Minn. Stat. § 219.26: PROTECTIVE CROSSING DEVICE; UNIFORMITY.

The commissioner, so far as practicable, shall secure uniformity in the devices used to protect grade crossings. No devices may be installed until they have been approved by the commissioner. All devices which, in the opinion of the commissioner, conflict with devices approved by the commissioner, either in design or method of operation, so as to create a hazard to travel at the crossing, must be immediately modified by the railroad company controlling the crossing to conform to those devices approved by the commissioner.