INDIANA, USA — Have you ever noticed tiny flashes of light illuminating your way home while driving on Indiana highways? The Indiana Department of Transportation is revealing a little-known technology they say could help Indiana drivers.
The glass beads are called “Highway Safety Marker Balls.” The colorless, nearly transparent spheres reflect headlights back at drivers. According to the Indiana Department of Transportation, the Highway Safety Marker Balls are designed to make driving directions clearer and road markings more visible, thereby increasing safety.
”The light from the headlights hits them and reflects back into the car, so even in pitch black darkness you can see them,” said Hunter Petrowiak, spokesman for the Indiana Department of Transportation’s Northeast District. “If you hold them in your hand, they feel like sand. If you squeeze them together, they’re very soft. You can barely see them in the paint.”
However, a recent post on the Indiana Department of Transportation (INDOT) Facebook page intended to clarify what these glass beads are has unintentionally angered some Indiana drivers, with many users writing that glass beads should not be used to replace reflective lights on Indiana roadways.
”Something needs to be done!!! Whether it’s glass beads, glow in the dark stripes, I don’t know…even just repainting them when we can’t see them anymore,” one Facebook user commented.
But the Indiana Department of Transportation (INDOT) wants to reiterate that glass beads are only used when painting Indiana roads. They are not installed in place of reflective lights. Rather, they are part of the painting process.
While the road marking sprayer sprays paint onto the road through one nozzle, the second nozzle sprays glass beads directly onto the wet paint.
”The wet paint creates a texture similar to cement. We actually only draw these lines when we place the glass beads,” Petroviak said.
According to the Indiana Department of Transportation, which developed the spheres to add a reflective layer to the painted lines, the beads will be glued to the markings after the paint dries.
”They go through rigorous testing to ensure that at least 80 percent of the balls in a batch are spherical,” Petroviak said.
The glass spheres are weather-resistant and undergo rigorous testing at DOT Materials and Testing Buildings throughout Indiana, including in Indianapolis, before they are installed on the road.
Scientists tested the spheres for reflectivity and percentage of roundness to help them stay on the drawn line as intended.
The beads are also sifted through a special set of sieves of different sizes to determine the number of beads of each size.
Different sized beads are combined to create a puzzle-like surface when applied to a paint surface. They are then tested for water resistance. The Indiana Department of Transportation (INDOT) says that without water resistance, the beads will stick together when exposed to moisture and clog nozzles.
”I think people will be interested in it because when you hear we’re going to put glass on the ground, it’s a little weird,” Mr. Petroviak said. “You almost think the paint is going to reflect the light.”
Indiana Department of Transportation districts and several contract partners across the state are responsible for their own painting projects.
Post time: Jul-04-2025