Everyone knows that surfaces do not walk or work, yet Oregon OSHA has many requirements that apply to them. So it’s important to know what they are. Essentially, a walking-working surface is any surface on which a person walks or works. But the devil is in the details. You will find a nuanced definition of a walking-working surface that only a lawyer could love in Oregon OSHA's construction rules. See: Division 3, Subdivision M: 437-003-1500(7).
You will find the general industry requirements for walking-working surfaces in Division 2, Subdivision D: Walking-working surfaces.