Bicycle DRLs - Actually reading the paper, actually looking at the

On 7/13/2015 5:28 PM, jbeattie wrote:


It's an interesting study. SMS is right that it reports dramatic safety improvement. Frank makes some valid points about solo injuries and one-way correction for under-reporting of injuries. Here is the quote (excuse formatting):

"It is likely that this apparent effect on solo accidents of the bicycle running lights actually reflect a systematic under-reporting of accidents in the treatment group due to an inherent bias in favour of the bicycle running lights amongst
the members of the treatment group. During the project, additional questionnaires were carried out in order to evaluate the design and functionality of the bicycle running lights. From the data gathered here, it is evident that the members of the
treatment group were very fond of the running light as they found the bicycle running lights very convenient, e.g. they did not have to buy batteries any more, they did not have to fear being stopped by the police for having forgotten their bicycle lights, they felt very safe with the bicycle running lights etc. As a consequence it is likely that the treatment group has been somewhat strategic in their reporting of accidents by omitting some of the minor bicycle accidents; as reflected by the apparent under reporting of solo accidents in the treatment group. The apparent effect for solo accidents is almost the same for relevant subgroups of solo accidents, see Table 9, which suggests that the underreporting is general and not associated with certain solo accident types."

Seems finessed.

Indeed.


Anyway, that whimpy Reelight light down at axle level would get lost in the forest of headlights and other light noise during most daylight riding around here. Maybe light behaves differently in Odense. Around here, one would need a big, manly light to get attention.

Regarding brightness, the Reelight FAQs have this:

======================================

6. How much light do bike lights emit?

Reelight SL100 emits 29,000 mcd (microcandela – a unit for measuring
light) from the front light and 10,000 from the rear light.

Reelight SL120 emits approx. 24,000 mcd from the front light and approx.
8,000 from the rear light.

======================================

I suspect they've got their units wrong. "mcd" would be millicandela,
not microcandela. One candela is roughly the brightness of an ordinary
candle. If it really is 29000 microcandela, it's going to be about 3%
as bright as a candle.

29,000 millicandela would be roughly 29 times the brightness of a
candle. Nothing to write home about.

OT but vaguely related: Bill Bryson's book _At Home_ is a sort of
history of home life through the ages. It had a fascinating chapter on
interior lighting. He makes the point that it's hard for us to realize
how dark everything was in the days before electric lights. Back then,
29 candela might have looked impressive!

Note widespread use of DRLs in Odense:
https://www.youtube.com/watch?v=bN8noxNpv3E

Gosh, those DRLs are somehow hard to spot.

Portland is different from Odense. We ride super fast! https://vimeo.com/41789264

And without DRLs. So many "foolish" bicyclists! You must not have any
professionals in your town.


--
- Frank Krygowski

On Mon, 13 Jul 2015 11:53:51 -0400, Frank Krygowski
wrote:

Another thread mentions Madsen et. al., "Safety Effects of Permanent
Running Lights for Bicycles", Accident Analysis & Prevention 50 (2013)
820-829. Scharf said "Read the study," But I'm pretty sure he's read
only the abstract. I downloaded the study and skimmed it a few days
ago. Last night I took the time to read it in detail. Here's what I found.

One might say the study is a promotion of the Reelight flashing light
system, powered by magnets on wheel spokes.
https://www.reelight.com/en/ Those are the lights "tested" in the
study. And there are enough weirdnesses in the results to indicate that
this is more a promotion than a serious study. Here are details and
(warning!) data analysis.

They advertized they wanted to do a study and asked who in Odense wanted
to participate in a light study, luring participants by promising free
lights. They got over 18000 applicants, about 10% of the population.
That's the first "self-selection" clue. Those who already had
sufficient lighting, those who didn't care about lights and those who
simply didn't hear about this would be excluded.

They used a random process to select 1845 of those people to get lights
immediately and 2000 people to act as a control group, promising the
controls free lights if they stayed in the study for a full year.
Obviously, those who got the lights knew they had them, so there's
nothing "blind" about this study. Placebo effects are certainly
possible, and certainly did occur - see below. Some people dropped out
in the course of the 1-year time period. 3306 completed the entire year.

The study scheme echoed one "Danger! Danger!" study from Portland, in
that they emailed the paricipants every two months (Portland used one
month) to ask about any bike "accidents" and "injuries." This is so
participants wouldn't forget any of those. It seems to me that if an
"accident" or "injury" is forgettable, it should be below the radar, so
to speak. But they didn't want to miss even the most minor "incident."

They defined "accident" as "an incident where you are forced off your
bike and/or crashed either by yourself or due to collision OR
NEAR-COLLISION with others." So actually, a near miss counted as an
"accident"! And I suppose "forced off you bike" could be coming to a
stop and having the bike topple as you stand over it. IOW, they are
exaggerating dangers, as usual. More on that later.

The paper does not define "injury," but recall that the Portland paper
counted _any_ injury. I assume this one did too. Broken fingernail?
Injury! But the injuries were still extremely rare.

Overall, there were 39672 "man-months" of bike use recorded. There was
no data on number of trips by bike, km traveled or hours exposure;
therefore all "rates" are "per man-month." And the numbers are very low
indeed.

Exactly how low is a bit difficult to tell. Examining data from three
of the paper's tables and doing some minor number crunching gave three
different answers for injuries per man-month. Table 6 works out to
0.00103 injuries per man-month; table 8 claims 0.00489 instead; and
table 9 implies 0.00318 instead. There may be something I'm missing;
but whichever is correct, all those figures are extremely low! The
worst yields an average of 204 months or 17 years of riding per
"injury," including (I assume) very minor and forgettable injuries.
Only 41 injuries were seen by medical people, and apparently none were
serious. Does that sound dangerous?

Similarly, accident rates per man-month were very low - only 261
"accidents" (including near-misses!) from 39672 man-months exposure.
That's less than 0.007 "accidents" per man-month, including (I assume)
putting one's foot down if one drops his bike.

Regarding the type of "accident": It would certainly be good to collect
data on what specific type of "accident" occurred or were "prevented."
But there's absolutely no mention of that in the paper. They give
separate numbers for winter vs. summer, daylight vs. darkness, solo vs.
"multiparty," etc. but nothing at all about whether they were cars
pulling out, left crosses, right hooks, cyclists running stop signs,
pedestrians jumping out, bike-bike collisions or anything else. This
makes actual analysis of causes impossible.

However, since "solo" accidents are listed, those must be simple falls
due to skidding, running into objects or pavement defects, simply losing
one's balance, etc. REELIGHTS SUPPOSEDLY PREVENTED ABOUT 25% OF SOLO
CRASHES! The authors acknowledge that this is flat impossible, and
evidence that the riders with the lights are cooking their reports, i.e.
not reporting some accidents.

The authors attempt a crude correction for this effect, but I see no
justification for its accuracy - certainly not down to the three
significant figure reporting of results. Still, they tried using their
correction (i.e. fudge factor) to improve their results, and (bottom of
page 827) said "... a result of the applied correction... has the effect
that NONE OF THE ESTIMATED DIFFERENCES IN THE INCIDENCE RATES ARE
[STATISTICALLY] SIGNIFICANT, the incidence rates for multiparty
accidents being the only but very important exception."

OK, so what's the rate of those multiparty (bike-ped, bike-bike,
bike-car) "accidents" (including near misses, which are not really
accidents? It's 0.00178 "accidents" per man-month. That means an
average of 562 months or 47 years of riding between each of those
"accidents" (including near misses).

How does this relate to Scharf's and Joerg's claims that DRLs make a
huge, obvious difference? As usual, the actual numbers indicate a very
strong probability of bull****. And the bull**** applies to the paper's
conclusions regarding Reelights' magic effectiveness as well.

This paper, like so many others, emphasizes changes in extremely rare
hazards. Even if Reelights or other DRLs reduce "accidents" (including
near misses) from - say - once every 47 years to once every 88 years on
average, which is what they claim - is it really worth yelling "Danger!
Danger! Buy our lights!"

Well, I suppose if you own the Reelight company, or if you get a
commission by selling Chinese flashlights on your web pages, you'll say
it's worth it. Less biased people probably have other opinions. Which
is why, contrary to Scharf's statements, only a minuscule percentage of
cyclists use daytime running lights.


But Frank! My gosh, think man! If There is a chance, no matter how
remote, that these light might, possibly, at least once in your life,
prevent you getting "injured", isn't that worth spending money on?

Particularly when Schwarfe and Reelight are such nice people? And
desperately need the money?

:-) (-:
--
cheers,

John B.

On Mon, 13 Jul 2015 12:29:55 -0700, sms
wrote:

On 7/13/2015 11:55 AM, David Scheidt wrote:
Frank Krygowski wrote:

:They defined "accident" as "an incident where you are forced off your
:bike and/or crashed either by yourself or due to collision OR
:NEAR-COLLISION with others." So actually, a near miss counted as an
:"accident"! And I suppose "forced off you bike" could be coming to a
:stop and having the bike topple as you stand over it. IOW, they are
:exaggerating dangers, as usual. More on that later.

That's a perfectly reasaonble definition. If a car pulls out in front
of you, and you avoid the car, but hit the curb and crash, the car has
caused an accident, even though you didn't collide with it. (That,
exactly, has happened to me.)

In San Francisco I see that kind of "near miss" often, though I prefer
to call it a "near hit."

With a DRL the driver behavior is visibly better. You can literally see
them hesitate, then yield the right of way. Does it always work? No.
Today a delivery truck did a right hook in front of me in Cupertino as
it turned into the Apple campus. It really wasn't a "near hit" but it
was still annoying.

The bottom line here is this. Frank doesn't use a DRL. Hence he believes
that DRLs are ineffective. Any study that shows that belief to be false
must have some terrible flaw in how it was conducted.

Or change "DRL" to "helmet." The schtick is always the same.


But why should we take your word that these things will actually
protect us? After all you tell lies, or to put it more kindly, talk in
a loud assertive voice about things which you know nothing about, and
insisted on the validity of your remarks even after others who
actually are competent state categorically that you are wrong.

Perhaps you are just as wrong in the case of flashing lights
protecting you, and are lying about it also.
--
cheers,

John B.

On 7/13/2015 5:02 PM, John B. Slocomb wrote:
On Mon, 13 Jul 2015 12:29:55 -0700, sms
wrote:

On 7/13/2015 11:55 AM, David Scheidt wrote:
Frank Krygowski wrote:

:They defined "accident" as "an incident where you are forced off your
:bike and/or crashed either by yourself or due to collision OR
:NEAR-COLLISION with others." So actually, a near miss counted as an
:"accident"! And I suppose "forced off you bike" could be coming to a
:stop and having the bike topple as you stand over it. IOW, they are
:exaggerating dangers, as usual. More on that later.

That's a perfectly reasaonble definition. If a car pulls out in front
of you, and you avoid the car, but hit the curb and crash, the car has
caused an accident, even though you didn't collide with it. (That,
exactly, has happened to me.)

In San Francisco I see that kind of "near miss" often, though I prefer
to call it a "near hit."

With a DRL the driver behavior is visibly better. You can literally see
them hesitate, then yield the right of way. Does it always work? No.
Today a delivery truck did a right hook in front of me in Cupertino as
it turned into the Apple campus. It really wasn't a "near hit" but it
was still annoying.

The bottom line here is this. Frank doesn't use a DRL. Hence he believes
that DRLs are ineffective. Any study that shows that belief to be false
must have some terrible flaw in how it was conducted.

Or change "DRL" to "helmet." The schtick is always the same.


But why should we take your word that these things will actually
protect us? After all you tell lies, or to put it more kindly, talk in
a loud assertive voice about things which you know nothing about, and
insisted on the validity of your remarks even after others who
actually are competent state categorically that you are wrong.

Cute. Of course you're well aware that those aren't things I do. I
provide referenced facts. You can disagree with the validity of the
studies I reference if you wish, but don't do as Frank does and
fabricate bizarre excuses as to why any study he doesn't like is fatally
flawed.

Perhaps you are just as wrong in the case of flashing lights
protecting you, and are lying about it also.

While I have had positive experiences with daytime lights, and have
stated those experiences, it's best to stick with case-controlled
studies if you want proof.

But you should also look at similar instances where daytime lights have
been proven to be beneficial, for cars and motorcycles and trucks, and
decide if you really want to jump on Frank's bandwagon of abandoning all
logic and common sense just because something you don't want to do has
been proven to be beneficial.

--

"It's best not to argue with people who are determined to lose. Once
you've told them about a superior alternative your responsibility is
fulfilled and you can allow them to lose in peace." Mark Crispin,
inventor of the IMAP protocol.

Am 13.07.2015 um 21:36 schrieb sms:

Everyone is aware of why some countries mandate DRLs on cars.

Simply because the car acessory industry has a massive earnings
potential, thus lobbying pressure.

Results for Europe:

Scandinavia: minor benefit from DRL in rular foresty regions, no benefit
in suburbian regions

Germany: No benefit in rural regions

Austria: No benefit countrywide

European technical standards: all new cars entering the market from 2011
onwards must have DRL (who cares about benefit when there are earnings
involved?)

On Mon, 13 Jul 2015 17:47:11 -0700, sms
wrote:

On 7/13/2015 5:02 PM, John B. Slocomb wrote:
On Mon, 13 Jul 2015 12:29:55 -0700, sms
wrote:

On 7/13/2015 11:55 AM, David Scheidt wrote:
Frank Krygowski wrote:

:They defined "accident" as "an incident where you are forced off your
:bike and/or crashed either by yourself or due to collision OR
:NEAR-COLLISION with others." So actually, a near miss counted as an
:"accident"! And I suppose "forced off you bike" could be coming to a
:stop and having the bike topple as you stand over it. IOW, they are
:exaggerating dangers, as usual. More on that later.

That's a perfectly reasaonble definition. If a car pulls out in front
of you, and you avoid the car, but hit the curb and crash, the car has
caused an accident, even though you didn't collide with it. (That,
exactly, has happened to me.)

In San Francisco I see that kind of "near miss" often, though I prefer
to call it a "near hit."

With a DRL the driver behavior is visibly better. You can literally see
them hesitate, then yield the right of way. Does it always work? No.
Today a delivery truck did a right hook in front of me in Cupertino as
it turned into the Apple campus. It really wasn't a "near hit" but it
was still annoying.

The bottom line here is this. Frank doesn't use a DRL. Hence he believes
that DRLs are ineffective. Any study that shows that belief to be false
must have some terrible flaw in how it was conducted.

Or change "DRL" to "helmet." The schtick is always the same.


But why should we take your word that these things will actually
protect us? After all you tell lies, or to put it more kindly, talk in
a loud assertive voice about things which you know nothing about, and
insisted on the validity of your remarks even after others who
actually are competent state categorically that you are wrong.

Cute. Of course you're well aware that those aren't things I do. I
provide referenced facts. You can disagree with the validity of the
studies I reference if you wish, but don't do as Frank does and
fabricate bizarre excuses as to why any study he doesn't like is fatally
flawed.


I wasn't talking about surveys.

I was talking about you insisting that it was impossible for someone
to install a Riv-nut in a bicycle without a completely equipped
machine shop. Remember that?

And when at least two people tried to advise you that it was/is
possible to install a Riv-nut all on your own with simple tools you
insisted that you were correct and without the machine shop it was
impossible.

So, you do in fact either tell lies, or are incredibly ignorant of
your subject. the only questions is do you do it out of malice or
ignorance.

Which does lead one to the question that since you have a history of
either lying or talking about things that you know nothing about, is
your present subject one, or the other? Or more bluntly, Ignorance or
Malice?




Perhaps you are just as wrong in the case of flashing lights
protecting you, and are lying about it also.

While I have had positive experiences with daytime lights, and have
stated those experiences, it's best to stick with case-controlled
studies if you want proof.

But you should also look at similar instances where daytime lights have
been proven to be beneficial, for cars and motorcycles and trucks, and
decide if you really want to jump on Frank's bandwagon of abandoning all
logic and common sense just because something you don't want to do has
been proven to be beneficial.
--
cheers,

John B.

On 14/07/2015 7:14 AM, Rolf Mantel wrote:
Am 13.07.2015 um 21:36 schrieb sms:

Everyone is aware of why some countries mandate DRLs on cars.

Simply because the car acessory industry has a massive earnings
potential, thus lobbying pressure.

Results for Europe:

Scandinavia: minor benefit from DRL in rular foresty regions, no benefit
in suburbian regions

Germany: No benefit in rural regions

Austria: No benefit countrywide

European technical standards: all new cars entering the market from 2011
onwards must have DRL (who cares about benefit when there are earnings
involved?)


Which massive earnings potential would that be? Using head lights
faster? I don't remember the last time I had a headlight burn out.

On 7/14/2015 4:14 AM, Rolf Mantel wrote:
Am 13.07.2015 um 21:36 schrieb sms:

Everyone is aware of why some countries mandate DRLs on cars.

Simply because the car acessory industry has a massive earnings
potential, thus lobbying pressure.

But these are not sold as accessories, at least in the U.S., they are
simply one more notch on the headllight/parking light control knob and
add no cost to production and no cost to the final product.

It is true that in some cases the benefits have been shown to be small
or even non-existent, but in some cases there has been a major benefit
(at least in the U.S.).

Early DRL implementations in the U.S. were terrible, and both owners of
cars with them, and other drivers complained bitterly. They are less bad
now, but still have the issue that many clueless drivers forget to turn
on their real headlights because they think they are already on due to
the DRLs.

In the U.S., there are many roads where drivers are advised to turn on
headlights in the daytime, so a DRL system which does this automatically
is preferable, but is not going to result in a decrease in crashes since
most people already followed the advice to turn on their lights.

The most significant increase in safety shown in the NHTSA report was:
Single-Passenger-Vehicle-to-Pedestrian/Pedalcyclist Crashes
(Single-PV-to-PED/CYC) were reduced by 19.1% (excluding dawn and dusk it
fell to 16.4%). Not huge reductions, but not insignificant either.

And of course there has been shown to be a positive effect for
motorcycles with a DRL is specific traffic situations. However there was
little difference for modulated versus non-modulated motorcycle
headlights, the closest equivalent to a flashing light on bicycles.

On 7/14/2015 5:55 AM, Duane wrote:
On 14/07/2015 7:14 AM, Rolf Mantel wrote:
Am 13.07.2015 um 21:36 schrieb sms:

Everyone is aware of why some countries mandate DRLs on cars.

Simply because the car acessory industry has a massive earnings
potential, thus lobbying pressure.

Results for Europe:

Scandinavia: minor benefit from DRL in rular foresty regions, no benefit
in suburbian regions

Germany: No benefit in rural regions

Austria: No benefit countrywide

European technical standards: all new cars entering the market from 2011
onwards must have DRL (who cares about benefit when there are earnings
involved?)


Which massive earnings potential would that be? Using head lights
faster? I don't remember the last time I had a headlight burn out.

It's a conspiracy by the oil companies since if you have DRLs on you use
a tiny bit more fuel.

Am 14.07.2015 um 14:55 schrieb Duane:
On 14/07/2015 7:14 AM, Rolf Mantel wrote:
Am 13.07.2015 um 21:36 schrieb sms:

Everyone is aware of why some countries mandate DRLs on cars.

Simply because the car acessory industry has a massive earnings
potential, thus lobbying pressure.

Results for Europe:

Scandinavia: minor benefit from DRL in rular foresty regions, no benefit
in suburbian regions

Germany: No benefit in rural regions

Austria: No benefit countrywide

European technical standards: all new cars entering the market from 2011
onwards must have DRL (who cares about benefit when there are earnings
involved?)

Which massive earnings potential would that be? Using head lights
faster? I don't remember the last time I had a headlight burn out.

Maximum power consumption targets for DRL can only be reached with LED
lights.
Light output expectations for high beam are very difficult to reach with
LED, so most new cars now have LED plus traditional lights (a few cars
have LED with intricate power control to switch between DRL mode and
night mode).