2
which needed a specialized drill bit (Fitz Simmons, 1979).
These borescopes did not meet the intrinsic safety criteria
required to obtain Mine Safety and Health Administration
(MSHA) approval for use inby the last open crosscut of
a development section. Because of that restriction, bore-
scopes could not be used to identify roof lithology at the
face of an active mining section.
The first fiberoptic borescope was developed in 1979
by the U.S. Bureau of Mines. The fiberscope was 6-ft long
and light enough to be operated by one person. The light
source for the scope utilized an MSHA-approved miner’s
cap light which was permissible inby the last open crosscut
of a development section. The scope also included a camera
to take still images of the strata in the roof (Fitz Simmons
1979).
Many papers have been written discussing the benefits
and deployment strategies of borescopes. This section will
discuss some of the key advancements utilizing borescopes,
since its inception, to identify roof lithology for roof con-
trol. James Tennant showed the practicality of borehole
scoping by describing the use and analysis of fiberscope
observations. The analysis included geologic cross sections
developed directly from the data collected from a borescope
that displayed changes in roof lithology through 4 entries
at Martinka No.1 Mine. The borescope observations high-
lighted mud seams in the roof that caused support issues
which resulted in the mine changing to longer primary
bolts to achieve anchorage above the mud seams (Tennant,
James M. 1982).
John Shepherd utilized the deployment of borescopes
to identify roof lithology and roof stability throughout
longwall gateroads. He concluded that borescopes are a
beneficial tool to identify lithological variations and roof
fractures. Identifying the changes in lithology and mapping
the features aids in determining roof support decisions
(Shepherd, J. et al. 1986).
Borescope usage has also led to roof control improve-
ments in other underground mining commodities such as
limestone. John Ellenberger developed a numeric rating
system for roof conditions in stone mines called the Roof
Quality Index (RQI). The RQI rating is based on borescope
observations and provides a numeric value to the observed
roof lithology based on partings, cracks, stylolites, and lith-
ologic changes. The system improved on the understanding
of roof control and its stability (Ellenberger, J. 2009).
Considerations to deploy borescopes for entry stability,
identify geologic hazards, and project hazards into future
reserves was developed in a paper by Mark Van Dyke et
al. (2019). The paper highlights how to collect geologic
data from borescopes, how to use borescopes to determine
supplemental roof support, key features to look for while
collecting information underground, and additional bore-
scope uses such as examining inside a pillar or the floor. A
case study, also discussed in the paper, proposes how the
use of borescope technologies can be applied to identify a
geologic transition zone from sandstone to limestone (Van
Dyke et al. 2019).
BORESCOPES OF TODAY
Fiberscopes (see Figure 1) are still in use today and are
remain the only practical option for permissible borescopes
in the United States. However, a popular and cost-effective
option to examine mine roof lithology is to utilize a video
borescope. Video borescopes have the advantage of record-
ing the image from the entire borehole to allow replay of the
video on a computer. Until recently, fiberoptic borescopes
were favored when examining roof lithology because of the
limitation of video borescopes recording in 480p resolution.
This is not optimal for lithology identification. Typically,
the limit of optical clarity of a fiberscope is dependent on
the user’s vision and the brightness of the light source being
used. Fiberoptic borescopes remain relatively costly, typi-
cally costing in the tens of thousands of dollars, so their use
is often limited to larger mining operations.
Videoscopes have become more prevalent as the tech-
nology improves and market prices drop. Their popularity
increased when videoscopes began to offer 1080p recording
resolution. This helped to bridge the gap of the advantage
of the resolution of fiberscopes with the videoscopes’ abil-
ity to record and keep a digital file. The higher resolution
of today’s videoscopes have all but made fiberoptic scopes
Figure 1. Fiberscope with a miner’s cap light
which needed a specialized drill bit (Fitz Simmons, 1979).
These borescopes did not meet the intrinsic safety criteria
required to obtain Mine Safety and Health Administration
(MSHA) approval for use inby the last open crosscut of
a development section. Because of that restriction, bore-
scopes could not be used to identify roof lithology at the
face of an active mining section.
The first fiberoptic borescope was developed in 1979
by the U.S. Bureau of Mines. The fiberscope was 6-ft long
and light enough to be operated by one person. The light
source for the scope utilized an MSHA-approved miner’s
cap light which was permissible inby the last open crosscut
of a development section. The scope also included a camera
to take still images of the strata in the roof (Fitz Simmons
1979).
Many papers have been written discussing the benefits
and deployment strategies of borescopes. This section will
discuss some of the key advancements utilizing borescopes,
since its inception, to identify roof lithology for roof con-
trol. James Tennant showed the practicality of borehole
scoping by describing the use and analysis of fiberscope
observations. The analysis included geologic cross sections
developed directly from the data collected from a borescope
that displayed changes in roof lithology through 4 entries
at Martinka No.1 Mine. The borescope observations high-
lighted mud seams in the roof that caused support issues
which resulted in the mine changing to longer primary
bolts to achieve anchorage above the mud seams (Tennant,
James M. 1982).
John Shepherd utilized the deployment of borescopes
to identify roof lithology and roof stability throughout
longwall gateroads. He concluded that borescopes are a
beneficial tool to identify lithological variations and roof
fractures. Identifying the changes in lithology and mapping
the features aids in determining roof support decisions
(Shepherd, J. et al. 1986).
Borescope usage has also led to roof control improve-
ments in other underground mining commodities such as
limestone. John Ellenberger developed a numeric rating
system for roof conditions in stone mines called the Roof
Quality Index (RQI). The RQI rating is based on borescope
observations and provides a numeric value to the observed
roof lithology based on partings, cracks, stylolites, and lith-
ologic changes. The system improved on the understanding
of roof control and its stability (Ellenberger, J. 2009).
Considerations to deploy borescopes for entry stability,
identify geologic hazards, and project hazards into future
reserves was developed in a paper by Mark Van Dyke et
al. (2019). The paper highlights how to collect geologic
data from borescopes, how to use borescopes to determine
supplemental roof support, key features to look for while
collecting information underground, and additional bore-
scope uses such as examining inside a pillar or the floor. A
case study, also discussed in the paper, proposes how the
use of borescope technologies can be applied to identify a
geologic transition zone from sandstone to limestone (Van
Dyke et al. 2019).
BORESCOPES OF TODAY
Fiberscopes (see Figure 1) are still in use today and are
remain the only practical option for permissible borescopes
in the United States. However, a popular and cost-effective
option to examine mine roof lithology is to utilize a video
borescope. Video borescopes have the advantage of record-
ing the image from the entire borehole to allow replay of the
video on a computer. Until recently, fiberoptic borescopes
were favored when examining roof lithology because of the
limitation of video borescopes recording in 480p resolution.
This is not optimal for lithology identification. Typically,
the limit of optical clarity of a fiberscope is dependent on
the user’s vision and the brightness of the light source being
used. Fiberoptic borescopes remain relatively costly, typi-
cally costing in the tens of thousands of dollars, so their use
is often limited to larger mining operations.
Videoscopes have become more prevalent as the tech-
nology improves and market prices drop. Their popularity
increased when videoscopes began to offer 1080p recording
resolution. This helped to bridge the gap of the advantage
of the resolution of fiberscopes with the videoscopes’ abil-
ity to record and keep a digital file. The higher resolution
of today’s videoscopes have all but made fiberoptic scopes
Figure 1. Fiberscope with a miner’s cap light