Originally Posted by
agent pombero
There is no academic literature to be found that supports the fear that super bright bike lights cause motorists to crash.
Perhaps then you'll post your academic survey of the literature.
A quick Google search turns up multiple citations of concern about the intensity of headlights. Here's one, part of a report from the National Highway Traffic Safety Administration:
Characterizing Glare
Glare is a sensation caused by bright light in one’s field of view. Glare can reduce one’s ability to see, create feelings of discomfort or both. The term headlamp glare is defined herewith as visibility reductions or discomfort caused by viewing oncoming vehicle headlamps or headlamps in rear view mirrors.
Glare reduces seeing distance because it causes light scatter in the eyes, which in turn reduces the contrast of roadway objects. This effect is known as “disability glare.” The greater the intensity of the glare light and the closer the glare light is to where one is looking, the greater the disability glare will be. Disability glare can lead to the following effects:
• Decreasing visibility distance. The distance at which an object can be seen is known as the “visibility distance.” This distance is reduced when disability glare is present.
• Increasing reaction times. As the intensity of oncoming headlamps increases, drivers’ reaction times to objects in and along the roadway become longer.
• Increasing recovery time. After drivers pass an oncoming vehicle, the glare has a lasting effect that increases the time it takes for the drivers’ eyes to recover their ability to detect objects. During that time, the visibility distance is reduced and reaction times are increased.
As described above, headlamps can produce a sensation termed “discomfort glare.” This is the feeling of annoyance or even pain that is possible when viewing a bright light. Experiencing discomfort can distract drivers from the driving task, cause them to slow down, and cause drift slightly in their lane.
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Vehicle headlamps are necessary for sufficient nighttime visibility and safety, and headlamp glare has long been recognized as a potential problem. However, concerns from the public about nighttime glare have increased in recent years. A public comment docket regarding headlamp glare opened in 2001 and has received more than 5700 comments to date, making it one of NHTSA’s most active dockets.
Several factors associated with recent vehicle and lighting developments may explain the driving public’s passion regarding nighttime glare. These include increasing light intensity levels, headlamp mounting height on larger vehicles, novel headlamp color appearance (specifically the bluish appearance of some headlamps), smaller headlamp size, variations in headlamp aim on the U.S. vehicle fleet, and an increase in the presence of auxiliary lighting, such as fog lamps. The increasing age of the driving public may be another factor. Since all of these factors have changed in parallel, assigning the cause of these concerns to any single factor is difficult.