Lengthening yellow-light intervals, for example, gives motorists more time to hit the brakes.

WSJ: Hard to Put Red-Light Violations Under a Lens

It is an interesting triple "coincidence, " which probably evolved over time, that our eyes are most sensitive to yellow-green light, which happens to be the characteristic color of sunlight as well as the color that can most easily be transmitted through the Earth's atmosphere.

CNN: Why gamma-ray burst shocked scientists