Michigan Compiled Laws, Chapters 220 to 244 General Highway Law § 235.8a

Sec. 8a. In case it shall be deemed necessary by the state highway commissioner or by the county road commissioners of any county where such drain or other public improvement is under construction to lay out and maintain a detour road for the safety and convenience of public travel, it shall be lawful, except in cities, that the full cost therefor shall be borne as part of the main project whether it be a drain, a road or a highway project.