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Why potholes occur more often during Montana's winter season

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Posted at 2:08 PM, Jan 24, 2023

HELENA - It can be one of the worst parts of winter driving, trying to avoid the patchwork of potholes that pop up after the freezing and thawing of city streets.

According to AAA, U.S. drivers spend nearly $3 billion a year fixing damage caused by potholes.

Potholes are created when the freezing and thawing of water weaken the road surface.

City of Helena Transportation Systems Director David Knoepke explains how potholes are created.

"Water expands and tends to start popping those bonds of the asphalt has," said Knoepke.

Traffic driving over the weak spot breaks apart the asphalt.

City street crews can repair potholes throughout the year, but how they are repaired, and how long those repairs last, depends on the season.

"There's cold mix and as hot mix. Hot mix comes from the hot mix plant and it's only available during the summertime. You know, when temperatures are above freezing. Cold mix is a produced asphalt mix that can be heated and then tamped into the ground for basically it's more of a temporary fix versus hot," said Knoepke.

When the weather gets warmer outside, street crews will go back and replace the cold patch of asphalt with its counterpart, the hot patch, for a longer-lasting solution.

"If it's a big enough pothole that you know or it's been in there, same area has been causing us problems. We'll go out and reevaluate that in the spring and maybe early summer and we'll set out the limit of the pothole and we'll cut out," said Knoepke.