The dangers of DRLs 4651

There are quite a few. Many are documented cases on file at the NHTSA. There are way to many to list here. Those documents are all available online. Have fun with your research.

But lets have a history lesson on how the military uses "negative contrast" and adding lighting as a form of camouflage (which means making a object less visible). But first, let's visit what "negative contrast" is. Negative contrast is the situation where a object appears in front of a light background. In those conditions, the object is most visible in dark silhouette against this light background (say the sky, a snow-sand bank or light faced mountain range brightly lit by direct sunlight). In that situation, a lighted object often becomes less visible compared to a unlighted object. These are lighting conditions commonly found in desert areas of the southwest and southern US. In WWII, the military very successfully used this negative contrast effect by equipping planters with floodlights that allowed the planes to virtually disappear in the daytime sky. It allowed them to get closer to targets undetected. The effects of how lighting on vehicles can be used to actually hide them has been known for several decades. So, the statement that DRLs make vehicles more visible is only partly correct. In certain lighting conditions, yes. In other lighting conditions, the opposite is true, But in most lighting conditions, it makes no real difference at all.