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Pavement Markings

April 9, 2009

Painted road markings reflect better in one direction than the other.

Transcript

BOB HIRSHON (host):
Drawing a bright line in the road…I’m Bob Hirshon and this is Science Update.

The yellow and white lines on a roadway are important for traffic safety and have to get repainted every couple of years. Joe Hummer is a civil engineering professor at North Carolina State University. One of his grad students, Guang Hua Zhang, noticed that the brightness of those lines depends on the direction you’re driving in.

HUMMER (NC State):
That is, if you’re driving from one direction, you’ll see a marking that looks about a year’s brighter than the other direction. In other words, the average difference is about a year’s worth of wear and tear.

HIRSHON:
Hummer says it’s because the reflective glass beads scattered onto the paint tend to build up in the direction the paint truck is traveling. He says repainting road markings costs two to three thousand dollars per mile. So understanding that process could help improve safety and save money. I’m Bob Hirshon for AAAS, the science society.