From time to time, roads in the area close - either from events, block parties, construction, flooding, accidents, or neglect. Here are some places to find out this information.
Downtown Ann Arbor events
City of Ann Arbor event road closures and detours are posted on the city web site. This can give you heads up about events coming up like road races and parades.
Washtenaw County
A roadwork map gives you road closures, road work and bridge out information county-wide.