Mich. Comp. Laws § 462.36
Authority is hereby given to the said commission, and it shall be its duty, if it shall deem it advisable, to prescribe the use of such modern generally approved system of protection for the safe operation of trains or cars at all crossings and junctions of railroads in this state, and at all crossings of draw bridges, upon which trains or cars are operated by steam, electricity or other power, such as will secure safety in the operation of trains or cars at such crossings, junctions and draw bridges, and to apportion the cost of construction, operation and maintenance of such system of protection among the several companies in such proportion as to the commission shall seem just. The commission, having determined such form of protection, shall immediately cause a description thereof over its official signature to be delivered to an officer of the railroad affected thereby, with notice that the same must be adopted and put into practical force within a reasonable time to be fixed by the commission.
MCL 462.36