Mich. Comp. Laws § 247.661c

Sec. 11c. (1) All construction projects of the department concerning highways, streets, roads, and bridges, whose cost exceeds $100,000.00 for construction or preservation as defined in section 10c, shall be performed by contract awarded by competitive bidding unless the department affirmatively finds that under the circumstances relating to those projects, some other method is in the public interest. The director of the department shall report his or her findings to the state transportation commission 90 days before work is commenced and promptly in writing to the appropriations committees of the senate and house of representatives. However, in a case in which the department determines emergency action is required, the reports need not be filed before a contract is awarded but shall be promptly filed. (2) All construction projects of a local road agency whose costs exceed $100,000.00 for construction or preservation, excluding maintenance, shall be performed by contract awarded by competitive bidding unless the local road agency affirmatively finds that under the circumstances relating to those projects, some other method is in the public interest. Installation or upgrading of advanced traffic management and signals is exempt from this subsection. A county road commission shall report its findings before work is commenced in writing to the county board of commissioners of that county. A city or village shall report its findings before work is commenced in writing to the governing elected body of that city or village. As used in this subsection, "local road agency" means that term as defined in section 9a.