Pros and cons of hi-vis

Topics relating to Advanced Riding on bikes
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GTR1400MAN
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Re: Pros and cons of hi-vis

Postby GTR1400MAN » Thu Jan 04, 2018 10:25 am

crr003 wrote:Now hang on, that’s brilliant.
My sister keeps four chickens and it’s a bugger finding them to bring them in at night sometimes.
Next Christmas present sorted!

Must be popular, out of stock. There's even a video of them.

https://www.omlet.co.uk/shop/chicken_keeping/high_vis_chicken_jacket/
Mike Roberts

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Horse
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Re: Pros and cons of hi-vis

Postby Horse » Thu Jan 04, 2018 10:36 am

crr003 wrote: Now hang on, that’s brilliant.
My sister keeps four chickens and it’s a bugger finding them to bring them in at night sometimes.
Next Christmas present sorted!


Stomp stomp stomp "Where are you y'beggars?" stomp stomp stomp Sqwawk! "Found it!"
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Horse
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Re: Pros and cons of hi-vis

Postby Horse » Thu Jan 04, 2018 10:50 am

ancient wrote: The conclusion . . . is that actually seeing a 'cyclist (motor or otherwise) is not the problem it is usually made out. SMIDSY is an excuse SMICBATL along with SEP are the predominant reasons for close passes (and pull-outs).


There's a clear progression, for example the typical 'SMIDSY' situation:
Driver arrives at junction . . .
1 Doesn't look
2 Looks, but rider is obscured (eg car door pillar, street furniture, other vehicle) [ie 'not visible']
3 Looks, but doesn't notice the rider
4 Looks, notices the rider, but makes incorrect decision on rider's speed and distance
5 Looks, makes correct decision about rider's speed and distance, but pulls out anyway because driver doesn't understand limitations on rider's braking ability etc
6 Looks, correct decisions, pulls out because they don't care

Hi-viz can really only influence '3' - and we're dealing with situations where the rider is close to the junction anyway!
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ancient
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Re: Pros and cons of hi-vis

Postby ancient » Thu Jan 04, 2018 12:43 pm

Horse wrote:There's a clear progression, for example the typical 'SMIDSY' situation:
Driver arrives at junction . . .
1 Doesn't look
2 Looks, but rider is obscured (eg car door pillar, street furniture, other vehicle) [ie 'not visible']
3 Looks, but doesn't notice the rider
4 Looks, notices the rider, but makes incorrect decision on rider's speed and distance
5 Looks, makes correct decision about rider's speed and distance, but pulls out anyway because driver doesn't understand limitations on rider's braking ability etc
6 Looks, correct decisions, pulls out because they don't care

Hi-viz can really only influence '3' - and we're dealing with situations where the rider is close to the junction anyway!

Agreed but even for '3', there are:
3.a. Looks, expects clear road and 'sees' that image. Hi-viz might (to be proved) cause an adjustment of that assumption; But drivers also pull out on large vehicles like this - even those wearing hi-viz. Images generated by planning (in the same part of the brain as process vision) are not always corrected by input, particularly where that input is easily assumed to be something else expected (speculatively: such as road signage).
3.b. Looks, sees much traffic large vehicle traffic, smaller rider looks like a gap. Again, hi-viz 'might' cause readjustment, or might be unconsciously dismissed ('cos brains work that way ;) ) as 'not a threat', or might be camouflaged (as Michael Mason was speculated to be, in a different scenario) against a complex background with many light sources.
All in all, a consideration of where hi-viz might help and how, does appear to show why there never seems to be evidence of a reduction in injury rates in population-level statistical analyses. It's potentially helpful actions are too easily over-ridden by other considerations.

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Horse
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Re: Pros and cons of hi-vis

Postby Horse » Thu Jan 04, 2018 1:01 pm

ancient wrote: 3.a. Looks, expects clear road and 'sees' that image. Hi-viz might (to be proved) cause an adjustment of that assumption; But drivers also pull out on large vehicles like this - even those wearing hi-viz. Images generated by planning (in the same part of the brain as process vision) are not always corrected by input, particularly where that input is easily assumed to be something else expected (speculatively: such as road signage).


See the other thread for more on this sort of aspect viewtopic.php?f=8&t=680

(Including the 'police driver who saw a sofa and thought it was an HGV' link)

ancient wrote: 3.b. Looks, sees much traffic large vehicle traffic, smaller rider looks like a gap. Again, hi-viz 'might' cause readjustment, or might be unconsciously dismissed ('cos brains work that way ;) ) as 'not a threat', or might be camouflaged


Might, or might not. Unless the 'wearer' trades places with the 'driver' there is little or no way to know quite how you appear - and even then you are aware of what you're looking for, not 'naive'. You're right that drivers probably don't look for vehicles, they look for gaps. Worse still, as the research here: http://www.google.co.uk/url?sa=t&rct=j& ... HVtKo-dcIK (see diagrams 4 & 5) shows is that experienced drivers may be worse at these observation skills than novices!

ancient wrote: It's potentially helpful actions are too easily over-ridden by other considerations.


And, as shown by some of the recent images posted, potentially unhelpful.
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crr003
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Re: Pros and cons of hi-vis

Postby crr003 » Thu Jan 04, 2018 4:43 pm

Horse wrote:
crr003 wrote:
GTR1400MAN wrote:
akirk wrote:you should miss the man as you will be avoiding the car!
Alasdair

?? Over my head.

The HATO/HETO picture?


Actually, you have hit on an important point. Many road workers feel safer when tthey're stood still close to their vehicle. Unfortunately, that vehicle is likely to bd more conspicuous than the worker. So if that person steps out the approaching driver is likely to be dazzled by the vehicle's retro-reflective material and beacons.

What am I missing here? How big's this person that's blocking the battenburg AND the light bar?!?! Policy/procedure should dictate where they should be standing?
Even crash cushion trucks get hit so maybe there's too much research on all this stuff.
What about the moth attracted to the light theory? http://www.poconorecord.com/article/201 ... /207150316

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Horse
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Re: Pros and cons of hi-vis

Postby Horse » Thu Jan 04, 2018 9:47 pm

Good article on the Visual Expert site about whether 'Moth effect' is a real effect.

CONCLUSION
The "moth effect" is a myth in one sense and reality in another. The idea that drivers may steer off the road when they fixate flashing lights is likely correct, but they are not drawn to the lights like moths to a flame. Rather, they inadvertently steer rightward, which may or may not take them into collision with the roadside vehicle. Even normal, alert drivers in daylight conditions may steer in the direction of eye position during periods of intense fixation, although factors reducing attentional capacity increase the probability. The cause is likely error in judging heading under eccentric fixation when optic flow cues are minimal and when attentional focus prevents sensing of the need to correct the error. Although bright lights and fascination are not required, of course, it is impossible to rule out these factors in some accidents.

http://www.visualexpert.com/Resources/motheffect.html
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Horse
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Re: Pros and cons of hi-vis

Postby Horse » Thu Jan 04, 2018 10:00 pm

crr003 wrote:
Horse wrote: . . . workers feel safer when tthey're stood still close to their vehicle. Unfortunately, that vehicle is likely to bd more conspicuous than the worker. So if that person steps out the approaching driver is likely to be dazzled by the vehicle's retro-reflective material and beacons.

What am I missing here? How big's this person that's blocking the battenburg AND the light bar?!?! Policy/procedure should dictate where they should be standing?
Even crash cushion trucks get hit so maybe there's too much research on all this stuff.


Other way around! :) The reflected light from the vehicle and direct light from its beacons are far brighter than the light reflected from the piddly little (technical term, hope you're keeping up) stripes on the PPE. Worse still, approacing drivers may be dazzled so unable to see anything close to the vehicle. If there is no phase in the vehicle's beacon flash pattern where all the beacons are off together.

Trust me, I know how often and how badly IPVs get clattered.
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Horse
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Re: Pros and cons of hi-vis

Postby Horse » Thu Jan 04, 2018 10:10 pm

Too much research? Perhaps look back to the Ambulance Visibility blog post, referring to the PPE research. The author seemed to think that research challenged commonly-held beliefs about the effectiveness of PPE.

But here's another report for you to consider:

http://assets.highways.gov.uk/specialis ... Report.pdf

Some of the findings and recommendations led to a change in policy for advice from the recovery industry to broken-down motorists.
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crr003
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Re: Pros and cons of hi-vis

Postby crr003 » Thu Jan 04, 2018 11:06 pm

Horse wrote:Good article on the Visual Expert site about whether 'Moth effect' is a real effect.

CONCLUSION
The "moth effect" is a myth in one sense and reality in another. The idea that drivers may steer off the road when they fixate flashing lights is likely correct, but they are not drawn to the lights like moths to a flame. Rather, they inadvertently steer rightward, which may or may not take them into collision with the roadside vehicle. Even normal, alert drivers in daylight conditions may steer in the direction of eye position during periods of intense fixation, although factors reducing attentional capacity increase the probability. The cause is likely error in judging heading under eccentric fixation when optic flow cues are minimal and when attentional focus prevents sensing of the need to correct the error. Although bright lights and fascination are not required, of course, it is impossible to rule out these factors in some accidents.

http://www.visualexpert.com/Resources/motheffect.html

I found that one, but as soon as I read
“If I'm a bicyclist, for example, I want as many lights as possible, preferably flashing.”
I left it.


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