Industrial – Heavy Equipment
Equipment operators were reporting low back concerns related to the operation of 776D tractor-trailer units on a prairie mine site in Alberta. The equipment had been brought in six months prior to the assessment request and operators were concerned that the tractor-trailer units were exposing to high levels of vibration over the 12-hour shift.
The assessment was divided into two components subjective and objective measurements. The assessment involved the equipment vendor, which required prior approval of the assessment strategy including review of the questionnaire.
Subjective measurements included the administration of a health and perception survey (Nordic Survey) to all operators. A return rate of sixty percent was received. Additionally, interviews were conducted with front-line operators, maintenance and supervision to further explore the concern.
Objective measurements included physical vibration testing of the equipment against ISO standards and observation of the key tasks that comprised the tasks.
Vibration levels measured were consistent with other studies of off-road vehicles used in similar situations. The analysis indicated that over a 12-hour shift individuals exceeded the lower boundary of the Health Guidance Caution Zone, but none of the tractor-trailer units exceeded the upper boundary. If it exceeded the upper boundary there would have definitely been a health risk associated with operation of the tractor-trailer unit.
It was determined with the key stakeholders that the primary factors that were affecting overall exposure included: low tire pressures, road conditions and maintenance of the equipment. Regularly monitoring of road conditions, operating speeds and tire pressures had a significant impact on overall vibration levels. Additional, recommendations implemented: proper seat adjustment and regular postural change throughout the shift.