Compatibility of the Direction Sign on the Pendant Switch of Overhead Cranes

Objective: The aim of this study is to suggest the standard of the direction sign on the pendant switch of overhead cranes which can reduce human errors in control. Background: A great number of crane accidents occur in industries. One of the major causes of the accidents is the mistake in the control of cranes by confusing the orientation of crane movements. Nevertheless, three different direction sign styles, "East, West, South, North (EWSN)", "Forward, Backward, Left, Right (FBLR)", and arrows for four directions are used without standardization. Method: An overhead crane simulator was installed for a laboratory experiment. It could move along six directions by the control of a pendant switch. 90 participants were evenly assigned to the three different conditions of direction sign styles. The participants were asked to control the pendant switch according to the continuously appearing 16 direction signs on a monitor ahead. The participants were allowed to refer an orientation sign board on the ceiling representing correct movement directions of the overhead crane simulator. Results: The direction sign style, "EWSN", showed statistically significant better performance in task completion time and number of errors than the other sign styles. The direction sign style, "EWSN", adopting the cardinal direction system, made the participants clear in direction controls after customizing to the crane movements. However, the direction sign styles, "FBLR" and the arrows adopting the relative direction system made conflicts in direction controls due to the egocentric view of human. Conclusion: The direction sign style, "EWSN", is the most appropriate for the standardization of the direction sign on the pendant switch of overhead cranes. Application: The results of this study can be applied to the standardization of direction sign in the legal notification on the safety certifications of crane manufacturing.