Potholes are created in a number of ways:

  • Ice/snow melting during the day filling cracks with water, at night the water freezes and expands, popping out the asphalt. (The most common cause)
  • Water seeping into cracks on the road's surface and combining with the vibration of traffic, causing to fail. This is why there are more potholes after it rains. 
  • Trucks and buses stressing the roadway cause movement of the subsurface. Once there is a weak spot, every car that travels over it worsens the problem, and eventually, a section of the material will fail.

Potholes and other roadway failures are repaired by the Street Division in order of priority. The problem is corrected initially by installing a temporary patching material. Then areas needing repair are prioritized by size, number, and street traffic volume to see if more extensive roadway repairs are warranted. More information regarding larger projects such as reconstruction, mill, and overlay or the annual Seal Coat Project may be found under Engineering Projects.

Filling Potholes in Cold Temperatures

In the winter, potholes are patched with a special type of asphalt called "cold mix." Cold mix uses a softer, stickier asphalt that can be compacted into a hole even in below-freezing temperatures. Winter patches are temporary as the mix warms with the spring and summer temperatures and the material becomes too soft to stay in place.

Filling Potholes in Warm Temperatures

In the spring, summer, and fall potholes are patched with "hot mix" asphalt - the same asphalt used to build new roads. Hot-mix patches last anywhere from a year to several years. Hot mix is not available until late March or April, depending on weather conditions