Mich. Comp. Laws § 257.1707

Sec. 7. For purposes of a racing event held under this act, the city may do all of the following: (a) Provide for the temporary closing or obstructing of highways or streets, alleys, and sidewalks located in the city. (b) Reroute pedestrian and vehicular traffic. (c) Waive ordinances and traffic regulations including speed limits and traffic control devices.