  Falling from elevated surfaces is the main cause of death and injury at
construction sites. Based on the Bureau of Labor Statistics (BLS) reports, an
average of nearly three workers per day suffer fatal injuries from falling.
Studies show that postural instability is the foremost cause of this
disproportional falling rate. To study what affects the postural stability of
construction workers, we conducted a series of experiments in the virtual
reality (VR). Twelve healthy adults, all students at the University of Nebraska
were recruited for this study. During each trial, participants heart rates and
postural sways were measured as the dependent factors. The independent factors
included a moving structural beam (MB) coming directly at the participants, the
presence of VR, height, the participants self-judgment of fear, and their level
of acrophobia. The former was designed in an attempt to simulate some part of
the steel erection procedure, which is one of the key tasks of ironworkers. The
results of this study indicate that height increase the postural sway.
Self-judged fear significantly was found to decrease postural sway, more
specifically the normalized total excursion of the center of pressure (TE),
both in the presence and absence of height. Also, participants heart rates
significantly increase once they are confronted by a moving beam in the virtual
environment (VE), even though they are informed that the beam will not hit
them. The findings of this study can be useful for training novice ironworkers
that will be subjected to height and steel erection for the first time.
