7
drilling limitation at the mine (McElhinney et al., 2023).
This required cutting the spring end on each anchor to be
installed which resulted in the additional hazard of cutting
metal with wire cutters. The researcher tasked with this job
wore safety glasses and gloves at all times and no injuries
occurred.
While both rib and roof extensometers share many
of the same installation hazards, they also present distinct
risks. A rib extensometer is installed within the pillar, much
like a BPC. On the other hand, a roof extensometer, as
its name suggests, is installed in the mine roof. The instal-
lation of a roof extensometer often necessitates the use of
a ladder, bringing along with it the ladder-related hazards
mentioned earlier.
MULTI-POINT BOREHOLE EXTENSOMETER
(MPBX) INSTALLATION HAZARDS
A multi-point borehole extensometer (MPBX) is used to
measure displacement at specific anchor depths in a bore-
hole (See Figure 11).
Similar to the multipoint roof/rib extensometer
installation, the MPBX installation utilizes a roof bolting
machine to drill boreholes typically into the rib for the
instrumentation to be placed.
Working in close proximity to the roof bolting machine
carries the hazards of being struck by the equipment and
caught in/between rotating parts during drilling. In addi-
tion to the hazards of the roof bolting machine, there are
roof and rib hazards.
Another major step in the process of installing MPBX
is grouting the instrumentation in the holes. While
Figure 11. Example of a multi-point borehole extensometer
typically grouted in place in the rib to measure horizontal
displacement
completing this step, researchers can be exposed to skin
burns, eye irritation, and respiratory hazards. The safe
installation of 6 MPBXs in addition to other instrumen-
tation was recently completed by NIOSH researchers
(Rashed et al., 2021).
STANDING-SUPPORT LOAD CELL
INSTALLATION HAZARDS
Standing-support load cells are used to measure the loading
performance of standing support in the mine (See
Figure 12). Hazards associated with the installation of a
standing-support load cell include manual handling haz-
ards and slip, trip, and fall hazards.
Manual handling hazards are of concern due to the size
and weight of the instrumentation where improper lifting
techniques and fatigue from prolonged handling can cause
injuries to the researcher. Slip, trip, and fall hazards are also
present, due to the environment of the mine and having to
physically carry the load cells to the study site.
An example of the material handling hazards associ-
ated with standing support load cells was encountered by
NIOSH researchers during the instrumentation installation
in the bleeder entries at a longwall mine in Southwestern
Virginia (Klemetti et al., 2018).
At this installation site, it was required that 23 pre-
filled loadcells be carried by hand from the end of the track
to the installation located in the longwall bleeder entries.
This required multiple trips by multiple researchers carry-
ing these heavy 28” and 36” load cells.
Figure 12. An example of a standing-support load cell
installed on top of a can type standing support between two
sheets of plywood.
drilling limitation at the mine (McElhinney et al., 2023).
This required cutting the spring end on each anchor to be
installed which resulted in the additional hazard of cutting
metal with wire cutters. The researcher tasked with this job
wore safety glasses and gloves at all times and no injuries
occurred.
While both rib and roof extensometers share many
of the same installation hazards, they also present distinct
risks. A rib extensometer is installed within the pillar, much
like a BPC. On the other hand, a roof extensometer, as
its name suggests, is installed in the mine roof. The instal-
lation of a roof extensometer often necessitates the use of
a ladder, bringing along with it the ladder-related hazards
mentioned earlier.
MULTI-POINT BOREHOLE EXTENSOMETER
(MPBX) INSTALLATION HAZARDS
A multi-point borehole extensometer (MPBX) is used to
measure displacement at specific anchor depths in a bore-
hole (See Figure 11).
Similar to the multipoint roof/rib extensometer
installation, the MPBX installation utilizes a roof bolting
machine to drill boreholes typically into the rib for the
instrumentation to be placed.
Working in close proximity to the roof bolting machine
carries the hazards of being struck by the equipment and
caught in/between rotating parts during drilling. In addi-
tion to the hazards of the roof bolting machine, there are
roof and rib hazards.
Another major step in the process of installing MPBX
is grouting the instrumentation in the holes. While
Figure 11. Example of a multi-point borehole extensometer
typically grouted in place in the rib to measure horizontal
displacement
completing this step, researchers can be exposed to skin
burns, eye irritation, and respiratory hazards. The safe
installation of 6 MPBXs in addition to other instrumen-
tation was recently completed by NIOSH researchers
(Rashed et al., 2021).
STANDING-SUPPORT LOAD CELL
INSTALLATION HAZARDS
Standing-support load cells are used to measure the loading
performance of standing support in the mine (See
Figure 12). Hazards associated with the installation of a
standing-support load cell include manual handling haz-
ards and slip, trip, and fall hazards.
Manual handling hazards are of concern due to the size
and weight of the instrumentation where improper lifting
techniques and fatigue from prolonged handling can cause
injuries to the researcher. Slip, trip, and fall hazards are also
present, due to the environment of the mine and having to
physically carry the load cells to the study site.
An example of the material handling hazards associ-
ated with standing support load cells was encountered by
NIOSH researchers during the instrumentation installation
in the bleeder entries at a longwall mine in Southwestern
Virginia (Klemetti et al., 2018).
At this installation site, it was required that 23 pre-
filled loadcells be carried by hand from the end of the track
to the installation located in the longwall bleeder entries.
This required multiple trips by multiple researchers carry-
ing these heavy 28” and 36” load cells.
Figure 12. An example of a standing-support load cell
installed on top of a can type standing support between two
sheets of plywood.