Underground » Health and Safety
For many coal mining operators, back injury now accounts for more OH&S claims than any other single factor. While back injury can arise from many factors, a well-documented leading cause is the exposure of workers to vibration, eg the vibrations experienced by operators of heavy mining surface vehicles. Both long-term exposure to continuous vibrations and high-amplitude shock vibrations can contribute to serious back injury.
Present Practice
Australian Standard AS2670.1 (1990) and its British Counterpart, BS 6841 (1987) contain guidelines for evaluating workers exposure to WBV.
The methodology is reasonably complex and requires a Vibration Specialist to measure vibration levels on the vehicle in the field during normal work cycles and analyse the data in accordance with the standards. This process is time-consuming and relatively costly.
When exposure to high vibration is reported, it is not unusual for mine operators to conduct a one-off test and limit the testing to just the worst vehicles, usually one or two.
In reality however, ride quality is influenced by several factors which are prone to change with time. To be efective all vehicles would need to be tested relatively frequently for an acceptable ride quality to be maintained.
The Solution
VIPAC Engineers & Scientists Ltd responded to this need by developing in the course of 1997 - 1998, a prototype Whole Body Vibration Dosimeter under C6008. The primary aim of this project was to develop a prototype field instrument capable of measuring computing and logging, while in the field and without expert assistance, the exposure to vehicle vibration of workers in the coal mining industry in accordance with Australian and British Standards.
Prior to the development of the proposed instrument, a review of currently available and relevant equipment was carried out. The finds of this review were documented in an earlier report and confirmed that none of the existing devices was suitable for the application or amenable to reconfigured simply.
After nearly 12 months of R&D effort, a prototype instrument was designed, built and successfully tested.
The objectives of ACARP project C8027 were to develop the prototype into a commercially viable instrument.
These objectives have now been achieved. A commercial model, the "Whole Body Vibration Dosimeter, Model WBVD/1" is now available as a commercial product.
Outcomes and Benefits
- Real possibility for mine operators to scan their whole fleet of vehicles and identify those likely to expose their occupants to excessive vibration levels.
- Identification of vehicles in which rough ride is due to inadequate seat suspension and target this area as a control measure.
- Routine monitoring of workers exposure to WBV in accordance with the standard in force in Australia, at any desired frequency. Such a procedure would detect abnormal changes in vibration levels which might be caused by a degradation of the road condition, worn vehicle suspension and/or worn seat suspension for example.
- Simplicity of operation of the instrument and in-house testing would encourage:
- Frequent testing of the whole fleet of vehicles in operation and the development of a strategy to maintain an acceptable ride quality.
- Evaluation of vehicles with regards to vibration transmitted to the occupants prior to hire or purchase.
- Manufacturers would be encouraged to address the issue of ride quality at the design stage.
Long term benefits would presumable flow from better vehicle design initiated by competition to produce vehicles which meet a measurable ride quality specification.