Mining and Machinery Struck-by Injuries

Overview

Mine workers perform tasks and control machinery in challenging conditions, often in close proximity to moving machines. At surface mines, large equipment often has limited visibility, making it difficult to see smaller vehicles and pedestrians. In underground mines, confined spaces, remote controlled equipment, and limited visibility make dangerous conditions for workers.

Injuries related to machinery strikes range from falls and crushing accidents to repetitive strain, like whole body vibration and overexertion.

Equipment control and emergency stop functions are now handled with software and programmable electronic systems. This means increased flexibility for mining machinery including:

• Rapidly changed or added control functions via software
• Improved quality by efficiently providing a variety of control functions and features
• Decreased costs

However, programmable electronic systems have also created new concerns and challenges about worker safety. New software programs can cause uncertainty and new failure modes that are different from electromechanical systems.

Dangers

Over 40% of the most serious injuries in the mining industry involve accidents classified as struck-by or caught-in machinery and equipment. These injuries include fatalities and permanent disabilities that occurred between 2000 and 2007.

For surface mining, collisions and driving over an unseen edge caused 3 to 4 fatalities per year between 2000 and 2007. For underground coal mining, pinning and striking hazards involving continuous mining machines have resulted in 37 fatalities since 1984. Striking and pinning accidents involving underground shuttle cars and scoops resulted in 16 fatalities between 2000 and 2010.

Prevention

Programmable electronic systems are widely used in the mining industry, including in longwall mining equipment, continuous mining machines, and mine hoists. However, the safe application of this new technology has been challenging.

Currently, only the permissibility of electrical equipment is addressed. This means the equipment can still be functionally unsafe when operated under PE control. This leaves unanswered questions on how to develop, evaluate, and maintain functional safety.

A safety panel composed of representatives from the mining industry and universities formed to discuss safety issues of PE-based mining equipment. NIOSH researchers used this input to develop a best practice recommendation report to address the safety life cycle for programmable electronic systems.

The reports consist of a nine-part series that address hardware and software for the life cycle stages of:

• Inception
• Design
• Approval and certification
• Commissioning
• Operation
• Change management maintenance
• Decommissioning

The safety panel developed these recommendations for use by mining companies, original equipment manufacturers, and aftermarket suppliers to these mining companies.

Proximity controls

NIOSH has developed specific research goals for preventing injuries involving powered machinery. Proximity detection is currently the primary research focus in this area. NIOSH has evaluated commercially available proximity detection systems for both underground and surface mining. Based on these findings, NIOSH introduced recommendations for testing and implementing systems and they are developing improvements.

For surface mining, NIOSH developed new proximity detection systems through research partnerships. This includes radar-based technology and one of the first GPS-based systems for mining equipment.

For underground mining, NIOSH is developing a prototype intelligent proximity detection system. It continuously monitors mine workers' positions in relation to machines and established safety zones. It disables specific machine functions to prevent unsafe movement toward mine workers. However, it still allows functions that do not put the worker at risk to remain operational.

After extensive research, NIOSH developed the Intelligent Proximity Detection (iPD) system. It provides situational protection based on the position of a mine worker relative to the machine. The iPD system can also accurately track the positions of mine workers and disable potentially hazardous machine motions.

Equipment design

Much work has been accomplished in the area of seating and whole body vibration effects on health and safety. NIOSH is developing and conducting testing in the areas of proximity warning systems.

These systems inform operators of how close they are to hazards in and around equipment. An audit program is also currently underway which will help mines to evaluate their equipment and jobs to reduce musculoskeletal injuries.

NIOSH is also conducting tests in the area of controls design to help limit acute injuries. For example, these are caused by operators inadvertently activating the incorrect control or the correct control in the wrong direction. Current research focuses on roof bolting equipment for underground mining. However, the principles and concepts will be applicable to the design of all equipment.

NIOSH also developed a shuttle car seat that has reduced major jarring and jolting better than any other commercially available seat. The leading manufacturer of shuttle car equipment in the U.S. provides the NIOSH seat as an option in its equipment list.