Annual Street Preventative Maintenance
Maintaining Ann Arbor’s roads to keep them in good condition for longer, requires various tools and techniques. Some of this work is scheduled years in advance through the Capital Improvement Plan (CIP), while other, more immediate issues are addressed by Public Works.
Ann Arbor’s Annual Street Preventative Maintenance Program, which is planned through the CIP, uses different forms of pavement preservation treatments to improve the surface quality of streets and help slow further deterioration of the asphalt (asphalt is the most common surface material on city streets). These treatments, done by contractors, apply the right fix, at the right time, meaning work is performed on roads in decent condition to keep them that way for longer.
Filling potholes is not part of this program and is instead done by Public Works. During winter months, cold patch is used to temporarily fill potholes and cracks while in the warmer months, hot patch, which better forms and seals, is used to create a better fix which can last much longer.
Work is funded by one or both of the following sources: ACT 51, which is money collected from taxes on gasoline or the city’s Street, Bridge, and Sidewalk Millage.
Street preventative maintenance methods
Cape Sealing
A preservation practice that consists of a two-step process: the application of a chip seal followed by a single course micro-surfacing treatment. This method is generally used on streets that are in fair structural condition and showing significant signs of aging. It repairs these types of pavements effectively and provides a smooth and durable pavement surface.
Step 1 of the cape seal process involves placing a chip seal, which includes an application of liquid asphalt sprayed over the pavement surface to penetrate the cracks and voids, followed by a layer of aggregate (chips) applied with a spreader. The aggregate is compacted and embedded into the liquid asphalt using a rubber-tired roller. After the asphalt cures, the surface is swept to remove any loose stones, resulting in a thickness of approximately 3/8 to 1/2 inches with a rough texture. Step 2 involves the application of a micro-surfacing treatment over the chip seal to eliminate the rough surface texture and cover any loose aggregates. It is typically applied the day after the completion of the chip seal work.
Cape seals are considered environmentally friendly as they have low energy requirements and emit no pollutants.
Potholes
Potholes form when water seeps into road cracks, freezes, expands, and then thaws, weakening the base. Each freeze/thaw cycle worsens the damage. The City of Ann Arbor aims to patch reported potholes within 3 business days, weather permitting.
To report a pothole to the city, please download the A2 Fix it mobile app for your smartphone or report online.
For potholes on freeways, freeway ramps and roads with an M, I, or US designation, please contact the Michigan Department of Transportation (MDOT) at 888.296.4546 or report online.