Potholes are defects in the road caused by water entering the asphalt or concrete's sub-base through surface cracks. Water freezes in early winter,
causing it to expand, then it thaws when it is warmer. Each freeze/thaw cycle causes the underlying base of the road to collapse, causing potholes in the road surface.
The City of Ann Arbor strives to patch all reported potholes within 3 business days, weather and other activities permitting.
Reporting a pothole
When a pothole isn't a pothole
Not all defects in the roadway are considered potholes and therefore, cannot be patched. Shallow depressions with sharp edges will not hold patch and must wait for resurfacing during warmer, drier months. Here are some other examples:
Long thin cracks that run parallel to the road for which normal patch does not work well. Cracks greater than 2 inches wide and 1.5 inches deep can be patched.
Crack seal/fill the cracks to prevent further deterioration or remove and reconstruct to full depth fixing any support issues. Limited resources within Streets O&M budget to do many locations. Crack sealing is a contracted activity based on available funding and competing roads with similar deterioration.
Utility cuts are temporary patches with straight edges which can range in size from 1 foot to more than 10 feet wide. These are the result of utility work such as on a water main break, gas line repair, or other work. Utility cuts in the fall and winter are monitored and refilled as necessary until a permanent repair can happen. Michcon, DTE and all private developers are in charge of the permanent repairs that come from their activities. These repairs are inspected by City staff. These are not considered potholes and are repaired under a separate program.