Mich. Comp. Laws § 41.274
If after such survey, establishment of grades, plans and specifications and estimates of cost have been filed with them, the commissioners shall still be of the opinion that the proposed improvement is necessary for the benefit of the public and is for the benefit of the public welfare and convenience, they shall make their first order of determination and attach a copy of the specifications to such order. These specifications shall not be final but may be changed by the commissioners at any time before the final order is made, but not after the hearing of the objections hereinafter provided for, except after due notice and hearing thereon. The commissioners shall also attach to such order either a description of the boundaries of the proposed assessment district or a description of the several parcels of land which may be liable to assessment for the benefits on account of the proposed improvement: Provided, however, That whenever the proposed improvement is located on a state trunk line, no hearing as above referred to shall be held unless the state highway commissioner shall have been furnished with a written determination of necessity signed by the county road commissioners and a complete file of the plans and specifications, and the approval of the state highway commissioner as to determination, plans and specifications has been obtained.
MCL 41.274