U. S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Public Health Service

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health TRAPED

MENT OF HEALTH & HUMAN SERVICES . USA

IC 9455

INFORMATION CIRCULAR/2001

An Analysis of Serious Injuries

to Dozer Operators in the 

U.S. Mining Industry
Information Circular 9455

An Analysis of Serious Injuries to Dozer

Operators in the U.S. Mining Industry 

By William J. Wiehagen, Alan G. Mayton, Jasinder S. Jaspal,

 and Fred C. Turin

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Public Health Service

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Pittsburgh Research Laboratory

Pittsburgh, PA

April 2001
This document is the public domain and may be freely copied or reprinted.

Disclaimer: Mention of any company or product does not constitute endorsement by NIOSH.

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DHHS (NIOSH) Publication No. 2001-126
CONTENTS

Page

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Introduction ................................................................................... 2

Purpose and scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Injury record selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Coding of the records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Serious injuries to dozer operators while performing common production tasks ............................... 4

General characteristics of the serious injuries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Dozer activity, result, operator impact, and contributing factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Injuries related to jolts and jars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Musculoskeletal injuries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Relevant NIOSH research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Appendix A.—Injury record selection and coding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Appendix B.—Analysis of fatality reports (1988-97) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Appendix C.—Supplemental injury tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

ILLUSTRATIONS

1. While operating a dozer: lost-time injuries by year and mining sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2. While operating a dozer: lost-time injuries and percent by State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3. While operating a dozer: number of fatalities by job experience ..................................... 6

4. While operating a dozer: jolting/jarring and musculoskeletal lost-time injuries by year . . . . . . . . . . . . . . . . . . . 8

TABLES

1. Surface mining, mobile equipment, and injuries involving dozers, 1988-97 ............................. 3

2. While operating a dozer: fatalities and lost-time injuries by year ..................................... 4

3. While operating a dozer: serious injuries by mining sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4. While operating a dozer: serious injuries by age of victim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

5. While operating a dozer: lost-time injuries by mining experience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6. While operating a dozer: lost-time injuries by job title and job experience ............................. 7

7. While operating a dozer: serious injuries by dozer activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

8. While operating a dozer: serious injuries by incident result . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

9. While operating a dozer: serious injuries and lost workdays by operator impact . . . . . . . . . . . . . . . . . . . . . . . . 7

10. Serious incident results by dozer activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

11. Serious incident results by operator impact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

12. Jolting and jarring injuries and seatbelt usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

13. Lost-time incident results by contributing factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

14. Lost-time injuries by operator impact and part of body injured . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

A-1. Criteria for the selection of injury records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

A-2. Author-defined variables and categories added to the injury set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

C-1. Lost-time injuries by subunit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

C-2. Dozer serious injuries by mine worker activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

C-3. Lost-time injuries by job title . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

C-4. Serious incidents by State and year . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

C-5. Lost-time injuries by State, industry sector, and lost workdays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

C-6. Lost-time injuries by job experience and incident result . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT

ft foot (feet) hr hour(s)

g standard acceleration of gravity Hz hertz (1 hertz = 1 cycle/sec)

 (1 g = 32 ft/sec2

)
AN ANALYSIS OF SERIOUS INJURIES TO DOZER 

OPERATORS IN THE U.S. MINING INDUSTRY

By William J. Wiehagen,1 Alan G. Mayton,2 Jasinder S. Jaspal,2 and Fred C. Turin1

ABSTRACT

This report describes serious injuries occurring to bulldozer operators working at U.S. coal, metal, and

nonmetal mines. The period covered is 1988-97. The data were collected by the Mine Safety and Health

Administration (MSHA). A total of 873 injury records are examined. These injuries resulted in 18 fatalities

and 31,866 lost workdays. All of these injuries occurred to dozer operators while they were doing common

production tasks.

An injury classification system was developed to code the narrative information that describes the

circumstances surrounding the injuries. Injury records are categorized by activity (task being done), incident

result (what apparently happened to the dozer), and operator impact (how the operator was injured). Where

information is available, contributing factors are identified. This classification system supplemented the

standard injury/illness data classification system compiled by MSHA.

The results of the study indicate that, from 1993 to 1997, the number of serious injuries to dozer operators

declined by 30%. The reduction in serious injuries was accompanied by a decrease in days lost due to injury.

Although the number of reported injuries has decreased, dozer operators being jolted and jarred accounts for

the largest percentage (70% of the incidents) and severity (75% of the workdays lost) of serious injuries while

operating the equipment. Vertical jars (while backing up the dozer) resulting in injury to the operator accounted

for a sizable percentage of jolting and jarring injuries.

Working near an edge carries significant risk for fatal injuries. Of 116 incidents where the dozer fell over

an edge, rolled over, or fell into a hidden void, 14 (12%) resulted in fatal injuries. In cases where the dozer

operator either jumped or was thrown out of the cab in a fallover or rollover, 7 out of 26 were killed. Overall,

80% of the fatalities occurred while working near an edge or hidden void or on a steep slope.

Further reductions in injury risk will require more widespread use of seatbelts, field and laboratory research

interventions to better assess the effect of alternative engineering (e.g., seat and seat suspension) designs to

dampen or isolate the effects of shock and vibration, and continued focus on hazard awareness, recognition,

and response.

1

Industrial engineer.

2

Mining engineer.

Pittsburgh Research Laboratory, National Institute for Occupational Safety and Health, Pittsburgh, PA.
2

INTRODUCTION

From 1988 to 1997, surface mine workers sustained nearly

80,000 serious injuries, including 619 fatalities. Off-highway

mobile equipment was involved in about 20% of these injuries

and 42% of the fatalities [Turin et al. 2001]. Bulldozers are a

common type of earthmoving equipment. Dozers are used

extensively in surface mining to do a variety of tasks. These

include clearing land, roadway construction, ripping unconsolidated earthen material, construction and maintenance of

stockpiles, assisting other equipment via towing or pushing,

building and maintaining waste dumps, and pushing material

short distances to assist in overburden removal or reclamation

work. The versatility of the dozer makes it an indispensable

asset at nearly all surface mine operations. The nature of mining

requires dozers to work in all types of weather and ground

conditions. The variety of conditions and difficulty of many of

the tasks adds both challenges and risk. Dozer operators work

in conditions that are dynamic with hazards that vary and can be

subtle and difficult to recognize. Many of the tasks require high

levels of skill in blade control, machine positioning, judgment,

and decision-making.

Dozer operators face some common hazards while doing a

variety of work activities. These include working on steep

slopes or near an edge, water, or hidden voids. There is also the

everyday risk of vertical jars and jolts due to uneven terrain,

lateral jolts and jars from working material, and being struck by

objects (such as fall of ground or tree limbs) that can bump the

dozer or enter the cab. These examples can be characterized as

acute or traumatic, whereby a singular event is identified as

responsible for the often unexpected energy release resulting in

the incident.

Injury surveillance studies [Sparrell 1980; Stanevich 1986;

May 1990; Cross and Walters 1994] sought to identify the types

of injuries and risk while operating off-highway mobile

equipment. Each of these studies examined injury data, in part

involving off-highway mobile equipment similar to that found

at surface mines. Their analyses were aggregated across

equipment types. Although the context for each of these studies

is different, their findings are somewhat common. They suggest

that general approaches involving training, work practices,

enhanced workstation design, and improved ingress and egress

offer good opportunities for reducing injury risk to those who

operate off-highway earth-moving equipment. None of these

studies examined dozer operation in detail nor the unique kinds

of injuries associated with common bulldozing tasks.

In addition to the risk of traumatic injury, there are other risk

factors that involve long-term, cumulative exposures to health

hazards. For dozer operators, relevant examples include the

potential health impact from exposures to silica dust, noise, and

whole-body vibration (WBV). The literature on the effects of

WBV on comfort, performance degradation, and worker health

is partially relevant to this study. There are two reasons for this.

WBV is an environmental stressor. It detracts from safe,

productive performance. Reviews of the literature suggest that

WBV can distract, induce fatigue, reduce comfort, impede

efficiency, lead to accidents, and may have bad health effects

[Love et al. 1992]. Secondly, the International Organization for

Standardization has established limits on WBV (ISO 2631/1)

[ISO 1985].

This report touches on some of the research literature related

to WBV. A few studies are referenced in later sections of

this report. Generally, we presume that the traumatic effects

of (short-duration) shock, along with the annoying and

performance-limiting effects of vibration, are logically intertwined and difficult to separate. Thus, the injuries sustained

by dozer operators are summarized without inferring or trying

to distinguish those injuries that might have been aggravated by

exposure to machine vibration versus those that are truly acute,

i.e., due to a singular event.

No attempt is made to attribute error to these injuries. Much

is written on the subject of human error in accident causation,

and attempts have been made to understand and parcel errors to

different entities. Errors will always be part of the workplace.

Our purpose is to organize and summarize information that can

help safety professionals understand risk and promote

discussion and experimentation on what might be done to

further reduce the chance of an injury.

PURPOSE AND SCOPE

The purpose of this work is to profile serious injuries

sustained by bulldozer operators while performing common

production tasks at mining sites. A set of 873 serious injuries is

examined. These include 18 fatalities and 855 lost-time

incidents that occurred during 1988-97. This study is based on

an analysis of occupational fatality and lost-time injuries to

those who operate dozers at surface mines or surface areas of

underground mines. The data are reported by mine operators

and independent contractors and are collected and compiled by

the Mine Safety and Health Administration (MSHA). Both

track and rubber-tired dozers are considered. From our analysis,

implications of the data are discussed within the context of

injury prevention strategies.

Table 1 provides the context for this study based on our

initial analysis of the MSHA injury data. This table builds on

the findings of Turin et al. [2001] and provides a general

framework for the serious injuries examined in this report.

Dozers were involved in 3.7% of all surface mining serious

injuries and accounted for 4.3% of the lost workdays. Table 1

categorizes the "dozer-related" injuries based on the activity

(MSHA code: "mine worker activity") being performed at the

time of the accident. "Operating dozers" was the largest risk
3

Table 1.—Surface mining, mobile equipment, and injuries involving dozers, 1988-97

Category Serious

injuries Fatalities Lost-time

injuries

Lost

workdays

Average

lost

workdays

Surface mining . . . . . . . . . . . . . . . . . . 79,601 619 78,982 2,289,152 28.98

Mobile equipment . . . . . . . . . . . . . . . . 15,601 262 15,339 507,594 33.09

 Percent of surface mining . . . . . . . . 20 42 19 22 114

Injuries involving dozers . . . . . . . . . . . 2,962 23 2,939 98,476 33.5

 Percent of surface mining . . . . . . . . 3.7 3.7 3.7 4.3 116

Mine worker activity:

 Getting on or off (dozer) . . . . . . . . . 875 1 874 30,889 35.3

 Maintenance and repair (dozer) . . . 612 3 609 17,978 29.4

 Operating dozer . . . . . . . . . . . . . . . 921 17 904 33,793 37.4

 All others (involving dozers) . . . . . . 554 2 552 15,816 28.7

category. It accounted for 17 fatalities (74% of the dozerrelated fatalities) and, overall, about one-third (921) of the

serious injuries and lost workdays (33,793). Of note, "getting

on and off the [dozer] equipment" accounted for the next highest

category of serious injury, about 30% (875) of both the incidents

and days lost (30,889) involving dozers.

A classification system was developed to help organize and

summarize the fatality and lost-time injury data for those

injuries sustained while dozers are being used to perform

common production tasks. The classification system is specific

to dozers and how this equipment is commonly used within

mine sites. Injury narratives were coded and categorized by

(1) activity

(task being done), (2) incident results (what apparently

happened to the dozer) and (3) operator impact (how the operator was injured). Where information is available, contributing factors are identified without attempting to rank their

relative importance.

The following sections provide the methods, results, and

analysis (discussion). Appendices are provided to offer more

detail with regard to the methods used to select, classify, and

code the injury records; supplementary findings from the review

of the 18 dozer operator fatality reports; and additional data on

the 855 lost-time injuries.

METHOD

Two data sets were used in this analysis:

1. Fatality reports.–MSHA personnel conduct investigations of every mine fatality. These reports were obtained from

MSHA and used to conduct a more in-depth review and compile

a summary of bulldozer operator fatalities over the 10-year

period.

2. The injury/illness data set.–MSHA regulations at 30 CFR

50.20 require mine operators and contractors to file a Mine

Accident, Injury and Illness Report (MSHA Form 7000-1) for

each accident, occupational injury, or occupational illness that

occurs at a mine site. Instructions for completing this form can

be found on the MSHA Web site at www.msha.gov/FORMS/

70001prv.HTM. Mine operators completing this form and

MSHA personnel constructing the database provided the input

data for this study. This comprehensive data set was sorted and

reviewed to select records, i.e., identify the subset of injuries

sustained by dozer operators while doing common production

tasks.

INJURY RECORD SELECTION

Records were chosen from the MSHA injury and fatality

database that met three criteria:

1. Each of the injury records resulted in death, permanent

disability, or lost work time. We excluded records that only

included days of restricted work time.

2. Each of the incidents involved operating a dozer on mine

property (by mining company employees or contractors) to

perform a common production task.

3. The period covered was January 1, 1988, to December 31,

1997.

Researchers selected injury records from the MSHA database

based on the decision rules shown in table A-1 in appendix A.

This strategy yielded a set of 960 records. Each injury

narrative3

 was reviewed to select the final set of records (873).

The set included 18 fatalities and 855 injuries involving lost

workdays.

CODING OF THE RECORDS

A qualitative analysis was performed based on the review

of the injury narratives to code the records. A classification

system was developed to code information contained in the

 3

The narratives are short summaries prepared by the individual (at the mine

site) completing the MSHA Form 7000-1. 
4

narrative. The new variables and descriptors are identified in

table A-2 in appendix A. These include:

Activity.—This variable was defined to code the specific task

being performed by the dozer operator at the time of injury. It

is a more specific clarification of the MSHA code "mine worker

activity." For this study, each injury record was assigned

one of seven different activities. These relate to the primary

tasks of bulldozer operation. A default activity—blade/

groundwork—was assigned if the narrative omitted specific task

information, but it was clear that the dozer was used to perform

a common production task.

Incident result (dozer impact).—This variable describes what

happened to the dozer. The categories for this field are

described in table A-2. If it was apparent that the injury occurred and there was no apparent impact on the dozer, then

these records were coded as "normal operations." Examples

include injuries due to twisting and turning in the seat, control

usage, or eye injuries due to dust blowing into the cab.

Operator impact.—This field describes the type of injury

sustained. Coding of this field was based on the injury narrative

with supplemental information obtained from other fields in the

MSHA database (e.g., part of body, nature of injury). Examples

include the operator being jolted or jarred, the operator was

jolted and struck against an object inside the cab, or the operator

landed outside of the cab. Other categories include the operator

was struck by an object, came in contact with a hot object, and

musculoskeletal injuries (injuries due to twisting and turning,

reaching, control usage, etc.). This latter category is often tied

directly to normal dozer operations where there was no apparent

impact to the dozer.

Contributing factors to the event.—This variable was coded

for those injury records where the narratives offered information

that may have contributed to the occurrence. The options for

this variable were not derived a priori, but were developed based

on the review of the narratives and common categories

identified.

Contributing factors to the severity.—This field was used in

those cases where the injury narratives offered information that

may have contributed (either to enhance or decrease) to the

severity of the injury. Examples include the use of seatbelts.

Team members reviewed and coded each of the 18 fatality

records and the 855 lost-time injury records. Several discussions were held to identify discrepancies and ambiguities in

the interpretation of the injury narratives. Where ambiguity was

found, these records were discussed and changes were made to

simplify or clarify the coding scheme or definitions of categories

within the new variables. Checks of other, but related fields in

the MSHA database were made to help with the coding. Appendix A provides more detail on how the records were selected

and coded.

For the fatality reports, variables were added to the data set

in addition to those identified in table A-2. Because the quality

and quantity of the information is much greater for the MSHA

fatality investigative reports, a more in-depth level of analysis

could be done.

SERIOUS INJURIES TO DOZER OPERATORS WHILE PERFORMING

COMMON PRODUCTION TASKS

GENERAL CHARACTERISTICS

OF THE SERIOUS INJURIES

There were 873 serious injuries that fit the parameters of this

study: (1) the injuries occurred while the worker was operating

a dozer and (2) the worker was injured to the degree where work

time was lost. Table 2 summarizes these serious injuries by

year. There were no dozer fatalities in 1996-97. Lost-time

incidents averaged 102 annual incidents in 1988-92 and

averaged 69 incidents in 1993-97. The data are not normalized

by hours of exposure. However, if one assumes that the number

of employee hours spent on the dozer has been fairly constant,

then the reported injury data suggest a 30% reduction in injury

risk. This assumption seems reasonable since surface mine

employment has remained fairly constant (about 250,000

employees) over the 10-year time period [Turin et al. 2001].

Overall, the 855 lost-time incidents resulted in a total of

31,886 days of lost work. This total does not include statutory

Table 2.—While operating a dozer: fatalities and lost-time

injuries by year

Year Fatalities Lost-time

injuries

Lost

workdays

Average

lost days

1988 . . . . . 1 91 3,149 34.6

1989 . . . . . 2 105 2,328 22.2

1990 . . . . . 1 114 4,655 40.8

1991 . . . . . 1 107 3,933 36.8

1992 . . . . . 2 94 4,848 51.6

1993 . . . . . 5 79 3,166 40.1

1994 . . . . . 3 67 2,793 41.7

1995 . . . . . 3 76 3,069 40.4

1996 . . . . . 0 58 2,063 35.6

1997 . . . . . 0 64 1,882 29.4

 Total . . . 18 855 31,886 37.3

days charged in cases of permanent disability. Over the 10-year

period, five injuries were classified as permanent disability.4

 4 We include “days lost” for these injuries as reported by the mine operator

or contractor, but do not include the statutory days charged.
5

0

15

30

45

60

75

90

1988 1989 1990 1991 1992 1993 1994 1995 1996 1997

YEAR

Bituminous

Stone

Sand and Gravel

Metal

NUMBER OF LOST-TIME INJURIES

Figure 1.—While operating a dozer: lost-time injuries by year and mining sector.

Table 3 describes these injuries and fatalities by mining

sector. Figure 1 illustrates the 10-year trend of lost-time injuries

by mining sector. Overall, bituminous coal had the largest share

(62%) of the serious injuries and 65% of the lost workdays. It

was also the sector with the largest improvement in lost-time

injuries over the 10-year period. Other sectors (sand and gravel,

metal, and stone) also experienced some improvement, although

the relative gain was small. The annual tally of dozer injuries

at anthracite and nonmetal mines was low compared to the other

sectors. Ninety-five percent of the injuries (822) were reported

by mine operators; the rest (51) was reported by independent

contractors.

Four States accounted for 53% of the total dozer injuries

and about the same percentage of the total days lost (figure 2).

Two States (Kentucky and West Virginia) account for the

largest individual and combined share of the lost-time injuries

(38% of the total incidents) and days lost (43% of the days lost).

Supplemental tables summarizing the incident data by State are

found in appendix C.

Tables 4 and 5 summarize the demographics of the injury

victims by age and mining experience. The injury victims were,

on average, 42 years old. Almost all (99.8%) were male.

Median days lost was the largest for the age group 40-49. The

large majority had a significant amount of total mining

experience (>5 years), although 21% of the lost-time injury

victims had 1 year or less of experience at the particular mine

site where the injury occurred.

For the 18 fatalities, figure 3 illustrates the amount of

experience on the dozer. This information was obtained from

the fatality investigation reports. Experience in the task (operating a dozer) ranged from only a few days to over 40 years.

Five of the victims had less than 2 months of experience on the

Table 3.—While operating a dozer: serious injuries by mining sector

Product class Serious injuries Fatalities Lost-time

injuries

Lost workdays Average

lost

No. % of total No. % of total workdays

Bituminous coal . . . 543 62 10 533 20,691 65 38.8

Stone . . . . . . . . . . . 99 11 2 97 2,755 9 28.4

Metal . . . . . . . . . . . . 96 11 2 94 3,610 11 38.4

Sand and gravel . . . 76 9 4 72 2,435 8 33.8

Nonmetal . . . . . . . . 36 4 0 36 1,418 4 39.4

Anthracite coal . . . . 23 3 0 23 977 3 42.5

 Total . . . . . . . . . . 873 100 18 855 31,886 100 37.3
6

All others

411 

47%

California

51 

6%

Kentucky

178 

21%

Pennsylvania

73 

9%

West Virginia

142 

17%

Figure 2.—While operating a dozer: lost-time injuries and percent by State.

Less than 2 months

(5)

2 months to 2 years

(2)

2 years to 10 years

(7)

10 years to 20 years

(2)

Over 20 years

(2)

Figure 3.—While operating a dozer: number of fatalities by job experience.

Table 4.—While operating a dozer: serious 

injuries by age of victim

(fatalities in parentheses)

Age range

(years)

Serious

injuries Percent Median days

lost1

Less than 29 . . . . . . 77 (2) 9 5

30 to 39 . . . . . . . . . . 291 (5) 33 14

40 to 49 . . . . . . . . . . 283 (4) 33 25

50 to 59 . . . . . . . . . . 160 (4) 18 19

60 or greater . . . . . . 33 (3) 4 22.5

Unknown . . . . . . . . . 29 (0) 3 —

 Total . . . . . . . . . . 873 (18) 100 N/A 1

Median days lost for the 855 lost-time injuries.

Table 5.—While operating a dozer: lost-time injuries

by mining experience

Experience

(years)

Total

mining Percent At this mine Percent

Less than 1 . . . . . 34 4 182 21

1 to 2 . . . . . . . . . . 31 4 86 10

2-3 . . . . . . . . . . . 31 4 66 8

3-5 . . . . . . . . . . . 52 6 78 9

More than 5 . . . . 595 69 379 44

Unknown . . . . . . . 112 13 64 8

 Total . . . . . . . . 855 100 855 100

dozer. Three of these five were on the job for less than a week.

Another two had 1-2 years of experience; the rest (11) had

2-40 years of experience.

Table 6 summarizes the lost-time injury data by job title and

experience in that job title. Overall, 701 injuries were sustained

by miners with the job title reported as "dozer/tractor operator";

154 had other job titles (see table C-3). For the dozer/tractor

operators, 616 records included information on the level of

experience in the job title. About 14% of the lost-time injuries

were incurred by miners with less than 1 year of job experience;

60% of the victims had more than 5 years of experience. The

number and percentage of workers injured with less than 1 year

of experience in the job are about twice the number and percentage as those with 1-2, 2-3, 3-4, and 4-5 years of experience.

DOZER ACTIVITY, RESULT, OPERATOR IMPACT,

AND CONTRIBUTING FACTORS

Tables 7-9 summarize the incidents by activity (task being

performed), incident results (what apparently happened to the

dozer) and operator impact (how the operator was injured).

These tables were based on the coding of the injury narratives

by the authors.
7

Table 6.—While operating a dozer: lost-time injuries by job title and job experience

Job experience

(years) All job titles Job title: 

dozer operator

% of

616

Job titles:

other

% of

146

1 or less . . . . . . . . . 111 85 14 26 18

1 to 2 . . . . . . . . . . . . 51 37 6 14 10

2-3 . . . . . . . . . . . . . 69 55 9 14 9

3-4 . . . . . . . . . . . . . 38 34 5 4 3

4-5 . . . . . . . . . . . . . 57 39 6 18 12

More than 5 . . . . . . 436 366 60 70 48

Subtotal . . . . . . . . . 762 616 100 146 100

Unknown/missing . . 93 85 — 8 —

 Total . . . . . . . . . . 855 701 — 154 —

Table 7.—While operating a dozer: serious injuries

by dozer activity (fatalities in parentheses)

Dozer activity Serious

injuries Percent

Blade/ground work .......... 500 (9) 57

Tramming backward . . . . . . . . . 266 (5) 30

Tramming forward . . . . . . . . . . 51 (3) 6

Land clearing . . . . . . . . . . . . . . 23 (1) 3

Ripping . . . . . . . . . . . . . . . . . . . 18 2

Towing equipment .......... 8 1

Pushing equipment .......... 7 1

Other/unknown . . . . . . . . . . . . . 0 0

 Total . . . . . . . . . . . . . . . . . . . 873 (18) 100

Table 8.—While operating a dozer: serious injuries by incident result

(fatalities in parentheses)

Incident result Serious

injuries Percent

Vertical jar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354 41

Normal operations (no apparent impact to the dozer) . . . 212 24

Fall over edge/roll over/hidden void ................. 116 (14) 12

Lateral jar/collision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 (1) 8

Dozer struck by an object . . . . . . . . . . . . . . . . . . . . . . . . . 56 6

Lateral jar/dozer lurched forward or backward . . . . . . . . . 28 3

Equipment failure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 3

Fire (external) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 <1

Other . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1

(3) <1

Unknown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 <1

 Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 873 (18) 100 1

Incidents involved a dozer operator run over by the machine he was using.

Table 9.—While operating a dozer: serious injuries and lost workdays

by operator impact (fatalities in parentheses)

Operator impact Serious

injuries Percent Days

lost

Average

days lost1

Jolted/jarred . . . . . . . . . . . . . . . . . . . 436 50 17,630 40.4

Jolted/jarred - struck against . . . . . . 142 16 5,388 37.9

Jolted/jarred - landed outside cab . . 26 (7) 3 906 47.7

Musculoskeletal injury (MSI) . . . . . . 155 18 5,656 36.5

Struck by object . . . . . . . . . . . . . . . . 78 9 1,733 22.2

Burned/contact with a hot object . . . 10 (1) 1 324 36

Asphyxiated . . . . . . . . . . . . . . . . . . . 4 (4) <1 — —

Drowned . . . . . . . . . . . . . . . . . . . . . . 3 (3) <1 — —

Crushed/run over by dozer . . . . . . . . 3 (3) <1 — —

Other . . . . . . . . . . . . . . . . . . . . . . . . . 16 2 249 15.6

 Total . . . . . . . . . . . . . . . . . . . . . . . 873 (18) 100 31,886 — 1

For the 855 lost-time injuries.
8

0

10

20

30

40

50

60

70

80

1988 1989 1990 1991 1992 1993 1994 1995 1996 1997

MSI Jolt / Jar

YEAR

NUMBER OF LOST-TIME INJURIES

Figure 4.—While operating a dozer: jolting/jarring and musculoskeletal lost-time injuries by year.

For activity (table 7), blade/groundwork was the most

common. This activity was unique to the other choices as it was

also the default value. Many narratives only indicated that the

employee was injured while operating the dozer. Thus, we

coded these injuries as blade/groundwork. Other narratives

were more specific. Thus, for dozer activities other than

"blade/groundwork", one can surmise that in at least 266 cases,

the dozer was backing up, or in at least 23 incidents, land was

being cleared, etc.

Table 8 summarizes the results of the incidents. For 24% of

the incidents, we coded those incidents as "normal operations"

with no apparent impact to the dozer. For the rest (76%) of the

incidents, there was some impact to the dozer that resulted in a

lost-time injury to the operator. This could be through vertical

or lateral jarring (52% of the cases), falling off an edge or

 rollover (13%), the dozer being struck by an object (6%), or

equipment failure (3%). Of note, in 12% of the cases (14 out of

116 incidents) where the dozer rolled or fell off an edge or into

a hidden void, the victim died.

Table 9 summarizes the categories chosen for describing the

impact to the dozer operator. These choices reflect functional

categories chosen by the authors. Categories related to jolts and

jars account for 69% of the serious injuries. Of note, where an

operator was jolted or jarred and landed outside of the cab

(either by jumping or being thrown out), 7 of 26 (27%)

sustained fatal injuries. In 142 cases (16%), the operator was

jolted to a degree that he or she struck something (inside

the cab).

Figure 4 presents the trend for the lost-time injury data by

operator impact. It groups the data into two broad categories:

(1) musculoskeletal injuries (MSI) and (2) injuries due to jolting and jarring. The jolting and jarring injuries included

(a) fallover/rollover, (b) jolted/jarred, and (c) jolted/jarred -

struck against. For the lost-time injuries, there was a fairly

consistent reduction from 1993 to 1997 in the annual tally of

incidents resulting from jolts and jars. The remaining categories

of operator impact (struck by, burns, and others) were too few

to show a trend.

Table 10 presents a cross tabulation of activity and incident

results. In total, vertical jars accounted for 354 injuries, about

40% of the injury set. In over one-half (185) of the injuries

resulting from a vertical jar, the dozer operator was backing up.

(Italicized sentences that follow in this section are examples of

actual narratives from the MSHA Form 7000-1.)

Table 10.—Serious incident results by dozer activity (fatalities in parentheses)

Incident result

Dozer activity

Blade/

groundwork

Tramming

forward

Tramming

backward

Land

clearing Ripping Towing/

pushing Total

Fallover/rollover/fall into void . . . . 66 (7) 13 (3) 30 (3) 4 (1) 1 2 116 (14)

Vertical jar . . . . . . . . . . . . . . . . . . 127 27 185 1 11 3 354

Lateral jar (collision) . . . . . . . . . . . 37 (1) 3 27 1 1 0 69 (1) 

Lateral jar (lurch forward/

 backward) . . . . . . . . . . . . . . . . . . 16 4 3 1 0 4 28

Fire (external source) . . . . . . . . . . 2 0 0 0 0 0 2

Normal operations (no apparent

 impact to the dozer) . . . . . . . . . . 185 4 14 1 5 3 212

Dozer struck by an object . . . . . . . 37 0 2 14 0 3 56

Equipment failure . . . . . . . . . . . . . 26 0 3 0 0 0 29

Unknown/other . . . . . . . . . . . . . . . 4 (1) 0 2 (2) 1 0 0 7 (3)

 Total . . . . . . . . . . . . . . . . . . . . . 500 (9) 51 (3) 266 (5) 23 (1) 18 15 873 (18)
9

Operator was backing a bulldozer over rough terrain and

was severely jolted, causing muscle spasms in the lower

back.

Victim was backing up dozer when it dropped off into

hole, causing jar.

When a dozer fell over or rolled over an edge, backing up was

involved in 25% of the cases. Backing up was also involved in

about 40% of the cases involving a collision.

In 102 cases, the dozer operator survived a rollover or falling

off/rolling off an edge. About 4,800 days of lost-time resulted

from these incidents.

Employee was operating a dozer cleaning a bench. He

backed dozer too close to edge. Dozer rolled off bench

and dropped 20 ft and landed on its top.

Injured was blading a road on the highwall bench. He

was pushing dirt out to the edge in order to build a berm.

He apparently ran his tracks too far off the edge. The

dozer tumbled off the edge and free fell approximately

30 ft.

Tramming dozer, dozer slid on frozen ground. Went over

highwall, dozer fell about 30 ft, and then rolled over.

Rollover structure and seatbelt held; however, the

employee apparently struck his face and fractured left

cheekbone.

Of these 102 incidents, a seatbelt was mentioned in 11 of the

narratives. Nine involved operators wearing a seatbelt. Six of

these workers lost 7 days or less because of the incident. The

other three lost a sizable amount of time, from 84 to 238 days.

In two cases involving a dozer falling over or rolling over, the

narrative mentioned that the seatbelt was not worn. These

incidents resulted in lost time of 20 and 25 days, respectively.

In one incident, the dozer fell off of a 5- to 6-ft lift; the other

incident was a rollover.

Lateral jars of the dozer were identified in 97 of the

incidents. A sudden stop (collision) occurred in 69 cases, and

the dozer pitched forward or backward in 28 cases.

Employee was operating dozer. He was pushing

overburden to high lift. The dozer slid from right to left,

then stopped suddenly. When the dozer slid right to left,

and then stopped suddenly, it caused a jerk to employee's

neck.

Employee stated that when he was backing up on the

dozer, he struck a large rock. The jolt caused the

transmission to shift to the next higher gear, causing him

to strain his neck when the dozer accelerated.

He was operating a dozer when the dozer slid on a rock,

causing him to be jarred.

An object such as a rockslide struck the dozer in 56 incidents.

Cutting drill bench and cleaning wall, wall fell on dozer.

Employee jumped to the other side of dozer and bruised

shin.

Employee was dozing out a ramp on a bench with a dozer

he got in close to a previous cut, and a large rock came

out of the bank onto the track, causing the dozer to rock

back and forth, jerking and straining his neck.

Table 11 summarizes the injury records by "incident result"

and "operator impact." The table shows that the dozer operator

was jolted or jarred in a large majority of cases. These are cases

where (1) the operator landed outside of the cab (26 cases),

(2) the operator was jolted or jarred and struck against an object

inside the cab (142 cases), or (3) the incidents were classified as

a "jolt/jar" (436 cases). Together they account for almost 70%

of the serious injuries and about 75% of the lost workdays.

In 78 cases, the operator was struck by something that

resulted in the injury. In 33 cases, something (e.g., rockslide,

Table 11.—Serious incident results by operator impact (fatalities in parentheses)

Incident result

Operator impact

Jolted/

jarred

Landed

outside

of cab

Struck against

an object

inside cab

Struck by

an object MSI

Burned/

contact with

 hot object

Asphyxiation or

drowning 

Other/

unknown Total

Fall over/roll over/fall into void 31 17 (7) 61 — — — 7 (7) — 116 (14)

Vertical jar . . . . . . . . . . . . . . 306 3 45 — — — — — 354

Lateral jar (collision) . . . . . . . 54 — 14 — — 1 (1) — — 69 (1)

Lateral jar (lurch forward/

 backward) . . . . . . . . . . . . 22 — 6 — — — — — 28

Fire (external source) . . . . . . — — — — — 2 — — 2

Normal operations . . . . . . . . — — 4 39 155 — — 14 212

Dozer struck by an object . . . 12 — 10 33 — 1 — — 56

Equipment failure . . . . . . . . . 9 4 2 6 — 6 — 2 29

Unknown/other . . . . . . . . . . . 2 2 — — — — — 3 (3) 7 (3)

 Total . . . . . . . . . . . . . . . . . 436 26 (7) 142 78 155 10 (1) 7 (7) 19 (3) 873 (18)
10

tree limbs) struck the dozer and the object impacted the

operator. In 39 of the struck-by cases, the "incident result" was

coded as "normal operation." Many of these were instances

where dust blew into the operator's eye. A few cases involved

fumes entering the cab or the dozer running over a bee's nest.

An MSI was identified for 155 of the incidents. In all cases,

there was no apparent impact to the dozer. These were incidents

where the operator was injured during the course of the shift,

but no specific information was offered (such as backing over

a rock). In fact, for many of the incidents, the narrative

specifically implied that it was not a singular event. Some of

these incidents related to the operator twisting or turning in the

seat, control usage, or general situations where the narrative

implied a back injury due to dozer usage.

Too much strain on back from turning in seat to back up.

Too many hours on dozer.

Injured claimed he was operating a dozer, ripping 2 ft of

overburden from off of the Dorchester Seam. While

ripping with the dozer, which caused a jerking motion

and the operator turning in the seat to watch his ripper,

he stated he strained his back.

The employee was operating a bulldozer performing

backfilling operation. During normal operator procedures, employee was turning and twisting while operating

dozer. Employee started to experience back pains and

swelling of muscles in the lower back.

Equipment failure was identified in 29 cases. Hydraulic

hoses and seats breaking were predominant in this small set of

incidents. In a few cases, a fire erupted with the rupturing of the

hydraulic lines near the exhaust manifold or engine. In the few

cases involving a fire, the operator jumped from the cab.

Employee states he was digging a large rock out of the

cast area with the left corner bit of the dozer. While

doing this, the right tilt cylinder end broke on the blade

ram. The dozer suddenly dropped down, shaking the

employee up, causing pain in his lower back.

The hydraulic line blew off fitting, resulting in an oil

vapor that hit the turbo charger that flashed, causing a

flash burn to operator's forearm.

Table 12 summarizes seatbelt usage for all cases involving

jolts and jars. There was seatbelt information on 25 lost-time

cases and all 7 of the fatalities where the operator landed outside

of the cab. For the fatalities, there were three instances that

involved dozers manufactured before the date requiring rollover

protection systems (ROPS) and seatbelts, three where the

seatbelt was not worn, and one where it seemed to the investigators that the seatbelt may have torn in the accident. For

the lost-time cases, there were 604 cases of jolting and jarring.

Table 13 summarizes the contributing factors that we were

able to identify from the lost-time injury narratives. Appendix B

provides a more detailed analysis of possible contributing

factors to the fatalities. Table 13 shows that contributing factors

could not be identified for 84% (733) of the cases. This is not

unusual or unexpected; injury narratives are rather short

descriptors. In cases where the dozer fell over an edge, edge

failure was mentioned 14 times and the dozer sliding was

mentioned in 13 cases. The dozer sliding was also mentioned

in several cases involving lateral and vertical jolts and jars. In

cases where the dozer was struck by an object, a rockslide was

mentioned in 21 of the incidents. Mechanical/hydraulic failure

was mentioned in 39 instances. Over 50% of these cases

involved the operator being jolted/jarred or struck by.

Table 14 summarizes information relative to operator impact,

part of the body injured, and workdays lost. This table shows

that injuries to the back, neck, and the classification of "multiple

body parts" were identified most often as the body part injured

in the MSHA database. Together, these three groups accounted

for 83% (25,960 days) of the days lost. This is not surprising

due to the nature of the injuries within this data set (jolts/jars,

struck against, struck by, and MSIs).

Table 12.—Jolting and jarring injuries and seatbelt usage (fatalities in parentheses)

Operator impact Serious

injuries Percent Seatbelt No

Worn Not worn information

Jolted/jarred . . . . . . . . . . . . . . . . . . . . 436 50 12 3 421

Jolted/jarred - struck against . . . . . . . 142 16 8 2 132

Jolted/jarred - landed outside cab . . . 26 1

(7) 3 2(1) (3) 19

Total - jolting and jarring ........... 604 (7) 69 — — —

All other injuries . . . . . . . . . . . . . . . . . 269 (11) 31 — — —

 Total . . . . . . . . . . . . . . . . . . . . . . . . 873 (18) 100 21 8 572 1

Three fatalities involved dozers manufactured prior to the requirement for ROPS. 2

Investigative report suggested that the belt may have torn in the accident.
11

Table 13.—Lost-time incident results by contributing factors

Contributing factors Fall over/

rollover

Vertical and

lateral jar

Dozer

struck by

an object

Other/

unknown Total

Edge failure . . . . . . . . . . . . . . . . 14 0 0 0 14

Mechanical/hydraulic failure . . . . 3 10 0 26 39

Hidden void ................ 4 1 0 0 5

Dozer slid . . . . . . . . . . . . . . . . . . 13 23 1 1 38

Rock slide . . . . . . . . . . . . . . . . . . 1 0 21 0 22

Other . . . . . . . . . . . . . . . . . . . . . . 2 — 2 0 4

Total . . . . . . . . . . . . . . . . . . . . . . 37 34 24 27 122

Unknown . . . . . . . . . . . . . . . . . . . 65 416 32 220 733

Table 14.—Lost-time injuries by operator impact and part of body injured

Body part injured

Operator impact

Jolted/

jarred

Landed

outside

of cab

Struck

against

an object

Struck

by an

 object

MSI

Burned/

contact with

hot object

Other/

unknown Total

Head . . . . . . . . . . . . . . . . . . . . . . 2 1 22 11 — — — 36

Eyes . . . . . . . . . . . . . . . . . . . . . . — — — 30 — 1 2 33

Back . . . . . . . . . . . . . . . . . . . . . . 272 — 21 3 99 — 1 396

Neck . . . . . . . . . . . . . . . . . . . . . . 71 — 6 — 13 — — 90

Multiple parts . . . . . . . . . . . . . . . 56 11 44 12 11 4 1 139

Trunk, shoulders, upper extremities, chest, hips, abdomen . . . . . 27 3 27 4 17 1 5 84

All other . . . . . . . . . . . . . . . . . . . 8 4 22 18 15 3 7 77

 Total . . . . . . . . . . . . . . . . . . . . 436 19 142 78 155 9 16 855

DISCUSSION

From 1993 to 1997, there was a notable reduction (30%) in

the number of serious injuries to dozer operators while

performing common production tasks compared to those in the

baseline period (1988-92). Specifically, there are fewer injuries

and workdays lost due to lateral and vertical jolts, MSIs, struck

by, struck against, and falling off an edge. It is difficult to name

the specific reasons for this improvement. It is likely a

combination of factors involving technology (e.g., better seating

and seat suspension systems), people (e.g., more frequent use of

restraint systems, higher skill levels in recognizing and

responding to difficult dozing conditions), and the work

environment (e.g., better ways to organize the work, better

training and awareness, more consistent work procedures and

practices tailored to the job conditions). The work (e.g.,

roadway, ramp and berm construction) accomplished by dozer

operators is essential in that it helps to enhance efficiency and

reduce injury risk for other parts of the mining plan.

It is noteworthy that, although this study only examined

serious injuries to dozer operators while performing common

production tasks, injuries sustained while mounting and dismounting the dozer (table 1) are almost equal in number and

severity to the injury set examined in this report.

INJURIES RELATED TO JOLTS AND JARS

Vertical and lateral jolting and jarring (including those where

the operator strikes an object inside the cab) are the most

common sources of injury to dozer operators while they are

operating the equipment. Although the incidents have declined

over the period examined, this area is still the most opportune to

achieve further reductions in injury risk. A total of 597 injuries

resulting in 23,924 lost workdays were due to jolts and jars.

These were all acute incidents where the operator was impacted

in any one of three ways: the operator (1) was jolted/jarred and

remained in the seat, (2) was thrown against an object inside the

cab, or (3) landed outside of the cab. This accounts for nearly

70% of the lost-time injuries and 75% of the workdays lost.

These findings are similar to another recent study that

identified jolts and jars as a significant concern to equipment

operators. Cross and Walters [1994] examined vibration and

jarring as a source of back pain in the mining industry in New

South Wales, Australia. Their study involved the review of

28,306 compensation claims over a 4-year period (July 1986 to

March 1990) and covered both surface and underground

environments. They identified 8,961 claims relating to the head,
12

back, and neck, of which 11% (986) were due to vehicular

jarring. Underground transporters and shuttle cars accounted for

53% of all vehicular jarring injuries. Surface loaders, dozers,

and dump trucks accounted for another 29% of the vehicular

jarring injuries.

Regardless of the source, all jolts and jars seem to come as

a complete surprise to the operator. The rough and variable

conditions present significant challenges to research and

engineering personnel to develop and test methods to protect the

operator.

Backing up the dozer was associated with many of the jolting

and jarring injuries. For 185 of the 357 vertical jarring incidents

(table 10) the dozer was backing up. Backing up is an activity

that most would like to minimize, both in terms of distance and

time. Dozer operators may tend to maximize their output

(material moved) by minimizing their necessary, but unproductive time in backing. Higher tram speeds (generally

about 5 miles per hour maximum for track dozers) in backing up

may introduce risk by exacerbating the effects of small rises or

rocks and provide a low margin of error in perception,

judgment, and corrective action (slowing down). If operators

recognized the hazard, the response might be direct and more

reliable—slow down and maneuver the dozer through or around

the obstacle.

Body posture also plays a role. Griffin [1990] and Bottoms

and Barber [1978] suggest that poor body posture partially

contributes to disorders among agricultural tractor operators.

Twisting and turning in the seat (to look behind) is likely to

contribute to the frequency and severity of these incidents as it

increases the risk of a back injury due to the uneven distribution

of the vibrating and shock forces on the spine. Bottoms and

Barber [1978], in their study of agricultural tractor injuries,

suggest that a swivel seat might be appropriate to minimize the

awkward postures that can increase the impact of vibration and

shock to the back.

High-energy, short-duration jolts and jars may also prematurely wear certain components of the dozer. Undercarriage,

track maintenance, wear items, and repair costs are estimated at

about $27 per hour [Hays 1990]. High-speed backing also

accelerates wear.

Strategies to reduce the effect of vehicular jarring include

seating (methods to dampen the shock or isolate the operator

from the shock) and use of operator restraint devices. For the

855 lost-time injuries, only 25 of the injury narratives provided

information on whether or not the seatbelt was in use at the time

of the incident. Of those cases, 20 indicated that the seatbelt

was worn.

It is difficult to conclude much from these data except that

seatbelt usage was only mentioned in a small percentage of the

cases. Table 11 shows that there were many cases where the

operator was jolted and struck against an object (inside the cab)

and a few cases where the operator landed outside of the cab.

We did not infer that the seatbelt was not being used. Where the

operators landed outside of the cab, they either jumped or were

thrown. Operators who were jolted and struck an object inside

the cab may have been within the zone of protection, even with

a seatbelt on. In many cases, one might reasonably surmise

from the narratives that the seatbelt was not worn. However,

we only noted seatbelt usage when specifically mentioned in

the narrative. At the same time, table 14 suggests that the

substantial injuries to various parts of the body might have been

reduced by more consistent use of restraint devices.

For off-highway equipment used in mining, the need to

protect the operator via operator restraint devices and protection

from rollover has been established for some time [Oitto and

McLellan 1975]. Although seatbelts have been required by

regulation for some time, there seems to be much variability in

their use among dozer operators. The reasons for this variability

might be further investigated.

Carlson and Hoffman [1981] conducted a series of field

studies of improved seatbelt restraint systems involving

retractable sheath designs and automatic and manual locking

features. The purpose was to design a restraint system that

would enhance comfort, fit, and convenience. Their previous

investigations found that the designs of conventional restraint

systems contributed to limited use among equipment operators.

A vehicle-sensitive retractor design was chosen, similar to the

automotive mechanisms. The off-highway equipment systems

were set to operate at 0.75 g, which is higher than what was

common with automotive designs. Their new seatbelt design

was a combination of commercially available retracting systems,

inertial-type locking mechanisms, and webbing material. The

new designs were field tested at mining sites. Results showed

better acceptance by equipment operators compared to the

conventional restraint system design.

The importance of integrating a restraint system with

appropriate seat and seat suspension designs was suggested by

Appel et al. [1984]. They report on the laboratory testing of

seatbelts, stating that early applications of seat restraints to offroad equipment were similar in design to those used for highway

applications (and frontal crashes). Their work proved the

designs to be less than effective for lateral impact forces (such

as those involved in a rollover). They also found that the

harness belt gave lateral protection, but was cumbersome and

restricted the operator. Appel et al. thought that a lap belt with

lateral shoulder supports would offer a good balance in

protection and usability that would go well beyond the

conventional lap belts. They also noted that the lack of a shockabsorbing seat was the weakest link in the restraint system.

Seat designs for surface off-highway equipment have improved greatly with features such as mechanical and pneumatic

suspension systems, lumbar spine support, and viscoelastic foam

padding. Assessing their usability and performance under

different shock and vibration test conditions might offer useful

information on ways to better secure the worker since many jolts

and jars are not predictable. Some researchers [Gouw et al.

1990] have developed computer simulation models to help

designers select seat suspension parameters. This research area

seems to have some potential in testing certain seating

(performance) characteristics before field application.

There has been much study of the potential health effects

of WBV among groups of workers operating off-highway

equipment such as agricultural tractors and surface mining/

construction equipment [Griffin 1990; Remington et al. 1983].

Although much of the literature is indirectly relevant, one study

is pertinent.
13

Robinson et al. [1997] gathered WBV data on 11 mining

vehicles, 3 of which included dozers. They profiled vehicles

and made recommendations that could help with a planned

reintegration of workers who experienced a back injury into jobs

at the mine site. Their goal was to reduce the likelihood of

reinjury (due to the cumulative effects of vibration and repeated

shocks) by not placing these workers into a vibration- or shockprone environment. Results showed that vibration levels varied

considerably across the vehicles tested. Newer equipment

tended to fare better. However, a severe mechanical shock level

(measured by the maximum crest factor) was recorded for all

production vehicles5

 monitored. This suggests that severe

mechanical shock can occur in any mine vehicle, and ground

conditions have a significant role. Vehicle speed was not

reported in this study.

Gagliardi and Utt [1993] collaborated with a mining firm to

assess the characteristics for mechanical and air suspension

seats, as well as various seat cushions. All tests were performed

in a laboratory. Information obtained offered guidance with

respect to the use (e.g., setting adjustments) of both types of

suspension systems and the performance of a variety of seat

density cushions. The tests applied mostly to vibration damping

versus damping the effects of high-energy shocks. Thus, the

results are more in line with parameters to counter fatiguedecreased proficiency (ISO 2631) as opposed to acute, highimpact jolts.

It is not certain how many dozer operators who were injured

by jolts and jars are able to return to the dozer to do the same

tasks once they return to work. One could reasonably surmise

from the injury data that those operators sustaining injuries that

require them to be off work for extended weeks may not

perform at the same level once they return to the worksite. On

average, 37 days were lost for all dozer operator injuries

reported to MSHA and examined in this set. The median was

19 days. On one end of the distribution, 25% of the incidents

resulted in 4 days or less of lost work time. On the other end,

25% of the incidents resulted in a loss of 45 to 485 days.

MUSCULOSKELETAL INJURIES

MSIs accounted for the next largest category that appeared

in the database. Overall, they accounted for 155 incidents

(table 11). All of these injuries were in situations where nothing

external to the dozer contributed to the incident. Many of these

did not seem to result from a single source. Many related to

awkward postures, tiring work, and difficult dozing conditions.

These injuries are often reported as having occurred during the

shift, but there was not a lot of detail surrounding these

incidents. Most involved back pain.

Zimmermann et al. [1997] reviewed the literature on workrelated musculoskeletal disorders (MSDs) and WBV among offhighway equipment operators. One study referenced by

 5

For three dozers in the sample, crest factors (max-along the z, or vertical

axis) of 12.4, 14.8, and 24 were measured.

Zimmermann et al. (Miyashita et al. [1992]) examined workrelated disorders for dozer operators. Common ailments among

the 127 dozer operator participants included reports of low back

pain (36.2%), general fatigue (44.1%), and stiff shoulders

(54.3%). Zimmerman et al. note that the frequency range in

which WBV is most problematic is 4 to 8 Hz. They concluded

that the high risk of MSD among equipment operators might be

caused by a combination of the sustained and awkward sitting

postures and the vibrating environments in which off-highway

equipment operators work. Based on their literature review,

they gave general suggestions regarding cab and control

designs, minimizing vibration exposures, and regular work

breaks among off-highway equipment operators.

The risk of injury due to twisting and turning in the seat is

a problem. If one accepts that jolts are unexpected, then one

solution is for the dozer operators to recognize terrain conditions that are likely to produce high levels of shock. Once

identified, the path is to slow down or carefully maneuver to

avoid the dip, rock, or other uneven ground. Backing up is a

common and necessary task. If operators are twisting to look

behind as they back up, then it could expose them to injury due

to the effect of lower level vibrations and shock. By twisting

and looking behind, their purpose is to avoid the larger hazards

(jolts). If they do not look behind (in order to maintain a good

body posture), then they become more susceptible to the risk of

larger shocks (jolts and jars) due to unseen undulations or

obstacles.

TRAINING

Hazard recognition and response skills seem to be an integral

part of safe and efficient dozer operation. Figure 3 shows that

five of the dozer operator fatalities had 2 months or less of

experience on the dozer. For lost-time injuries (tables 6

and C-6), dozer operators with less than 1 year of experience are

involved in a sizable number of lost workday incidents. Almost

15% of the lost-time injuries were incurred by operators who

worked less than 1 year in the job classification. For fallover

and rollover incidents, job experience data were available for 93

incidents. Fourteen of these incidents occurred to those with

less than 1 year of experience. By contrast, injury victims with

1-5 years of experience in their job classification were involved

in 16 out of 93 fallover, rollover lost-time incidents.

Of 116 incidents where the dozer fell over an edge, rolled

over, or fell into a hidden void, 14 (12%) resulted in fatal

injuries. Overall, 80% of the fatalities and 12% of the lost-time

injuries occurred while working near an edge or hidden void or

on a steep slope. Thus, the hazards of working near an edge or

on a steep slope is especially evident from the analysis of the

lost-time and fatality data. Part of the training task is to teach

hazard recognition and response skills, especially in areas that

can likely result in serious injury or economic loss.

It makes good economic sense to invest in training when an

employee is assigned to a job that involves sizable risk, capital,

and significant hourly costs in fuel, repair, and maintenance.

For dozers, this investment can total well over $100 per hour.

The operator's wages are a small percentage of the total hourly
14

investment. This offers an obvious opportunity to invest in

skills, as many recognize that dozer operator performance can

have a sizable impact on the return on the technology investment. Provisions to formally teach and evaluate (integrating

safety with efficiency) skills are common within many organizations. Many use experienced dozer operators who have been

taught how to teach and evaluate skills.

Skill in operating a dozer does not come quickly or easily.

Blade control takes time. The more sophisticated the dozer

control systems, the greater the need to ensure that there is a

good and reasonable fit between the operator and the technology. Judgment and decision-making are always important in

day-to-day operation of off-highway equipment. It would seem

to be of even greater importance as the value of the investment

increases. Training can serve to enhance the fit between the

technology and how it is used at the job site. Hazard

recognition and response skills seem to be an indispensable

component of safe and efficient dozer operation. Many of the

incidents affected both the dozer and the operator. Hazards can

be subtle and hidden. Each of the serious injuries in the data set

resulted in a significant social and economic cost.

RELEVANT NIOSH RESEARCH

NIOSH is currently conducting collaborative work to help

reduce the effects of shock and vibration. This work is framed

within a series of research experiments [Biggs and Miller 1999]

to characterize jolting and jarring on surface mine haulage

trucks. Biggs and Miller describe the use of a global positioning

system in conjunction with truck-mounted accelerometers as a

tool for profiling mine site locations that are associated with

jolts in excess of 2 g. The experimental system could be useful

to map locations where workers are most likely to be exposed to

jolting and jarring hazards. The mapping and acceleration

measurements are monitored in real time.

CONCLUSIONS

Risk is part and parcel of everyday worklife. The purpose

of this study is to examine injury experience to dozer operators while performing common production tasks. Our goal is

to organize information to help understand risk and what might

be done to further reduce the risk of serious injury. We suggest that the factors that reduce risk are also the ones that

increase risk. They involve technology, people, and the work

environment.

Although this study suggests a sizable reduction in injury risk

from 1993 to 1997, one should keep in mind that the odds of a

fatal injury are quite high if a dozer is involved in a rollover or

falling over an edge. In 12% (14 out of 116 incidents) of the

incidents involving a rollover or a dozer falling over an edge,

the operator died. Not wearing seatbelts (or older equipment

without a ROPS or seatbelt) contributed to six of the fatalities.

In cases where the dozer operator either jumped or was thrown

out of the cab, 7 of 26 were killed.

Vertical and lateral jolting and jarring is the most common

source of injury to dozer operators while they are operating the

equipment. Although the incidents have declined over the

period examined, this still seems to be the most opportune area

for further decreases in injury risk. MSIs are also an area where

further progress could be made with regard to reducing the

frequency and severity of incidents resulting from everyday

usage of dozers.

Seating, seat suspension systems, and operator restraint

devices are critical tools that can enhance safety and efficiency.

The effects of shock and vibration are complex, and there are no

simple ways to measure, lessen, or neutralize their effects. The

very unique and often uncertain conditions that dozers work can

make interfacing the technology with the operator difficult.

Incremental improvements in designing and field testing

innovative seating, seat suspension, and operator restraint

technologies offer good opportunities to further reduce the risk

of serious injury. For some dozer tasks, isolating the operator

via remote operation might also be a promising option [Singh

1997]. Lastly, continued emphasis on hazard recognition of

edge, hidden voids, and difficult ground conditions could reduce

the number of surprises and allow for corrective action. All

potential solutions have components of technology, people, and

the work environment. The relative merits of any solution

should be accurately described in field tests.

ACKNOWLEDGMENTS

The authors thank Thomas L. Friend (former Supervisor,

Skills and Mandatory Training, Cyprus-AMAX Coal Co.,

Evansville, IN) for providing technical information on dozer

tasks, training of dozer operators, and assistance during several

field visits to surface mining operations. Much of the

information on dozer and operator performance in this report

was based on collaborative work with Mr. Friend and personnel

from Cyprus-AMAX's Chinook Mine, Terre Haute, IN. It was

performed under a Cooperative Research and Development

Agreement (U.S. Bureau of Mines CRADA No. 6200-0121).
15

REFERENCES

Appel H, Vu-Han V, Pirshel H [1984]. Occupant protection in earth-moving

machines. In: Advances in Belt Restraint Systems: Design, Performance, and

Usage. P-84/141. Warrendale, PA: Society of Automotive Engineers, Inc.,

pp. 87-100.

Biggs FR, Miller R [1999]. Characterization of jolting and jarring on

operators of surface mine haulage trucks. Presented at the NIOSH Open

Industry Briefing, 105th Annual Meeting of the Northwest Mining Association

(Spokane, WA, November 30, 1999). Available from Fred R. Biggs, NIOSH

Spokane Research Laboratory, e-mail: fbb3@cdc.gov

Bottoms DJ, Barber TS [1978]. A swiveling seat to improve tractor drivers'

posture. Appl Ergonomics 9:77-84.

Carlson LE, Hoffman AG [1981]. Development of improved seatbelt

systems for surface mining equipment. Mobility Systems and Equipment Co.

U.S. Bureau of Mines contract No. H0202005, pp. 6-12.

Cross J, Walters M [1994]. Vibration and jarring as a cause of back injury

in the NSW coal mining industry. Saf Sci 17(4):269-274.

Gagliardi JC, Utt WK [1993]. Vibration testing of off-road vehicle seats.

Minneapolis, MN: U.S. Department of the Interior, Bureau of Mines, RI 9454.

Gouw GJ, Rakheja S, Sankar S, Afework Y [1990]. Increased comfort and

safety of drivers of off-highway vehicles using optimal seat suspension. In:

Society of Automotive Engineers Transactions 99:541-548.

Griffin MJ [1990]. Handbook of human vibration. Academic Press Ltd.

ISO [1985]. ISO 2631/1 - Guide for the evaluation of human exposure to

whole body vibration. Geneva, Switzerland: International Organization for

Standardization.

Love AC, Unger RL, Bobick TG, Fowkes RS [1992]. A summary of current

Bureau research into the effects of whole-body vibration and shock on operators

of underground mobile equipment. Pittsburgh, PA: U.S. Department of the

Interior, Bureau of Mines, RI 9439, pp. 2-5.

May JP [1990]. Analysis of dump-point accidents involving mobile

equipment. Minneapolis, MN: U.S. Department of the Interior, Bureau of

Mines, IC 9250, p. 15.

Miyashita K, Morioka I, Tanebe T, et al. [1992]. Symptoms of construction

workers exposed to whole body and local vibration. Int Arch Occup Env Health

64:347-351.

Oitto RH, McLellan RR [1975]. Analysis of fatal accidents involving frontend loaders at metal and nonmetal mines, 1972-1974. U.S. Department of the

Interior, Mine Enforcement and Safety Administration (MESA), Informational

Report 1019.

Remington PJ, Stahr J, Andersen DA [1983]. Assessment of whole body

vibration levels of coal miners. Volume I: Whole body vibration exposure of

surface coal mining machine operators. Cambridge, MA: Bolt, Beranek and

Newman, Inc. U.S. Bureau of Mines contract No. J0308045.

Robinson D, Martin S, Roddan G, Gibbs G, Dutnall J [1997]. The

application of vibration assessment in mining vehicles to return-to-work

protocols. J Low Frequency Noise, Vibration and Active Control 16(2):73-79.

Singh S [1997]. State of the art in automation of earthmoving. J Aerospace

Eng 10(4):179-188.

Sparrell CF [1980]. Off-highway vehicle accidents and operator training.

In: Proceedings of the International Off-Highway Meeting and Exposition.

Warrendale, PA: Society of Automotive Engineers, Inc., preprint 800945.

Stanevich RL [1986]. A study of earthmoving and highway construction

machinery fatalities and injuries. Ann Am Conf Gov Ind Hyg 14:703-710.

Turin FC, Wiehagen WJ, Jaspal JS, Mayton AG [2001]. Haulage truck

dump-site safety: an examination of reported injuries. Pittsburgh, PA: U.S.

Department of Health and Human Services, Public Health Service, Centers for

Disease Control and Prevention, National Institute for Occupational Safety and

Health, DHHS (NIOSH) Publication No. 2001-124, IC 9454.

Zimmermann CL, Cook TM, Rosecrance JC [1997]. Work-related

musculoskeletal symptoms and injuries among operating engineers: a review

and guidelines for improvement. Appl Occup Env Hyg 12(7):480-484.
16

APPENDIX A.—INJURY RECORD SELECTION AND CODING

RECORD SELECTION

MSHA injury data for 1988-97 were analyzed based on the

decision rules listed in table A-1. Selecting on "mining machine

' bulldozer" yielded 2,962 records. The mine worker activity

criteria were used to select those records that primarily involved

"operating the dozer." Other selection criteria (e.g., escaping a

hazard) were used to capture relevant records that may have

been coded differently, but still involved an injury to a miner

while performing common production tasks with the dozer.

The set of 960 injury records included 17 fatalities. We

reviewed the narratives of all 23 fatals involving dozers for

1988-97. This review yielded one additional record that is

included in the data set. Upon reviewing the set of 960 records,

the authors selected 873 that met these criteria: (1) the injuries

occurred while the worker was operating a dozer and (2) the

worker was injured to the degree where work time was lost.

Table A-1.—Criteria for the selection of injury records

Target data MSHA data field Selection criteria No. of

records

Surface Mining

Serious Injuries

Subunit Surface OR Underground OR

Strip OR

Auger OR

Culm Bank OR

Dredge OR

Other Surface OR

Preparation Plant 79,601

Degree of Injury Death OR 

Permanent Disability OR

Days away from Work Only OR

Days Away and Restricted Activity

Surface Mining

Injuries Involving

Bulldozers

Mining Machine Bulldozer 2,962

Surface Mining

Dozer Serious Injuries

Mine Worker

Activity

Escaping a Hazard OR

Bulldozer OR

Front-end Loader OR

Haulage Truck OR

Surface Equipment NEC

 (not elsewhere classified)

960

Surface Mining

Dozer Serious Injuries

Narrative Author Selection 873
17

CODING OF THE RECORDS

Table A-2 specifies the variables and categories used to code the injury narratives.

Table A-2.—Author-defined variables and categories added to the injury set

Variable Description of categories

Activity . . . . . . . . . . . . . . . . . . . . . . . . . Blade/groundwork (default value if narrative vague)

Tramming forward

Tramming backward

Ripping

Land clearing

Towing

Pushing equipment

Other

Incident result (dozer impact) . . . . . . . . Fallover/rollover/fall into void

Lateral jar (collision)

Lateral jar (lurch forward/backward)

Dozer struck by an object

Vertical jar

Equipment failure

Fire - external source

Normal operations (no apparent impact to the dozer)

Other

Unknown

Operator impact . . . . . . . . . . . . . . . . . . Jolted/jarred

Jolted/jarred (landed outside of cab)

Jolted/jarred (struck against an object inside cab)

Struck by an object

Burned/contact with a hot object

Asphyxiation

Drowned

Musculoskeletal injury (MSI) - operator hurt while twisting and turning,

 reaching too far, pulling or pushing on something, (often cannot be

 tied to a singular source/event)

Other

Unknown

Contributing factors to the event . . . . . Edge failure

Hidden void

Equipment failure

Dozer slid

Rock slide

Other

Unknown

Contributing factors to the severity . . . . Operator jumped out of cab

Operator thrown out of cab

Operator either jumped from or thrown out of cab

Seatbelt worn

Seatbelt not worn

Other

Unknown
18

APPENDIX B.—ANALYSIS OF FATALITY REPORTS (1988-97)

This analysis of the 18 dozer fatalities during 1988-97 is

obtained from the review of MSHA investigative reports

supplemented by information from the MSHA Form 7000-1

filed by the mine operator or independent contractor. Included

in this analysis are variables/fields added to the fatality database

that are in addition to those variables referred to in table A-1.

The depth of information contained in the fatality reports

allowed for supplemental analysis.

The mines where these fatalities occurred ranged in size from

2 to 1,400 employees. Seven of the fatalities were at mines

employing 25 or fewer miners. Of note, 5 of these occurred in

a single year—1993. Six fatalities occurred at mines employing

more than 100 workers. The rest (5) occurred at mines ranging

in size from 26 to 100 employees. For 11 of the 18 fatalities,

MSHA noted the "last quarter" frequency rate at the mine site

compared to an average rate for similar mines. In 8 of the 11

cases, the mines where the fatalities occurred had an injury rate

(for the past quarter) that was below the industry average.

Although most of the lost-time injuries were concentrated

within 4 States (see figure 2), the fatalities were spread across

13 States. However, by industry sector, bituminous coal mines

had the highest number (10) of dozer fatalities, followed by sand

and gravel (4); stone and metal mines each had 2.

Witnesses to the accidents were present in one-half of the

18 cases. The other half were discovered anywhere from within

a few minutes to several hours after the incident.

AGE AND EXPERIENCE

All victims were male between the ages of 21 and 70. The

median age was 43. Experience in the task ranged from only a

few days to over 40 years. Five of the victims had less than

2 months of experience on the dozer. Three of these five were

on the job for less than a week. Another two had 1-2 years of

experience. The rest (11) had from 3 to 40 years of experience.

Of the seven victims that had less than 2 years of experience,

five fell over an edge or into a void. The other two were run

over by the dozer they were operating. Four victims had more

than 10 years of experience. In all of these cases, the dozer fell

over an edge; three of the victims landed outside of the

compartment, and one victim drowned. No witnesses were

present at these four incidents.

INCIDENT RESULT

Falling over an edge.—In 11 cases, the dozer fell over an

edge. In seven of these cases, the operators were found outside

of the cab; they either had jumped or were thrown out. In one

of these seven cases, the fatality report indicated that the

operator tried to jump clear of the machine as it was falling. In

three cases, the cause of death was drowning. In one case, the

dozer fell over an edge and loosened material covered the

machine.

A seatbelt was not available in the dozer in three of these

incidents (the machine had been manufactured before the

requirements for ROPS and seatbelts1

). In three other cases, it

was noted that the seatbelts were not worn. In one of these

cases, the investigators indicated that the operator had removed

his belt. In another case, it seemed to the investigators that the

belt was being worn, but had torn due to the nature of the

incident.

Edge failure was a factor in four incidents. Working near

bodies of water was implicated in two other cases (one case was

at dusk, the other involved pushing material at the edge of a

frozen pond). In two cases, the investigators noted that the

operators lost control of the dozer as they were working near an

embankment or elevated road.

 1

ROPS and seatbelts are not required on dozers manufactured before

July 1, 1969. See 30 CFR 56.14130 and 30 CFR 77.403(a), “Roll-over

protective structures (ROPS) and seat belts.”

Falling into a hidden void.—There were three incidents

where the dozer fell over an edge into a hidden void. In all

cases, the void was hidden (bridged). In one other case (noted

above), the dozer fell (backed) over the edge of an open draw

hole and the loosened material engulfed the machine. In all

cases, suffocation was noted as the cause of death. In each case,

the stockpile was the work area, and these operators were

working in an active area. Rescue attempts were made right

away (once the incident was discovered) by mine personnel to

dig the operators out of the material. In two cases, the feeders

were turned on to see if the dozer could be more quickly

uncovered versus the time-consuming process of digging out the

equipment from the outside edges or crest of the stockpile/

loosened material. Both of these cases failed, and digging

operations continued from the periphery. Rescue operations

took from 2 to over 10 hr. The fatality investigation found that

in all of four cases, the windows of the equipment were pushed

in or broken by the material that engulfed the dozer cab. One

entrapped operator was in voice contact with rescuers for about

8 hr. In two cases, the operators had 2 months or less of task

experience.

Unmanned dozer.—Three dozer operators were run over by

their own dozer. No witnesses were present at any of these

incidents. Investigators concluded that these operators had

attempted to exit or enter their machine either while the dozers

were in gear, or the dozers jumped into gear, or the controls
19

were accidentally activated. Failure to take the machine out of

gear and set the parking brake was mentioned in two of the

reports. One of these operators had 2 days of experience; the

other two had 1.5 and 9.9 years of dozer experience,

respectively.

Collision.—In one case, the dozer hit a (buried) natural gas

line, and the operator was killed by the ensuing fire.

Time of the incidents and time into work shift.—With regard

to when these incidents occurred, we summarized both the

"time" and "time into shift." Twelve incidents occurred between

8:00 a.m. and 4:00 p.m. Four were between 4:00 p.m. and

7:30 p.m. The remaining two were between midnight and

8:00 a.m. The large majority of incidents (15) occurred within

8 hr of beginning work. One incident was slightly over 10 hr

into the shift, and one case was estimated at 5-10 hr into the

shift. For the remaining case, there was no information in the

investigation report that allowed us to calculate a value for the

"time into shift."

Dozer year of manufacture.—In eight of the incidents, the

age of the equipment was mentioned in the fatality reports. The

year of manufacture ranged from 1936 to 1991. Three were

manufactured before the requirement (July 1, 1969) for ROPS

and seatbelts. In these three incidents, the dozer fell over an

edge and the operator landed outside of the cab. Seatbelts were

not available to the operator in these cases. The age of the dozer

was not directly available in the investigative report for 10 of

the incidents.

30 CFR violations/citations issued.—Based on the results of

four of the investigations, no violations were found by MSHA.

However, for the other 14 investigations, violations of the

following regulations were identified: 30 CFR 48.27, 50.10,

56.14100, 56.14101, 56.14130, 56.16002, 56.3401, 59.9101,

56.9303, 77.1000, 77.1606, 77.1607, 77.1710, 77.1713, and

77.410. The general areas noted include seatbelt usage,

machine defects (e.g., brakes), aspects related to mine design

(e.g., ramps, bins, and hoppers), training, failure to notify

MSHA, workplace inspections, and maintaining control of

mobile equipment.
20

APPENDIX C.—SUPPLEMENTAL INJURY TABLES

Table C-1.—Lost-time injuries by subunit

Subunit Lost-time

injuries Percent Days lost Percent

Surface or underground . . . . 25 3 1,243 4

Strip . . . . . . . . . . . . . . . . . . . 728 85 26,833 84

Auger . . . . . . . . . . . . . . . . . . 2 <1 43 <1

Culm banks . . . . . . . . . . . . . 11 1 461 1

Preparation plants . . . . . . . . 77 9 2,841 9

Dredges . . . . . . . . . . . . . . . . 11 1 458 1

Other surface . . . . . . . . . . . . 1 <1 7 <1

 Total . . . . . . . . . . . . . . . . . 855 100 31,886 100

Table C-2.—Dozer serious injuries by mine worker activity

(fatalities in parentheses)

Mine worker activity Serious

injuries

Haulage truck .......................... 2

Escaping a hazard . . . . . . . . . . . . . . . . . . . . . . 7

Surface equipment NEC .................. 6

Get on or off equipment . . . . . . . . . . . . . . . . . . 1 (1)

Bulldozer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 855 (17)

Front-end loader ........................ 2

 Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 873 (18)

Table C-3.—Lost-time injuries by job title

Job title Lost-time

injuries Percent

Bulldozer/tractor operator . . . . 701 82

Crane operator/dragline . . . . . . 32 4

Laborer/utilityman . . . . . . . . . . . 32 4

Truck driver . . . . . . . . . . . . . . . . 16 2

Highlift operator/end loader . . . 14 1

Other (20 other job titles) . . . . . 50 6

Unknown . . . . . . . . . . . . . . . . . . 10 1

 Total . . . . . . . . . . . . . . . . . . . 855 100
21

Table C-4.—Serious injuries by State and year (fatalities in parentheses)

State or

territory

Year Total

1988 1989 1990 1991 1992 1993 1994 1995 1996 1997

Alabama ....... 2 5 3 2 1 1 (1) 2 1 3 — 20 (1)

Alaska . . . . . . . . . — 1 — — — — — — 3 — 4

Arizona . . . . . . . . 2 2 1 2 2 1 1 1 — — 12

Arkansas . . . . . . 1 — 1 — 1 — — — — — 3

California . . . . . . 6 7 10 8 6 3 3 5 (1) 2 2 52 (1)

Colorado . . . . . . . 1 — — 1 — — 1 1 — 1 5

Florida . . . . . . . . . 1 1 1 1 3 2 — 1 3 3 16

Georgia . . . . . . . . 1 1 2 — — — — — — — 4

Hawaii . . . . . . . . . — — 3 — 2 2 1 — — 1 9

Idaho .......... 2 — 1 1 — — 1 1 1 1 8

Illinois . . . . . . . . . 6 5 6 7 5 1 — 3 — 1 34

Indiana . . . . . . . . 1 2 4 (1) 6 — 2 2 2 1 3 23 (1)

Iowa . . . . . . . . . . — — — 2 — 2 — 1 — — 5

Kansas . . . . . . . . ———————1 1 — 2

Kentucky . . . . . . . 14 20 26 19 25 15 22 (1) 20 (1) 10 9 180 (1)

Louisiana ...... 1 1 1 — — — — — — — 3

Maine . . . . . . . . . 1 ———— ————— 1

Maryland . . . . . . . ————— ———— 1 1

Massachusetts . . (1) — — — — — — — 1 — 1 (1)

Michigan . . . . . . . 3 5 3 2 1 7 (1) — 2 — 5 26 (1)

Minnesota . . . . . . — 5 (2) 2 2 — 5 1 1 1 1 18 (2)

Mississippi . . . . . 1 — — — 1 — 1 — — — 3

Missouri . . . . . . . 1 — — — 3 — — 1 1 1 7

Montana . . . . . . . 1 1 — 1 1 2 1 — 1 — 8

Nevada . . . . . . . . 6 4 4 6 3 1 2 2 1 5 34

New Jersey . . . . . — — — 1 — 2 — — — 1 4

New Mexico . . . . 2 3 1 2 2 (1) 2 (1) — 2 1 — 15 (2)

New York . . . . . . 3 — 1 2 1 — — 1 (1) 1 — 9 (1)

North Carolina . . — 2 — — — — — — 1 — 3

North Dakota . . . — 2 — 2 — — — — 1 — 5

Ohio . . . . . . . . . . 4 3 5 2 7 2 3 (1) 1 1 — 28 (1)

Oklahoma ...... — — — 1 — — — — — 2 3

Oregon ........ ———— 1 2 —— 1 — 4

Pennsylvania . . . 9 6 11 10 8 (1) 8 (1) 7 8 4 4 75 (2)

Puerto Rico . . . . . — 1 1 — — — — — 1 1 4

South Carolina . . — 1 — — — — — — — — 1

South Dakota . . . 1 — 1 — — 1 1 1 — — 5

Tennessee ..... 2 2 2 3 1 — — — — — 10

Texas . . . . . . . . . 4 3 1 2 2 1 2 (1) 2 1 2 20 (1)

Utah . . . . . . . . . . — 1 — — — — 2 — — 1 4

Virginia . . . . . . . . 7 5 5 3 4 1 5 5 2 2 39

Washington . . . . — 2 2 1 1 ———— 1 7

West Virginia . . . 7 14 16 17 (1) 15 19 (1) 12 15 15 14 144 (2)

Wyoming . . . . . . . 1 2 1 2 — 2 — 1 — 2 11

 Total . . . . . . . . 92 (1) 107 (2) 115 (1) 108 (1) 96 (2) 84 (5) 70 (3) 79 (3) 58 (0) 64 (0) 873 (18)
22

Table C-5.—Lost-time injuries by State, industry sector, and lost workdays

State or

territory

Industry sector Total

incidents

Total

days lost Anthracite

coal

Bituminous

coal

Sand and

gravel Stone Nonmetal Metal

Alabama . . . . . . . . — 14 1 4 — — 19 573

Alaska . . . . . . . . . . — 1 — — — 3 4 42

Arizona . . . . . . . . . — 4 — 1 1 6 12 669

Arkansas . . . . . . . — — — 2 — 1 3 251

California . . . . . . . — — 30 9 4 8 51 1,074

Colorado . . . . . . . . — 2 2 1 — — 5 44

Florida . . . . . . . . . . — — 1 7 8 — 16 744

Georgia . . . . . . . . . — — — 1 3 — 4 84

Hawaii . . . . . . . . . . — — — 9 — — 9 179

Idaho . . . . . . . . . . . — — 1 — 6 1 8 242

Illinois . . . . . . . . . . — 30 — 4 — — 34 1,816

Indiana . . . . . . . . . — 21 1 — — — 22 949

Iowa . . . . . . . . . . . — — — 5 — — 5 111

Kansas . . . . . . . . . — — — 2 — — 2 8

Kentucky . . . . . . . . — 174 — 4 — — 178 7,541

Louisiana . . . . . . . — 1 2 — — — 3 14

Maine . . . . . . . . . . — — 1 — — — 1 124

Maryland . . . . . . . . — — — 1 — — 1 62

Massachusetts . . . — — — 1 — — 1 45

Michigan . . . . . . . . — — 2 6 — 19 27 1,135

Minnesota . . . . . . . — — 1 — — 15 16 347

Mississippi . . . . . . — — 2 — 1 — 3 42

Missouri . . . . . . . . — 5 — 2 — — 7 149

Montana . . . . . . . . — 3 2 — — 3 8 258

Nevada . . . . . . . . . — — 3 — 3 28 34 1,561

New Jersey . . . . . . — — 2 2 — — 4 40

New Mexico . . . . . — 9 — — — 4 13 191

New York . . . . . . . — — 1 6 1 — 8 300

North Carolina . . . — — 2 1 — — 3 51

North Dakota . . . . — 5 — — — — 5 27

Ohio . . . . . . . . . . . — 22 1 2 2 — 27 476

Oklahoma . . . . . . . — 2 — 1 — — 3 28

Oregon . . . . . . . . . — — 2 1 — 1 4 179

Pennsylvania . . . . 23 43 — 7 — — 73 2,660

Puerto Rico . . . . . . — — 1 3 — — 4 66

South Carolina . . . — — — — — 1 1 32

South Dakota . . . . — — 2 — — 3 5 98

Tennessee . . . . . . — 2 2 3 3 — 10 286

Texas . . . . . . . . . . — 9 2 5 3 — 19 1,372

Utah . . . . . . . . . . . — 1 2 — — 1 4 136

Virginia . . . . . . . . . — 32 2 5 — — 39 1,374

Washington . . . . . — 5 2 — — — 7 141

West Virginia . . . . — 141 — 1 — — 142 6,087

Wyoming . . . . . . . . — 7 2 1 1 — 11 278

 Total . . . . . . . . . 23 533 72 97 36 94 855 31,886
23

Table C-6.—Lost-time injuries by job experience and incident result

Job

experience

(years)

Incident result

Fall over/

rollover/

fall into

void

Vertical

jar

Lateral

jar

(collision)

Lateral jar

(lurch forward/

backward)

Dozer

struck by

an object

Normal

operations

Equipment

failure

Other/

unknown Total

<1 . . . . . . . . . 14 43 10 3 12 28 1 — 111

1-2 . . . . . . . . 4 19 6 2 3 16 1 — 51

2-3 . . . . . . . . 4 33 3 6 4 16 3 — 69

3-4 . . . . . . . . 3 18 3 — 2 11 1 — 38

4-5 . . . . . . . . 5 29 5 — 2 13 2 1 57

>5 . . . . . . . . . 63 172 40 14 29 97 17 4 436

Subtotal . . . . 93 314 67 25 52 181 25 5 762

Unknown . . . . 9 40 1 3 4 31 4 1 93

 Total . . . . . 102 354 68 28 56 212 29 6 855
Delivering on the Nation’s Promise:

Safety and health at work for all people

Through research and prevention

For information about occupational safety and health topics contact NIOSH at:

1-800-35-NIOSH (1-800-356-4674)

Fax: 513-533-8573

E-mail: pubstaft@cdc.gov

www.cdc.gov/niosh

DHHS-(NIOSH)

Publication No. 2001-126