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 thawing with warmer temperatures. 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 potholes isn't a pothole
Not every defect in the roadway is considered a pothole 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 is ineffective. Cracks greater than 2 inches wide and 1.5 inches deep can be patched with reasonable success.
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 numerous 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 one foot to more than ten feet wide and is created after service work (water main break, gas line repair, etc.). Utility cuts that take place in the fall and winter are monitored and refilled as necessary until a permanent repair can used when asphalt plants open in the spring. Michcon, DTE and all private developers are responsible for the permanent repairs resulting from their activities and their repairs are inspected by City staff. . These are not considered potholes and are repaired under a separate program.