(CBS) — Cook County’s transportation superintendent estimates 5 percent to 10 percent of the county’s road miles are showing some signs of “frost heave,” or “road heave,” caused by the freeze-thaw cycle.

Supt. John Yonan says this occurs when water freezes and expands underneath the pavement — forcing it up into washboards, or bumps.

Yonan says warmer weather and the weight of passing traffic will remedy much of the problem, though some areas may have to be patched.

In Carpentersville, some frost heave is so bad municipal engineers have had to put up warning signs alongside roadways turned into washboards by frost heave.

The superintendent says the frost heave seems to be focused in pockets in the northwest and southwest portions of Cook County.

Yonan has spent Thursday driving throughout the county, inspecting the 135 bridges and 1,500 lane miles of roads for which he’s responsible.

Watch & Listen LIVE