Overhead work is very prevalent in almost any occupational setting. Picking apples, stocking store shelves, operating valves in chemical plants, threading strip material through the rollers of a tower accumulator, performing maintenance on equipment, and changing light bulbs are examples. Wherever it is performed, overhead work often requires elevation of the worker. There are literally dozens of ways to elevate workers, ranging from portable ladders, to fixed platforms, to boom lifts and other vehicle-mounted platforms. Facility and equipment designers often assume that maintenance and other activities can be performed at any elevation, giving little consideration to how workers will reach areas above floor level.
A few studies have looked at the ergonomics of ladder carrying (Beyer et al. 816), setting up ladders (Young and Wogalter 111), and ladder climbing (Bloswick and Chaffin 17). Rather than focusing on climbing or the process of getting to an elevated position, what this presentation addresses is the ergonomics of performing work from elevated platforms. That is, the focus is on activity after the means of elevation has been positioned and the employee is somewhat stationary. Very little research has been conducted in this specific area, so we are left applying what we know from non-elevated work studies to explain observed phenomena.
According to data reported in the 2003 Edition of the National Safety Council's Injury Facts, falls to lower levels accounted for 6,078 occupational fatalities for the ten year period from 1992–2001 (NSC 67) That's an average of just over 600 occupational fatalities annually. For private industry, 96,359 non-fatal cases were reported for the same ten-year period (NSC 67).
The causes of all these falls from elevation vary widely, from electrical shock to scaffold failure to loss of balance, as well as numerous other causes (James 32). Certainly defective equipment contributes significantly (Rundstrom 477), but it is suggested that these so-called causes are often not the "root cause." Back strains and other injuries are prevalent among elevated workers (Bloswick and Chaffin 18). Perhaps ergonomics and human factors play a significant underlying role in many of these incidents.
Consider a couple of hypothetical scenarios:
Joe the electrician uses a stepladder to access an elevated electrical panel servicing the hoist on a jib crane. Upon reaching the panel, he pulls the disconnect and locks it out. He then opens the panel and begins work. Twenty minutes into the job, Joe becomes uncomfortable, shifts his weight on the ladder, and inadvertently contacts the hot lead in the panel. Joe falls. Why? The cause of the fall would be listed as electrical shock, but is that really the cause? Joe fell because he experienced discomfort and fatigue, moved to alleviate it, and momentarily lost situational awareness of the end of his screwdriver. Getting to the root cause, one must ask, "Why did Joe become fatigued and uncomfortable?"
