Back to The MINER Act of 2006 and Related NIOSH Activities

Overview

Recent mine emergencies at the Sago, Alma, Darby, Quecreek, and Jim Walters Resources No. 5 mines highlighted the need for emergency communications between mine workers inside and personnel outside the mine. The Sago Mine disaster generated much discussion on the benefits of a miner tracking system.

Mines generally use reliable and effective communications systems1 for routine operations, but these systems require hard-wired networks, power supplies, and other infrastructure that are likely to be damaged or destroyed by a catastrophic event, such as a fire, explosion, or water inundation. Technologies are needed that will function in post-disaster environments. Knowing the locations of mine workers would obviously facilitate rescue operations, but reliable signal transmission to the outside of a mine after a catastrophic event is problematic. An electronic tracking system requires a reliable communications signal to relay location information to the surface. Technical barriers to in-mine or through-the-earth signal propagation must be overcome before reliable emergency communications and miner tracking will reach acceptable functionality.

1 Preliminary Assessment of Communications Systems for Underground Mines [Draft], Appendix E gives a comprehensive summary of available underground coal mine communications and commercially available communications technology.

The most basic requirement of a post-tragedy communication system is a communication link between the underground miner and the surface. A two-way system would be more useful than a one-way system, since escaping or trapped miners could relay valuable information outside. Moreover, a voice rather than text system is likely to prove much more useable in emergency conditions. However, the difficulty in using a voice-based system while wearing an SCSR with a mouthpiece must be addressed (this has been resolved for certain military and first responder applications - those solutions should be adaptable to mining). The emergency communication system should be part of a mine’s routine system, not a separate system, to better ensure that it will properly function when an emergency occurs. The urgent timetable for deployment of these systems means that a phased-in and evolutionary approach will be needed. Each mine will need different mixes of technologies to address its site-specific conditions and infrastructure. Finally, it's unrealistic to expect a system to operate in all parts of the mine. Nonetheless, it's imperative that the system provide the desired functionality in and around active panels and in escape ways.

Presently no system has been demonstrated that meets the most basic requirement for emergency communications, other than the PED system, which is limited in application based on the characteristics of the mine overburden, electromagnetic interference issues, and other application constraints. However, based on the work of the Mine Emergency Communications Partnership, there is considerable optimism that one or more two-way voice communication system prototypes could be further developed and brought to a commercialization phase within coming years. Moreover, other steps could be taken immediately to provide miners with emergency communication systems with a reasonable degree of functionality.

It's important to have realistic criteria/expectations for the performance of these systems given the state of technology or we'll be unable to deploy badly needed technologies:

1. It's unlikely that any system will work in all parts of all mines. We should strive for systems that will work in most parts of the mine, especially the active panels and the escape ways. Even within those areas there are likely to be dead zones. We should attempt to minimize or eliminate those.
2. It's unlikely that any system will work with every worst-case disaster scenario imagineable. While the goal should be to achieve ultimate reliability, we should not delay developing or deploying systems which will work for most but not all cases. For example, if the best system would work only for the majority of explosions that could occur in a given mine, it should be deployed.
3. The commercial availability and deployment of newer and better communications technologies could be at least 2 - 3 years into the future. In the meantime, more immediate actions can and must be taken to improve emergency communications. It's important to recognize that these actions can be building blocks for improved future technologies.
4. The performance requirements and expectations for a communications and tracking system are really mine specific. They should be considered within the context of the mine’s risk analysis and management plan, including the mine’s overall disaster response system, to ensure that the best possible protections are afforded to miners despite limitations in technologies.

NIOSH Projects

• Mine Emergency Communications Partnership

References