Underground » Health and Safety
The Australian underground diesel vehicle fleet has evolved since diesel powered Baldwin locos were introduced in 1964. Today, there are some 1140 diesel powered free steered vehicles in service, and perhaps in excess of 100 track locos with various power sources. Caterpillar diesel engines predominate the market. Cable tethered vehicles like shuttle cars are numerous. All underground vehicles classes in Australian collieries are virtually unique. Diesel powered free steered vehicles are between 15% and 30% more expensive to purchase, and 50% more expensive to operate than their counterparts in Australian underground metal mines. These cost premiums are largely due to a combination of the unique regulatory requirements and the few machines of any type built at any one time. Australian collieries appear to want to alter every machine before they consider it fit for use, and this is also adversely affecting their cost.
Whilst the mechanical design of cable tethered vehicles is similar to that in the country of origin i.e., USA, the electrical equipment is designed to specific Australian Standards.
The Australian market has been driven into a position where its unique regulations and attitudes preclude the efficient importation and use of overseas developed machines, which generally are built in larger volumes, and therefore should be cheaper. It also requires all diesel vehicles to be explosion protected regardless of the operational location.
Colliery vehicles can be associated with a number of significant risks, including:
- their ability to ignite flammable gases and other matter
- loss of control, particularly on slopes
- pinch, entrapment & sprain injuries from use or maintenance
- injuries from unwanted release of stored pneumatic, hydraulic or spring energies
Of these significant risks, the ignition of flammable gas is isolated to those areas (generally close to the working face) where legislation requires the installation of explosion protected electrical equipment. However the other risks can be manifested at any place in any coal mine. This means that controls for these general risks should ideally be in place for all vehicles. However controls unique to flammable gas ignition, should only occur where there is some significant risk of flammable gas being present.
Whilst electrical installations comply with this principle, this is not the current legislative position with diesel powered equipment. there is a significant opportunity for change and reduced cost of ownership. Means of controlling vehicle access into hazardous areas are available and these uses should be evaluated.
The proposed legislative model for diesel powered vehicles in the USA, which has 3 classes of vehicle, is put forward as more reflecting the balance between risk and control, and should receive consideration here.
The existing legislation and Australian Standards provide little opportunity for innovation, whilst still managing risk to acceptable levels. For example, non polluting fuels like CNG and LPG are precluded because of the prohibition on spark ignition, and in NSW, because of the direct stipulation for diesel fuel.
Legislated raw exhaust gas (engine) emission limits, when coupled with legislated ventilation values, result in atmospheric gas pollution far less than the Australian community standards (viz Worksafe) and these stringent raw gas levels are restricting the introduction of new generation, high performance engines.
In particular, regulating diesels to produce limited NO is resulting in increased CO and particulates. It is suggested that largely unaltered diesel engines, used in normally ventilated mines, would result in atmospheric pollution levels, less than the appropriate Community Standards, and therefore the raw gas control is a costly and redundant measure.
Risk Review Results
A team of highly experienced industry personnel reviewed all the risks associated with operating vehicles. They suggested a number of activities which, if implemented, would improve the management of risks in a number of areas.
Low Energy Electrics
- Fire suppression systems should be considered to counter electrical fires and may particularly apply to vehicles used in single entries.
- Design should limit the build up of static electricity for vehicles in hazardous areas
- Good practice codes and standards like IP55 should be applied to exclude dust
- Design & operational reviews should incorporate potential errors with Programmable Electronic Systems
- The NSW MDG1 should cover this
- Controls for electronic systems should be incorporated in risk reviews
High Energy Electrics
A design guide is needed to cover all aspects of wiring. AS3000 may assist
The Mine Managers transport rules should deal with tyre loadings
Speed Control Systems
- Effective speed indication is needed. Alarms linked to grade and mass may assist
- Direction indication needed.
Vehicle Cabins & Loading Systems
- Correct ergonomic consideration is needed in design reviews
- Draft MDG on cab design to be applied
- Occupational safety requirements should prevail
Guarding standards should be driven by occupational safety needs
- A standard is required for traction battery use
- Dangerous Goods Acts should apply
- Australian Standards on elevated work platforms should apply
- Managers Rules should reflect risks
- Parts of vehicles should not become work platforms unless designed as such
- Good engineering practice should apply. MDG1 gives some guidance.
- Wherever possible they should be eliminated from design
- Effective protection needed against bursting, impact damage, overpressure
The report contains the following Appendices:
- Appendix A: Risk analysis process and results
- Appendix B: Legislation comparison.
- Appendix C: Discussion on particulate emission and studies related to exposure.
- Appendix D: Design restraints and costs of underground vehicles.