By Lee Buchsbaum

Since 1984, at least 33 coal miners have been killed nationwide while operating remote control continuous miner units. Of those, 28 victims had possession of the remote control in their hands when they were killed. Another six were killed while performing maintenance on the units. Alarmingly, in the five years between 2000 and 2004, 11 miner operators were crushed by their machines. Since then, four more continuous miner operators have been killed. Last year there were two more fatal crushing accidents from remote controlled continuous miner units in addition to three fatalities from shuttle car accidents. Crushing or pinning deaths from continuous miner and shuttle cars, in terms of preventable and controllable risks, have become perhaps the number one hazard for underground miners according to safety experts.

After tracking the rising number of injuries and fatalities, the Mine Safety and Health Administration (MSHA) began to search for answers to combat this trend. Over time, MSHA and industry safety officials began to turn to the emerging technology of infrared and electronic proximity detection as a way forward. In February 2009, MSHA’s New Technology Program Manager David Chirdon published results of the agency’s long study on proximity detection. Conducted to address what it perceived to be a large number of crushing and pinning type fatal accidents with the operation of remote control continuous mining machines, MSHA initiated a program “to pursue the development of a tag-based, electromagnetic technology that can be deployed on mining machinery” to alert miners once they breached what MSHA terms “a danger zone around operating machinery.”

MSHA developed several criteria for a new detection system. The agency wanted to create, test and promote a system that provides automatic proximity detection and machine shutdown to protect personnel from being run over, crushed or pinned when they are positioned in a hazardous area near the machine. The proposed systems also needed to be capable of giving the operator an audible or visual warning when entering a “protection” zone before the machine shuts down. Similar systems have been developed and are currently in widespread usage in South Africa where SASOL uses proximity detection systems extensively underground.

The purpose of the new MSHA-created system, which may become part of another series of federally mandated safety measures, is to visually and physically alert miners as they approach and encroach upon known dangerous areas around heavy mining equipment and in other dangerous work zones.

Real World Use & Industry Skepticism
To date MSHA has approved three systems for underground use, all of which involve the miner himself wearing an electronic unit that communicates or determines proximity with the miner unit via antennae. These approved proximity detection systems include Nautilus International’s Coal Buddy System, Matrix Design Group’s M3-1000 System and Strata’s HazardAvert System, which was developed by Frederick Mining Controls. Each has undergone extensive real world testing, either domestically, internationally or both, in a variety of underground production applications.  According to the agency, “the systems have proven to be reliable.”

Early in the development stages, MSHA conducted a position study of the operation of remote control continuous mining machines at several mines in West Virginia to determine when proximity detection was most needed. This study concluded that proximity detection “should be activated while tramming in high or turbo speed and not be activated during production due to the operating location of the remote controlled continuous miner operator relative to the continuous miner.” The study concluded the operator often had to be positioned very near the machine for adequate vision while turning crosscuts. This was determined not to be detrimental to the effectiveness of the proposed technology due to the limited machine movement and therefore limited hazard exposure during this particular operation.

The study further concluded that “proximity detection should be available around the entire machine during tramming” and “should be provided to others on the section who assist the continuous miner operator tram the miner.” Based on the position study conclusions and the relative location of the victims of fatal accidents, it was determined that MSHA’s goal should be to provide proximity detection around the entire machine perimeter when tramming in high speeds. Proximity detection could be disabled during cutting and loading. Other section personnel should be protected in addition to the remote control continuous mining machine operator.

Probably the most difficult determination of all has been identifying the ideal protection zone. This discussion inevitably becomes a tradeoff between optimal miner protection and practical operation of the system. While technologically it is relatively simple to provide a 10-ft protection zone around the entire machine, it is nearly impossible for a remote control continuous miner operator to adequately and safely perform all of the necessary machine operation tasks while continuously positioned that far from the machine. Machine operators have expressed concern over the inability to properly set their sights when turning crosscuts from remote locations.

One of the on-going concerns MSHA has is that the operators who work around this equipment know they are supposed to stay out of the so-called red zone. While trying to achieve the highest degree of productivity they may inadvertently work in this dangerous area up to 80% of the time. And, studies, MSHA said, show individual miners know they are putting themselves at risk.

Beyond installing proximity systems MSHA counsels continuous miner operators to adhere to safe working habits and stay out of the machine’s red-zone. The debate over installing or mandating proximity detection is going to be a very polarized discussion. “Half the people you talk to are going to say it cannot be done. That it’s not realistic for a miner operator to stay outside of the red zone and do their job. The other half are going to say he can do just that and proximity detection is the answer to staying out of that red zone,” said one MSHA researcher.  

MSHA has documented that most of the continuous miner accidents occur when equipment is being moved from one place to another. The two miners killed in 2010 were operating and re-positioning their remote control continuous miner machines when they were crushed. The operator accidently had bumped the controls, and split the trim levers while standing too close to the machine.  

Three Approved Systems
Currently, many mine operators are pushing back claiming the technology isn’t ready yet. And indeed, there have been problems with it as it has evolved. Estimated costs for each proximity detection system range from $25,000 to $35,000 per machine.

Basically two out the three approved systems have field generators on them that create a magnetic field around the continuous miner. The miner himself is wearing a transceiver on his belt or in his coveralls that measures the strength of that magnetic field. Field strength changes depending on the distance away from the field generator. If an operator approaches the outer zone, the system will send a command to the machine to activate a warning light. If the operator ignores warning light and continues to get closer to the machine, the belt pack unit can tell the machine to turn off.

Following extensive testing of Nautilus International Buddy System MSHA issued an approval for compliance to Title 30 Code of Federal Regulations (30 CFR) Part 18 for the Nautilus Coal Buddy Proximity Detection System in July 2006.

According to MSHA, by the end of 2010, Nautilus International’s Coal Buddy was installed and being tested at ICG’s Sentinel mine and Massey Energy’s Independent Coal Cook and Randolph Mines.  One system was also ordered by Patriot Energy for its Federal No. 2 mine and Massey had also ordered another 16 Buddy systems.  

In recent years, Massey Energy’s official policy was for the operators to not work within that red zone. The company at first was very bullish about the system, but over time, and after both some testing and failures, its march toward adoption has slowed. Alliance Resources, however, has gone further than any other company in terms of system deployment. Currently, they have at least 10 systems installed on continuous miners and some reports indicate it plans to have all of its continuous miners so equipped by 2012.

Matrix Design Group submitted an application to MSHA in late 2007 for approval of its M3-1000 Proximity Detection System. This system reportedly uses a different approach. While it uses the same electromagnetic, tag-based technology as other systems, the device worn by the miner generates the field and the receivers are mounted on the continuous miner.

The M3-1000 system was approved by MSHA in February 2009 and has been installed at Alliance’s River View, Pattiki, Dottiki, Mettiki and new Tunnel Ridge mines. Matrix is currently conducting field tests and anticipates the system will be commercially available in early 2011. Joy Mining Equipment, in partnership with Matrix, has stated it is going to start offering the system to its customers.

The M3-1000 system creates several different zones based on the distance between the operator and the machine. As the operator moves closer to it, he’ll first enter a warning zone which triggers a series of yellow LED lights mounted on each system receiver mounted on the miner machine.  As he gets closer to the machine, he will enter the “shutdown” zone that triggers a series of red LED lights and disables certain functions such as the tram and conveyor swing.

Strata’s HazardAvert system creates a magnetic marker field around machinery using a field generator. Installed on the machine, the generator creates low-frequency electromagnetic signals to mark areas considered to be potentially hazardous. The marker field can encompass the entire machine and its turning radius, or be specific to certain areas. Workers and operators wear a Personal-Alarm Device (PAD) that detects and measures the magnetic marker field to determine their proximity to the machine and alert them of possible danger to their safety.

Single or multiple generators can be used on the same machine to create the marker field. For smaller equipment, a single generator can define a zone that covers all parts of the machine and its turning radius.  Multiple generators can be used to create complex zone shapes. These are done according to user preference and to accommodate tight working spaces. Shaped silent zones can be added inside the marker field to allow operators to function in specified areas close to the machine without activating the alarm or disabling the machine.

Strata’s HazardAvert System has been tested at CONSOL Energy’s Jones Fork mine, ICG’s Viper mine, and CONSOL’s Buchanan mine.

It was the first one improved in 2006. It received extensive testing by SASOL in South Africa where it is installed and in operation at more than 20 sections. Strata currently has hardware underground on several continuous miners and has an experimental permit for testing in Virginia and Alabama, but the company has no systems currently in full operation in the U.S.

Buchsbaum is a Denver-based freelance writer and photographer specializing in industrial subjects. He can be reached through his Web site at or by phone at 303-746-8172.