Iowa DOT News

Bumps in the road? Here’s the “hole” story


AMES, Iowa – March 14, 2023 – This has been a pretty wild winter for many parts of Iowa. When you’re out on Iowa’s highways, you may notice more potholes than in the last few mild winters.

The Iowa Transportation Commission just took steps to help get these potholes repaired by approving an additional $15 million specifically for additional maintenance to be done on interstates, U.S., and state highways.  

Why do potholes form in the first place?   

The answer has to do with a combination of factors, including an aging and deteriorating road system, an unusual amount of precipitation, and fluctuating temperatures. 

Think of it this way. Have you ever placed a canned beverage in the freezer to chill and forgotten to take it out?  If you were lucky, the can just bulges and get bumpy. If you were not so lucky, it burst, creating a mess in your freezer.  

This is very similar to what is happening to our roadways. The moisture that has seeped through the cracks and joints of our roads is trapped beneath. When the subsurface temperatures freeze, the moisture expands. Pressure from expanding moisture can cause the pavement to bulge, heave, and/or break. 

When the pavement heaves or breaks, it can be damaged even more by snowplow blades and traffic. Bit by bit each break and crack spreads and, before you know it, you have a good-sized pothole. 

So, what can be done about the problem? While some temporary pothole patching is being performed between winter storms, there is nothing that can be done about heaved sections until warmer temperatures arrive and pavement can naturally resettle in place. Once this happens road crews can make short-term repairs by sealing cracks and joints and patching the potholes and fractured areas with longer-lasting materials.

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For media inquiries, contact: John Hart at 515-239-1547 or john.hart@iowadot.us.

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