Reflections on Things That Go Bump in the Night

Driving along a stretch of roadway in the dark, you may notice that the road doesn’t seem to get quite as dark as it used to. That’s because of the little reflective bumps along the pavement. Some of these reflectors come in surprising colors — typically red, yellow, and white. There are, however, blue and green ones as well. Regardless of their color, these reflectors are actually called pavement markers, and it turns out that their colors do have meaning. Red, as you would expect, is bad. It typically means you’re going the wrong way. If you turn around, the reflectors typically appear white to signal that you’re driving in the correct direction. Yellow markers show the center line of a road, or the left edge of a one-way road. White markers also separate lanes of same-direction traffic and may also appear on the right edge of the road. Blue reflectors are designed to catch the eye of emergency vehicle drivers because they indicate the presence of a fire hydrant on the side of the road. They're typically placed at the center of the road or on the side. If a hydrant stands at a corner, then each road might have its own marker. Blue reflectors also indicate emergency entrances onto roads near firehouses. Green reflectors have several purposes. They’re most often used on roads around gated communities to indicate access for emergency vehicles. Utility companies may also deploy green reflectors to help them find roadside installations quickly, especially in an emergency. Additionally, hunters use them to mark trails; homeowners use them to highlight driveways or paths; and warehouses use them to indicate where pallets should be stacked.