Evaluation of Peripheral Visual Performance When Using Incandescent and LED Miner Cap Lamps

Illumination plays a critical role in an underground miner's safety because miners depend most heavily on visual cues to recognize hazards. Mobile mining machinery, located in the miner's peripheral field of view ( plusmn10deg to about plusmn60deg off-axis), may pose potential pinning and striking hazards. The main objective of this research was to determine if there were peripheral visual performance improvements for the detection of moving objects when using cool-white light-emitting diode (LED) cap lamps as compared to incandescent (INC) light bulbs commonly used in miner cap lamps. The cap lamp variable of interest is the spectral power distribution. The illuminances were normalized by a diffusion filter. The second objective was to determine if age is a factor for the peripheral visual performance. This is important because the workforce is aging-the average miner age is about 43 years old. Thirty subjects participated in the study, ten subjects each in the age groups of younger (18-25 years), middle (40-50 years), and older (51+ years). Visual performance was quantified by the subjects' speed and accuracy of response to detect the rotation of high-contrast (white) circular targets located 3.83 m away at -20deg, 40deg, and 50deg off-axis. The speed of detection and the number of missed target rotations (accuracy) were measured. The prototype LED cap lamp results were best with an 11%-15% improvement compared to the INC and LED cap lamps, respectively. Age does appear to be a significant factor. For the middle and older age groups, the target movement detection time increased 75% and 60%, and the number of missed targets increased 500% and 450%, respectively, in comparison to the youngest age group. The results also suggest that target location is a significant factor. The subjects' target movement detection time for the 40deg and 50deg target movements increased 16% and 69%, respectively, as compared to the -20deg target.