“Sometimes you’re the windshield. Sometimes you’re the bug.” So go the lyrics of the Mary Chapin Carpenter song, “The Bug”. Recent collisions between student pedestrians and cars bring to mind the issue of car-bug collisions. Some of the same principles of car-bug collisions apply to car-pedestrian collisions. At speeds of 20 mph or lower, most “bugs” are able to avoid collision with the windshield or are swept over the top of the car by the airstream. The same is true for pedestrians. When cars are moving more slowly, it is easier for pedestrians to get out of the way and drivers have more time to brake or alter course before colliding.
At faster speeds, insects are less able to avoid the collision and the airstream travels closer to the windshield increasing the number of windshield-bug collisions. The aerodynamics can be altered by bug deflectors, strips of plastic that are mounted on the front of the hood of a car. The bug deflector alters the aerodynamics. The deflector creates a thicker “dead air” zone between the windshield and the moving air. This makes it more likely that the bug will stay in the airstream and pass over the windshield rather than collide and splatter. Bug deflectors themselves will intercept some of the insects that are on a trajectory to collide with the windshield. Bug deflectors are popular in the US, although they can reduce gas mileage.
Here is the Dire Straits version of “The Bug”:
Living With Insects Blog 