http://twowheelsoapbox.com/?p=26
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Daytime Highbeam Usage: Not the Brightest Idea May 31, 2007
It is such a commonly held myth that I, and everyone I know, does it , and advocates it. And it just might get you killed.
Most motorcyclists I have talked to agree that being as visible to other drivers as possible is an essential safety practice. To this end, many advocate the use of their motorcycle’s high beam during daytime riding. This is believed to increase the distance that another driver might notice you, as well as keep their attention throughout the time you are in their sight. It is a plausible idea, and in theory seems the right thing to do. Just a few days ago I was riding as a passenger in a car when I noticed something strange. I saw what I interpreted to be a motorcycle approaching. I say interpreted because, though I would usually not be paying so close attention, I was intent on noticing motorcycles, as these days I am always looking for something to write about, and, while I knew what I was “seeing” was most likely a motorcycle, I could not see the motorcycle. What I saw, or more precisely, what I did not see, was a bright light, and nothing else. I knew it was a bike with its high beam on, but I couldn’t tell you anything else about the bike, because I could not see it. Therein lies the problem.During the day, you can look at any patch of the sky, and assuming that it is not obscured by buildings or clouds, and you are not looking directly at the sun, you will see a blue, starless field. The stars are not gone, they are right there where you are looking, but you cannot see them because your vision is awash in the diffused light of the sun. The US, Canadian, and British Navies tested camouflage concepts during World War II called Active Camouflage or Diffused Lighting Camouflage that used this principle. The idea was a ship’s silhouette stands out against a light background, but by lighting up the ship, the structure blends in with the diffused light of the sky behind it. Recently, armies have experimented with using bright lights to disguise tanks and other vehicles on the horizon.
That same effect occurs when a driver looks directly into the headlight of a motorcyclist using their high beam. Unlike the low beam setting, which intentionally shifts the beam down and to the right, away from oncoming traffic, the high beam setting shines its light directly down and across the road, and into the eyes of the drivers of oncoming vehicles. This is why the law says you must turn off your high beams within a certain distance of approaching traffic, and why vehicles must have a high beam indicator, and the law makes no distinction as to the time of day when addressing this subject. Motorcyclists may think that the law only applies at night, since it is silent on the subject, and that daytime use is both acceptable and an appropriate safety practice.
What actually happens, often enough, is that when a motorcyclist leaves their high beam on as they approach another car, they become a white fog of light. Unfortunately, this is often interpreted by the driver’s brain as meaning nothing is there. If the brain can’t see it, and the driver is already not paying attention, he or she is almost certain not to see the motorcycle. Even if the driver is alert enough to be aware of the presence of another vehicle, the masking effect of the light may make it impossible to judge things like speed, lane position, or even the motorcycle’s use of a turn signal. This can lead to drivers turning left in front of a motorcycle they did not see or could not judge speed and distance on, among other things.
This phenomena seems most troublesome on motorcycles with the standard, large diameter bowl type round headlights favored on cruiser type motorcycles. A possible solution to the problem may lay in a uniquely “motorcyclish” product, the headlamp modulator. This relatively cheap and easy to install device rapidly alternates between high and low beam, displaying as a flashing or pulsing light that drivers have come to associate with emergency vehicles, and so are trained to pay more attention to them, not less. As far as I know these devices are legal in California, as they are widely used out here and I have not heard of anyone crossing paths with the police due to one.
So if you are a motorcyclist, the next time you throw a leg over your ride and head out, resist the temptation to switch on the high beam and forget it. Take a more active role in your own safety and manually toggle the high beam on and off when approaching traffic you're concerned about, or better yet, buy a modulator. And for the drivers reading this, when you are driving, especially when you are going to turn across traffic, make sure you actively see that not only is their nothing on the road, but that you can see what lay beyond the road. Because that nothing you think you are seeing might just be the motorcycle you hit.
