March 12, 2009

Road paint reflectivity is studied

A U.S. study suggests painted road markings such as lines separating lanes of traffic reflect headlights better in the direction the paint was applied.

In other words the paint reflects more light if you are following the painting truck than if you are driving from the other direction, said the study co-author, North Carolina State University Professor Joe Hummer.

Hummer, who conducted the research with Professor William Rasdorf and graduate student Guanghua Zhang, said the findings could help state transportation departments better predict how long painted markings will perform properly. If a state can repaint road markings every three years instead of every two, it will save a lot of money, he said.

Hummer said the difference in reflectivity occurs because glass beads are scattered onto freshly painted traffic markings to make them reflective. Since the painting truck is moving, the beads tend to bounce and roll before coming to rest.

The beads skid and build up paint on one side, Hummer said Therefore, they are less reflective in that direction.

The research was published in the journal Public Works Management & Policy.