Why Are Traffic Lanes Painted So You Can Barely Make Them Out on a Rainy Night? Shouldn’t Busy Thoroughfares Feature Reflectors?

In a city that sees more rain than shine, why are traffic lanes painted so you can barely make them out on a rainy night? Shouldn't busy thoroughfares feature reflectors? Or at least better paint that's more visible in a drizzle or downpour? —Vikram S.

I periodically receive letters in which the writer mistakes the human condition for a municipal management problem: "When I was in college in California in the '90s, my body was young and strong. Now that I live in Portland, it's all old and gnarly. Why is Ted Wheeler such a jerk?"

I don't know where you lived (if anywhere) before arriving in Portland, Vikram. That said,  the reason folks from Southern California never had this problem back home probably isn't because LA uses better paint.

In the rest of weather-having America, complaining about lane markers being invisible in the rain is second only to "Drivers in [City X] are the worst in the country!" on the bellyaching hit parade. While I can't solve the problem, I can give you some cool optical terms to describe it!

In dry weather, the stripes on the highway—along with the highway itself and pretty much everything else in the world—exhibit what is called diffuse reflection. This just means that light bounces off them in all directions, and you can see them from anywhere.

However, wet surfaces—along with mirrors, glassy lakes and the limpid pools of your lover's eyes—display specular reflection: Under the right circumstances, you can see yourself in them, but when you're driving, all they do is reflect the darkness of the night back toward your eyes.

To combat this, engineers have developed pavement markers and paints that employ retroreflection: They reflect light back in the direction it came from—toward you, assuming you have working headlights.

Unfortunately, these wear out or wear off over time (and the markers tend to chew up snowplow blades) so deploying them is a case-by-case  judgment call. If you see a state road you think could use some, go to the Oregon Department of Transportation's "Ask ODOT" page. (Now you're their problem.)