This study examined the effect that pulse rate, pulse pattern, and onset distance had on the performance of an auditory warning signal. The warning signal's purpose was to alert mobile crane operators of their proximity to overhead power lines. The study consisted of two experimental phases. The first phase consisted of three sections; A) development and construction of the PWD's auditory warning signal. B) development of the experimental tasks and a pilot study, and C) an examination of the workload level of the secondary tracking task. Phase two consisted of a full factorial experiment which examined the performance effects caused by pulse rate range, pulse pattern, and onset distance manipulations. The experimental task required subjects to monitor an auditory warning system while simultaneously operating a single-axis driving simulation task. Subjects were required to initiate braking responses based on the information conveyed through the auditory collision warming system. In addition, subjective ratings were obtained to compare subjects’ actual performance using the warning system to their subjective preferences. Results indicate that subjects performed optimally under warning signals with moderate onset distances and low pulse rates. The pulse pattern did not have a large impact on subjects' performance across the various warning signals. Overall, it was concluded that a pulsing auditory warning signal comprised of a moderate onset distance and low pulse rate was subjectively preferred and would work effectively as a proximity warning device for mobile cranes. / Master of Science