| 摘要 |
PROBLEM TO BE SOLVED: To promote safety. SOLUTION: A floor board 41 is constituted of an aluminum alloy extrusion formed section. Extrusion-molding of a plurality of projected threads 45 is made in a part constituing the floor surface of the floor board 41, and a plurality of holes 42 are punched in the floor surface. The arranged and formed holes 42 can be so selected that they have such a size as objects (worker, tool or the like) positioned from one side holding the floor board 41 to the other end can be visually confirmed through the holes 42. The worker tool or the like can be confirmed through the floor board 41 accordingly.
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