Machine-related injuries in the US mining industry and priorities for safety research

Todd Ruff*,

*Corresponding author. Email: truff@cdc.gov

The findings and conclusions in this article have not been formally disseminated by the National Institute for Occupational

Safety and Health and should not be construed to represent any agency determination or policy.

Patrick Coleman and Laura Martini

National Institute for Occupational Safety and Health, Office of Mine Safety and Health Research, 315 E. Montgomery Ave.,
 

Spokane, WA 99207, USA
 

Researchers at the National Institute for Occupational Safety and Health studied mining accidents that involved a

worker entangled in, struck by, or in contact with machinery or equipment in motion. The motivation for this study

came from the large number of severe accidents, i.e. accidents resulting in a fatality or permanent disability, that are

occurring despite available interventions. Accident descriptions were taken from an accident database maintained by

the United States Department of Labor, Mine Safety and Health Administration, and 562 accidents that occurred

during 2000–2007 fit the search criteria. Machine-related accidents accounted for 41% of all severe accidents in the

mining industry during this period. Machinery most often involved in these accidents included conveyors, rock

bolting machines, milling machines and haulage equipment such as trucks and loaders. The most common activities

associated with these accidents were operation of the machine and maintenance and repair. The current methods to

safeguard workers near machinery include mechanical guarding around moving components, lockout/tagout of

machine power during maintenance and backup alarms for mobile equipment. To decrease accidents further,

researchers recommend additional efforts in the development of new control technologies, training materials and

dissemination of information on best practices.
 

1. Introduction

Although the total number of mine worker fatalities in

the United States, as well as fatality incidence rates,

have trended downward during the past 20 years, the

proportion of these accidents involving mine machinery

and mobile equipment has consistently been significant

(Kecojevic, Komljenovic, Groves, & Radomsky, 2007).

Researchers at the National Institute for Occupational

Safety and Health (NIOSH) have been concerned with

the interaction of workers and machinery and with the

number of severe accidents classified as struck-by or

caught-in (Burgess-Limerick & Steiner, 2006a; Ruff,

2007; Schiffbauer, 2005; Venem, Shutske, & Gilbert,

2006). These accidents include workers entangled in

rotating machinery, struck by moving machine components or run over by mobile equipment. An analysis

of accident data available from the Mine Safety and

Health Administration (MSHA) was conducted to

better understand the problem and scope of machinery-related accidents.

Ensuring worker safety near machines is a challenging problem. In many cases it is an industry-accepted

practice to allow workers to be near moving machinery in

order to perform their jobs. For example, workers often

perform cleanup of material near conveyors while the

conveyor is operating. Loose clothing or a shovel being

used by a worker can get caught in pinch points near

idlers or pulleys. Workers and large mobile machinery

are often in close proximity, especially in underground

mines and smaller surface operations. Collisions between

workers and mobile machines occur despite widespread

use of backup alarms. Another troubling accident

scenario occurs during maintenance when workers are

entangled in machine components when the machine is

unexpectedly reenergised. Lockout/tagout procedures

are required in the mining industry, but are sometimes

either not followed or not adequate for a particular

machine design. During the past few decades, the mining

industry has put in place many types of safeguards to

reduce these types of accidents. Yet, challenges still

remain as evidenced by the persistent recurrence of

certain types of accidents and the significant proportion

of machine-related accidents as compared to all accidents

that occur during mining.

The goals of this study were to better understand

the contributing factors in machinery and haulage
equipment accidents, assess available safety interventions, propose new ideas if needed, and determine

whether certain types of equipment or mines should

receive special focus. The following discussion summarises these efforts and provides some suggestions for

future intervention research.

2. Methodology

Using the MSHA accident database (MSHA, 2000–

2007a), researchers studied accidents that involved

machinery and haulage equipment in all types of

surface and underground mining. The criteria for

selecting accidents included MSHA accident classifica­

 1 tions of powered haulage, machinery and hoisting

with accident types identified as caught-in/under/

between and struck-by/against. Table 1 shows the

specific MSHA accident codes used.

Table 1. MSHA accident data codes.

Degree of Classification

injury code code Accident type code

01 – Fatal 12 – Powered 01 – Struck against

haulage stationary object

02 – Permanent 13 – Hoisting 02 – Struck against

disability, 17 – Machinery moving object

partial or total 04 – Struck by falling

object

05 – Struck by

flying object

06 – Struck by rolling

object (sliding)

07 – Struck by powered

moving object

08 – Struck by not

elsewhere

classified (NEC)

20 – Caught in/under/

between running or

meshing objects

21 – Caught in/under/

between a moving

and stationary object

22 – Caught in/under/

between several

moving objects

23 – Caught in/under/

between collapsing

material or buildings

24 – Caught in/under/

between NEC

This first analysis

studied accidents involving mine employees (no contractors or office workers) and only included severe

accidents (accidents resulting in a fatality or permanent

disability). Studying severe injuries allowed researchers

to focus the dataset and concentrate on life-threatening

problems. Limiting the study to mine employees

allowed incidence rates to be calculated using MSHA

employment estimates (MSHA 2000–2007b) (employment estimates do not include contractors or office

workers). Data from the years 2000–2007 were

collected and 562 accidents fit the criteria.

A subsequent analysis involved studying MSHA

fatalgrams and fatal investigation reports for machinerelated deaths at surface mines during the same period

(MSHA, 2000–2007c). More details are contained in

these reports, offering further insight into the worker’s

activity during the accident, possible root causes and

interventions that may have prevented the accident.

3. Results

Figure 1 shows the number of severe machine-related

accidents for each commodity mined and includes the

breakdown for surface and underground mining

methods for that commodity.

Figure 1. Number of severe mobile and stationary machinerelated accidents by commodity, 2000–2007.

The highest number of

severe accidents involving machines occurred in coal

mining (242), followed by stone (136), sand and gravel

(83), nonmetal (53) and then metal mining (48). The

majority of accidents in coal mining occurred in underground operations, while for other commodities the

majority of accidents occurred at surface operations.

Incidence rates per 100,000 employees were then

calculated using MSHA employment estimates of total

hours worked (MSHA, 2000–2007b) (Table 2) and the

assumption of 200,000,000 exposure hours. This gives

the number of injuries per 100,000 full-time equivalent

employees working 2000 hours per year. Confidence

limits for the overall incidence rate were calculated

assuming that the accidents studied were distributed as

Poisson variables.

Incidence rates for each commodity indicated a

fairly even distribution for exposure to haulage and
machinery-related hazards (first data set of Figure 2).

Coal mining had the highest incidence rate of severe

machinery accidents (36.8 per 100,000 employees),

followed by nonmetal mining (32.0), sand and gravel

(30.9), stone (23.6) and metal mining (20.7). This

resulted in an average of 29.6 severe injuries per

100,000 employees across all commodities (95%

confidence limits (27.2, 32.1)). These machine-related

accident rates were then compared with rates for all

types of accidents (second data set of Figure 2). On

average, severe machine-related accidents classified as

struck-by or caught-in accounted for 41% of all severe

accidents at mining operations.

Researchers then determined the most common

machinery involved in these severe accidents. Figure 3

shows the top 20 machine types and, for each machine,

the breakdown for mine type (surface or underground). Eighty (14%) of the 562 accidents involved

conveyors with most accidents occurring at surface

operations. Roof bolting machines, haul trucks and

front-end loaders were most frequently involved in

accidents involving mobile machines. The activity of

the worker during the accident was also of interest

(Figure 4) – a significant portion of injuries and

fatalities occurred during maintenance and repair of all

types of machines (25%). A closer look at maintenance

accidents revealed 4 fatalities and 21 amputations

resulting from a machine being unexpectedly restarted

while someone was working on it.

Finally, incidence rates for machine-related severe

accidents were calculated for mine employment-size

classes (Table 3). Small mines with 10 or fewer

employees had the highest rate – 41.3 accidents per

100,000 employees. The highest number of accidents

occurred at mines with 50–249 employees and that

group had the second highest incidence rate.

Table 2. Total employee hours by commodity, 2000–2007.

Commodity

Total employee

hours

Average

hours/year

Coal

Stone

Sand and gravel

Metal

Nonmetal

1,316,232,708

1,151,639,753

537,344,125

464,622,830

331,558,981

164,529,089

143,954,969

67,168,016

58,077,854

41,444,873

3.1. Closer look at surface mining

Researchers were interested in more detailed injury

information regarding machine-related accidents at

surface mining operations. Again, the conveyor system

was the machine most often involved in severe

accidents at surface mines – 18% of the 348 total

accidents. Further breakdown showed that for the top

three stationary machines involved in accidents at

surface mines (conveyors, milling machines and

crushers), the most common activity during the

accident was maintenance and repair. For mobile

earth-moving machinery (trucks, loaders, scrapers and

dozers) most of the severe accidents occurred during

the operation of the machinery.

To better understand these accidents, MSHA

fatalgrams and fatal investigation reports for machine-related deaths at surface mines were collected for

the years 2000–2007 (MSHA, 2000–2007c). The first

analysis concentrated on fatal struck-by or caught-in

accidents involving stationary machines and 42 accidents fit the criteria. This analysis provided further

insight into the worker’s activity during the accident,

common machines involved, root causes and interventions that may have prevented the accident. Most of

the fatal accidents involving stationary machinery at

surface mines occurred at sand and gravel (38%) and

stone operations (26%). Entanglement in conveyor

components was the most common cause of fatal

accidents (48%). These were followed by accidents

involving crushers (10%). In 83% of the surface

mining fatalities, the worker was performing maintenance or cleanup. In one-third of the accidents,

MSHA listed failure to shut down and lock out the

machine as one of the contributing factors. Researchers estimated that a system that could detect a worker’s

proximity to hazardous machine components and

provide an alarm or control signal may have prevented

almost half of the accidents.

For the second fatality analysis, researchers also

used MSHA fatalgrams and fatal investigation reports,

but concentrated on struck-by and caught-in mobile

machinery fatalities at surface mining operations

(MSHA, 2000–2007c). Most of these accidents were

due to operators losing control of the machine. Sixtyone fatalities were attributed to brake failure, some

other mechanical problem or operator error that

resulted in a roll-over or collision. Figure 5 shows

the breakdown by machine type. The majority of these

fatalities occurred at surface coal operations (44%),

followed by stone operations (30%) and sand and

gravel (10%), with the remaining accidents split

equally between other metal and nonmetal mines.

Another common accident involved operator visibility issues such as collisions or backing over an

unseen edge. Twenty-seven fatalities fit this criteria and

Figure 6 shows a breakdown of these accidents by

machine type. Of these fatalities, 16 involved collisions

with workers on the ground or with other vehicles, and

11 involved driving over an unseen edge. The majority

(67%) occurred while the machine or vehicle was in

reverse motion (Figure 7). These visibility-related

surface mine fatalities occurred at coal operations
(37%), stone operations (37%), and sand and gravel

mines (22%), with one fatality at a mill.

Figure 2. Incidence rates for severe machine-related accidents compared to all severe accidents, 2000–2007.

Figure 3. Severe mobile and stationary machine-related accidents by machine involved, 2000–2007 (top 20).

3.2. Other mine accident studies

The above findings are in agreement with other studies

of mining accidents in the United States. For example,

during 1994–2003, machinery and powered haulage

equipment contributed to the majority of fatalities in

surface stone and sand and gravel operations (Karra,

2006a,b). Machine maintenance and repair and the

operation of equipment, such as trucks and loaders,

were the most dangerous activities. The study by Karra

(2006a,b) concluded that worker activities during

maintenance and repair of machines should be a top

priority in safety programmes.
Figure 4. Severe mobile and stationary machine-related accidents by worker activity, 2000–2007 (top 20).

Table 3. Severe machine-related accident incidence rates by

mine employment size, 2000–2007.

Incidence

Number of

FTE employees

Number

of cases

Total hours

worked

rate per 100,000

employees

10 and below

11–49

50–249

250–999

1000 and up

104

148

210

95

5

503,464,997

1,116,799,876

1,291,845,757

816,254,434

73,033,333

41.3

26.5

32.5

23.3

13.7

Kecojevic et al. (2007) analysed all equipmentrelated fatalities at underground and surface mining

operations in the United States during 1995–2005.

Their study showed that the greatest proportion of

fatalities involved haul trucks (22.3%), followed by

belt conveyors (9.3%). They also examined the

relationship between fatalities and mining experience,

which showed that miners with less than five years of

experience were involved in 44% of the accidents.

Zainalabidin, Kecojevic, Komljenovic and Groves

(2008) concentrated on risk assessment for loaders and

dozers using MSHA accident data from 1995 to 2006.

This study determined that the most frequent hazards

for loaders involved failures in following adequate

maintenance procedures and failures of machine

components. For dozers the most common hazard

involved failures to identify adverse site conditions.

Studies of mining accidents in other countries have

also highlighted the need to address machine safety

issues. For example, Burgess-Limerick and Steiner

(2006b) provided an analysis of mobile machinery

accidents in coal mines in New South Wales, Australia.

That study identified six high-priority hazards: handling cable; strain while bolting; slipping off a continuous miner platform; incorrect operation of controls;

rough roadways; and collisions with other vehicles,

mine structures, or pedestrians. Another detailed

analysis of 103 fatalities that occurred in all Australian

mines during the period 1982–1984 was conducted by

Mitchell, Driscoll and Harrison (1998). That study

found that the most common activity being performed

during the fatal accident was travelling for work

purposes (to and from the mine and within the mine).

Other common activities during the accidents included

miners involved in the process of obtaining coal or

minerals, and workers performing maintenance or

repair. The most common source of the injury was

falling objects (34%), vehicle incidents (29%) and being

struck by a vehicle or machine component (18%).

Dhillon (2009) has cited statistics regarding fatalities in quarries in the United Kingdom. Vehiclerelated fatalities (collisions, travelling over an edge,

rollovers) comprised 41% of all fatalities that occurred

in those quarries during the period 1983–1993. Workers entangled in conveyor belt components comprised

11% of all fatalities.
Figure 5. Mobile surface mining machines or vehicles

involved in fatal accidents attributed to loss of control,

2000–2007.

Figure 6. Mobile surface mining machines or vehicles

involved in fatal accidents attributed to visibility issues,

2000–2007.

Figure 7. Direction of travel during the fatal accident

involving visibility around mobile surface mining machines,

2000–2007.

A study by Ural and Demirkol (2008) analysed

surface mining accidents that occurred in Turkey. In

2004, 68 fatal accidents occurred in their mining

industries, resulting in the highest incidence rate

among major mineral-producing countries. The most

common fatal accident types in surface mines were

reported as blasting operation (18%), powered haulage

(16%), fall of ground (14%) and machinery (12%).

Recommendations from this study included the need

for increased use of personal protection devices, new

safety technology, improved training for younger

workers and slope stability risk assessment.

4. Discussion

To further define the possible research priorities,

accident narratives for the MSHA data on severe

machine-related accidents in underground and surface

mines were studied (MSHA, 2000–2007a). Of the 562

accidents, 259 (46%) occurred during the operation of

the machine and 139 (25%) occurred during maintenance or repair. The next most frequent activity

during the accident was handling supplies or materials,

with 34 accidents (6%). Thus, focus was placed on the

top two worker activities during the accident and the

top 10 types of machines involved. Suggested research

priorities were primarily determined from the information contained in each accident narrative regarding

circumstances, type of injury and other factors. Input

for priorities was also obtained from related MSHA

fatality investigation reports and from interactions

with industry. Table 4 summarises the data and

suggested research priorities for accidents that occurred during operation of a machine. Table 5

summarises priorities for accidents that occurred

during maintenance and repair. A discussion of the

suggested research priorities follows.

4.1. Stationary machines

Current methods to safeguard moving components on

stationary machines at mine sites are numerous. Some

methods, such as guarding, are required by MSHA

(CFR, 2007). Other safeguards, such as proximity

sensors, are recommended or suggested (MSHA,

2004). The most common safety device is a mechanical

guard around moving components such as head

and tail pulleys, gears, chains, shafts, etc. that

prevents a worker from contacting the hazardous
area. Emergency stop buttons or pull cords are

required on unguarded portions of the conveyor next

to travel ways (except in metal/nonmetal mines where

railing is an acceptable method to prevent contact).

Lockout/tagout procedures to prevent machine movement during maintenance or repair are also required at

mines in the United States. In addition, proximity

sensors and switches are available to detect when a

worker is in a hazardous area, but they are not often

used. These include safety mats, bump strips, light

curtains, laser ranging devices, radar, sonar, infrared

and capacitive sensors.

Despite the requirements for safeguarding machines, accidents at mine sites are still occurring with

regularity. There are many factors that contribute to

these accidents, but it is believed that improved

methods of sensing worker presence in hazardous

locations and providing additional accountability for

following required safe practices may further impact

accidents involving stationary machinery. Innovative

engineering controls should be investigated, including

human presence sensors and devices that allow workers to remain at a safe distance from hazardous

locations while performing maintenance or cleanup.

Methods to ensure that a machine guard is in place and

improved lockout/tagout training and technology may

further decrease these accidents.

Researchers at NIOSH have studied new devices to

detect the presence of workers in hazardous areas near

stationary machines. Radio transponder or tag-based

systems were investigated that use radio-wave or

magnetic-field generators mounted near hazardous

areas of the machine. Electronic tags are worn by

miners that detect the generated marker field and

provide a warning when in dangerous proximity to

moving components (Schiffbauer, 2005). Another

effort investigated the use of intelligent video systems

to monitor hazardous locations. Originally developed

for security and surveillance applications, these systems use a computer to analyse video images generated

from cameras that monitor critical areas around and

inside machines. The systems can automatically detect

a person entering into predefined zones within the

camera’s field of view and provide an alarm or a

machine control signal. Initial testing showed the

ability to provide precise hazardous zone demarcation,

the ability to distinguish between humans and other

objects in the zone, and the potential to distinguish

between hazardous and nonhazardous proximity

(Ruff, 2008). Additional work is needed to determine

the effectiveness of the technology in the harsh

environmental conditions of an actual mine site.

Table 4. Suggested research priorities for severe machine-related accidents (top 10 machines) with activity during accident listed

as ‘operate.’

No. of

Machine accidents Suggested research priorities

Rock or roof bolting machine 51 Improved guarding of moving machine components; proximity warning to

prevent worker entanglement, pinning, striking

Ore haulage trucks – off highway 28 Proximity warning and/or improved visibility to prevent collisions or

and underground driving over an unseen edge, improved training, machine and

environment status monitoring to prevent loss of control, operator

fatigue detection

Load-haul-dump, scoop tram, 15 Proximity warning and/or improved visibility to prevent collisions or

CAVO, bobcat driving over an unseen edge, improved cab design to protect operator

Continuous miner, tunnel borer 13 Proximity warning to prevent operator pinning, striking

Conveyor (all types) 13 Proximity warning and/or improved guarding to prevent worker

entanglement, improved lockout/tagout procedures and technology

Bulldozer, dozer, crawler tractor 12 Detection of edges and drawpoints, systems to monitor machine stability,

improved seatbelts

Milling machine (all other NEC) 12 Proximity warning and/or improved guarding to prevent worker

entanglement, improved lockout/tagout procedures and technology

Trucks (not ore haulage) 11 Machine and environment status monitoring to prevent loss of control,

improved training, proximity warning and/or improved visibility to

prevent collisions or driving over an unseen edge

Front-end loader, tractor-shovel 11 Proximity warning and/or improved visibility to prevent collisions or

driving over an unseen edge, improved seatbelts and training, machine

and environment status monitoring to prevent loss of control

Shuttle car 9 Proximity warning or assisted steering/guidance to prevent contact with

walls or roof

Top 10 total for ‘operate’ 175

4.2. Mobile machines

Loss-of-control of haulage equipment and other

mobile machines is a leading source of machine-related

fatalities in surface mining (Kecojevic & Radomsky,
2004; MSHA, 2000–2007c). The root causes vary

greatly and include mechanical failure, failure to set

brakes, weather-related issues, operator fatigue and

travelling too fast. In many cases, after losing control of

the machine, the operator jumped from the vehicle or

simply was not wearing a seat belt. A reduction in these

accidents may be achieved through improved training

for operators, which has been listed in the literature as a

need in the mining industry (Fesak, Breland, &

Spadaro, 1996; Kecojevic et al., 2007; Saperstein,

2007). Development of systems to monitor and alert

operators regarding the status of safety-critical machine components, machine stability, traffic hazards

and road conditions would also be of benefit.

Table 5. Suggested research priorities for severe machine-related accidents (top 10 machines) with activity during accident listed

as ‘maintenance/repair.’

No. of

Machine accidents Suggested research priorities

Conveyor (all types) 35 Proximity warning and/or improved guarding to prevent worker

entanglement, improved lockout/tagout procedures and technology,

improved emergency stop controls and activators, remote and/or

automatic lubrication, improved material cleanup methods

Milling machine 17 Improved lockout/tagout procedures and technology, proximity warning

(all other NEC) and/or improved guarding to prevent worker entanglement, improved

material cleanup methods

Crusher, breaker, 9 Improved lockout/tagout technology, proximity warning to prevent worker

mills (ball and rod) entanglement, methods to prevent or dislodge jammed material

Front-end loader, 9 Proximity warning and/or improved visibility to prevent collisions with

tractor-shovel workers, improved maintenance training (stored energy hazards)

Crane, derrick 8 Detection of overhead power lines, systems to monitor load and stability

Screen (for sizing 7 Proximity warning and/or improved guarding to prevent worker

and washing) entanglement, improved lockout/tagout procedures and technology

Pump 7 Improved lockout/tagout procedures and technology

Ore haulage trucks - off 5 Improved maintenance training (stored energy hazards)

highway and underground

Forklift 4 Improved maintenance training (stored energy hazards)

Dragline, shovel 3 Proximity warning and/or improved visibility to prevent pinning and

striking

Top 10 total for 104

‘maintenance/repair’

For mobile machines, operator visibility persists as

a problem for both underground and surface mining

operations. Devices to monitor blind spots near heavy

mobile machinery include sonar, radar, radio transponders or tag detection systems, video cameras and

GPS technology. Increasing the machine operator’s

awareness of obstacles, people, and changes in terrain

near their machines could reduce these accidents. Only

video cameras are used extensively on surface haulage

equipment in the United States. Sensor-based warning

systems have not been widely accepted because of their

cost and complexity. However, the popularity of these

devices in both surface and underground operations is

increasing worldwide. For example, magnetic fieldbased proximity warning systems to protect continuous miner operators are now being tested in the

United States and implemented in South Africa, and

GPS-based proximity warning systems are gaining

popularity in surface mines. Ruff (2007) discusses

details on available systems for surface mining equipment and guidance for the effective placement and

mounting of obstacle detection sensors and cameras.

NIOSH researchers were interested in the effectiveness of backup alarms that are required on mobile

mining machines. Laroche (2006) and Purswell and

Purswell (2001) also noted issues regarding backup

alarms. Of the 16 collision-related fatalities at surface

mines, nine occurred while the machine was moving in

reverse. All of the machines involved in these accidents

that were required to have backup alarms had

functioning alarms at the time of the accident (except

the scraper backing accident for which this information could not be found) (MSHA, 2000–2007c).

Worker habituation to alarms, difficulties in localising

and prioritising alarms in congested work areas, and

workers wearing hearing protection may all contribute

to decreased effectiveness. Despite these concerns,

backup alarms have decreased the occurrence of

accidents since being introduced. However, the number

of accidents that still occur suggests that improvements

could be made or supplemental systems should be

used to further enhance a worker’s awareness of

approaching machines and, at the same time, the

machine operator’s awareness of surrounding obstacles and workers. The additional seven collisionrelated fatalities show this is also true for the forward
motion of the machine, for which backup alarms offer

no benefit.

4.3. Mine size and type

Coal mining operations have the highest machinerelated incidence rates and the highest number of

severe accidents, especially in underground operations.

Understandably, safety research efforts have and

should continue to concentrate on this industry. In

addition, the number of machine-related severe accidents at sand, gravel, and stone operations indicates

that these mines have challenges that may need more

research. Further challenges may be associated with

this industry because it predominately operates smaller

mines (MSHA, 2006). In fact, 89% of sand and gravel

operations operate with 10 or fewer employees

(calculated using data from MSHA, 2000–2007b). As

shown in Table 3, mines with 10 or fewer employees

had the highest incidence rate.

MSHA addressed this issue by creating the small

mine office (SMO) in 2002 to help small mining

operations develop and implement safety and health

programs specific to their needs. Potential challenges

for smaller mines include personnel turnover, lower

budgets for safety-related training and equipment, and

the lack of a full-time health and safety professional.

Since the formation of the SMO, the rate of all types of

accidents at small mines has decreased (MSHA, 2008).

Additional efforts to disseminate best practices and

innovative safety solutions could build on the programme’s success.

5.	 Conclusions

Machine safety should continue to be a high priority for

mining operations, research organisations, and regulators. Data from this and other studies indicate specific

safety challenges with stationary and mobile machinery –

severe injuries involving these machines account for more

than 40% of all severe accidents at mining operations in

the United States. Most severe accidents are associated

with the operation or maintenance of the machines.

Current research is addressing many machine safety

issues in both underground and surface mining. This

study identified some specific miner activities and

machine types that may need further attention.

With regard to stationary machinery, additional

emphasis on safety interventions and training should be

directed towards conveyor systems, especially for tasks

associated with machine maintenance, repair or cleanup. Innovative sensors to detect the presence of workers

near hazardous components should be studied further,

along with devices that allow lubrication of components and cleanup of spilled material without requiring

workers to be in hazardous proximity to the machine.

Innovative methods for ensuring machines are not

restarted while undergoing maintenance may build on

the success of current lockout/tagout procedures.

For mobile equipment, most fatal accidents occur

during the operation of the machine. For example,

fatalities involving powered haulage equipment at

surface mines, such as trucks and loaders, most often

involved loss of control or visibility-related issues.

Improved operator training should continue to be

pursued and emphasised in mine safety programmes.

Improvements in edge detection and collision warning

technology, with an emphasis on combining technologies to increase reliability, may increase acceptance

(Ruff, 2006; Saperstein, 2007). While backup alarms

can offer some protection for workers near mobile

machines travelling in reverse, improvements should be

investigated to overcome issues such as worker

habituation, background noise and accidents involving

forward motion of machines. In underground mining,

accidents during the operation of roof bolters, loaders

and continuous miners are most common. Research

should focus on improved guarding of machine

components and proximity warning systems to prevent

pinning of operators and other workers between the

machine and the mine walls.

Finally, machine safety issues at smaller mines and

quarries are of concern. Further research efforts could

address small mine challenges by evaluating and

distributing information on inexpensive and easily

implemented machine safety devices. A survey of best

practices at the safest mines and the dissemination of

unique intervention or training ideas may also be

helpful. For this and other intervention research, close

partnerships between the mining industry, machine

manufacturers, labour organisations, government regulators and research organisations offer the best

chance of making significant reductions in mining

accidents and injuries.

Note

1.	 MSHA classifications of machinery, powered haulage

and hoisting will be grouped and referred to as

‘machinery’ or ‘machines’ in this article. Note that this

usage of ‘machinery’ differs from MSHA usage and in

this context includes powered haulage equipment (e.g.

trucks, loaders, conveyors), earth-moving machines (e.g.

dozers, graders), and stationary machines (e.g. crushers,

washers, hoists). Machinery is then further categorised in

this article as mobile vs. stationary or fixed.

References

Burgess-Limerick, R., & Steiner, L. (2006a). Analysis of

injuries highlights high priority hazards associated with

underground coal mining equipment. American Longwall

Magazine, August, 19–20.
Burgess-Limerick, R., & Steiner, L. (2006b). Injuries

associated with continuous miners, shuttle cars, loadhaul-dump and personnel transport in New South Wales

underground coal mines. Mining Technology: IMM

Transactions, 115(4), 160–168.

Code of Federal Regulations (CFR) (2007). Title 30-Mineral

resources, Part 56-Safety and health standards, surface

metal and nonmetal mines, Subpart M-Machinery and

Equipment, Section 14107-Moving machine parts

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