225 ILCS 710/45.10

During shift making operations no other work in any other place in the shaft shall be executed, nor shall any material or tools be hoisted or lowered from or to any other place in the shaft while people are at work in the bottom of the shaft unless the people are protected from the danger of falling material by a securely constructed covering extending over the whole area of the shaft, sufficient closable openings being left in the covering for the passage of people and the bucket or other conveyance used in the sinking operation.