225 ILCS 710/45.27

In every mine in which mechanical haulage is employed there shall be at intervals of not more than 100 feet on each main haulage way, except in shafts, places of refuge affording a space of at least 2 feet in width between the widest portion of the car or train running on the tramway and the side of the haulageway. When electric trolley haulage is used or when there is a lighting circuit in the haulageway such places of refuge shall be marked by lights of a distinctive color, so placed as to be plainly visible from a distance of at least 50 feet in each direction in the haulageways.