Line-of-sight testing on underground mining equipment has previously been performed using tedious, manual methods. The advent of computer-aided design programs has made line-of-sight testing both faster and more versatile. These programs allow accurate, 3-D models of machinery to be loaded and assessed with simple, user-friendly commands. Advanced anthropometric and human motion characteristics have also been incorporated into these programs to allow realistic analysis of the human body within the modeled machine.

Operators of load-haul-dump (LHD) machines use postures that include twisting, lateral and forward bending of the trunk and twisting of the neck to spot hazards. These postures may be held statically, at extreme ranges of motion for long shift periods while the operator is exposed to vibration. These conditions have been associated with increased risk of low back pain - a frequently reported injury in the mining industry and a problem that many companies are attempting to reduce or eliminate.

This research developed two audit procedures to assess line-of-sight for the LHD operator. The visibility audit and target audit was performed in the simulated, computer environment. Modifications to various machine components showed improvements in line-of-sight and increased visible area (by as much as 15%) around the virtual machine. The tested components that were shown to improve visibility include cab design with greater window openings, thinner light posts and light brackets, triangular bucket lip, lowered back/engine profile, minimized mud guards and minimized cylinder covers. General recommendations for sign height and driving scenarios were also provided to increase visibility awareness in the underground environment.

Subsequently, a seat rotation intervention was appraised in the virtual environment in an effort to improve posture while also improving line-of-sight. Results revealed that a seat rotation of 20 degrees provided reductions in joint force, muscular asymmetry and joint angles while 45 degrees provided even greater postural benefit. There was a concurrent increase in the number of visual attention locators that were observed.

Using human factor assessment tools in a virtual environment was a safe and cost-effective manner for testing design prototypes and for demonstrating which driving scenarios cause undue postural stress on the operator.