note that
both studies seem to have been performed at Aalborg University,
Denmark.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Sat, 06 Apr 2019 21:07:14 -0700, Jeff Liebermann
wrote:

On Sun, 07 Apr 2019 10:31:41 +0700, wrote:

You need to do some more research.

I need to go back to working on my income taxes.

Reelight, the maker of the little magnet powered lights that were used
in the study, seems to have provided the lights used in the study
free. Now THINK! Someone just gave you almost 2,000 lights so that you
can make your study...

Yep. The way it works is the researchers own the content of the
paper, while the driving force behind the project owns the conclusion.
Since most readers will never read beyond the initial summary, this is
sufficient. I've read research papers where the conclusions have
little or no connection to the data in the body of the report.

However, we have a new contender in the bicycle safety study business.
Flashing headlights are out, and bright yellow jackets are in:
https://ars.els-cdn.com/content/image/1-s2.0-S0925753517313528-gr1_lrg.jpg
"The effect of a yellow bicycle jacket on cyclist accidents"
https://www.sciencedirect.com/science/article/pii/S0925753517313528
The accident rate (AR) (accidents per person month) for
personal injury accidents (PIAs) for the test group was
47% lower than that of the control group. For accidents
involving cyclists and motor vehicles, it was 55% lower.
I wonder if Denmark will also make wearing bright yellow bicycle
jackets manditory, just like the daylight running lights? Note that
both studies seem to have been performed at Aalborg University,
Denmark.


I'm not sure that it is simply the bright *yellow* jacket, but I do
believe that bright colored clothing - red, yellow, orange - make one
more visible, or perhaps a better term is "noticeable". At least I saw
a couple of guys wearing black or dark blue jerseys on my morning ride
this morning and they didn't stand out as well as another guy with an
orange jersey.

But in essence, isn't that what a flashing light does?

--
cheers,

John B.

On 07/04/2019 03.39, wrote:
On Sat, 6 Apr 2019 11:59:39 -0400, Frank Krygowski
wrote:

On 4/6/2019 10:20 AM, sms wrote:


Since multiple studies have shown a big benefit for DRLs, for cyclists
and motorcyclists more than for cars, it would be pretty foolish not to
use them...

That's an excellent example of the hand wringer's Safety Inflation
Creed. "Someone claimed a big benefit, so it's foolish not to use it!"

No specifics are given on the "multiple studies" (at least one of which
is known to be crap). And in the general Safety Inflation case, no
studies are really needed. As long as someone's tried it and _believed_
it helped, it's foolish not to use it. No skepticism allowed!

In the famous Odense study it was found that even solo accidents were
decreased by the use of tiny little "flea watt" lights.
(Thanks to Jay for the definition "flea watts")

One can only assume that there is something akin to magic in the tiny
little magnet powered Reelights used in the study, if they even
decrease the numbers of solo accidents. Akin to a St. Christopher
Medal one supposes.

See:
http://vbn.aau.dk/files/274548813/Sa...bic ycles.pdf
for the complete study report.

I see a lot of those, and as a last chance backup, just leaving them
fitted at the axle and on, I've considered them, but they are relatively
expensive.