Digging deeper: Road condition health requires more in-depth analysis

The health of our road conditions goes deeper than how smooth the surface is.

KDOT engineering technician Bill Vacura operates the core drill on a section of U.S. 283 in southern Norton County.

Engineering technicians from the Norton district materials lab took advantage of some nice February days to obtain several core samples from U.S. 283 and K-9 in northwest Kansas.

Vacura (left) and Mark Weiser, engineering technician specialist,
 extract the core sample from the roadway.

While it’s easy to see how conditions are on top of the road, that driving surface is just the tip of the iceberg, with many more layers underneath. Core samples allow KDOT to take a deeper look below the surface to see how the various layers of pavement are performing.

Vacura (left) and Mark Weiser, engineering technician specialist, extract the core sample from the roadway.

Technicians utilize a specialized core drill to obtain the samples. The drill acts much like a hole saw and is water-cooled to keep the bit from overheating. Once the technicians have drilled to the desired depth, the core is retrieved, labeled with the date and location, and sent back to the lab for analysis. Measurements are also taken of both the hole and core, then the hole is filled and patched with asphalt.

Weiser and Vacura patch the hole left behind
by the core drill. 

Back at the lab, technicians photograph the sample and conduct a visual assessment on the conditions of the different layers. They also note if the core was extracted as a whole or if it was in separate pieces. This information helps KDOT engineers determine what kind of action may be needed on the road and how deep that work needs to take place.