Driving along a stretch of asphalt in the dark, you may notice that the road doesn’t seem to get quite as dark as it used to. One reason? Those little reflective bumps along the pavement. Some of these reflectors come in unsurprising colors—red, yellow, white.
What about the blue ones, though? And the green ones? Are they purely an aesthetic choice, or is there a reason behind the color variations?
Red, as usual, is bad. It typically indicates you’re going the wrong way. If you turn around—probably a good idea—the RPMs will likely appear white or yellow to those driving in the correct direction.
Yellow (or amber) markers typically show the center-line of a road, or the left edge of a one-way road.
White markers separate lanes of same-direction traffic and may also appear on the right edge of the road.
Blue is designed to catch the eye of emergency vehicle drivers as they indicate the presence of a hydrant on the side of the road.
Green RPMs 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 RPMs to help them find roadside installations quickly, especially in an emergency.
The purpose of pavement reflectors is, of course, to save lives. They have been shown to help drivers see lanes better and sooner, especially when it’s raining, and to cut crashes by 0.5 accidents per million vehicle miles. That explains why you’re seeing more and more of them.