A Different Perspective: NIOSH researchers learn from 

CM operator responses to proximity detection systems

Written by Emily Haas and Joseph DuCarme 

Coal Age, October 2015 

Researchers collect some of their information in the field. 

Given the consistent increase in the number of proximity detection systems (PDSs) being used in 

underground coal mines, it is critical to understand ways that PDS technology influences mineworkers’ 

assessment of their environment and subsequent behaviors. Regardless of the particular PDS model, it 

is important to document these general responses to the technology and any changes in workers’ 

ability to perceive, understand and make safe decisions on the job. 

More specifically, being able to anticipate certain behavioral responses may help minimize preventable 

incidents and guide future safety training and communication related to the PDS. To this end, the 

National Institute for Occupational Safety and Health (NIOSH) recently completed a preliminary 

assessment to understand continuous mining machine (CMM) operators’ perceptions and behaviors in 

response to the PDS. 

In its preliminary assessment, NIOSH researchers interviewed nine CMM operators during January and 

February 2014. The nine CMM operators represented five mine sites in the Appalachian region. Six of 

the operators had been using PDS between seven months and two years. The other three had 

knowledge of, but no experience using PDS. 

The mining experience for the nine operators ranged from three to 33 years (mean = 20.8 years) and 

their experience as CMM operators ranged from 1.5 to 33 years (mean = 11.8 years). In the interviews, 

the operators discussed participation in high-risk behaviors, hazard identification, mitigation strategies 

and the impact of PDS in relation to these topics. 
The following offers these mineworkers’ perspectives, and highlights how their job tasks and 

environment could be and are affected when learning how to use PDS technology. A more detailed 

discussion of the results summarized in this article can be found by referring to Haas and Rost (2015). 

PERCEIVED INFLUENCE OF PDS ON OPERATORS’ HAZARD RECOGNITION, 

COMPREHENSION, RESPONSE 

Prior to having a PDS equipped on their CMM, operators communicated that they had the confidence, 

training, and experience to mitigate hazards in their mine and make decisions quickly, if necessary. 

Due to their perceived ability to make these safe and quick decisions, CMM operators discussed times 

they had previously chosen to stand in the red zone (e.g., increased visibility or production). 

Broadly, one operator said, “It’s really all about balance — what makes my job easier between not. 

When I’m standing in the red zone I always think about that [it being risky]. You’re always weighing the 

pros and cons when you’re doing it or thinking about doing it.”

In contrast, since the installation of the PDS, operators noted standing in the red zone much less or not 

at all. As one operator said, “Honestly, I was surprised when we started using this. I eventually learned 

to do things different. I learned what I shouldn’t be doing, but was. I was surprised how many times it 

shut off on me at first.”

In the interviews, the operators often discussed the process of retraining themselves to regularly stand 

outside of the red zone again once using the PDS. As one CMM operator said, “It is frustrating and 

you’re learning all over again.” Also, because operators started to place themselves in different, more 

unfamiliar positions, they discussed needing to be more aware of additional hazards including visibility 

of other equipment and mineworkers. One operator explained, “I’m not in the red zone, which is safer. 

But at times I have to stand too far away to tram and I don’t want to be that far away because I can’t 

see as well.” In response to being in different placement positions around their CMM, operators 

discussed the importance of re-acclimating themselves with certain place-change scenarios and 

maintaining heightened awareness on the job. 

Although changes in CMM operator comprehension and behavior occurred mainly in response to 

operating from a different place in relation to their CMM, they also discussed other risky decisions they 

made while learning how to operate their CMM with the PDS such as “cheating” the technology and 

working faster to meet production goals. Despite these initial frustrations with the PDS, most CMM 

operators recognized the positive outcomes of using the technology and eventually felt they were able 

or would be able to safely identify and mitigate project workplace hazards while using the technology. 

ASSISTING WITH SAFE TECHNOLOGY INTEGRATION

These discussions with CMM operators indicate that mine operators and mine health and safety 

personnel play a key role in helping the workforce anticipate and safely respond to changes in their 

environment upon operating a mining machine that is equipped with proximity detection. Based on 

these discussions, the following considerations are offered for mine operators and safety personnel to 

support workers’ ability to continue making safe decisions on the job:

 Introduce and discuss PDS technology as a learning tool. CMM operators commonly said that 

mine technologies, including the PDS, helped them to recognize and avoid emerging hazards 

and learn or relearn about safety rather than change their behaviors. This learning-oriented 

communication approach to framing the technology, rather than characterizing it as a tool that 

“does not let an operator stand in the red zone,” may encourage a more positive response 

toward the technology. 
 Be mindful of potential complacency. Regardless of the technology being used, it is possible for 

anyone to become complacent and momentarily lose focus while completing a job task. To help 

maintain worker awareness, communication and safety meetings related to PDSs should not 

end once the technology is fully integrated. Rather, dialogue should continue beyond initial onthe-job awareness and training to ensure that operators stay alert for potential hazards on the 

job. 

 Acknowledge changes in the mine environment after introducing the PDS. Realistic dialogue 

with CMM operators about how the PDS technology is affecting their work environment and 

ability to make safe, quick decisions may be needed. One barrier referenced by CMM operators 

after using the PDS was a loss in production time. Perhaps at first use, discussion of a balance 

between production and safety during the introduction of this safety device should be 

considered. 

Despite potential barriers when first introducing a PDS into a mine, operator feedback revealed that if 

the technology is working properly and individuals receive realistic training and communication about 

how the technology should function, it can be a useful device to help call attention back to hazards in 

the mine environment. As one operator said, “In my opinion, I think it can be easy to get distracted, 

there is so much to watch for, you can always watch for the wrong thing one time.”

Although no technology is foolproof, providing operators the opportunity to notice and adapt to additional 

hazards of which they may not be aware of may continue to enhance their awareness on the job. 

PROGRESS IN INTELLIGENT PROXIMITY DETECTION SYSTEMS

Based on the results of several field performance tests, feedback from stakeholders and comments 

from the CMM operators throughout our interviews, NIOSH researchers have been working on the 

development of a more advanced version of PDS technology. They have recently created an intelligent 

proximity detection system (iPDS) using Mine Safety and Health Administration-approved 

electromagnetic proximity detection hardware (for more information, see DuCarme et al., 2015). This 

technology contains efficient software that determines the real-time position of any worker relative to 

the CMM. 

The system then intelligently responds with visual signals and disables only machine motion that could 

cause striking or pinning — thus greatly reducing the frequency of false alarms. By blocking only 

dangerous machine functions while allowing other motions to continue, the iPDS would be less 

interruptive to the CMM operator’s work. As a result, the incorporation of this technology into 

commercially available PDSs may lead to greater acceptance by the mining workforce while continuing 

to maintain the safety of mineworkers. 

References

DuCarme, J.P.; Carr, J.L.; and Jobes, C.C. (2015). Proximity Detection With Selective Machine Shutdown. Print 

proceedings of 144th Annual Society for Mining, Metallurgy, & Exploration Conference held in Boulder, Colorado, 

February 15-18, 2015. (Preprint 15-083). 

Haas, E.J., & Rost, K.A. (2015). Integrating technology: Learning from mine worker perceptions of proximity 

detection systems. Print proceedings of 144th Annual Society for Mining, Metallurgy, and Exploration Conference 

held in Boulder, Colorado, February 15-18, 2015. (Preprint 15-083). 

Emily Haas and Joseph DuCarme are part of the National Institute for Occupational Safety and Health’s (NIOSH) 

Office of Mine Safety and Health Research in Pittsburgh.