4
5,000-plus PSI fiber-reinforced concrete. Once cured and
removed from molds, the rocks are painted in different
color schemes to distinguish various sizes and shapes to
aid in rock identification during post-test runout or bench
catchment analysis. Examples of the finished product of
varying synthetic rocks are shown in Figure 2.
Local Rock Collection
In order to analyze runout of rocks that are representative of
the geology of the specific bench configuration, local rocks
of three size categories are collected and tested for runout
analysis. The three size categories are small (3-to-6-inch
diameter), medium (6-to-12-inch diameter), and large (12-
inch and larger diameter). A minimum of 15 rocks are cho-
sen for each size category. A rockfall testing form is used to
note each rock’s type as well as dimensions (short, inter-
mediate, and long axis). The rocks are then spraypainted
according to size category for easy detection when measur-
ing runout distance. An example of collected, measured,
and spray-painted local rocks is shown in Figure 3.
Data Acquisition
Researchers at NIOSH collaborated with project partners
to develop a data acquisition program that captures the
rockfall test from multiple angles using several imagery
methods. The current project data acquisition equipment
used by researchers on the Highwall Safety project team is
outlined in Table 3. It is important to note that the data
acquisition methodology is always evolving as more project
partners get involved and procedures are refined. This is
further explained in the Lessons Learned section of this
paper.
Data Processing
Each rockfall test will have a set of associated data collected
from each piece of equipment outlined in Table 3. The
photos taken from the DJI Phantom 4 Pro Drone to scan
the bench/slope pre and post rockfall test are uploaded into
Agisoft Metashape Pro to develop photogrammetry models
using the following procedure:
Figure 2. Completed and demolded synthetic rocks colored
to distinguish size and shape during post-test analysis.
Table 2. Characteristics of synthetic rocks used for rockfall
testing across varying bench configurations
Synthetic Rock
Attribute
Attribute
Range Notes
Rock Size 3, 6, 12,
and 18-inch
diameter
Cast using reusable steel,
wood, and 3D printed
silicon molds.
Rock Shape Cube,
European
Technical
Approval
Guideline
(ETAG) 27,
and plates
ETAG 27 is the standard
shape for testing of
rockfall barriers in Europe
[12]. Plate rocks have an
aspect ratio of 0.1 to 0.2
to simulate shale, argillite,
and other bedded/foliated
rockfall behavior.
Reinforcement Synthetic and
steel fiber, steel
wire mesh
used for plates
Several reinforcement
methods tested to
compare handling and
durability characteristics
of synthetic rocks.
Table 3. NIOSH Highwall Safety project data acquisition
equipment
Equipment Use
DJI Phantom 4
Pro Drone
Taking photos for photogrammetry model
development (pre and post rockfall testing)
which is used for measuring rockfall
runout distance taking videos during
rockfall testing.
Sony 4K
Handycam FDR-
AX53
Taking videos during rockfall testing from
a distance that best captures the entire
slope taking videos to document the
testing process.
FLIR T620
Thermal Camera
Taking thermal videos during rockfall
testing from a distance that best captures
the entire slope taking pictures before
or after the rockfall test to make sure
temperature range is captured (due to
video not showing temperature range)
5,000-plus PSI fiber-reinforced concrete. Once cured and
removed from molds, the rocks are painted in different
color schemes to distinguish various sizes and shapes to
aid in rock identification during post-test runout or bench
catchment analysis. Examples of the finished product of
varying synthetic rocks are shown in Figure 2.
Local Rock Collection
In order to analyze runout of rocks that are representative of
the geology of the specific bench configuration, local rocks
of three size categories are collected and tested for runout
analysis. The three size categories are small (3-to-6-inch
diameter), medium (6-to-12-inch diameter), and large (12-
inch and larger diameter). A minimum of 15 rocks are cho-
sen for each size category. A rockfall testing form is used to
note each rock’s type as well as dimensions (short, inter-
mediate, and long axis). The rocks are then spraypainted
according to size category for easy detection when measur-
ing runout distance. An example of collected, measured,
and spray-painted local rocks is shown in Figure 3.
Data Acquisition
Researchers at NIOSH collaborated with project partners
to develop a data acquisition program that captures the
rockfall test from multiple angles using several imagery
methods. The current project data acquisition equipment
used by researchers on the Highwall Safety project team is
outlined in Table 3. It is important to note that the data
acquisition methodology is always evolving as more project
partners get involved and procedures are refined. This is
further explained in the Lessons Learned section of this
paper.
Data Processing
Each rockfall test will have a set of associated data collected
from each piece of equipment outlined in Table 3. The
photos taken from the DJI Phantom 4 Pro Drone to scan
the bench/slope pre and post rockfall test are uploaded into
Agisoft Metashape Pro to develop photogrammetry models
using the following procedure:
Figure 2. Completed and demolded synthetic rocks colored
to distinguish size and shape during post-test analysis.
Table 2. Characteristics of synthetic rocks used for rockfall
testing across varying bench configurations
Synthetic Rock
Attribute
Attribute
Range Notes
Rock Size 3, 6, 12,
and 18-inch
diameter
Cast using reusable steel,
wood, and 3D printed
silicon molds.
Rock Shape Cube,
European
Technical
Approval
Guideline
(ETAG) 27,
and plates
ETAG 27 is the standard
shape for testing of
rockfall barriers in Europe
[12]. Plate rocks have an
aspect ratio of 0.1 to 0.2
to simulate shale, argillite,
and other bedded/foliated
rockfall behavior.
Reinforcement Synthetic and
steel fiber, steel
wire mesh
used for plates
Several reinforcement
methods tested to
compare handling and
durability characteristics
of synthetic rocks.
Table 3. NIOSH Highwall Safety project data acquisition
equipment
Equipment Use
DJI Phantom 4
Pro Drone
Taking photos for photogrammetry model
development (pre and post rockfall testing)
which is used for measuring rockfall
runout distance taking videos during
rockfall testing.
Sony 4K
Handycam FDR-
AX53
Taking videos during rockfall testing from
a distance that best captures the entire
slope taking videos to document the
testing process.
FLIR T620
Thermal Camera
Taking thermal videos during rockfall
testing from a distance that best captures
the entire slope taking pictures before
or after the rockfall test to make sure
temperature range is captured (due to
video not showing temperature range)