Michigan Compiled Laws, Chapter 259. Aviation § 259.482e

Sec. 2e. The perimeter of a horizontal surface is constructed by swinging an arc with a radius as specified by this section from the center point of each end of the primary surface of each runway of an airport and connecting adjacent arcs by a line tangent to those arcs. The radius of an arc for a utility runway or for other than a utility runway with a visual approach equals 5,000 feet. The radius of an arc for any other runway equals 10,000 feet. The radius of the arc specified for the end of a runway shall not be less than the longest radius for the other end of the runway. If a 5,000 foot arc is encompassed by a tangent connecting adjacent 10,000 foot arcs, the 5,000 foot arc shall be disregarded in constructing the perimeter of the horizontal surface.