Summer Driving - Insects, Glare and Eye Fatigue
Why are insects on your windshield dangerous? It is not just that they are annoying and ruin the view, they are the main cause of windshield glare and vision obstruction during summer driving. Glare is a form of visual noise. Most objects you see are from light reflecting from the surface of that object, not light directly entering your eye. In the case of glare, your eye adapts to a high light level. This involuntary restriction of the eye's iris masks or makes invisible any source reflecting less light. The probability of a collision during this period of "object invisibility" which lasts two to five seconds after the glare is removed is greatly increased. Think of how well you see right after a camera flash.
Small objects that absorb light, like pedestrian in dark clothes a wild animal or a vehicle parked at the side of the road with no lights on at night can be almost impossible to see until you are very close. Couple that with glare that restricts the eye's iris and you have the perfect recipe for disaster. The problem with insects on the windshield (besides vision obstruction) is that the irregularity of the insect residue on a windshield causes light to be reflected in all directions, (see figure 1) As the light is scattered by the insect residue it appears to glow. The stronger the light source and the more insects you have on the windshield, the brighter the glow and presto... disability glare!
You probably learned in your first year of driving that nighttime glare is more disorienting than glare during the daytime. Light levels and the resulting visual references in the nighttime environment are low and limited when looking outside the illumination available from your headlights. This requires you to focus upon the highway, specifically the highway center line to keep up directional control, a condition that ensures your eyes will be affected by the headlights of oncoming traffic, especially when insect residue is creating glare.
At night as a vehicle approaches, insect residue will continue to become brighter until it reaches its maximum luminance level. This is determined by the strength and proximity of the approaching headlamps. It is followed by virtually complete darkness as the approaching vehicle headlamps no longer illuminate the windshield. This is when you are in the most danger as your eye's try to catch up to the changing light levels.
For example; during the approach of vehicles traveling opposite directions on the two-lane road at 60 miles per hour, the closure rate toward each other is 176 feet/second or 120 MPH. Glare and obscuration from an insect covered windshield severely limits both drivers ability to see and reduces critical visual clues to maintain vehicle separation. After passing the eye dilates to allow more light in improving the contrast level within the eye itself, during this second of reacquisition of dark adaptation the vehicles travel an additional 88 feet.
In other words both vehicles traveled 264 feet in 3 seconds with very limited or in some cases no visual clues to maintain directional control. A condition that can be found on any rural highway in America.
The scientific term is transient adaptation, and the rest of us know it as the eye's light/dark adaptation. With each approaching vehicle the process is repeated and the muscles in the eye that control this process become tired. The scientific term is transient adaptation factor, commonly called eye fatigue.
Excessive eye fatigue leads to eye fixating and reduced situational awareness, this coupled with long driving hours invites spatial disorientation.
These conditions are why the Power Wiper was developed. It has the ability to clean insects at highway speed anytime insects become a problem. The Power Wiper also has the unique patented ability to polish micro-scratches from the windshield (another source of glare) allowing much clearer windshield in all weather conditions.
So whether you make your living behind the wheel or just have a family road trip planned, get yourself a Power Wiper and make the highway safer for you and all the other drivers on the road. Oh and by the way, make sure to enjoy the view through a clean windshield.