Operators of load-haul-dump (LHD) vehicles, common in underground mining, are exposed to a range of whole body vibration (WBV) and jolting from normal vehicle operation. Whole body vibration has acute detrimental effects on visual acuity, equilibrium, manual dexterity and muscular fatigue:​ Chronic effects include back, digestive and circulatory disorders. This study was designed to quantify the nature and extent of WBV from LHD vehicles and investigate the health, safety and performance effects on LHD operators.

The WBV levels, measured in 11 LHD vehicles from two Ontario mines, ranged from 0.1-2.8 m.s^-2 with dominant frequency bands from 1.6-3.15 Hz. When mean daily exposure levels were compared with the International Standards Organization (ISO) guidelines, the 6-hour exposure limit was exceeded in the transverse and vertical directions by 71% and 90% of the LHD vehicles respectively. Exposure ratios using a summed acceleration vector were found to exceed the IS0 recommended permissible value in all LHD vehicles tested. Vibration signals also contained high level random peaks among various operational tasks and for all directions. Statistically significant differences were calculated among LHD sizes and operational tasks, with the smaller vehicles and the driving tasks producing the highest vibration levels.

The incidence of accident and injury among LHD operators in Ontario was similar to underground miners;​ 180 and 183.5 injuries per 1000 workers respectively. The most frequent LHD operator injuries were to the back, eye, neck, finger and hand. Injuries to the neck were more prevalent among LHD operators than among other occupations underground. The majority of LHD injuries occurred during vehicle operation. Major contributing factors were found to include the sudden start-stop motion of the vehicle and the rough road surface. It was hypothesized that the high level WBV and jolting may have contributed to the incidence of back and neck injuries.

There were no significant differences in visual acuity among LHD operators following a workshift of WBV exposure;​ however, a significant decrement in manual. dexterity test scores was found. This post-shift decrement may indicate even greater decrements occurring during operation of the LHD vehicle.

Procedures for reducing the levels of WBV in underground LHD vehicles are discussed.