AMES, Iowa ñ March 10, 2011 ñ While the impending spring is always welcome after another tough winter, the recent fluctuating temperatures, ample moisture and aging pavements are keeping the Iowa Department of Transportation (Iowa DOT), as well as county and city road crews, busy fixing potholes and addressing other structural damage to our streets, roads and bridges.
Potholes are mostly caused by moisture getting into or underneath pavement. During the late winter/early spring freeze and thaw periods, moisture causes the asphalt or concrete material to shift, buckle or fracture. Vehicles traveling over these weakened areas dislodge the pavement material, leaving those dreaded potholes. Potholes can also occur on previously patched pavements where snowplow operations dislodge the old patches.
As a temporary fix and to quickly minimize traffic impacts, Iowa DOT crews use cold-mix asphalt materials to repair potholes. Using cold-mix material is a necessity during the winter months when Iowa’s hot-mix asphalt plants are closed. Although cold-mix patches can function well for repairing smaller potholes, large defects or damage to heavily traveled roads often require further patching when warmer, dryer weather allows for permanent patching.
Either hot-mix asphalt or Portland cement concrete is used for permanent patches. These materials perform best when placed at temperatures well above freezing, so this work is usually completed in the spring and summer. The Iowa DOT typically hires contractors to construct these partial- and full-depth patches.
In a typical year, the Iowa DOT spends approximately $3 million on permanent patching projects on the Primary Road System and nearly $4 million on the interstates.
Iowans may report potholes and shoulder or pavement failures on the interstates, Iowa numbered routes and U.S. highways to the Iowa DOT’s maintenance manager located nearest the problem roadway. For potholes on streets or county roadways, contact the local city administrator/engineer or county engineer.|
