Originally Posted by
jputnam
Cars that move significantly faster than other traffic (police cars, ambulances) and cars that move significantly slower than other traffic (heavy equipment, delivery trucks, mail carriers, etc.) definitely do use flashing lights. Other than emergency vehicles, though, they flash lights with a diffuse beam, not a projecting beam, while their headlights remain steady.
+1 This is a key point. No motor vehicles are allowed to drive with just blinking lights at night but around where I live anyway, if bicycles are using lights, flashing lights only seems to be the norm for bicycles. There are two elements to being seen if you want to be safe: 1. you want to be noticed and 2. you also want those who notice you to be able to tell where you are in the road (including the direction and speed you are moving at). Using flashing lights only on a moving vehicle makes it more difficult for people to accurately track your motion and this is also true if the flashing light is very bright in comparison to the steady light. This is a problem even in well lite urban areas where you are using a flashing light just to be noticed because the flashing lights encountered in this environment are usually standing still, for example the flashing lights on construction barriers or signs. This is particularly a problem for vehicles pulling out from a cross street - they will glance in your direction, see the flashing light, perceive you as a stationary object, and pull out right in front of you. Yes, they noticed your light, but they misjudged your speed and still hit you even though they "noticed" you. This is the key point that you bright flashing light advocates are missing - being noticed is not enough, to be safe you must also allow other road users to accurately judge the speed and direction of your motion, and, unless you are a complete idiot, you will have to admit that a steady light is much better at this latter task than a flashing one.