Operators and other mine personnel are faced with the question of where they
should position themselves while remotely operating machinery. The most important
factors are visibility, roof condition, ventilation and avoidance of moving machinery. The
optimum location for an operator to stand may differ depending on length of cut and a
number of other variables. The goal of the work sampling method was to identify
differences in operator positioning in standard versus extended cuts. In particular, it was
necessary to determine what cues and information were used. The locations of workers and
equipment at the face area were recorded along with the direction the operators were
looking and at what stage they were in the mining process. There did not appear to be a
large difference between the before and after conditions. However, continuous miner
operators would sometimes stand in an unsafe area in order to observe the longer cuts.
Turning a crosscut appears to be the most variable and difficult task for operators regardless
of length of cut. In addition to operator position and direction of view data, efforts continue
to identify specific cues used to operate equipment remotely. Further research and analysis
will determine the effects these changes have had on the continuous miner operator's ability
to safely operate with new work methods and equipment changes.

2.5 Analysis of Proposed Recommendations

Once the human factors problem areas were more specifically defined, the next
slep was to investigate several alternative solutions and to study their impact on the
technical aspects of the system. Work is underway to determine how to increase operator
visibility through alternative mining plans and angled crosscuts. These changes rely heavily
on ground control and ventilation analysis of the proposed systems. It is essential to
attempt to determine the effects of these possible solutions prior to their implementation
and continuously evaluate the solution after implementation.

3. Discussion

When changing from on-board operation to remote operation, the continuous miner
operators were not the only ones impacted. Other mobile equipment operators in the face
area were affected by this change as well. Before remote control, other face crew workers,
always knew the miner operator was on the mining machine. Now, the operator could be in
several locations, presenting problems for everyone. Though work is progressing to resolve
existing problems through the methods outlined, many of these concerns could already have
been dealt with if a design team had integrated human factors methods in the development
stages. Extended cut technology is just one example of a process that could have benefitted
by early ergonomic intervention. Many industries other than mining can use this approach
to evaluate current and new designs. If human factors issues are ignored, and major design
decisions have been made, it is difficult to make more than minor changes after the fact.
Simply put, the earlier human factors becomes involved in a design process, the better (2].

References

[1] Robert K. Merton, Social Theory and Social Structure. Glencoe, IL. Free Press, 1949.

(2] A. Chapanis, Human Factors in Systems Engineering. John Wiley & Sons, Inc., 1996.

(3) E. Bauer, L. Steiner, and C. Hamrick, Extended Cut Mining and Worker Safety in
Underground Coal Mines. SME preprint 95-60, 1994

[4] L. Steiner, F. Turin, and C. Hamrick, An Ergonomic and Statistical Assessment of
Safety in Deep Cut Mining. In: Improving Safety at Small Underground Mines. Special
Publication 18-94, United States Department of Interior, Bureau of Mines, 1994.


A Method for Evaluating System Interactions
in a Dynamic Work Environment

L. Steiner, F. Turin, and K. Cornelius
National Institute for Occupational Safety and Health
Pittsburgh Research Center
P.O. Box 18070
Cochrans Mill Road
Pittsburgh, PA USA 15236

As technology evolves, accidents may occur because human-system interactions were
not considered adequately in the process. A systematic methodology can be used to
evaluate the causes of mishaps and to develop recommendations that will enhance
salety. A recent trend observed in underground coal mining is used to illustrate this
Principle because an underground mine is a dynamic work environment. Mining is
characterized not only by frequent geologic changes but by technological evolution
that ean seriously degrade human performance and compromise worker health and
safely. The case exemplified in this paper involves implementation of remotely
controlled equipment for extended cut mining. Extended cut mining technotozy
evolved with minimal ergonomic consideration even though the change from an-
buard to remote machine operation dramatically modified the role of the human
component. In response to concern that system interactions should be examined more
closely. a methodology was developed to identify hazards.

1. Introduction

Almost every process has a predecessor, and studying the predecessor helps to
define needs and shortcomings to be addressed in the new design. It also suggests what
information is needed by the users in order for them to be able to operate safely and
effectively. The end users of a system can provide important feedback to better evaluate
current and proposed designs. When new technology is introduced into a system, accidents
may occur before it ts realized that human-system interactions were not considered
adequately in the design process. A systematic methodology to evaluate the causes of these
mishaps and to develop remedial recommendations can enhance safety. This paper
illustrates how such an approach was used to assess remote machine operation in
underground coal mines

The dynamic work environment of underground mining with its unpredictable
geologic anomalies can result in numerous hazards. Most of these hazards, including mine
roof collapse, occur near the working face where coal is being extracted. The face area is
also where the most intricate interactions of people and equipment occur. For these
reasons. a high priority has been placed upon minimizing hazards to the workers at the face.
During the past decade remote control technology has been introduced to provide the safer
environment. Now, machine operators are not required to be on the equipment, but can
position themselves back and behind the machine. Because of that innovation, however,
the technology has also provided a way for mines to take longer lengths of cuts, thus
increasing production and leading to widespread adoption.


Once remote control technology began to be widely used, new issues became
evident. Operator positioning was the primary human factors’ concern expressed by
industry personnel, but there were many technical questions involving ventilation and
ground control during increased cut depths. From a researcher's perspective. the ability to
answer these questions is confounded by the fact that each mine is very different in terms of
geological characteristics, management and mine planning. equipment. seam height. and
geographical area. Solutions are difficult to generalize. Nevertheless. it is essentizt to
develop mechanisms for mines to evaluate new systems in order to predict and reduce
accidents.

Extraction methods and equipment changes must allow for the ability of workers to
adapt to changes in their dynamic mining environment. Consideration should be given to
how the worker will use familiar information to make decisions in now unfamiliar
situations. There will be both intended and unintended consequences. Robert Merton {1}
denoted the impact these “functions” have on systems. Manifest functions are “intended
and recognized by participants in the system” and latent functions are “those which are
neither intended nor recognized.” Merton's notion reiterates the need to provide
comprehensive information for workers transitioning to a new system. Designers try to
anticipate and eliminate surprises, but it is impossible to eliminate them all, How. then.
will the new system affect the tasks the workers are currently used to? As suggested below.
this question may be addressed and more “latent functions” predicted with a planned design
process which includes strong ergonomics input to determine interactions and behaviors of
participants.

2. Approach

A simple system or product design process involves several stages proceeding from
general to specific. It starts with the definition of a need and a plan to produce a solution.
and ends with a final product to monitor and evaluate. The process is iterative and each
stage can be revisited at any time to improve the design of the system. It is critical to
integrate ergonomics into each stage of the process {2}. Injuries can be reduced or avoided
through proper consideration, planning, testing and retesting. Effort should be given to the
human-machine-methods-environment interface from the onset. Regarding extended cut
mining, the authors have investigated changes to interfaces in order to determine what
impact the new process has on the worker's ability to adapt in the dynamic work
environment. The following questions needed to be answered: What effect does the
equipment change have on the operator and other workers in the face area? How do work
methods change due to equipment change and relocation of the operator?

Several analytical methods were used to answer these questions. The methods were
used interactively at different stages of the investigation.

2.1 Literature Review

‘An examination of the literature about new mining equipment and methods revealed
that most concerns with implementation of the extended cut method lay in the areas of
ground control and ventilation. These discussions centered upon regulatory compliance and
production enhancements. There was little evident concern for specific operator needs.
This review led to a better understanding of the system and guided development of methods
that could be used to target human factors problem areas.

2.2 Accident Analysis

An important aspect of research to assess the safety of extended cut mining has _
been examination of accident data compiled by the Mine Safety and Health Administration
(MSHA). The results of evaluations for 1990 and 1991 are provided by Bauer (3] and


Steiner [4]. Accident data of mines that had MSHA approval to take extended cuts were
compared to accident data of mines which did not have extended cut approval. It was
hoped that a comparison of injury incidence rates would offer insight into whether extended
cut mining introduced new hazards or exacerbated existing hazards. Injury rates at mines
with approval were higher than those at mines without approval, but fatality rates were
lower. Mines with extended cut approval had higher injury incident rates for accidents that
involved a worker being struck by or against something, accidents related to the handling of
materials, and accidents involving a slip or fall. However, it was not possible to relate
safety issues directly to extended cut mining activities. It would have been desirable to
compare characteristics of accidents that occurred when an extended cut was being taken to
those of shorter standard cuts; however, this information could not be derived from MSHA.
accident records. The implication to be drawn from this is that reporting methodologies
should be changed to reflect changes in technology.

As a corollary, an exploratory study was initiated at two mines following the
occurrence of fatal accidents to machine operators working within an intersection during
extended cut mining. This study included a review of MSHA accident reports, interviews
with face crew members, and meetings with representatives of MSHA, the United Mine
Workers of America (UMWA), and the US Bureau of Mines (USBM). Safety concerns
specific to worker activities within an intersection were identified. Although the accident
data analysis had significant limitations, the results of those efforts combined with findings
from the exploratory study provided insights that were used to develop more specific mine
site evaluation strategies.

2.3 Interviews

An interview guide was developed to identify general safety issues. In particular,
the goal was to determine what aspects of this technology were problematic to the mining
industry. Topics included mining experience, work methods and procedures used,
accidents and injuries, manual materials handling, control layout and design of equipment,
visibility, ventilation, operator protection, maintenance, and general safety. Overall,
workers had a positive attitude toward this technology. However, visibility of continuous
miner operators and some aspects of maintenance were identified as common problems. It
was learned that major differences exist in the specific type of problems encountered at
each mine. A generalized solution approach would be an ineffective way to deal with
diverse miner problems. Instead, data obtained from the interview guide was used to
identify what areas needed further examination and to devise a systematic approach to
analyze this technology.

A subsequent questionnaire was administered at mines in a particular geographical
area in order to more narrowly focus some problem areas. The physical location of the
operator during the turning task was an evident concem. The questionnaire also revealed a
less than optimal illumination scheme on the continuous mining machine. Further research
found that no changes had been made to the lighting systems on the machines since remote
control was introduced.

2.4 Activity Analvsis/Structured Observations

More information was required to determine the needs of workers doing specific
tasks in the mining cycle. Work sampling techniques are frequently employed to provide
information on the proportion of time spent by a worker on various activities. Ideally,
collecting and analyzing. information prior to implementing new technology would help to
address potential problems. Mines that had not yet implemented extended cut technology,
but were preparing to start, were identified. It was determined that useful information could
be collected using work sampling techniques by examining mines both before and after
implementing the longer cuts.