Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

IC 9528

INFORMATION CIRCULAR/2012
Information Circular 9528 

National Survey of the Mining Population 

Part II: Mines 

Linda Jansen McWilliams, Patricia J. Lenart, Jamie L. Lancaster, John R. Zeiner, Jr.

DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Centers for Disease Control and Prevention 

National Institute for Occupational Safety and Health 

Office of Mine Safety and Health Research 

Pittsburgh, PA • Spokane, WA 

June 2012 
ii 

This document is in the public domain and may be freely 

copied or reprinted.

Disclaimer 

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National Institute for Occupational Safety and Health (NIOSH). In addition, citations to Web 

sites external to NIOSH do not constitute NIOSH endorsement of the sponsoring organizations 

or their programs or products. Furthermore, NIOSH is not responsible for the content of these 

Web sites. All Web addresses referenced in this document were accessible as of the publication 

date. 

Ordering Information 

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contact NIOSH at 

Telephone: 1–800–CDC–INFO (1–800–232–4636) 

TTY: 1–888–232–6348 

e-mail: cdcinfo@cdc.gov 

or visit the NIOSH Web site at www.cdc.gov/niosh. 

For a monthly update on news at NIOSH, subscribe to NIOSH eNews by visiting 

www.cdc.gov/niosh/eNews. 

DHHS (NIOSH) Publication No. 2012–153 

June 2012 

SAFER • HEALTHIER • PEOPLETM
SECTION CONTENTS

Mine Statistics for All Mines

Mine Statistics for All Underground Mines

Mine Statistics for All Surface Mines

Mine Statistics for Coal Mines

Mine Statistics for Underground Coal Mines

Mine Statistics for Metal Mines

Mine Statistics for Underground Metal Mines

Mine Statistics for Surface Coal Mines
Mine Statistics for Surface Metal Mines 

Mine Statistics for Nonmetal Mines 

Mine Statistics for Underground Nonmetal Mines 

Mine Statistics for Surface Nonmetal Mines 

Mine Statistics for Stone Mines 

Mine Statistics for Surface Stone Mines 

Mine Statistics for Sand and Gravel Mines 

Mine Statistics for Underground Stone Mines 
v 

Contents 

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

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

Background and Overview .............................................................................................. 2 

Survey Materials ............................................................................................................. 3 

The Paper Questionnaire ........................................................................................ 3 

The Internet Questionnaire ...................................................................................... 4 

Sample Design and Selection ......................................................................................... 4 

Definition of the Target Population .......................................................................... 4 

Construction of the Sampling Frame ....................................................................... 5 

Stratification Guidelines ........................................................................................... 5 

Sampling Plans ............................................................................................................. 15

Data Collection .............................................................................................................. 19 

Survey Packet ....................................................................................................... 19 

Survey Promotion .................................................................................................. 20 

Follow-up Contacts ............................................................................................... 21 

Data Imputation and Statistical Weighting Procedures.................................................. 21 

Data Imputation ..................................................................................................... 21 

Data Weighting, Estimation, and Variance Estimation .......................................... 22 

Lessons Learned ........................................................................................................... 22 

Survey Results .............................................................................................................. 23 

Statistical Analysis......................................................................................................... 28 

Mine Statistics for All Mines .......................................................................................... 29 

Mine Statistics for All Underground Mines ..................................................................... 39 

Mine Statistics for All Surface Mines ............................................................................. 51 

Mine Statistics for Coal Mines ....................................................................................... 61 

Mine Statistics for Underground Coal Mines ................................................................. 71 

Mine Statistics for Surface Coal Mines .......................................................................... 83 

Mine Statistics for Metal Mines ...................................................................................... 93 

Mine Statistics for Underground Metal Mines .............................................................. 103 

Mine Statistics for Surface Metal Mines ...................................................................... 115 

Mine Statistics for Nonmetal Mines ............................................................................. 125 

Mine Statistics for Underground Nonmetal Mines ....................................................... 135 
vi 

Mine Statistics for Surface Nonmetal Mines ................................................................ 147 

Mine Statistics for Stone Mines ................................................................................... 157 

Mine Statistics for Underground Stone Mines ............................................................. 167 

Mine Statistics for Surface Stone Mines ...................................................................... 179 

Mine Statistics for Sand and Gravel Mines .................................................................. 189 

Acknowledgements ..................................................................................................... 199 

References .................................................................................................................. 201 

Appendices ................................................................................................................. 203 

Appendix A. Questionnaire Booklet ............................................................................. 205 

Appendix B. Questions and Answers Brochure ........................................................... 229 

Appendix C. MSHA Form 7000-2: Quarterly Mine Employment and Coal Production 

Report .................................................................................................................... 233

Appendix D. Standard Industrial Classifications (SIC) for Active Mines in 2007 ......... 237 

Appendix E. Stratification and Sample Size Guidelines .............................................. 241 

Appendix F. Sample Size Allocation Using MSHA Data from the Second Quarter of 

2002 ....................................................................................................................... 247 

Appendix G. Critical Items from the Questionnaire ..................................................... 259 

Appendix H. Glossary of Mining Terms ....................................................................... 265 
vii 

Figures 

Figure 1. Map of Active Coal Mining Operations for 2007. ............................................. 7 

Figure 2. Map of Active Metal Mining Operations for 2007. ............................................ 8 

Figure 3. Map of Active Nonmetal Mining Operations for 2007. ..................................... 9 

Figure 4. Map of Active Stone Mining Operations for 2007. ......................................... 10 

Figure 5. Map of Active Sand and Gravel Mining Operations for 2007. ........................ 11 

Figure 6. Density Map for Mine Operator Employees for 2007. ................................... 12 

Figure 7. Density Map for Underground Mine Operator Employees for 2007. .............. 13 

Figure 8. Density Map for Surface Mine Operator Employees for 2007. ...................... 14 

Figure 9. Weighted Response Rates by Sector and Mine Type. .................................. 26

 
viii 

Tables

Table 1. Sample Allocation for Underground Coal Mines ............................................. 16 

Table 2. Sample Allocation for Surface Coal Mines ..................................................... 16 

Table 3. Sample Allocation for Underground Metal Mines ........................................... 16 

Table 4. Sample Allocation for Surface Metal Mines .................................................... 17 

Table 5. Sample Allocation for Underground Nonmetal Mines ..................................... 17 

Table 6. Sample Allocation for Surface Nonmetal Mines ............................................. 17 

Table 7. Sample Allocation for Underground Stone Mines ........................................... 18 

Table 8. Sample Allocation for Surface Stone Mines ................................................... 18 

Table 9. Sample Allocation for Sand and Gravel Mines ............................................... 18 

Table 10. Number of Mines in the Final Sample by Sector, Type, and Reporting 

Week ........................................................................................................................ 20 

Table 11. Summary of Final Results for All Sampled Mines ......................................... 24 

Table 12. Number of Completed Surveys by Mode ...................................................... 24 

Table 13. Summary of Ineligible Mines by Sector ........................................................ 25 

Table 14. Summary of Refusal by Mine Sector and Type of Refusal ........................... 25 

Table 15. National Estimates of Mines and Mine Employees in Spring/Summer 

2008 ......................................................................................................................... 27 

Table 16. Miner Training Within the Past 12 Months at All Mines ................................ 32 

Table 17. Frequency of Periodic Safety Meetings at All Mines .................................... 32 

Table 18. Employee Safety Training Materials and Methods at All Mines .................... 33 

Table 19. Non-English Languages at All Mines ............................................................ 33 

Table 20. Work Schedules at All Mines ........................................................................ 34 

Table 21. Shift Work Schedules at All Mines ................................................................ 35 

Table 22. Activities of Independent Contractor Employees During the Reporting 

Week at All Mines .................................................................................................... 36 

Table 23. Communication Devices and Systems at All Mines ...................................... 37 

Table 24. Personal Locators, Trackers, and Devices at All Mines ............................... 37 

Table 25. Emergency Early Warning Methods at All Mines .......................................... 38 

Table 26. Rescue Teams at All Mines .......................................................................... 38 

Table 27. Miner Training Within the Past 12 Months at Underground Mines ............... 42 

Table 28. Frequency of Periodic Safety Meetings at Underground Mines .................... 42 

Table 29. Employee Safety Training Materials and Methods at Underground Mines ... 43 

Table 30. Non-English Languages at Underground Mines ........................................... 43 
ix 

Table 31. Work Schedules at Underground Mines ....................................................... 44 

Table 32. Shift Work Schedules at Underground Mines ............................................... 45 

Table 33. Activities of Independent Contractor Employees During the Reporting 

Week at Underground Mines ................................................................................... 46 

Table 34. Communication Devices and Systems at Underground Mines ..................... 47 

Table 35. Personal Locators, Trackers, and Devices at Underground Mines ............... 47 

Table 36. Emergency Early Warning Methods at Underground Mines ......................... 48 

Table 37. Rescue Teams at Underground Mines ......................................................... 48 

Table 38. Emergency Equipment and Supplies at Underground Mines ....................... 49 

Table 39. Escape Aids at Underground Mines ............................................................. 49 

Table 40. Miner Training Within the Past 12 Months at Surface Mines ........................ 54 

Table 41. Frequency of Periodic Safety Meetings at Surface Mines ............................ 54 

Table 42. Employee Safety Training Materials and Methods at Surface Mines ........... 55 

Table 43. Non-English Languages at Surface Mines ................................................... 55 

Table 44. Work Schedules at Surface Mines ............................................................... 56 

Table 45. Shift Work Schedules at Surface Mines ....................................................... 57 

Table 46. Activities of Independent Contractor Employees During the Reporting 

Week at Surface Mines ............................................................................................ 58 

Table 47. Communication Devices and Systems at Surface Mines ............................. 59 

Table 48. Personal Locators, Trackers, and Devices at Surface Mines ....................... 59 

Table 49. Emergency Early Warning Methods at Surface Mines ................................. 60 

Table 50. Rescue Teams at Surface Mines ................................................................. 60 

Table 51. Miner Training Within the Past 12 Months at Coal Mines ............................. 64 

Table 52. Frequency of Periodic Safety Meetings at Coal Mines ................................. 64 

Table 53. Employee Safety Training Materials and Methods at Coal Mines ................ 65 

Table 54. Non-English Languages at Coal Mines ........................................................ 65 

Table 55. Work Schedules at Coal Mines .................................................................... 66 

Table 56. Shift Work Schedules at Coal Mines ............................................................ 67 

Table 57. Activities of Independent Contractor Employees During the Reporting 

Week at Coal Mines ................................................................................................. 68 

Table 58. Communication Devices and Systems at Coal Mines .................................. 69 

Table 59. Personal Locators, Trackers, and Devices at Coal Mines ............................ 69 

Table 60. Emergency Early Warning Methods at Coal Mines ...................................... 70 

Table 61. Rescue Teams at Coal Mines ...................................................................... 70 

Table 62. Miner Training Within the Past 12 Months at Underground Coal Mines ....... 74 
x 

Table 63. Frequency of Periodic Safety Meetings at Underground Coal Mines ........... 74 

Table 64. Employee Safety Training Materials and Methods at Underground Coal 

Mines ....................................................................................................................... 75 

Table 65. Non-English Languages at Underground Coal Mines .................................. 75 

Table 66. Work Schedules at Underground Coal Mines ............................................... 76 

Table 67. Shift Work Schedules at Underground Coal Mines ...................................... 77 

Table 68. Activities of Independent Contractor Employees During the Reporting 

Week at Underground Coal Mines ........................................................................... 78 

Table 69. Communication Devices and Systems at Underground Coal Mines ............ 79 

Table 70. Personal Locators, Trackers, and Devices at Underground Coal Mines ...... 79 

Table 71. Emergency Early Warning Methods at Underground Coal Mines ................ 80 

Table 72. Rescue Teams at Underground Coal Mines................................................. 80 

Table 73. Emergency Equipment and Supplies at Underground Coal Mines ............... 81 

Table 74. Escape Aids at Underground Coal Mines ..................................................... 81 

Table 75. Miner Training Within the Past 12 Months at Surface Coal Mines ................ 86 

Table 76. Frequency of Periodic Safety Meetings at Surface Coal Mines .................... 86 

Table 77. Employee Safety Training Materials and Methods at Surface Coal Mines ... 87 

Table 78. Non-English Languages at Surface Coal Mines ........................................... 87 

Table 79. Work Schedules at Surface Coal Mines ....................................................... 88 

Table 80. Shift Work Schedules at Surface Coal Mines ............................................... 89 

Table 81. Activities of Independent Contractor Employees During the Reporting 

Week at Surface Coal Mines ................................................................................... 90 

Table 82. Communication Devices and Systems at Surface Coal Mines ..................... 91 

Table 83. Personal Locators, Trackers, and Devices at Surface Coal Mines ............... 91 

Table 84. Emergency Early Warning Methods at Surface Coal Mines ......................... 92 

Table 85. Rescue Teams at Surface Coal Mines ......................................................... 92 

Table 86. Miner Training Within the Past 12 Months at Metal Mines ........................... 96 

Table 87. Frequency of Periodic Safety Meetings at Metal Mines ................................ 96 

Table 88. Employee Safety Training Materials and Methods at Metal Mines ............... 97 

Table 89. Non-English Languages at Metal Mines ....................................................... 97 

Table 90. Work Schedules at Metal Mines ................................................................... 98 

Table 91. Shift Work Schedules at Metal Mines ........................................................... 99 

Table 92. Activities of Independent Contractor Employees During the Reporting 

Week at Metal Mines ............................................................................................. 100 

Table 93. Communication Devices and Systems at Metal Mines ............................... 101 
xi 

Table 94. Personal Locators, Trackers, and Devices at Metal Mines ......................... 101 

Table 95. Emergency Early Warning Methods at Metal Mines ................................... 102 

Table 96. Rescue Teams at Metal Mines ................................................................... 102 

Table 97. Miner Training Within the Past 12 Months at Underground Metal Mines .... 106 

Table 98. Frequency of Periodic Safety Meetings at Underground Metal Mines ........ 106 

Table 99. Employee Safety Training Materials and Methods at Underground Metal 

Mines ..................................................................................................................... 107

Table 100. Non-English Languages at Underground Metal Mines ............................. 107 

Table 101. Work Schedules at Underground Metal Mines ......................................... 108 

Table 102. Shift Work Schedules at Underground Metal Mines ................................. 109 

Table 103. Activities of Independent Contractor Employees During the Reporting 

Week at Underground Metal Mines ........................................................................ 110 

Table 104. Communication Devices and Systems at Underground Metal Mines ....... 111 

Table 105. Personal Locators, Trackers, and Devices at Underground Metal Mines . 111 

Table 106. Emergency Early Warning Methods at Underground Metal Mines ........... 112 

Table 107. Rescue Teams at Underground Metal Mines ........................................... 112 

Table 108. Emergency Equipment and Supplies at Underground Metal Mines ......... 113 

Table 109. Escape Aids at Underground Metal Mines ............................................... 113 

Table 110. Miner Training Within the Past 12 Months at Surface Metal Mines .......... 118 

Table 111. Frequency of Periodic Safety Meetings at Surface Metal Mines .............. 118 

Table 112. Employee Safety Training Materials and Methods at Surface Metal 

Mines ..................................................................................................................... 119

Table 113. Non-English Languages at Surface Metal Mines ...................................... 119 

Table 114. Work Schedules at Surface Metal Mines .................................................. 120 

Table 115. Shift Work Schedules at Surface Metal Mines .......................................... 121 

Table 116. Activities of Independent Contractor Employees During the Reporting 

Week at Surface Metal Mines ................................................................................ 122 

Table 117. Communication Devices and Systems at Surface Metal Mines ................ 123 

Table 118. Personal Locators, Trackers, and Devices at Surface Metal Mines ......... 123 

Table 119. Emergency Early Warning Methods at Surface Metal Mines .................... 124 

Table 120. Rescue Teams at Surface Metal Mines .................................................... 124 

Table 121. Miner Training Within the Past 12 Months at Nonmetal Mines ................. 128 

Table 122. Frequency of Periodic Safety Meetings at Nonmetal Mines ..................... 128 

Table 123. Employee Safety Training Materials and Methods at Nonmetal Mines .... 129 

Table 124. Non-English Languages at Nonmetal Mines ............................................ 129 
xii 

Table 125. Work Schedules at Nonmetal Mines ........................................................ 130 

Table 126. Shift Work Schedules at Nonmetal Mines ................................................ 131 

Table 127. Activities of Independent Contractor Employees During the Reporting 

Week at Nonmetal Mines ....................................................................................... 132 

Table 128. Communication Devices and Systems at Nonmetal Mines ...................... 133 

Table 129. Personal Locators, Trackers, and Devices at Nonmetal Mines ................ 133 

Table 130. Emergency Early Warning Methods at Nonmetal Mines .......................... 134 

Table 131. Rescue Teams at Nonmetal Mines .......................................................... 134 

Table 132. Miner Training Within the Past 12 Months at Underground Nonmetal 

Mines ..................................................................................................................... 138

Table 133. Frequency of Periodic Safety Meetings at Underground Nonmetal 

Mines ..................................................................................................................... 138

Table 134. Employee Safety Training Materials and Methods at 

Underground Nonmetal Mines ............................................................................... 139 

Table 135. Non-English Languages at Underground Nonmetal Mines ...................... 139 

Table 136. Work Schedules at Underground Nonmetal Mines ................................... 140 

Table 137. Shift Work Schedules at Underground Nonmetal Mines .......................... 141 

Table 138. Activities of Independent Contractor Employees During the Reporting 

Week at Underground Nonmetal Mines ................................................................. 142 

Table 139. Communication Devices and Systems at Underground Nonmetal 

Mines ..................................................................................................................... 143

Table 140. Personal Locators, Trackers, and Devices at Underground Nonmetal 

Mines ..................................................................................................................... 143

Table 141. Emergency Early Warning Methods at Underground Nonmetal Mines .... 144 

Table 142. Rescue Teams at Underground Nonmetal Mines ..................................... 144 

Table 143. Emergency Equipment and Supplies at Underground Nonmetal Mines ... 145 

Table 144. Escape Aids at Underground Nonmetal Mines ......................................... 145 

Table 145. Miner Training Within the Past 12 Months at Surface Nonmetal Mines .... 150 

Table 146. Frequency of Periodic Safety Meetings at Surface Nonmetal Mines ........ 150 

Table 147. Employee Safety Training Materials and Methods at Surface Nonmetal 

Mines ..................................................................................................................... 151

Table 148. Non-English Languages at Surface Nonmetal Mines ............................... 151 

Table 149. Work Schedules at Surface Nonmetal Mines ........................................... 152 

Table 150. Shift Work Schedules at Surface Nonmetal Mines ................................... 153 

Table 151. Activities of Independent Contractor Employees During the Reporting 

Week at Surface Nonmetal Mines .......................................................................... 154 
xiii 

Table 152. Communication Devices and Systems at Surface Nonmetal Mines ......... 155

Table 153. Personal Locators, Trackers, and Devices at Surface Nonmetal Mines ... 155

Table 154. Emergency Early Warning Methods at Surface Nonmetal Mines ............. 156

Table 155. Rescue Teams at Surface Nonmetal Mines ............................................. 156

Table 156. Miner Training Within the Past 12 Months at Stone Mines ....................... 160

Table 157. Frequency of Periodic Safety Meetings at Stone Mines ........................... 160

Table 158. Employee Safety Training Materials and Methods at Stone Mines .......... 161

Table 159. Non-English Languages at Stone Mines .................................................. 161

Table 160. Work Schedules at Stone Mines .............................................................. 162

Table 161. Shift Work Schedules at Stone Mines ...................................................... 163

Table 162. Activities of Independent Contractor Employees During the Reporting 

Week at Stone Mines ............................................................................................. 164

Table 163. Communication Devices and Systems at Stone Mines ............................ 165

Table 164. Personal Locators, Trackers, and Devices at Stone Mines ...................... 165

Table 165. Emergency Early Warning Methods at Stone Mines ................................ 166

Table 166. Rescue Teams at Stone Mines ................................................................ 166

Table 167. Miner Training Within the Past 12 Months at Underground Stone Mines . 170

Table 168. Frequency of Periodic Safety Meetings at Underground Stone Mines ..... 170

Table 169. Employee Safety Training Materials and Methods at 

Underground Stone Mines ..................................................................................... 171

Table 170. Non-English Languages at Underground Stone Mines ............................ 171

Table 171. Work Schedules at Underground Stone Mines ......................................... 172

Table 172. Shift Work Schedules at Underground Stone Mines ................................ 173

Table 173. Activities of Independent Contractor Employees During the Reporting 

Week at Underground Stone Mines ....................................................................... 174

Table 174. Communication Devices and Systems at Underground Stone Mines ...... 175

Table 175. Personal Locators, Trackers, and Devices at Underground Stone Mines 175

Table 176. Emergency Early Warning Methods at Underground Stone Mines .......... 176

Table 177. Rescue Teams at Underground Stone Mines ........................................... 176

Table 178. Emergency Equipment and Supplies at Underground Stone Mines ......... 177

Table 179. Escape Aids at Underground Stone Mines ............................................... 177

Table 180. Miner Training Within the Past 12 Months at Surface Stone Mines .......... 182

Table 181. Frequency of Periodic Safety Meetings at Surface Stone Mines .............. 182

Table 182. Employee Safety Training Materials and Methods at Surface Stone 

Mines ..................................................................................................................... 183
xiv 

Table 183. Non-English Languages at Surface Stone Mines ..................................... 183

Table 184. Work Schedules at Surface Stone Mines ................................................. 184

Table 185. Shift Work Schedules at Surface Stone Mines ......................................... 185

Table 186. Activities of Independent Contractor Employees During the Reporting 

Week at Surface Stone Mines ............................................................................... 186

Table 187. Communication Devices and Systems at Surface Stone Mines ............... 187

Table 188. Personal Locators, Trackers, and Devices at Surface Stone Mines ......... 187

Table 189. Emergency Early Warning Methods at Surface Stone Mines ................... 188

Table 190. Rescue Teams at Surface Stone Mines ................................................... 188

Table 191. Miner Training Within the Past 12 Months at Sand and Gravel Mines ..... 192

Table 192. Frequency of Periodic Safety Meetings at Sand and Gravel Mines .......... 192

Table 193. Employee Safety Training Materials and Methods at Sand and 

Gravel Mines ......................................................................................................... 193

Table 194. Non-English Languages at Sand and Gravel Mines ................................. 193

Table 195. Work Schedules at Sand and Gravel Mines ............................................. 194

Table 196. Shift Work Schedules at Sand and Gravel Mines ..................................... 195

Table 197. Activities of Independent Contractor Employees During the Reporting 

Week at Sand and Gravel Mines ........................................................................... 196

Table 198. Communication Devices and Systems at Sand and Gravel Mines ........... 197

Table 199. Personal Locators, Trackers, and Devices at Sand and Gravel Mines ..... 197

Table 200. Emergency Early Warning Methods at Sand and Gravel Mines ............... 198

Table 201. Rescue Teams at Sand and Gravel Mines ............................................... 198

Table E-1. Half-Length of 95% Confidence Intervals in Percentage Points for 

Various Percentages Being Estimated for Domains of Various Sizes with 

Various Design Effects ........................................................................................... 246

Table F-1. Sample Allocation for Underground Coal Mines ........................................ 249

Table F-2. Sample Allocation for Surface Coal Mines ................................................. 250

Table F-3. Sample Allocation for Underground Metal Mines ....................................... 251

Table F-4. Sample Allocation for Surface Metal Mines ................................................ 252

Table F-5. Sample Allocation for Underground Nonmetal Mines ................................ 253

Table F-6. Sample Allocation for Surface Nonmetal Mines ......................................... 254

Table F-7. Sample Allocation for Underground Stone Mines ...................................... 255

Table F-8. Sample Allocation for Surface Stone Mines ............................................... 256

Table F-9. Sample Allocation for Sand and Gravel Mines ........................................... 257
xv 

Acronyms and Abbreviations 

CI Confidence Interval 

DEFF Design Effect 

DSU Data suppressed 

FPC Finite population corrected 

FSR Filter self-rescuer 

FTE Full-time Equivalent 

IC Information Circular 

MIPS Mining Industry Population Survey 

MSHA Mine Safety and Health Administration 

NA Not applicable 

NIOSH National Institute for Occupational Safety and Health 

OMB Office of Management and Budget 

OMSHR Office of Mine Safety and Health Research 

PED Personal emergency device 

SCSR Self-contained self-rescuer 

SIC Standard Industrial Classification 

TTE Through-the-Earth 

 

Definition of Terms 

Confidence Interval: An interval that gives an estimated range of values 

which is likely to include an unknown population 

parameter, with the estimated range being 

calculated from a given set of sample data. 

Jackknife Repeated 

Replication: 

A commonly used resampling approach to variance 

estimation. 

National Estimate: A weighted statistical calculation which uses the 

results from a probability sample survey to estimate 

a national number. 

Survey Count: The actual number of responses obtained from the 

National Survey of the Mining Population. 
 
National Survey of the Mining Population 

Part II: Mines 

Linda Jansen McWilliams, Patricia J. Lenart, Jamie L. Lancaster, John R. Zeiner, Jr. 

Office of Mine Safety and Health Research 

National Institute for Occupational Safety and Health 

Abstract 

The National Institute for Occupational Safety and Health (NIOSH) conducted the first 

comprehensive survey of the U.S. mining population in more than 20 years. The National 

Survey of the Mining Population captured the current profile of the U.S. mining workforce. Data 

collection began in March 2008 and continued through August 2008. Randomly selected mining 

operations in all of the major mining sectors (i.e., coal, metal, nonmetal, stone, and sand and 

gravel) received the survey and had the option of completing a paper or web-based 

questionnaire. A total of 737 mining operations returned completed questionnaires and reported 

data for 9,008 employees. 

Two sets of data were collected in this national survey. There were questions about the 

mining operation, including employee training, work schedules, the use of independent 

contractor employees, and mine communication and safety systems. The employee questions 

included demographic and occupational questions about individual employees. The survey 

sample data were weighted in order to provide national estimates of mine and employee 

characteristics. 

This Information Circular (IC) is published in two parts—“Part I: Employees” presents the 

employee-level data and “Part II: Mines” presents the mine-level data. Both parts of this IC 

include an overview of the survey background, development of the survey materials, sample 

design and sample selection, data collection and processing, statistical weighting, and lessons 

learned. The survey data are summarized for the overall U.S. mining industry and the five major 

mining sectors. The information gathered from the survey respondents is being published only 

as summarized data so that no single mining operation or employee can be identified. 
2 

Introduction 

Surveillance of occupational injuries, illnesses, and exposures has been an integral part of 

the work of the National Institute for Occupational Safety and Health (NIOSH) since its creation 

by the Occupational Safety and Health Act in 1970. Surveillance activities at the Office of Mine 

Safety and Health Research (OMSHR) are focused on the nation’s mining workforce. These 

surveillance activities make extensive use of data from a number of different national databases. 

The most frequently used databases are those maintained by the Mine Safety and Health 

Administration (MSHA). Included are databases of reported employment, 

accidents/injuries/illnesses, hazardous exposures, coal production, mine inspections, violations 

and citations, etc. Two of the most commonly used databases are the mine operator and 

contractor address/employment file and the file listing reports of accidents, injuries, and 

illnesses. 

Analysis of data from the existing MSHA employment and accident/injury/illness 

databases has been able to meet some, but not all, of the OMSHR surveillance needs. For 

example, to identify subpopulations in each major mining sector or type of mining operation at 

risk of adverse health and safety outcomes, OMSHR needs the capability to calculate age-, 

gender-, and occupation-specific rates of injuries, fatalities, and disease. Additionally, due to the 

reduced reporting requirements for independent contractors, OMSHR cannot determine the 

number of contractor employees working separately in metal, nonmetal, stone, or sand and 

gravel operations. The National Survey of the Mining Population was designed to collect mineand employee-level information to address these and other data gaps. 

Background and Overview 

The last national survey targeting the mining workforce, the Mining Industry Population 

Survey (MIPS), was conducted in 1986 by the U.S. Bureau of Mines (USBM) in the U.S. 

Department of the Interior. The mining industry has experienced many changes since the MIPS 

was conducted, and its data are too outdated to be considered useful for surveillance on the 

current mining workforce. In addition, the MIPS did not include any information on independent 

contractor employees. Therefore, the National Institute for Occupational Safety and Health, 

Office of Mine Safety and Health Research conducted this survey to provide updated 

demographic and occupational information on the mining workforce. The National Survey of 

the Mining Population collected information from each of the five major mining sectors (coal, 

metal, nonmetal, stone, and sand and gravel). The survey’s main objectives were to: 

 Collect basic information about mining operations. 

 Establish the demographic and occupational characteristics of mine operator 

employees. 

 Estimate the number of independent contractor employees used by mining operations. 

Data collection began in March 2008 and continued through August 2008. A survey 

packet was mailed to each sampled mining operation. Respondents were given the option of 

completing a paper questionnaire or using a web questionnaire. Two sets of data were collected 
3 

in this survey. The mine questions included items about the mining operations, communication 

and safety systems, and the mine’s use of independent contractor employees. The employee 

questions included demographic and occupational questions about individual employees. The 

survey’s employee-level data will be used by OMSHR to determine the accident rates for various 

demographic and occupational categories as well as provide information that will be used to 

improve the safety and health of miners. 

This Information Circular (IC) is published in two parts—“Part I: Employees” presents 

the employee-level data and “Part II: Mines” presents the mine-level data. The employee and 

mine data are summarized for the overall U.S. mining industry and the major mining sectors. In 

addition, the data in the Mines IC is stratified by underground and surface for the coal, metal, 

nonmetal, and stone sectors. The information gathered from the survey respondents is being 

published only as summarized data so that no single mining operation or employee can be 

identified. The intent of this IC is to present the methodology used to design and conduct the 

survey and to provide up-to-date information about U.S. mining operations and their employees. 

Survey Materials 

A survey packet was developed which contained a cover letter, a questionnaire booklet 

with employee sampling instructions (Appendix A), directions for accessing the Internet version 

of the questionnaire, a Questions and Answers (Q&A) brochure (Appendix B), and a stamped, 

self-addressed return envelope. 

The Paper Questionnaire 

Each survey paper questionnaire booklet was personalized with a box at the top of page 1 

which included: the mine ID number, the mine name, the reporting week (date), and a “submitby” date. The Questionnaire Overview section presented general instructions and guidelines for 

completing the survey. The survey consisted of five parts as summarized below: 

 Mine Questions—This first part of the questionnaire included sections on: Training; 

Other Languages; Work Schedules for Production Workers, Production Support 

Workers, and Preparation Plant/Mill Workers; Shift Work for these same three types 

of workers; Independent Contractor Employees; and Safety, Communication, and 

Rescue Measures. 

 Employee Selection Instructions—This page contained step-by-step instructions for 

selecting the sample of employees to be included in the Employee Questions. 

Personalized mine information was preprinted at the top of this page, including: the 

mine ID number, the mine name, the reporting week (date), the range of the estimated 

number of employees working at the mine, a “start-with” number and a “take-every” 

number for selecting employees from the mine’s employee roster. 

 Instructions for Employee Questions—This two-page section of the questionnaire 

provided item-by-item explanations for the Employee Questions. 
4 

 Employee Questions—These items were formatted as a fold-out answer form. The 

sections included: Regular Job Title, Mining Experience, Number of Hours Worked 

During the Reporting Week, Primary Work Location, Gender, Race, Ethnicity, Birth 

Year, and Education Level. Two pages of the form were included, with the first page 

containing lines for reporting up to 15 employees and the second page containing 

lines for reporting up to 14 additional employees, or a maximum of 29 sampled 

employees. 

 Final Questions and Comments—This two-page section of the questionnaire 

included: questions for reporting unusual events or circumstances at the mine during 

the designated reporting week; the date the questionnaire was completed; the name, 

title and telephone number of the company representative who should be contacted 

regarding questionnaire completion; space for entering comments or explanations 

related to specific responses; and mailing instructions. 

The Internet Questionnaire 

Beginning in October 2004, a pilot study was conducted to evaluate the recruitment 

materials, questionnaire and survey procedures developed for the nationwide survey of the 

mining population. This study allowed OMSHR to explore the feasibility of developing a webbased version of the questionnaire. The pilot study debriefing interview contained several 

questions to determine whether the mine had access to the Internet, and how convenient this 

would be for completion of the questionnaire. The majority of respondents indicated that an 

Internet connection was available at their mine and more than 50 percent reported preferring an 

electronic response option. Thus, for the National Survey of the Mining Population, a web-based 

survey was made available. The survey contractor developed the web survey, including 

programming of the administrative interface, Section 508 compliance, data validation, quality 

assurance, and programming of the critical questions. 

Sample Design and Selection 

Definition of the Target Population 

The target population for a survey is the entire set of population units about which the 

survey data are to be used to make inferences. Establishment surveys such as the National 

Survey of the Mining Population must delineate the level of the business organization that 

constitutes the units of the target population. Because hazards vary across mines, the target 

population for this survey was defined in terms of the individual mining operation. 

The target population of mines consisted of active mines in current production. The 

survey was further restricted to operations that were covered under Title 30 of the U.S. Code, 

specifically mines whose mineral output was sold or used in commerce. The target population of 

employees was restricted to those mine employees for whom the mine operator must report hours 

worked using the MSHA Form 7000-2: Quarterly Mine Employment and Coal Production 
5 

Report (Appendix C). This includes all direct employees working at the mine, but not contract 

employees brought in periodically or regularly to perform work at the mine. 

There is an important temporal aspect to these definitions for mines and for mine operator 

employees. Over time, some mines will go in and out of operation. Similarly, employees join 

the mining labor force and leave the labor force over time. Accordingly, the National Survey of 

the Mining Population focused on mines in operation during a particular calendar quarter and the 

current employees of those mines. 

Construction of the Sampling Frame

The sampling frame for a survey is the list or mechanism used to enumerate target 

population members for sample selection purposes. Individual sampling frames for each of the 

five major mining sectors (see Figures 1–5) were constructed using the 2007 second quarter data 

released by the Mine Safety and Health Administration, so that the sampling frames would be in 

sync with the actual time period when data collection would begin (the second quarter of 2008). 

To ensure that any startup or intermittent mining operations would not be missed, all mines 

reporting zero employment hours were included in these frames. Any mines with a status of 

abandoned or abandoned/sealed were excluded from the sampling frames. The Standard 

Industrial Classification (SIC) for the active coal, metal, nonmetal, stone, and sand and gravel 

mines used in the sampling frames is presented in Appendix D. 

Stratification Guidelines 

For the National Survey of the Mining Population, mine-level and employee-level 

analyses were planned, which required adequate sample sizes of mines and of employees. 

Because multiple employees were to be sampled from each responding mine, sample size 

requirements for mine-level analyses tended to drive the total number of mines that needed to be 

sampled. The sample size for employees was determined by the number of sampled mines 

responding and the average number of employees sampled per mine. 

The competing needs of mine-level analysis versus employee-level analysis required the 

use of a compromise design that supported the objectives of both types of analyses. For minelevel analyses, the best design was one that selected mines with equal probability, while for 

employee-level analyses the best design was one that selected mines with probability 

proportional to the number of employees. The compromise design met both needs by stratifying 

by the number of employees and then sampling mines with equal probability within strata. Strata 

associated with large mines (in terms of employment) were given greater selection probabilities 

than small mines, which would facilitate employee-level analyses by making the employee 

selection probabilities less variable across mines. 

Mine size was an important domain for study at the mine level as well as at the employee 

level. For example, mines might be more likely to vary in their training procedures based upon 

employee size. Small mines may be more likely to use trainers from outside the organization, 

while large mines may be more likely to rely on in-house trainers. Hence, stratifying by the 

number of employees when sampling mines served an analytic purpose, as well as facilitated the 

over sampling of large mines needed for employee-level analyses (see Figure 6). 
6 

From an analysis standpoint, it was also desirable to control for underground versus 

surface mines when sampling mines and employees (see Figures 7 and 8). Underground coal 

mines, in particular, have higher injury and fatality rates than surface mines. There is substantial 

diversity in the incidence of injuries and fatalities at underground mines versus surface mines 

across all mining sectors. Nearly one-third of coal and metal mines are underground. Less than 

ten percent of nonmetal and stone mines are underground and sand and gravel mines are surface 

only. Stratification by underground mines versus surface mines allows for the control over 

sample sizes needed for effective comparisons of underground mines to surface mines. A more 

in-depth discussion of the stratum size formation and sample size guidelines used in this survey 

can be found in Appendix E.
7 

Figure 1. Map of Active Coal Mining Operations for 2007. 
8 

Figure 2. Map of Active Metal Mining Operations for 2007.
9 

Figure 3. Map of Active Nonmetal Mining Operations for 2007.
10 

Figure 4. Map of Active Stone Mining Operations for 2007.
11 

Figure 5. Map of Active Sand and Gravel Mining Operations for 2007.
12 

Figure 6. Density Map for Mine Operator Employees for 2007.
13 

Figure 7. Density Map for Underground Mine Operator Employees for 2007.
14 

Figure 8. Density Map for Surface Mine Operator Employees for 2007.
15 

Sampling Plans 

The original sampling plans were finalized in 2004 after a pretest with eight mining 

operations. These plans were developed using MSHA data from the second quarter of 2002. 

The number of actual employees was used to develop these designs rather than the number of 

full-time equivalent (FTE) employees, because the mine operator would be sampling based upon 

counts of actual employees, not FTEs. Mines were classified as surface or underground based 

upon MSHA subunit codes. Mines reporting any employment at underground work locations 

were classified as underground mining operations. 

Because there would actually be two surveys, one for mines and one for employees, the 

sampling allocation needed to be balanced. An approach that Cochran [1977] suggested was 

used where the size strata were defined so that they were equal in terms of the square root of the 

size measure (in this case, the number of employees). The square root was used as a 

compromise between the needs of mine-level estimation where equal selection probabilities were 

best (size = 1) and employee-level estimation was best (size = number of employees). Detailed 

sample size allocation tables based on 2002 data for coal, metal, nonmetal, stone, and sand and 

gravel mines can be found in Appendix F. 

Following the Office of Management and Budget (OMB) approval to conduct the 

national survey, the final sampling allocations were updated using 2007 second quarter MSHA 

data. Nine sampling frames were constructed based on the mining sector and mine type 

(underground or surface). The sampling was conducted using the SurveySelect procedure in the 

SAS statistical software package (SAS Institute Inc., Cary, NC). Systematic random sampling 

within the employee size strata was used together with controlled sorting by the state where the 

mine was located. The latter was done to ensure that the sample of mines was geographically 

representative. All metal mines and all underground nonmetal mines were selected with 

certainty from every stratum. The final survey sample of mines consisted of 331 underground 

coal, 385 surface coal, 74 underground metal, 159 surface metal, 39 underground nonmetal, 286 

surface nonmetal, 96 underground stone, 498 surface stone, and 453 sand and gravel, for a total 

of 2,321 mining operations. Tables 1–9 present the sample allocations by mining sector and mine 

type. 
16 

Table 1. Sample Allocation for Underground Coal Mines 

Stratum

Number of 

Mines

Percentage of 

Total Mines

Number of 

Employees

Percentage of 

Total 

Employees

Sample 

Mines

1–9 146 25.4% 331 0.8% 56

10–25 118 20.5% 1,972 4.8% 68

26–50 117 20.3% 4,460 10.8% 67

51–75 58 10.1% 3,622 8.8% 35

76–100 32 5.6% 2,790 6.8% 22

101–250 61 10.6% 9,267 22.5% 49

251+ 43 7.5% 18,750 45.5% 34

Total 575 100% 41,192 100% 331

Table 2. Sample Allocation for Surface Coal Mines 

Stratum

Number of 

Mines

Percentage of 

Total Mines

Number of 

Employees

Percentage of 

Total 

Employees

Sample 

Mines

1–9 725 51.8% 2,147 5.7% 101

10–25 302 21.6% 4,945 13.1% 84

26–50 209 14.9% 7,305 19.4% 75

51–75 65 4.6% 4,057 10.8% 36

76–100 30 2.1% 2,612 6.9% 20

101–250 44 3.1% 7,235 19.2% 44

251+ 25 1.8% 9,407 24.9% 25

Total 1,400 100% 37,708 100% 385

Table 3. Sample Allocation for Underground Metal Mines 

Stratum

Number of 

Mines

Percentage of 

Total Mines

Number of 

Employees

Percentage of 

Total 

Employees

Sample 

Mines

1–9 26 35.1% 137 1.8% 26

10–25 8 10.8% 134 1.8% 8

26–50 9 12.2% 327 4.3% 9

51–75 7 9.5% 443 5.8% 7

76–100 2 2.7% 168 2.2% 2

101–250 13 17.6% 2,312 30.4% 13

251+ 9 12.2% 4,077 53.7% 9

Total 74 100% 7,598 100% 74
17 

Table 4. Sample Allocation for Surface Metal Mines 

Stratum

Number of 

Mines

Percentage of 

Total Mines

Number of 

Employees

Percentage of 

Total 

Employees

Sample 

Mines

1–9 60 37.7% 217 0.9% 60

10–25 21 13.2% 325 1.3% 21

26–50 13 8.2% 454 1.9% 13

51–75 4 2.5% 239 1.0% 4

76–100 3 1.9% 254 1.0% 3

101–250 26 16.4% 4,518 18.7% 26

251+ 32 20.1% 18,204 75.2% 32

Total 159 100% 24,211 100% 159

Table 5. Sample Allocation for Underground Nonmetal Mines 

Stratum

Number of 

Mines

Percentage of 

Total Mines

Number of 

Employees

Percentage of 

Total 

Employees

Sample 

Mines

1–9 7 17.9% 30 0.6% 7

10–25 5 12.8% 95 1.9% 5

26–50 6 15.4% 258 5.2% 6

51–75 4 10.3% 257 5.2% 4

76–100 2 5.1% 170 3.5% 2

101–250 11 28.2% 1,980 40.3% 11

251+ 4 10.3% 2,125 43.2% 4

Total 39 100% 4,915 100% 39

Table 6. Sample Allocation for Surface Nonmetal Mines 

Stratum

Number of 

Mines

Percentage of 

Total Mines

Number of 

Employees

Percentage of 

Total 

Employees

Sample 

Mines

1–9 339 53.6% 1,305 7.5% 92

10–25 128 20.2% 1,990 11.4% 65

26–50 81 12.8% 3,052 17.6% 46

51–75 32 5.1% 2,026 11.7% 32

76–100 19 3.0% 1,689 9.7% 17

101–250 25 3.9% 3,805 21.9% 25

251+ 9 1.4% 3,520 20.2% 9

Total 633 100% 17,387 100% 286
18 

Table 7. Sample Allocation for Underground Stone Mines 

Stratum

Number of 

Mines

Percentage of 

Total Mines

Number of 

Employees

Percentage of 

Total 

Employees

Sample 

Mines

1–9 15 14.0% 78 2.0% 14

10–25 42 39.3% 733 18.8% 32

26–50 30 28.0% 1,030 26.4% 30

51–75 13 12.1% 812 20.8% 13

76–100 2 1.9% 174 4.5% 2

101–250 4 3.7% 511 13.1% 4

251+ 1 0.9% 560 14.4% 1

Total 107 100% 3,898 100% 96

Table 8. Sample Allocation for Surface Stone Mines 

Stratum

Number of 

Mines

Percentage of 

Total Mines

Number of 

Employees

Percentage of 

Total 

Employees

Sample 

Mines

1–9 2,034 49.6% 9,039 11.9% 116

10–25 1,345 32.8% 21,224 28.0% 114

26–50 426 10.4% 15,002 19.8% 95

51–75 107 2.6% 6,537 8.6% 51

76–100 56 1.4% 4,903 6.5% 36

101–250 128 3.1% 18,294 24.1% 83

251+ 3 0.1% 911 1.2% 3

Total 4,099 100% 75,910 100% 498

Table 9. Sample Allocation for Sand and Gravel Mines 

Stratum

Number of 

Mines

Percentage of 

Total Mines

Number of 

Employees

Percentage of 

Total 

Employees

Sample 

Mines

1–3 2,846 44.3% 5,555 13.0% 119

4–6 1,615 25.1% 7,761 18.2% 80

7–9 729 11.3% 5,682 13.3% 37

10–25 1010 15.7% 14,629 34.4% 110

26–50 190 3.0% 6,411 15.1% 70

51–75 27 0.4% 1,632 3.8% 27

76–100 8 0.1% 684 1.6% 8

101–250 2 0.0% 219 0.5% 2

251+ 0 0.0% 0 0.0% 0

Total 6,427 100% 42,573 100% 453
19 

Data Collection 

Survey Packet 

The survey packet mailed to each sampled mining operation contained the following 

materials: 

 A cover letter from NIOSH that introduced the study to the selected mines and 

stressed the importance of the study to the safety and health of miners. The letter was 

personalized and addressed to the best respondent identified through initial contacts 

with the mine. 

 A Questions and Answers brochure that answered frequently asked questions. 

 A copy of the paper questionnaire. 

 Personalized directions for accessing the Internet questionnaire. 

 A postage-paid return envelope for returning the hard-copy questionnaire. 

The mine respondents were given the option of completing either the paper questionnaire 

booklet or the web-based survey questionnaire. The Questions and Answers brochure explained 

that both surveys asked the same questions. To minimize the employee-level questionnaire 

burden, mines with 30 or more employees were asked to provide data for only a sample of the 

total employees working during the specific reporting week. Mines with less than 30 employees 

were asked to report for all of them. 

For mines with 30 or more employees working in the reference week, the mine 

respondent was asked to select the sample of employees by following sampling instructions 

included in the survey questionnaire. The sampling instructions were designed to select from 15 

to 25 employees per mine, with employee counts from the frame used to determine the sampling 

rate. The employees were selected using systematic sampling with custom-generated “startwith” and “take-every” numbers included on the instructions page of the questionnaire. The 

“take-every” number was determined by dividing the number of employees the mine reported to 

MSHA by 30 and then rounding down. A random number table was consulted to get a random 

number between 1 and the “take-every” number which would be the “start-with” number. The 

“start-with” number constituted the first selection made from the list, prepared by the mine, of 

employees working during the reference week. The “take-every” number needed to be added 

repeatedly to the “start-with” number to determine the remaining selections. The variable 

number of employees selected per mine resulted from the need to use an integer as the “takeevery” number to simplify the mathematics for the respondent. 

The MSHA employment data printed on the mine’s questionnaire may not have been 

current for the data collection period. This limitation was handled by instructing the mine 

respondents to call in when their mine employment for the reference week was 20 percent 

greater or 20 percent less than the employment projected from the MSHA data. The survey 

contractor would then provide alternative “start-with” and “take-every” numbers to these mine 

respondents, after determining that the respondents were reporting for the correct mine. 

Each sampled mining operation was randomly assigned a reporting week, balanced by 

mine type and sector. The reporting week was a seven-day period that the mine respondent was 
20 

asked to reference when answering some items in the questionnaire. The reporting week was 

described in the questionnaire as the mine’s payroll week, which included the date that was 

preprinted on the first page of the questionnaire. Over the course of the survey, there were a total 

of 12 reporting weeks. On average, 193 mines were assigned to each reporting week (see Table 

10). 

Table 10. Number of Mines in the Final Sample by Sector, Type, and Reporting Week 

Week

Total 

Mines Coal Metal Nonmetal Stone

Sand 

and 

Gravel Surface Underground

1 193 59 20 27 50 37 147 46

2 193 60 19 27 49 38 148 45

3 194 60 19 28 50 37 148 46

4 193 60 19 27 49 38 148 45

5 194 60 19 27 50 38 149 45

6 194 60 19 27 50 38 149 45

7 193 59 20 27 49 38 149 44

8 194 60 20 27 50 37 148 46

9 193 60 19 27 49 38 148 45

10 193 59 20 27 49 38 149 44

11 193 59 20 27 49 38 149 44

12 194 60 19 27 50 38 149 45

Total 2,321 716 233 325 594 453 1,781 540

Survey Promotion 

Several initiatives were implemented before the start of data collection to promote the 

survey and to maximize response rates. OMSHR undertook considerable efforts to publicize the 

survey. At the start of data collection in March 2008, the National Mining Association offered to 

prepare and publish an article about the survey in its newsletter. Throughout the data collection 

period, OMSHR continued to pursue additional publicity efforts, promoting the survey both 

within NIOSH and to the mining community. A sand and gravel industry newsletter included an 

article about the survey. A notice about the survey was also published in the May 2008 issue of 

CoalUSA magazine. 

Prior to the mailing of the survey packet, initial telephone calls were made to the contacts 

identified for each selected mine. In some cases the same contact individuals were found to be 

associated with multiple mines; for example, nine contacts were affiliated with mining 

companies that each had seven or more mines in the sample. A special effort was made by 

OMSHR to contact these individuals and inform them of the selection of multiple mining 

operations, determine the most appropriate addressee/recipient of the survey packet, and 

encourage participation in the survey. Throughout the data collection period, OMSHR continued 

to assist the survey contractor in both initiating and receiving calls with mine contacts and in 

responding to e-mails from the sampled mining operations. 
21 

Follow-up Contacts 

Once the survey packet had been sent to the contact person at the mine, the data 

collection schedule provided for a three-week waiting period, to allow the contact the 

opportunity to complete the survey. After the waiting period, follow-up reminder calls were 

made to those mines that did not return their questionnaires or complete the web surveys by the 

“please submit” date printed on the survey. The main functions of the follow-up calls were to: 

 Ensure that the survey materials had been received and that the materials were 

delivered to the appropriate person. 

 Answer any questions regarding completing the survey. 

 Serve as a reminder to complete the survey. 

The most difficult challenge of follow-up was simply reaching the contacts. To deal with 

this issue, various approaches and initiatives were implemented. Because e-mail addresses were 

often available for mine contacts, an e-mail initiative was developed whereby an e-mail reminder 

was sent to anyone who had: (1) started, but did not complete a web survey; (2) not yet opened a 

web survey; (3) not returned a questionnaire; or (4) not made contact during the follow-up calls. 

This resulted in some immediate responses to the e-mails, along with many calls to the toll-free 

study telephone line and directly to OMSHR, often from contact persons who had a question on 

how to complete the survey. There were also a number of out-of-office replies that were useful in 

determining when another follow-up attempt could be made. 

In addition, OMSHR also prepared a follow-up letter, cosigned by the study project 

director and the director of the NIOSH Office of Mine Safety and Health Research, with space at 

the bottom for the web survey login information and mine-specific password. This letter was 

mailed to contacts at more than 1,000 mining operations. As a result, OMSHR received some 

additional completed questionnaires. However, a large number of letters were returned as 

undeliverable. 

Data Imputation and Statistical Weighting Procedures 

A questionnaire was considered completed if it was missing no more than two of the 52 

critical items listed in Appendix G. Returned questionnaires with more than two missing critical 

items were considered partially complete and, when possible, data imputation was used to 

complete these missing items. 

Data Imputation 

Imputation is the process of replacing missing data with legitimate values derived 

through logical deduction, regression models, or other probabilistic means. For the National 

Survey of the Mining Population, an attempt was made to impute missing data for the questions 

in the Training; Prep Plant/Mill Workers (found in the Work Schedules and Shift Work 

sections); Independent Contractor Employees; Safety, Communication, and Rescue Measures; 

and Employee Length of Service sections of the questionnaire. The Prep Plant/Mill Workers 

questions were imputed via information retrieved from the MSHA data on mines not having a 
22 

preparation plant. In these cases, the relevant questionnaire items were set equal to zero or to the 

“not applicable” response. The questions in the Training; Independent Contractor Employees; 

and Safety, Communication and Rescue Measures sections were imputed via logical deduction, 

that is, when one or more responses were affirmative within the section and no negative 

responses were recorded, all missing items were set to the negative response. The Employee 

Length of Service section was completed via a regression model that predicted one or more 

missing items for the Total Years in this Job Title, Total Years at this Mine, and Total Years in 

Mining questions from those of the three that were reported. 

Data Weighting, Estimation, and Variance Estimation 

Sample survey data are weighted in order to provide unbiased or nearly unbiased 

estimates. The weights take into account variable probabilities of selection as well as 

compensate for bias introduced by differences between respondents and nonrespondents. For the 

National Survey of the Mining Population, weights were calculated in two steps. First, a base 

weight was calculated as the reciprocal of a given mine’s probability of selection. These 

probabilities varied by major mining sector (coal, metal, nonmetal, stone, and sand and gravel), 

mine type (underground or surface), and mine size (number of employees). Second, a 

nonresponse adjusted weight was calculated as the product of the base weight and a nonresponse 

adjustment factor. The nonresponse adjustment factor was calculated as the ratio of the sum of 

weights for all eligible mines within a primary stratum (sector by mine type) to the sum of the 

weights for all responding mines. 

Survey sampling implies some imprecision in the estimates and this imprecision is 

measured as variance and standard errors. For this survey, the Jackknife Repeated Replication 

(JRR) method was used to support variance estimation. One hundred replicate weights were 

created for each record in the dataset, with every replicate weight repeating the two steps 

described previously. Each replicate weight was used to derive a replicate estimate, and the 

variance in the replicate estimates (across the 100 replicates) could then be used to estimate the 

variance and standard error of each survey estimate. 

Lessons Learned 

The following lessons learned are based on project staff observations (by both OMSHR 

and the survey contractor) and the feedback obtained from the survey respondents. Also 

presented are any additional methods that could have been implemented to potentially increase 

the response rate or the efficiency of the study management. 

 The questionnaire, with its foldout employee section and sample selection approach, 

appeared to be a barrier to completion. It is possible that the perceived level of effort for 

completing the survey prevented some mines from participating. 

 Comments regarding ease of use of the survey were similar for both paper and web-based 

respondents. Partial responses on both versions of the questionnaire often stopped at the 

beginning of the employee section. This may have occurred when the mine contact 

realized that he/she could not complete the full questionnaire without retrieving 
23 

information from other people in the mine organization, or from records not conveniently 

located, or that other staff may have been unable or unwilling to complete the 

questionnaire. 

 There was no incentive provided for completion of the survey, other than to assist 

OMSHR. 

 Most refusal information related to time/burden issues. Some contacts refused after 

learning that they were assigned to complete questionnaires for multiple mines in their 

organization. Health and safety contacts often said that the survey content focused too 

little on health and safety issues and too much on human resource questions. 

 The e-mail follow-up reminders and OMSHR follow-up letter were helpful initiatives, 

but may have been more effective had they been initiated at an earlier time in the data 

collection process. 

 Even though multiple contact attempts and various response modes were used in this 

survey, conducting a nonresponse survey could have helped to ascertain whether the 

population of nonresponders differed measurably from the participants. It also could 

have been very useful in understanding and characterizing barriers to participation. 

 Some suggestions for future surveys are the following: 

o Conducting the survey to focus on one major mining sector at a time in order to 

improve performance. 

o Reducing the length of the questionnaire, in response to complaints from mines 

that did not have the staff or the time to complete it. 

o Involving large mining companies in early reviews of the survey to obtain their 

input on questions they might find objectionable and their feedback on how to 

best administer the survey. 

Survey Results 

Overall, 954 completed or partial surveys were returned from the sampled mining 

operations. The outcomes of data collection for each of the sampled mines are summarized in 

Table 11. The 651 “critical items complete” and 86 “final missing critical items” questionnaires 

were the 737 survey responses that were used for the estimates presented in this IC. The mode 

of completion by the respondents is shown in Table 12. 

 
24 

Table 11. Summary of Final Results for All Sampled Mines 

Result Code Description Total

Critical items complete * 651

Final missing critical items * 86

Partial response 217

Final refusal—explicit refusal by corporate management 56

Final refusal, other reason—explicit refusal by local mine management 77

Final refusal, records unavailable—explicit refusal by local mine management 5

Final refusal, staff time—explicit refusal by local mine management 85

Ineligible mine 85

Ineligible, no contact 32

Initialized, no response 1,020

Hard-copy questionnaire received, but blank 7

Total 2,321

 *Comprised final survey dataset 

Table 12. Number of Completed Surveys by Mode 

Mode Count Percentage

Web questionnaire 360 49%

Paper questionnaire 377 51%

Total 737 100%

Based on the review of the results of all contact attempts, 117 mines were determined to 

be ineligible. A summary of the ineligible mines by sector is presented in Table 13. Some of the 

reasons for ineligibility were: 

 Mine has been closed. 

 No contact was ever made with anyone at the mine. 

 Mine is nonproducing. 

 Construction work on the mine has not yet begun. 

 Mine is shutting down and moving out equipment. 

 Mine was just an exploration mine and was never in a producing status. 

 Mine contracts out all of its mining operations. 
25 

Table 13. Summary of Ineligible Mines by Sector 

Mine Sector

Ineligible

Mine

Ineligible

No Contact Total

Coal 53 14 67

Metal 10 7 17

Nonmetal 9 4 13

Stone 7 3 10

Sand and Gravel 6 4 10

Total 85 32 117

Refusals to participate in the survey were received from 223 mines. The major reasons for 

refusal are shown in Table 14. 

Table 14. Summary of Refusal by Mine Sector and Type of Refusal 

Reason for Refusal Coal Metal Nonmetal Stone

Sand 

and 

Gravel Total

Corporate refusal 20 1 11 16 8 56

General refusal 18 7 13 23 16 77

Records unavailable 1 3 0 0 1 5

Staff time 27 8 12 16 22 85

Total 66 19 36 55 47 223

The overall weighted response rate for the survey was 36.7 percent, with the lowest response 

rate for coal mines (25.8 percent) and the highest for nonmetal mines (48.8 percent). 

Underground mines responded at 30.1 percent compared to surface mines at 37.1 percent. The 

response rate data are presented in Figure 9. 

The weighted response rates were calculated as the ratio of the sum of the weights of 

responding mines divided by the sum of the weights for all eligible sampled mines. The 

denominator included all nonresponding mines that were known to be eligible along with a 

percentage, p, of the weight corresponding to mines which did not respond but for whom it was 

not possible to determine whether in fact they were eligible. The percentage, p, was computed as 

the ratio of the weights of known eligible nonrespondents, plus respondents, plus ineligible 

mines. The ratios were computed separately for each nonresponse adjustment cell, which was 

defined by sector, mine type, and mine size. 
Figure 9. Weighted Response Rates by Sector and Mine Type. 

36.7%

36.2%

39.7%

48.8%

34.9%

25.8%

37.1%

36.2%

39.9%

48.3%

37.7%

25.3%

30.1%

33.9%

55.5%

29.8%

27.2%

0% 10% 20% 30% 40% 50% 60%

All Mining Sectors

Sand and Gravel

Stone

Nonmetal

Metal

Coal

Weighted Response Rate, Percent

Sector MiningUnderground Surface

Overall

26 
27 

Based on the data collected in this survey, Table 15 represents national estimates of the 

number of mines and the mine operator employees (with associated 95 percent confidence 

intervals) by sector during a typical week in the spring/summer of 2008. There were an 

estimated 231,549 employees working in 12,321 mines. Of these employees, 53,326 worked in 

668 underground mines and the remaining 178,222 worked in 11,654 surface mines. 

Table 15. National Estimates of Mines and Mine Employees in Spring/Summer 2008 

Mine Sector

Number of 

Mines* 95% CI

Number of 

Employees* 95% CI

Coal, underground 454 (411, 498) 38,290 (31,088, 45,492)

Coal, surface 1,053 (925, 1,181) 31,717 (23,810, 39,625)

Metal, underground 71 (62, 79) 8,653 (2,419, 14,887)

Metal, surface 130 (113, 147) 30,430 (9,332, 51,528)

Nonmetal, underground 38 (29, 47) 3,424 (1,919, 4,928)

Nonmetal, surface 577 (506, 647) 15,925 (10,668, 21,182)

Stone, underground 105 (92, 118) 2,959 (2,491, 3,427)

Stone, surface 3,852 (3,600, 4,104) 68,006 (62,641, 73,372)

Sand and Gravel 6,042 (4,774, 7,309) 32,144 (26,275, 38,013)

Total 12,321 (11,003, 13,640) 231,549 (204,685, 258,413)

*Data do not sum to total due to independent rounding. 
 

28 

Statistical Analysis 

The statistical analysis of the data from the National Survey of the Mining Population 

was conducted using the SAS statistical software package. The SAS SURVEYFREQ and 

SURVEYMEANS procedures were used to create the weighted summary statistics that are 

reported in the IC. These procedures properly analyze data from complex sample surveys by 

taking the sample design into account. The variance estimation method used with these data was 

the Jackknife Repeated Replication (JRR). At this time, the subpopulation analysis for JRR is 

not available in SAS 9.2. In order to provide national estimates for the coal, metal, nonmetal, 

stone, and sand and gravel mining sectors, a SAS macro, using a reweighting method, proposed 

by Wang and Waldron [2010] was adopted for these subpopulation analyses. In their paper, 

Wang and Waldron compared the results of a subgroup analysis using their macro with PROC 

SURVEYMEANS and found these results were almost identical to those obtained when using 

the standard subpopulation analysis procedure in both the Stata 10.0 (StataCorp LP) and 

SUDAAN 10 (RTI International) statistical analysis software packages. In order to provide a 

measure of precision, a 95 percent confidence interval (CI) has been calculated for all survey 

estimates reported in this IC. Data were suppressed, and no national estimates were computed 

when the unweighted survey count was fewer than five responses (i.e., the number of responses 

was too small to be able to produce a reliable estimate) [NCHS 2002, 2004]. 

 
29 

Mine Statistics for 

All Mines 
30 
31 

Summary of Mine Statistics for All Mines 

The data for training and non-English languages can be found in Tables 16–19. For the 

U.S. mining industry, the weighted survey estimates indicate that more training is conducted by 

the mine’s employees including: annual refresher training (70.5 percent); newly hired 

inexperienced miner training (64.3 percent); and newly hired experienced miner training (60.5 

percent) when compared to the mine’s use of outside trainers. Lectures (87.6 percent), written 

materials (85.0 percent) and videos (79.0 percent) are the top three methods and materials used 

for training. Estimates from the survey indicate that 40.1 percent of all mines have employee 

safety meetings once a week. Overall, approximately seven percent of mine employees use a 

language other than English. 

 Tables 20 and 21 present the national estimates for work schedules and shift work. The 

average number of hours worked per week is 39.2 for production workers, 38.6 for production 

support workers, and 39.7 for preparation plant/mill workers. The majority of mines operate one 

shift per day (76.9 percent for production workers, 81.9 percent for production support workers, 

and 65.7 percent for preparation plant/mill workers). 

National estimates for independent contractor employees are presented in Table 22. 

During a typical week, mines use independent contractor employees for various types of work 

including: drilling and blasting (11.2 percent); construction or reconstruction of mine facilities 

(8.9 percent); equipment service or repair of equipment on mine property (7.5 percent); and 

material handling (5.8 percent). 

 

Tables 23–26 present national estimates for safety, communication, and rescue measures. 

Cell phones (88.6 percent) are the most frequently used communication system followed by 

hand-held two-way radios (62.1 percent), and dedicated telephones (40.1 percent). Forty-eight 

percent of mines use telephones for emergency early warnings. Eight percent of mines report 

having their own mine rescue team composed of approximately eight team members. The 

majority of mine rescue teams train on an annual basis (54.6 percent). 

 
32 

Table 16. Miner Training Within the Past 12 Months at All Mines 

Training Conducted by

Percentage 

of Mines 95% CI

Mine employees

Annual miner refresher 70.5 (66.7, 74.2)

Newly hired inexperienced miner 64.3 (59.7, 68.9)

Newly hired experienced miner 60.5 (56.2, 64.8)

 

Outside trainer

Annual miner refresher 58.5 (53.2, 63.8)

Newly hired inexperienced miner 19.6 (16.3, 22.9)

Newly hired experienced miner 15.5 (10.9, 20.1)

 

Outside contract trainer

Annual miner refresher 51.1 (45.6, 56.5)

Newly hired inexperienced miner 58.0 (46.2, 69.8)

Newly hired experienced miner 65.4 (53.5, 77.4)

 

Outside state grantee

Annual miner refresher 36.2 (28.0, 44.4)

Newly hired inexperienced miner 38.3 (23.1, 53.5)

Newly hired experienced miner 29.2 (11.4, 46.9)

 

Outside other trainer

Annual miner refresher 17.2 (12.5, 21.9)

Newly hired inexperienced miner 8.4 (4.9, 12.0)

Newly hired experienced miner 12.4 (3.4, 21.3)

Notes: Data are national estimates; multiple responses permitted. 

Table 17. Frequency of Periodic Safety Meetings at All Mines 

Response

Percentage 

of Mines 95% CI

Less than once a year 1.9 (0.9, 2.9)

Annually 5.0 (2.9, 7.2)

Less than once a month 8.8 (6.3, 11.4)

Once a month 21.3 (17.1, 25.4)

Once every 2 weeks 6.6 (3.9, 9.4)

Once a week 40.1 (33.6, 46.7)

Several times a week 6.7 (4.6, 8.9)

Daily 9.5 (5.9, 13.0)

Note: Data are national estimates.
33 

Table 18. Employee Safety Training Materials and Methods at All Mines 

Response

Percentage 

of Mines 95% CI

Lectures 87.6 (84.7, 90.5)

Written materials 85.0 (81.2, 88.9)

Videos 79.0 (75.9, 82.0)

Self-guided interactive computer programs 17.3 (12.6, 22.0)

Demonstrations 62.8 (56.7, 68.9)

Hands-on training exercises 65.6 (60.9, 70.4)

Group exercises (role playing, games, problem solving) 33.4 (29.8, 36.9)

Classroom simulations (e.g., virtual reality) 11.9 (9.5, 14.4)

Worksite simulations 32.3 (27.7, 36.9)

Narrative storytelling 46.5 (41.3, 51.7)

Other 3.2 (1.8, 4.6)

Notes: Data are national estimates; multiple responses permitted. 

Table 19. Non-English Languages at All Mines 

Response Percentage 95% CI

Employees use a language other than English to 

communicate

7.3 (4.8, 9.9)

 

Mining operations provide training materials, signs, or 

written materials, in language(s) other than English

20.3 (15.7, 24.9)

Language(s) provided1

Spanish 99.7 (99.2, 100.0)

Other DSU DSU

 

Helpful to have training materials, signs, or written 

materials in other languages, in addition to those 

already provided

32.6 (19.2, 46.0)

 

Helpful to have training materials, signs, or written 

materials in language(s) other than English 

9.8 (7.2, 12.5)

1

Multiple responses permitted. Abbreviation: DSU, data suppressed. 

Note: Data are national estimates.

 
34 

Table 20. Work Schedules at All Mines 

Response

Production 

Workers 95% CI

Production 

Support 

Workers 95% CI

Preparation 

Plant/Mill 

Workers 95% CI

Scheduled days per week (average) 4.8 (4.8, 4.9) 4.9 (4.8, 5.0) 4.9 (4.8, 5.0)Scheduled hours per day (average) 9.1 (8.9, 9.3) 9.7 (8.7, 10.7) 9.1 (8.8, 9.5)

Actual hours worked per week 

(average)

39.2 (37.5, 40.9) 38.6 (36.7, 40.5) 39.7 (36.0, 43.5)

Work crews change shifts at active 

mining site (percentage)

12.1 (9.9, 14.2) 11.1 (8.1, 14.2) NA NA

Average time spent traveling to and 

from active mining site while being paid (hours)

1.6 (1.5, 1.7) 1.6 (1.5, 1.7) NA NA

Abbreviation: NA, not applicable. Note: Data are national estimates. 
35 

Table 21. Shift Work Schedules at All Mines 

Response

Production 

Workers

 Percentage 

of Mines 95% CI

Production 

Support 

Workers 

Percentage 

of Mines 95% CI

Preparation 

Plant/Mill 

Workers 

Percentage 

of Mines 95% CI

Number of shifts per day 

1 shift 76.9 (73.4, 80.4) 81.9 (77.7, 86.2) 65.7 (58.2, 73.1)

2 shifts 18.7 (15.4, 22.1) 13.3 (9.6, 17.0) 23.0 (16.5, 29.6)

3 shifts 2.8 (1.9, 3.7) 4.6 (3.1, 6.1) 10.3 (7.6, 12.9)

4 shifts 1.6 (1.3, 1.9) DSU DSU DSU DSU

Rotating shifts 7.7 (5.6, 9.8) 5.9 (4.1, 7.8) 11.5 (8.0, 15.0)Frequency workers rotate shifts

Weekly 62.3 (50.4, 74.2) 59.1 (45.0, 73.2) 51.0 (35.6, 66.3)

Twice a month 20.7 (13.6, 27.8) 19.1 (10.7, 27.6) 17.1 (8.8, 25.4)Monthly DSU DSU DSU DSU 15.9 (1.0, 30.8)

Other 5.5 (2.1, 8.9) 9.3 (3.9, 14.8) 16.0 (2.6, 29.4)

Direction the shift rotates

Clockwise  (day—afternoon—night)

75.3 (67.0, 83.7) 68.4 (56.9, 79.9) 67.0 (53.7, 80.2)

Counterclockwise 

(night—afternoon—day)

6.4 (2.5, 10.3) 13.0 (6.3, 19.8) 11.1 (4.5, 17.6)

Other 18.2 (11.1, 25.4) 18.6 (9.0, 28.1) 21.9 (8.8, 35.1)

Unique work shifts 4.0 (2.3, 5.6) 3.4 (1.8, 4.9) 4.6 (2.3, 7.0)

Abbreviation: DSU, data suppressed. Note: Data are national estimates. 
36 

Table 22. Activities of Independent Contractor Employees During the Reporting Week at All Mines 

Response

Percentage 

of Mines 

Reporting 

Contractors 95% CI

Average 

Number of 

Contractor 

Employees 95% CI

Average 

Total Hours 95% CI

Mine development 2.1 (1.0, 3.2) 8.5 (4.4, 12.7) 217.1 (65.2, 369.0)Construction or reconstruction of 

mine facilities

8.9 (6.3, 11.5) 10.9 (5.4, 16.3) 298.5 (110.8, 486.3)

Demolition of mine facilities 0.2 (0.0, 0.4) 50.4 (0.0, 148.0) DSU DSU

Construction of dams DSU DSU DSU DSU DSU DSU

Excavation or earthmoving 

activities (involving mobile equipment)

5.5 (3.7, 7.3) 6.9 (4.3, 9.6) 234.5 (132.2, 336.8)

Equipment installation 2.4 (1.1, 3.7) 7.1 (0.0, 14.7) 309.2 (0.0, 693.2)

Equipment service or repair of 

equipment on mine property (exceeding 5 consecutive days)

7.5 (5.3, 9.6) 5.0 (0.9, 9.1) 121.7 (54.0, 189.4)

Material handling (within mine 

property)

5.8 (4.1, 7.6) 8.0 (5.5, 10.6) 214.4 (138.4, 290.4)

Drilling and blasting 11.2 (8.8, 13.5) 3.0 (2.3, 3.8) 66.3 (34.9, 97.7)

Production support work 2.2 (1.3, 3.1) 9.5 (5.6, 13.4) 367.1 (169.8, 564.4)

Mineral extraction 1.2 (0.5, 2.0) 4.7 (1.6, 7.9) 173.4 (40.9, 305.8)

Other work 1.2 (0.6, 1.9) 9.7 (2.9, 16.5) 294.4 (23.4, 565.5)

Abbreviation: DSU, data suppressed. Note: Data are national estimates. 
37 

Table 23. Communication Devices and Systems at All Mines 

Response

Percentage 

of Mines 95% CI

Dedicated telephones 40.1 (34.6, 45.7)

Mine page phones 8.5 (6.6, 10.4)

Trolley phones DSU DSU

Shaft or hoist phones 0.8 (0.4, 1.2)

Cell phones 88.6 (85.8, 91.4)

Voice over internet protocol (VOIP) phones 1.0 (0.4, 1.5)

Hand-held two-way radios 62.1 (57.1, 67.2)

Wireless paging devices 4.6 (2.7, 6.5)

Leaky feeder communications system (not running a 

PED)

1.6 (1.0, 2.1)

Personal emergency device (PED) cap lamp/pager 0.9 (0.0, 2.0)

Through-the-Earth (TTE) technology (other than a PED) DSU DSU

Inductive coupled radios 2.1 (1.0, 3.1)

Ethernet 3.9 (2.5, 5.3)

TRACKER tagging system 0.6 (0.2, 1.0)

Longwall face communication systems 0.4 (0.1, 0.6)

None of the above 1.5 (0.7, 2.4)

Other 19.2 (14.3, 24.0)

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 24. Personal Locators, Trackers, and Devices at All Mines 

Response

Percentage 

of Mines 95% CI

Electronic or computerized tagging or tracking 0.7 (0.3, 1.1)

Tag boards 7.9 (6.5, 9.2)

Reflective vests/clothing 36.2 (29.4, 43.1)

Chemical light sticks 2.5 (1.3, 3.8)

Lighted vests 1.7 (0.9, 2.5)

Laser lights/pointers DSU DSU

Strobe lights 10.9 (7.3, 14.5)

None of the above 56.7 (49.4, 63.9)

Other 4.9 (2.9, 6.8)

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

 
38 

Table 25. Emergency Early Warning Methods at All Mines 

Response

Percentage 

of Mines 95% CI

Stench gas 0.6 (0.4, 0.8)

Audible systems 31.0 (27.6, 34.5)

Visual systems 15.2 (11.5, 18.9)

Pager phones 8.1 (6.0, 10.3)

Telephones 48.3 (44.3, 52.4)

Messengers 13.9 (8.2, 19.6)

Electronic personal communication systems 2.1 (0.7, 3.6)

None of the above 26.6 (20.7, 32.6)

Other 16.3 (12.2, 20.4)

Notes: Data are national estimates; multiple responses permitted. 

Table 26. Rescue Teams at All Mines 

Response

Percentage 

of Mines 95% CI

Mine has own rescue team 8.2 (5.1, 11.3)

Average number of rescue team members 7.8 (6.1, 9.5)

 

Frequency of team training

Less than once a year DSU DSU

Annually 54.6 (32.6, 76.6)

Less than once a month 2.6 (0.5, 4.7)

Once a month 30.4 (16.6, 44.2)

Once every 2 weeks 3.2 (0.3, 6.2)

Once a week DSU DSU

Other time interval DSU DSU

Abbreviation: DSU, data suppressed. Note: Data are national estimates.

 
39 

 

Mine Statistics for All 

Underground Mines 
40 
41 

Summary of Mine Statistics for All Underground Mines 

The data for training and non-English languages can be found in Tables 27–30. For all 

underground mines, the weighted survey estimates indicate that more training is conducted by 

the mine’s employees including: annual refresher training (75.2 percent), newly hired 

inexperienced miner training (69.8 percent), and newly hired experienced miner training (83.1 

percent) when compared to the mine’s use of outside trainers. Lectures (97.3 percent), written 

materials (92.0 percent), and demonstrations (85.4 percent) are the top three methods and 

materials used for training. Estimates from the survey indicate that 47.8 percent of underground 

mines have safety meetings once a week. Approximately four percent of underground mine 

employees use a language other than English. 

 Tables 31 and 32 present the national estimates for work schedules and shift work. The 

average number of hours worked per week is 42.9 for production workers, 41.8 for production 

support workers, and 42.7 for preparation plant/mill workers. The majority of underground 

mines operate two shifts per day for production workers (46.7 percent) and preparation plant/mill 

workers (38.1 percent) and one shift per day for production support workers (58.0 percent). 

National estimates for independent contractor employees are presented in Table 33. 

During a typical week, underground mines use independent contractor employees for various 

types of work including: material handling (18.1 percent); production support work (16.2 

percent); mine development (11.7 percent); and construction or reconstruction of mine facilities 

(11.7 percent). 

 

Tables 34–39 present national estimates for safety, communication, and rescue measures. 

Mine page phones (83.8 percent) are the most frequently used communication system followed 

by dedicated telephones (62.6 percent), and hand-held two-way radios (56.1 percent). Tag 

boards (93.1 percent) and reflective vests/clothing (69.5 percent) are the most frequently used 

personal locators/trackers in underground mines. Colored reflectors (78.2 percent) and signage 

(75.1 percent) are the most frequently reported escape aids. First aid kits (88.9 percent), beltworn self-contained self-rescuers (SCSRs) (74.6 percent), and cached water/food supplies (64.4 

percent) are the top three emergency equipment and supplies found in these mines. Seventy-two 

percent of underground mines use pager phones for emergency early warnings. Approximately 

40 percent of underground mines report having their own mine rescue team composed of 11 

team members. The majority of mine rescue teams train once a month (64.6 percent). 

 
42 

Table 27. Miner Training Within the Past 12 Months at Underground Mines 

Training Conducted by

Percentage 

of Mines 95% CI

Mine employees

Annual miner refresher 75.2 (67.3, 83.1)

Newly hired inexperienced miner 69.8 (63.3, 76.4)

Newly hired experienced miner 83.1 (76.5, 89.6)

 

Outside trainer

Annual miner refresher 58.5 (49.9, 67.1)

Newly hired inexperienced miner 37.3 (27.8, 46.7)

Newly hired experienced miner 18.5 (10.0, 27.0)

 

Outside contract trainer

Annual miner refresher 73.9 (64.6, 83.1)

Newly hired inexperienced miner 68.5 (54.8, 82.2)

Newly hired experienced miner 83.2 (69.5, 96.8)

 

Outside state grantee

Annual miner refresher 27.0 (17.6, 36.3)

Newly hired inexperienced miner 26.8 (14.7, 38.8)

Newly hired experienced miner 29.6 (13.3, 45.9)

 

Outside other trainer

Annual miner refresher 11.9 (2.4, 21.5)

Newly hired inexperienced miner 11.4 (2.0, 20.8)

Newly hired experienced miner DSU DSU

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 28. Frequency of Periodic Safety Meetings at Underground Mines 

Response

Percentage 

of Mines 95% CI

Less than once a year 0.0 NA

Annually DSU DSU

Less than once a month DSU DSU

Once a month 9.9 (5.6, 14.3)

Once every 2 weeks DSU DSU

Once a week 47.8 (38.3, 57.3)

Several times a week 14.6 (8.1, 21.0)

Daily 23.3 (14.8, 31.9)

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
43 

Table 29. Employee Safety Training Materials and Methods at Underground Mines 

Response

Percentage 

of Mines 95% CI

Lectures 97.3 (94.7, 100.0)

Written materials 92.0 (87.5, 96.6)

Videos 84.9 (78.7, 91.1)

Self-guided interactive computer programs 10.4 (4.9, 15.9)

Demonstrations 85.4 (80.1, 90.6)

Hands-on training exercises 83.8 (77.2, 90.5)

Group exercises (role playing, games, problem solving) 54.7 (47.5, 61.9)

Classroom simulations (e.g., virtual reality) 21.3 (15.0, 27.5)

Worksite simulations 39.7 (32.7, 46.7)

Narrative storytelling 54.6 (47.0, 62.2)

Other 5.0 (0.9, 9.1)

Notes: Data are national estimates; multiple responses permitted. 

Table 30. Non-English Languages at Underground Mines 

Response Percentage 95% CI

Employees use a language other than English to 

communicate

3.9 (0.6, 7.1)

 

Mining operations provide training materials, signs, or 

written materials, in language(s) other than English

9.9 (4.6, 15.2)

Language(s) provided1

Spanish 90.1 (73.3, 100.0)

Other DSU DSU

 

Helpful to have training materials, signs, or written 

materials in other languages, in addition to those 

already provided

DSU DSU

 

Helpful to have training materials, signs, or written 

materials in language(s) other than English 

8.6 (4.2, 13.0)

1

Multiple responses permitted. Abbreviation: DSU, data suppressed. 

Note: Data are national estimates. 
44 

Table 31. Work Schedules at Underground Mines 

Response

Production 

Workers 95% CI

Production 

Support 

Workers 95% CI

Preparation 

Plant/Mill 

Workers 95% CI

Scheduled days per week (average) 5.1 (5.0, 5.2) 5.1 (5.0, 5.3) 5.0 (4.8, 5.3)Scheduled hours per day (average) 9.3 (9.2, 9.5) 9.2 (9.0, 9.4) 9.3 (8.9, 9.7)

Actual hours worked per week 

(average)

42.9 (40.3, 45.5) 41.8 (38.9, 44.6) 42.7 (38.9, 46.5)

Work crews change shifts at active 

mining site (percentage)

47.0 (38.4, 55.6) 26.6 (18.9, 34.3) NA NA

Average time spent traveling to and 

from active mining site while being paid (hours)

1.7 (1.5, 1.8) 1.7 (1.5, 1.8) NA NA

Abbreviation: NA, not applicable. Note: Data are national estimates. 
45 

Table 32. Shift Work Schedules at Underground Mines 

Response

Production 

Workers

 Percentage 

of Mines 95% CI

Production 

Support 

Workers 

Percentage 

of Mines 95% CI

Preparation 

Plant/Mill 

Workers 

Percentage 

of Mines 95% CI

Number of shifts per day 

1 shift 31.9 (24.9, 38.9) 58.0 (49.9, 66.1) 33.1 (23.6, 42.7)

2 shifts 46.7 (38.4, 55.0) 16.3 (9.8, 22.9) 38.1 (26.8, 49.3)

3 shifts 20.3 (13.4, 27.1) 24.8 (17.2, 32.5) 27.1 (17.0, 37.3)

4 shifts DSU DSU DSU DSU DSU DSU

Rotating shifts 42.2 (35.4, 49.0) 20.1 (14.4, 25.9) 22.9 (14.3, 31.5)Frequency workers rotate shifts

Weekly 49.9 (34.6, 65.1) 40.0 (20.1, 60.0) 52.7 (28.8, 76.7)

Twice a month 45.0 (29.9, 60.1) 44.1 (22.1, 66.1) 41.7 (17.8, 65.6)Monthly 0.0 NA 0.0 NA DSU DSU

Other DSU DSU DSU DSU 0.0 NA

Direction the shift rotates

Clockwise 

(day—afternoon—night)

65.0 (50.6, 79.5) 56.2 (36.4, 76.1) 63.4 (39.3, 87.5) 

Counterclockwise 

(night—afternoon—day)

7.0 (0.0, 14.6) DSU DSU 28.2 (4.8, 51.7)

Other 28.0 (15.3, 40.6) 27.6 (12.1, 43.1) DSU DSU

Unique work shifts 19.1 (12.1, 26.1) 12.5 (6.4, 18.5) 7.6 (0.7, 14.4)

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
46 

Table 33. Activities of Independent Contractor Employees During the Reporting Week at Underground Mines 

Response

Percentage 

of Mines 

Reporting 

Contractors 95% CI

Average 

Number of 

Contractor 

Employees 95% CI

Average 

Total 

Hours 95% CI

Mine development 11.7 (5.8, 17.5) 14.0 (4.7, 23.4) 487.9 (83.2, 892.7)Construction or reconstruction of 

mine facilities

11.7 (7.5, 16.0) 10.5 (0.0, 22.2) 184.4 (80.9, 288.0)

Demolition of mine facilities 0.0 NA NA NA NA NA

Construction of dams DSU DSU DSU DSU DSU DSU

Excavation or earthmoving 

activities (involving mobile equipment)

6.8 (2.7, 11.0) 8.0 (3.2, 12.7) 323.0 (110.1, 535.8)

Equipment installation DSU DSU DSU DSU DSU DSU

Equipment service or repair of 

equipment on mine property (exceeding 5 consecutive days)

8.0 (4.6, 11.4) 3.4 (1.8, 5.1) 115.5 (0.0, 247.3)

Material handling (within mine 

property)

18.1 (9.3, 26.8) 5.6 (3.1, 8.1) 211.9 (111.1, 312.7)

Drilling and blasting 4.9 (2.1, 7.7) 7.5 (0.8, 14.2) 282.8 (0.0, 579.3)

Production support work 16.2 (10.1, 22.3) 11.3 (6.4, 16.1) 432.7 (222.0, 643.4)

Mineral extraction 4.8 (1.1, 8.5) 11.9 (3.0, 20.7) 461.5 (98.1, 825.0)

Other work 5.5 (1.4, 9.5) 14.1 (0.9, 27.3) 620.2 (0.0, 1256.1)

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
47 

Table 34. Communication Devices and Systems at Underground Mines 

Response

Percentage 

of Mines 95% CI

Dedicated telephones 62.6 (54.3, 71.0)

Mine page phones 83.8 (79.3, 88.4)

Trolley phones DSU DSU

Shaft or hoist phones 9.8 (5.9, 13.7)

Cell phones 40.1 (32.0, 48.2)

Voice over internet protocol (VOIP) phones 6.7 (2.9, 10.5)

Hand-held two-way radios 56.1 (46.9, 65.2)

Wireless paging devices 4.4 (0.4, 8.4)

Leaky feeder communications system (not running a 

PED)

23.3 (17.1, 29.6)

Personal emergency device (PED) cap lamp/pager 5.0 (2.0, 8.0)

Through-the-Earth (TTE) technology (other than a PED) DSU DSU

Inductive coupled radios DSU DSU

Ethernet 9.5 (4.6, 14.5)

TRACKER tagging system 6.4 (2.9, 9.8)

Longwall face communication systems 5.6 (2.2, 9.1)

None of the above DSU DSU

Other 7.7 (3.1, 12.4)

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 35. Personal Locators, Trackers, and Devices at Underground Mines 

Response

Percentage 

of Mines 95% CI

Electronic or computerized tagging or tracking 6.6 (2.7, 10.6)

Tag boards 93.1 (88.1, 98.0)

Reflective vests/clothing 69.5 (61.7, 77.2)

Chemical light sticks 20.8 (13.7, 27.9)

Lighted vests DSU DSU

Laser lights/pointers DSU DSU

Strobe lights 23.4 (15.7, 31.2)

None of the above DSU DSU

Other 10.1 (4.2, 16.0)

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

 
48 

Table 36. Emergency Early Warning Methods at Underground Mines 

Response

Percentage 

of Mines 95% CI

Stench gas 10.4 (6.7, 14.1)

Audible systems 65.0 (57.7, 72.4)

Visual systems 59.3 (51.8, 66.8)

Pager phones 72.2 (67.2, 77.1)

Telephones 42.7 (34.4, 50.9)

Messengers 18.5 (11.9, 25.2)

Electronic personal communication systems 6.4 (2.7, 10.1)

None of the above DSU DSU

Other 10.1 (5.4, 14.9)

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 37. Rescue Teams at Underground Mines 

Response

Percentage 

of Mines 95% CI

Mine has own rescue team 39.5 (31.9, 47.0)

Average number of rescue team members 11.0 (8.8, 13.2)

 

Frequency of team training

Less than once a year 0.0 NA

Annually DSU DSU

Less than once a month 8.0 (1.1, 15.0)

Once a month 64.6 (49.7, 79.4)

Once every 2 weeks 12.1 (1.9, 22.3)

Once a week DSU DSU

Other time interval DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
49 

Table 38. Emergency Equipment and Supplies at Underground Mines 

Response

Percentage 

of Mines 95% CI

Belt-worn self-contained self-rescuers (SCSRs) 74.6 (68.8, 80.3)

Cached self-contained self-rescuers (SCSRs) 59.5 (53.9, 65.2)

Filter self-rescuers (FSRs) 26.6 (20.5, 32.7)

Stationary emergency refuge chambers 27.1 (20.2, 34.0)

Mobile emergency refuge chambers 11.4 (6.0, 16.9)

Sealing materials 57.0 (51.4, 62.6)

Cached water/food supplies 64.4 (58.5, 70.4)

First aid kits 88.9 (84.2, 93.6)

Defibrillator 45.0 (35.5, 54.6)

None of the above DSU DSU

Other DSU DSU

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 39. Escape Aids at Underground Mines 

Response

Percentage 

of Mines 95% CI

Lifelines 46.5 (39.7, 53.2)

Directional lifelines 59.6 (55.2, 64.0)

Signage 75.1 (68.7, 81.5)

Colored reflectors 78.2 (73.5, 82.8)

Lighting 20.9 (14.1, 27.8)

Strobe lights 16.3 (10.3, 22.3)

None of the above DSU DSU

Other DSU DSU

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

 
50 

 
51 

 

Mine Statistics for All 

Surface Mines 
52 
53 

Summary of Mine Statistics for All Surface Mines 

The data for training and non-English languages can be found in Tables 40–43. For all 

surface mines, the weighted survey estimates indicate that more training is conducted by the 

mine’s employees including: annual refresher training (70.2 percent); newly hired inexperienced 

miner training (64.0 percent); and newly hired experienced miner training (59.2 percent) when 

compared to the mine’s use of outside trainers. Lectures (87.0 percent), written materials (84.6 

percent), and videos (78.6 percent) are the top three methods and materials used for training. 

Estimates from the survey indicate that 39.7 percent of surface mines have employee safety 

meetings once a week. Approximately eight percent of surface mine employees use a language 

other than English. 

Tables 44 and 45 present the national estimates for work schedules and shift work. The 

average number of hours worked per week is 39.0 for production workers, 38.3 for production 

support workers, and 39.5 for preparation plant/mill workers. The majority of surface mines 

operate one shift per day (79.8 percent for production workers, 83.8 percent for production 

support workers, and 68.0 percent for preparation plant/mill workers). 

National estimates for independent contractor employees are presented in Table 46. 

During a typical week, surface mines use independent contractor employees for various types of 

work including: drilling and blasting (11.5 percent); construction or reconstruction of mine 

facilities (8.8 percent); equipment service or repair of equipment on mine property (7.4 percent), 

and excavation or earthmoving activities (5.4 percent). 

 

Tables 47–50 present national estimates for safety, communication, and rescue measures. 

Cell phones (91.3 percent) are the most frequently used communication system followed by 

hand-held two-way radios (62.5 percent), and dedicated telephones (38.9 percent). Forty-nine 

percent of surface mines use telephones for emergency early warnings. Approximately seven 

percent of surface mines report having their own mine rescue team composed of about seven 

team members. The majority of mine rescue teams train on an annual basis (70.3 percent). 
54 

Table 40. Miner Training Within the Past 12 Months at Surface Mines 

Training Conducted by

Percentage 

of Mines 95% CI

Mine employees

Annual miner refresher 70.2 (66.3, 74.2)

Newly hired inexperienced miner 64.0 (59.1, 68.8)

Newly hired experienced miner 59.2 (54.7, 63.8)

 

Outside trainer

Annual miner refresher 58.5 (52.9, 64.1)

Newly hired inexperienced miner 18.5 (15.1, 21.9)

Newly hired experienced miner 15.3 (10.5, 20.2)

 

Outside contract trainer

Annual miner refresher 49.7 (44.1, 55.4)

Newly hired inexperienced miner 56.8 (43.8, 69.8)

Newly hired experienced miner 64.2 (51.6, 76.7)

 

Outside state grantee

Annual miner refresher 36.8 (28.1, 45.5)

Newly hired inexperienced miner 39.6 (22.8, 56.5)

Newly hired experienced miner 29.1 (10.1, 48.2)

 

Outside other trainer

Annual miner refresher 17.5 (12.6, 22.4)

Newly hired inexperienced miner 8.1 (4.3, 11.8)

Newly hired experienced miner 13.0 (3.5, 22.6)

Notes: Data are national estimates; multiple responses permitted. 

Table 41. Frequency of Periodic Safety Meetings at Surface Mines 

Response

Percentage 

of Mines 95% CI

Less than once a year 2.0 (1.0, 3.1)

Annually 5.3 (3.0, 7.6)

Less than once a month 9.3 (6.6, 12.0)

Once a month 21.9 (17.5, 26.4)

Once every 2 weeks 6.9 (4.0, 9.8)

Once a week 39.7 (32.8, 46.6)

Several times a week 6.3 (4.1, 8.5)

Daily 8.6 (4.9, 12.4)

Note: Data are national estimates.
55 

Table 42. Employee Safety Training Materials and Methods at Surface Mines 

Response

Percentage 

of Mines 95% CI

Lectures 87.0 (84.0, 90.1)

Written materials 84.6 (80.5, 88.7)

Videos 78.6 (75.4, 81.8)

Self-guided interactive computer programs 17.7 (12.7, 22.7)

Demonstrations 61.5 (54.9, 68.0)

Hands-on training exercises 64.6 (59.6, 69.5)

Group exercises (role playing, games, problem solving) 32.1 (28.4, 35.8)

Classroom simulations (e.g., virtual reality) 11.4 (8.8, 14.0)

Worksite simulations 31.8 (27.0, 36.6)

Narrative storytelling 46.0 (40.6, 51.4)

Other 3.1 (1.6, 4.6)

Notes: Data are national estimates; multiple responses permitted. 

Table 43. Non-English Languages at Surface Mines 

Response Percentage 95% CI

Employees use a language other than English to 

communicate

7.5 (4.8, 10.2)

 

Mining operations provide training materials, signs, or 

written materials in language(s) other than English

20.9 (16.0, 25.8)

Language(s) provided1

Spanish 100.0 NA

Other DSU DSU

 

Helpful to have training materials, signs, or written 

materials in other languages, in addition to those 

already provided

33.0 (19.2, 46.7)

 

Helpful to have training materials, signs, or written 

materials in language(s) other than English 

9.9 (7.1, 12.7)

1

Multiple responses permitted. Abbreviations: DSU, data suppressed; NA, not applicable. 

Note: Data are national estimates. 
56 

Table 44. Work Schedules at Surface Mines 

Response

Production 

Workers 95% CI

Production 

Support 

Workers 95% CI

Preparation 

Plant/Mill 

Workers 95% CI

Scheduled days per week (average) 4.8 (4.7, 4.9) 4.9 (4.8, 4.9) 4.9 (4.8, 5.0)Scheduled hours per day (average) 9.1 (8.9, 9.3) 9.7 (8.7, 10.8) 9.1 (8.7, 9.5)

Actual hours worked per week 

(average)

39.0 (37.2, 40.7) 38.3 (36.4, 40.3) 39.5 (35.5, 43.6)

Work crews change shifts at active 

mining site (percentage)

9.8 (7.6, 12.1) 9.9 (6.6, 13.2) NA NA

Average time spent traveling to and 

from active mining site while being paid (hours)

1.6 (1.5, 1.7) 1.6 (1.5, 1.7) NA NA

Abbreviation: NA, not applicable. Note: Data are national estimates. 
57 

Table 45. Shift Work Schedules at Surface Mines 

Response

Production 

Workers

 Percentage 

of Mines 95% CI

Production 

Support 

Workers 

Percentage 

of Mines 95% CI

Preparation 

Plant/Mill 

Workers 

Percentage 

of Mines 95% CI

Number of shifts per day 

1 shift 79.8 (76.2, 83.3) 83.8 (79.5, 88.1) 68.0 (60.3, 75.6)

2 shifts 16.9 (13.5, 20.4) 13.1 (9.2, 16.9) 22.0 (15.1, 28.8)

3 shifts 1.7 (0.8, 2.6) 3.0 (1.7, 4.4) 9.1 (6.4, 11.7)

4 shifts 1.6 (1.3, 1.9) DSU DSU DSU DSU

Rotating shifts 5.5 (3.4, 7.6) 4.8 (2.9, 6.7) 10.7 (7.1, 14.4)Frequency workers rotate shifts

Weekly 68.4 (51.7, 85.1) 65.4 (47.7, 83.1) 50.7 (33.5, 67.8)

Twice a month 8.7 (3.3, 14.1) 10.9 (3.9, 17.9) 13.4 (5.2, 21.6)

Monthly DSU DSU DSU DSU 17.5 (0.9, 34.1)

Other 5.7 (1.5, 10.0) 7.2 (2.2, 12.2) 18.4 (3.1, 33.8)

Direction the shift rotates

Clockwise 

(day—afternoon—night)

80.4 (70.8, 90.1) 72.4 (59.1, 85.7) 67.5 (52.5, 82.6)

Counterclockwise 

(night—afternoon—day)

6.1 (1.5, 10.8) 12.0 (4.2, 19.7) 8.5 (2.4, 14.6)

Other 13.4 (5.5, 21.4) 15.6 (4.4, 26.8) 24.0 (9.0, 39.0)

Unique work shifts 3.0 (1.4, 4.6) 2.6 (1.0, 4.3) 4.4 (2.0, 6.9)

Abbreviation: DSU, data suppressed. Note: Data are national estimates.
58 

Table 46. Activities of Independent Contractor Employees During the Reporting Week at Surface Mines 

Response

Percentage 

of Mines 

Reporting 

Contractors 95% CI

Average 

Number of 

Contractor 

Employees 95% CI

Average 

Total 

Hours 95% CI

Mine development 1.5 (0.4, 2.6) 6.2 (2.8, 9.5) 98.7 (31.5, 165.8)Construction or reconstruction of 

mine facilities

8.8 (6.0, 11.5) 10.9 (5.1, 16.7) 307.3 (104.3, 510.3)

Demolition of mine facilities 0.2 (0.0, 0.4) 50.4 (0.0, 148.0) DSU DSU

Construction of dams DSU DSU DSU DSU DSU DSU

Excavation or earthmoving 

activities (involving mobile equipment)

5.4 (3.5, 7.4) 6.9 (4.1, 9.7) 228.1 (121.5, 334.7)

Equipment installation 2.5 (1.1, 3.9) 7.2 (0.0, 15.1) 314.0 (0.0, 708.8)

Equipment service or repair of 

equipment on mine property (exceeding 5 consecutive days)

7.4 (5.2, 9.6) 5.1 (0.7, 9.5) 122.1 (49.0, 195.2)

Material handling (within mine 

property)

5.1 (3.4, 6.9) 8.5 (5.4, 11.6) 214.9 (122.8, 307.0)

Drilling and blasting 11.5 (9.0, 14.0) 2.9 (2.2, 3.7) 61.0 (29.9, 92.1)

Production support work 1.4 (0.5, 2.3) 8.3 (2.4, 14.2) 323.3 (14.7, 631.8)

Mineral extraction 1.0 (0.3, 1.8) 2.8 (0.8, 4.9) 97.5 (3.8, 191.2)

Other work 1.0 (0.2, 1.7) 8.3 (0.7, 15.9) 191.4 (0.0, 449.5)

Abbreviation: DSU, data suppressed. Note: Data are national estimates.
59 

Table 47. Communication Devices and Systems at Surface Mines 

Response

Percentage 

of Mines 95% CI

Dedicated telephones 38.9 (33.1, 44.6)

Mine page phones 4.3 (2.5, 6.0)

Trolley phones 0.0 NA

Shaft or hoist phones NA NA

Cell phones 91.3 (88.4, 94.3)

Voice over internet protocol (VOIP) phones 0.6 (0.1, 1.2)

Hand-held two-way radios 62.5 (57.1, 67.8)

Wireless paging devices 4.6 (2.6, 6.6)

Leaky feeder communications system (not running a 

PED)

0.3 (0.0, 0.7)

Personal emergency device (PED) cap lamp/pager DSU DSU

Through-the-Earth (TTE) technology (other than a PED) DSU DSU

Inductive coupled radios 2.2 (1.1, 3.2)

Ethernet 3.6 (2.1, 5.0)

TRACKER tagging system DSU DSU

Longwall face communication systems NA NA

None of the above 1.5 (0.6, 2.3)

Other 19.8 (14.6, 25.0)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 48. Personal Locators, Trackers, and Devices at Surface Mines 

Response

Percentage 

of Mines 95% CI

Electronic or computerized tagging or tracking 0.4 (0.0, 0.7)

Tag boards 3.0 (1.8, 4.2)

Reflective vests/clothing 34.3 (27.1, 41.5)

Chemical light sticks 1.5 (0.3, 2.7)

Lighted vests 1.8 (1.0, 2.6)

Laser lights/pointers DSU DSU

Strobe lights 10.2 (6.4, 13.9)

None of the above 59.7 (52.2, 67.2)

Other 4.6 (2.5, 6.7)

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

 
60 

Table 49. Emergency Early Warning Methods at Surface Mines 

Response

Percentage 

of Mines 95% CI

Stench gas DSU DSU

Audible systems 29.1 (25.4, 32.7)

Visual systems 12.7 (8.8, 16.5)

Pager phones 4.4 (2.5, 6.3)

Telephones 48.7 (44.4, 53.0)

Messengers 13.6 (7.6, 19.7)

Electronic personal communication systems 1.9 (0.4, 3.4)

None of the above 28.0 (21.9, 34.2)

Other 16.6 (12.3, 21.0)

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 50. Rescue Teams at Surface Mines 

Response

Percentage 

of Mines 95% CI

Mine has own rescue team 6.5 (3.3, 9.7)

Average number of rescue team members 6.7 (5.0, 8.4)

 

Frequency of team training

Less than once a year DSU DSU

Annually 70.3 (45.5, 95.0)

Less than once a month 0.9 (0.0, 2.1)

Once a month DSU DSU

Once every 2 weeks DSU DSU

Once a week DSU DSU

Other time interval 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. 

Note: Data are national estimates. 
61 

Mine Statistics for 

Coal Mines 
62 
63 

Summary of Mine Statistics for Coal Mines 

The data for training and non-English languages can be found in Tables 51–54. For the 

U.S. coal mining industry, the weighted survey estimates indicate that annual miner refresher 

training is conducted slightly more often by an outside trainer (68.8 percent) compared to the 

mine’s own employees (67.6 percent). However, newly hired inexperienced and experienced 

miner training is more often conducted by the mines own employees (58.1 percent and 74.8 

percent, respectively). Lectures (98.0 percent), written materials (89.5 percent), and videos (87.9 

percent) are the top three methods and materials used for training. Estimates from the survey 

indicate that 51.7 percent of all coal mines have employee safety meetings once a week. Only 

two percent of coal mine employees use a language other than English. 

 Tables 55 and 56 present the national estimates for work schedules and shift work. The 

average number of hours worked per week is 46.9 for production workers, 44.3 for production 

support workers, and 45.6 for preparation plant/mill workers. The majority of coal mines 

operate two shifts per day for production workers (56.1 percent) and preparation plant/mill 

workers (48.8 percent) and one shift per day for production support workers (51.4 percent). 

National estimates for independent contractor employees are presented in Table 57. 

During a typical week, coal mines use independent contractor employees for various types of 

work including: material handling (29.5 percent); construction or reconstruction of mine 

facilities (18.4 percent); drilling and blasting (16.1 percent); and equipment service or repair of 

equipment on mine property (14.1 percent). 

 

Tables 58–61 present national estimates for safety, communication, and rescue measures. 

Cell phones (73.6 percent) are the most frequently used communication system followed by 

hand-held two-way radios (59.2 percent), and dedicated telephones (52.4 percent). Reflective 

vests/clothing (51.8 percent) and tag boards (31.2 percent) are the most frequently used personal 

locators/trackers in coal mines. Fifty-six percent of coal mines use telephones for emergency 

early warnings. Nineteen percent of these mines report having their own mine rescue team 

composed of approximately 10 team members. The majority of mine rescue teams train once a 

month (69.8 percent). 

 
64 

Table 51. Miner Training Within the Past 12 Months at Coal Mines 

Training Conducted by

Percentage 

of Mines 95% CI

Mine employees

Annual miner refresher 67.6 (60.0, 75.1)

Newly hired inexperienced miner 58.1 (49.6, 66.7)

Newly hired experienced miner 74.8 (62.6, 87.1)

 

Outside trainer

Annual miner refresher 68.8 (61.1, 76.5)

Newly hired inexperienced miner 34.2 (25.7, 42.8)

Newly hired experienced miner 27.8 (15.4, 40.2)

 

Outside contract trainer

Annual miner refresher 74.2 (66.1, 82.3)

Newly hired inexperienced miner 73.7 (59.3, 88.2)

Newly hired experienced miner 84.9 (69.6, 100.0)

 

Outside state grantee

Annual miner refresher 22.1 (14.2, 30.0)

Newly hired inexperienced miner 26.1 (14.5, 37.6)

Newly hired experienced miner 8.1 (1.0, 15.3)

 

Outside other trainer

Annual miner refresher 13.1 (7.9, 18.2)

Newly hired inexperienced miner 9.0 (1.8, 16.1)

Newly hired experienced miner DSU DSU

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 52. Frequency of Periodic Safety Meetings at Coal Mines 

Response

Percentage 

of Mines 95% CI

Less than once a year DSU DSU

Annually DSU DSU

Less than once a month 5.6 (0.4, 10.8)

Once a month 10.6 (5.1, 16.1)

Once every 2 weeks 5.1 (0.0, 10.6)

Once a week 51.7 (42.6, 60.8)

Several times a week 12.4 (5.1, 19.7)

Daily 12.2 (6.0, 18.3)

Abbreviation: DSU, data suppressed. Note: Data are national estimates.
65 

Table 53. Employee Safety Training Materials and Methods at Coal Mines 

Response

Percentage 

of Mines 95% CI

Lectures 98.0 (95.9, 100.0)

Written materials 89.5 (83.7, 95.4)

Videos 87.9 (80.6, 95.2)

Self-guided interactive computer programs 6.1 (2.5, 9.7)

Demonstrations 77.6 (67.4, 87.7)

Hands-on training exercises 78.4 (67.9, 88.9)

Group exercises (role playing, games, problem solving) 53.3 (44.3, 62.3)

Classroom simulations (e.g., virtual reality) 22.6 (15.2, 30.0)

Worksite simulations 36.5 (26.7, 46.4)

Narrative storytelling 47.0 (35.3, 58.7)

Other 5.0 (1.2, 8.9)

Notes: Data are national estimates; multiple responses permitted. 

Table 54. Non-English Languages at Coal Mines 

Response Percentage 95% CI

Employees use a language other than English to 

communicate

2.0 (0.0, 4.5)

 

Mining operations provide training materials, signs, or 

written materials, in language(s) other than English

7.0 (0.8, 13.2)

Language(s) provided1

Spanish 93.8 (82.1, 100.0)

Other DSU DSU

 

Helpful to have training materials, signs, or written 

material in additional language(s) than those 

language(s) already provided

DSU DSU

 

Helpful to have training materials, signs, or written 

materials in languages(s) other than English 

3.2 (0.8, 5.6)

1

Multiple responses permitted. Abbreviation: DSU, data suppressed. 

Note: Data are national estimates. 

 
66 

Table 55. Work Schedules at Coal Mines 

Response

Production 

Workers 95% CI

Production 

Support 

Workers 95% CI

Preparation 

Plant/Mill 

Workers 95% CI

Scheduled days per week (average) 5.4 (5.3, 5.6) 5.3 (5.2, 5.5) 5.1 (4.9, 5.3)Scheduled hours per day (average) 9.5 (9.0, 9.9) 9.3 (8.9, 9.8) 9.7 (9.3, 10.1)

Actual hours worked per week 

(average)

46.9 (44.1, 49.7) 44.3 (40.6, 47.9) 45.6 (35.1, 56.0)

Work crews change shifts at active 

mining site (percentage)

39.4 (29.9, 49.0) 24.4 (17.1, 31.6) NA NA

Average time spent traveling to and 

from active mining site while being paid (hours)

1.7 (1.6, 1.8) 1.7 (1.5, 1.8) NA NA

Abbreviation: NA, not applicable. Note: Data are national estimates. 
67 

Table 56. Shift Work Schedules at Coal Mines 

Response

Production 

Workers

 Percentage 

of Mines 95% CI

Production 

Support 

Workers 

Percentage 

of Mines 95% CI

Preparation 

Plant/Mill 

Workers 

Percentage 

of Mines 95% CI

Number of shifts per day 

1 shift 30.6 (22.6, 38.6) 51.4 (41.6, 61.3) 24.8 (7.1, 42.6)

2 shifts 56.1 (47.7, 64.5) 29.6 (20.7, 38.5) 48.8 (31.4, 66.1)

3 shifts 12.2 (7.2, 17.2) 17.7 (11.1, 24.3) 25.3 (15.4, 35.2)4 shifts DSU DSU DSU DSU DSU DSU

Rotating shifts 31.2 (23.6, 38.8) 19.0 (12.2, 25.7) 22.3 (11.9, 32.7)Frequency workers rotate shifts

Weekly 63.3 (50.7, 76.0) 66.1 (50.2, 82.1) 49.2 (17.4, 81.0)

Twice a month 31.8 (19.6, 43.9) 20.3 (6.2, 34.3) 21.3 (2.1, 40.5)

Monthly 0.0 NA 0.0 NA DSU DSU

Other DSU DSU 13.6 (1.9, 25.3) DSU DSU

Direction the shift rotates

Clockwise 

(day—afternoon—night)

67.4 (53.4, 81.4) 65.3 (45.3, 85.3) 60.5 (24.8, 96.3)

Counterclockwise

 (night—afternoon—day)

DSU DSU DSU DSU DSU DSU

Other 27.0 (13.8, 40.3) 25.6 (6.2, 45.0) DSU DSU

Unique work shifts 17.8 (10.4, 25.2) 12.8 (6.2, 19.4) 10.7 (4.5, 16.9)

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
68 

Table 57. Activities of Independent Contractor Employees During the Reporting Week at Coal Mines 

Response

Percentage 

of Mines

 Reporting 

Contractors 95% CI

Average 

Number of 

Contractor 

Employees 95% CI

Average

 Total 

Hours 95% CI

Mine development 7.1 (2.7, 11.4) 10.7 (7.4, 14.1) 212.5 (87.8, 337.2)Construction or reconstruction of 

mine facilities

18.4 (12.8, 23.9) 14.7 (0.8, 28.5) 545.3 (0.0, 1105.6)

Demolition of mine facilities 0.0 NA NA NA NA NA

Construction of dams DSU DSU DSU DSU DSU DSU

Excavation or earthmoving 

activities (involving mobile equipment)

9.3 (4.7, 13.9) 11.5 (6.8, 16.2) 430.8 (172.9, 688.6)

Equipment installation DSU DSU DSU DSU DSU DSU

Equipment service or repair of 

equipment on mine property (exceeding 5 consecutive days)

14.1 (7.3, 20.9) 4.0 (2.6, 5.4) 153.1 (88.2, 218.0)

Material handling (within mine 

property)

29.5 (21.5, 37.4) 8.7 (5.5, 11.9) 225.9 (134.4, 317.4)

Drilling and blasting 16.1 (10.3, 21.8) 2.7 (1.8, 3.7) 80.8 (32.3, 129.2)

Production support work 8.8 (4.4, 13.1) 12.9 (6.3, 19.6) 539.3 (206.3, 872.3)

Mineral extraction DSU DSU DSU DSU DSU DSU

Other work 4.7 (0.2, 9.1) 7.2 (0.0, 18.9) 282.3 (0.0, 824.4)

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
69 

Table 58. Communication Devices and Systems at Coal Mines 

Response

Percentage 

of Mines 95% CI

Dedicated telephones 52.4 (43.2, 61.7)

Mine page phones 42.5 (35.6, 49.4)

Trolley phones DSU DSU

Shaft or hoist phones 3.4 (0.9, 6.0)

Cell phones 73.6 (66.0, 81.3)

Voice over internet protocol (VOIP) phones 1.8 (0.2, 3.5)

Hand-held two-way radios 59.2 (47.8, 70.5)

Wireless paging devices 9.2 (3.1, 15.2)

Leaky feeder communications system (not running a 

PED)

7.7 (3.8, 11.5)

Personal emergency device (PED) cap lamp/pager 1.7 (0.5, 3.0)

Through-the-Earth (TTE) technology (other than a PED) DSU DSU

Inductive coupled radios DSU DSU

Ethernet 11.3 (7.0, 15.6)

TRACKER tagging system 2.5 (0.8, 4.1)

Longwall face communication systems 2.9 (1.2, 4.6)

None of the above DSU DSU

Other 17.8 (9.4, 26.2)

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 59. Personal Locators, Trackers, and Devices at Coal Mines 

Response

Percentage 

of Mines 95% CI

Electronic or computerized tagging or tracking 2.9 (1.1, 4.7)

Tag boards 31.2 (27.1, 35.3)

Reflective vests/clothing 51.8 (41.8, 61.8)

Chemical light sticks 13.8 (8.6, 19.0)

Lighted vests 0.0 NA

Laser lights/pointers DSU DSU

Strobe lights 22.9 (14.2, 31.6)

None of the above 32.1 (22.4, 41.9)

Other 6.3 (2.1, 10.4)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 
70 

Table 60. Emergency Early Warning Methods at Coal Mines 

Response

Percentage 

of Mines 95% CI

Stench gas DSU DSU

Audible systems 47.4 (39.8, 55.1)

Visual systems 31.4 (23.1, 39.8)

Pager phones 39.6 (32.1, 47.1)

Telephones 55.8 (46.5, 65.1)

Messengers 10.6 (5.2, 16.0)

Electronic personal communication systems 3.4 (1.0, 5.7)

None of the above 20.5 (13.6, 27.5)

Other 7.0 (2.4, 11.6)

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 61. Rescue Teams at Coal Mines 

Response

Percentage 

of Mines 95% CI

Mine has own rescue team 19.2 (13.9, 24.4)

Average number of rescue team members 10.2 (8.3, 12.2)

Frequency of team training

Less than once a year 0.0 NA

Annually DSU DSU

Less than once a month DSU DSU

Once a month 69.8 (53.7, 85.9)

Once every 2 weeks DSU DSU

Once a week DSU DSU

Other time interval DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 

 
71 

 

Mine Statistics for 

Underground Coal Mines 
72 
73 

Summary of Mine Statistics for Underground Coal Mines 

The data for training and non-English languages can be found in Tables 62–65. For 

underground coal mines, the weighted survey estimates indicate that more training is conducted 

by the mine’s employees including: annual refresher training (71.5 percent); newly hired 

inexperienced miner training (65.1 percent); and newly hired experienced miner training (85.9 

percent) when compared to the mine’s use of outside trainers. Lectures (97.5 percent), written 

materials (92.8 percent), and videos (89.4 percent) are the top three methods and materials used 

for training. Estimates from the survey indicate that 52.9 percent of underground coal mines 

have employee safety meetings once a week. Approximately three percent of underground coal 

mine employees use a language other than English. 

Tables 66 and 67 present the national estimates for work schedules and shift work. The 

average number of hours worked per week is 43.5 for production workers, 41.9 for production 

support workers, and 42.1 for preparation plant/mill workers. The majority of underground coal 

mines operate two shifts per day for production workers (49.8 percent) and preparation plant/mill 

workers (44.1 percent) and one shift per day for production support workers (51.4 percent). 

National estimates for independent contractor employees are presented in Table 68. 

During a typical week, underground coal mines use independent contractor employees for 

various types of work including: material handling (22.6 percent); production support work (21.1 

percent); mine development (14.0 percent); and construction or reconstruction of mine facilities 

(10.9 percent). 

 

Tables 69–74 present national estimates for safety, communication, and rescue measures. 

Mine page phones (95.7 percent) are the most frequently used communication system followed 

by dedicated telephones (62.7 percent), and hand-held two-way radios (48.5 percent). Tag 

boards (90.9 percent) and reflective vests/clothing (75.2 percent) are the most frequently used 

personal locators/trackers in underground coal mines. Colored reflectors (87.9 percent) and 

directional lifelines (87.5 percent) are the most frequently reported escape aids. First aid kits 

(89.4 percent), belt-worn self-contained self-rescuers (SCSRs) (87.4 percent), and cached selfcontained self-rescuers (84.6 percent) are the top three emergency equipment and supplies found 

in these mines. Eighty-seven percent of underground coal mines use pager phones for 

emergency early warnings. Approximately 41 percent of underground coal mines report having 

their own mine rescue team composed of 9 team members. The majority of mine rescue teams 

train once a month (65.6 percent). 
74 

Table 62. Miner Training Within the Past 12 Months at Underground Coal Mines 

Training Conducted by

Percentage 

of Mines 95% CI

Mine employees

Annual miner refresher 71.5 (60.4, 82.6)

Newly hired inexperienced miner 65.1 (55.9, 74.4)

Newly hired experienced miner 85.9 (77.1, 94.6)

 

Outside trainer

Annual miner refresher 65.6 (54.4, 76.9)

Newly hired inexperienced miner 40.3 (28.0, 52.6)

Newly hired experienced miner 17.1 (5.5, 28.7)

 

Outside contract trainer

Annual miner refresher 78.8 (68.3, 89.4)

Newly hired inexperienced miner 67.4 (49.9, 85.0)

Newly hired experienced miner 91.5 (73.9, 100.0)

 

Outside state grantee

Annual miner refresher 24.2 (12.4, 35.9)

Newly hired inexperienced miner 28.1 (11.5, 44.8)

Newly hired experienced miner DSU DSU

 

Outside other trainer

Annual miner refresher DSU DSU

Newly hired inexperienced miner DSU DSU

Newly hired experienced miner 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 63. Frequency of Periodic Safety Meetings at Underground Coal Mines 

Response

Percentage 

of Mines 95% CI

Less than once a year 0.0 NA

Annually 0.0 NA

Less than once a month 0.0 NA

Once a month DSU DSU

Once every 2 weeks DSU DSU

Once a week 52.9 (40.3, 65.6)

Several times a week 17.9 (8.9, 26.9)

Daily 22.2 (10.1, 34.3)

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates.
75 

Table 64. Employee Safety Training Materials and Methods at Underground Coal Mines 

Response

Percentage 

of Mines 95% CI

Lectures 97.5 (93.9, 100.0)

Written materials 92.8 (86.9, 98.7)

Videos 89.4 (82.2, 96.6)

Self-guided interactive computer programs 9.8 (2.4, 17.2)

Demonstrations 87.2 (81.1, 93.2)

Hands-on training exercises 89.1 (81.4, 96.7)

Group exercises (role playing, games, problem solving) 64.5 (56.1, 72.9)

Classroom simulations (e.g., virtual reality) 22.0 (13.6, 30.4)

Worksite simulations 41.0 (31.2, 50.7)

Narrative storytelling 54.0 (42.8, 65.1)

Other DSU DSU

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 65. Non-English Languages at Underground Coal Mines 

Response Percentage 95% CI

Employees use a language other than English to 

communicate

2.5 (0.0, 6.6)

 

Mining operations provide training materials, signs, or 

written materials, in language(s) other than English

DSU DSU

Language(s) provided1

Spanish DSU DSU

Other DSU DSU

 

Helpful to have training materials, signs, or written 

materials in other languages, in addition to those 

already provided

0.0 NA

 

Helpful to have training materials, signs, or written 

materials in language(s) other than English 

5.8 (0.7, 10.9)

1

Multiple responses permitted. Abbreviations: DSU, data suppressed; NA, not applicable. 

Note: Data are national estimates. 
76 

Table 66. Work Schedules at Underground Coal Mines 

Response

Production 

Workers 95% CI

Production 

Support 

Workers 95% CI

Preparation 

Plant/Mill 

Workers 95% CI

Scheduled days per week (average) 5.2 (5.0, 5.4) 5.2 (5.0, 5.4) 5.1 (4.7, 5.5)Scheduled hours per day (average) 9.2 (9.0, 9.4) 9.1 (8.8, 9.4) 9.0 (8.3, 9.7)

Actual hours worked per week 

(average)

43.5 (39.9, 47.0) 41.9 (37.9, 45.9) 42.1 (36.0, 48.2)

Work crews change shifts at active 

mining site (percentage)

61.7 (49.7, 73.7) 36.9 (25.6, 48.2) NA NA

Average time spent traveling to and 

from active mining site while being paid (hours)

1.6 (1.5, 1.8) 1.6 (1.5, 1.8) NA NA

Abbreviation: NA, not applicable. Note: Data are national estimates. 
77 

Table 67. Shift Work Schedules at Underground Coal Mines 

Response

Production 

Workers

Percentage 

of Mines 95% CI

Production 

Support 

Workers 

Percentage 

of Mines 95% CI

Preparation 

Plant/Mill 

Workers 

Percentage 

of Mines 95% CI

Number of shifts per day 

1 shift 22.5 (13.0, 31.9) 51.4 (40.0, 62.7) 14.4 (0.0, 30.5)

2 shifts 49.8 (37.8, 61.7) 13.3 (4.4, 22.2) 44.1 (24.0, 64.3)

3 shifts 26.0 (16.5, 35.6) 34.1 (23.1, 45.0) 38.1 (20.8, 55.4)

4 shifts DSU DSU DSU DSU DSU DSU

Rotating shifts 46.3 (36.9, 55.7) 20.1 (11.9, 28.3) 21.0 (6.3, 35.7)Frequency workers rotate shifts

Weekly 46.5 (27.8, 65.2) 33.7 (8.5, 58.9) DSU DSU

Twice a month 50.8 (32.1, 69.5) 47.0 (18.3, 75.7) DSU DSU

Monthly 0.0 NA 0.0 NA 0.0 NA

Other DSU DSU DSU DSU 0.0 NA

Direction the shift rotates

Clockwise 

(day—afternoon—night)

66.1 (48.9, 83.3) 61.1 (36.6, 85.5) DSU DSU

Counterclockwise 

(night—afternoon—day)

DSU DSU DSU DSU DSU DSU

Other 28.5 (12.1, 44.9) DSU DSU 0.0 NA

Unique work shifts 23.5 (13.8, 33.3) 13.3 (5.0, 21.6) DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
78 

Table 68. Activities of Independent Contractor Employees During the Reporting Week at Underground Coal Mines 

Response

Percentage 

of Mines 

Reporting 

Contractors 95% CI

Average 

Number of 

Contractor 

Employees 95% CI

Average 

Total 

Hours 95% CI

Mine development 14.0 (5.5, 22.4) 7.9 (4.1, 11.7) 200.7 (159.4, 242.1)Construction or reconstruction of 

mine facilities

10.9 (5.1, 16.6) 4.2 (2.9, 5.6) 104.0 (18.3, 190.3)

Demolition of mine facilities 0.0 NA NA NA NA NA

Construction of dams 0.0 NA NA NA NA NAExcavation or earthmoving 

activities (involving mobile equipment)

5.2 (0.6, 9.8) 3.5 (2.1, 4.8) 88.4 (57.3, 119.4)

Equipment installation 0.0 NA NA NA NA NA

Equipment service or repair of 

equipment on mine property (exceeding 5 consecutive days)

DSU DSU DSU DSU DSU DSU

Material handling (within mine 

property)

22.6 (10.4, 34.8) 6.1 (3.2, 9.0) 237.1 (120.4, 353.7)

Drilling and blasting 0.0 NA NA NA NA NA

Production support work 21.1 (11.8, 30.4) 12.2 (6.1, 18.2) 462.1 (210.9, 713.2)

Mineral extraction DSU DSU DSU DSU DSU DSU

Other work DSU DSU DSU DSU DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
79 

Table 69. Communication Devices and Systems at Underground Coal Mines 

Response

Percentage 

of Mines 95% CI

Dedicated telephones 62.7 (50.8, 74.7)

Mine page phones 95.7 (90.6, 100.0)

Trolley phones DSU DSU

Shaft or hoist phones 6.1 (2.0, 10.2)

Cell phones 32.9 (22.2, 43.6)

Voice over internet protocol (VOIP) phones 6.3 (0.8, 11.7)

Hand-held two-way radios 48.5 (35.8, 61.2)

Wireless paging devices DSU DSU

Leaky feeder communications system (not running a 

PED)

17.5 (10.3, 24.8)

Personal emergency device (PED) cap lamp/pager 5.9 (1.7, 10.1)

Through-the-Earth (TTE) technology (other than a PED) DSU DSU

Inductive coupled radios 0.0 NA

Ethernet 11.6 (4.7, 18.5)

TRACKER tagging system 8.3 (2.9, 13.8)

Longwall face communication systems 8.3 (3.2, 13.5)

None of the above DSU DSU

Other DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 70. Personal Locators, Trackers, and Devices at Underground Coal Mines 

Response

Percentage 

of Mines 95% CI

Electronic or computerized tagging or tracking 9.4 (3.6, 15.2)

Tag boards 90.9 (83.7, 98.2)

Reflective vests/clothing 75.2 (64.9, 85.4)

Chemical light sticks 30.1 (19.3, 40.8)

Lighted vests 0.0 NA

Laser lights/pointers DSU DSU

Strobe lights 20.7 (10.8, 30.6)

None of the above DSU DSU

Other 13.8 (5.3, 22.3)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

 
80 

Table 71. Emergency Early Warning Methods at Underground Coal Mines 

Response

Percentage 

of Mines 95% CI

Stench gas DSU DSU

Audible systems 74.3 (64.8, 83.9)

Visual systems 61.8 (51.4, 72.2)

Pager phones 87.0 (80.6, 93.5)

Telephones 44.9 (34.3, 55.6)

Messengers 13.5 (5.8, 21.1)

Electronic personal communication systems 8.1 (2.9, 13.3)

None of the above DSU DSU

Other DSU DSU

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 72. Rescue Teams at Underground Coal Mines 

Response

Percentage 

of Mines 95% CI

Mine has own rescue team 40.9 (29.7, 52.0)

Average number of rescue team members 8.8 (6.7, 11.0)

 

Frequency of team training

Less than once a year 0.0 NA

Annually 0.0 NA

Less than once a month DSU DSU

Once a month 65.6 (46.6, 84.5)

Once every 2 weeks DSU DSU

Once a week DSU DSU

Other time interval DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
81 

Table 73. Emergency Equipment and Supplies at Underground Coal Mines 

Response

Percentage 

of Mines 95% CI

Belt-worn self-contained self-rescuers (SCSRs) 87.4 (80.3, 94.5)

Cached self-contained self-rescuers (SCSRs) 84.6 (77.1, 92.0)

Filter self-rescuers (FSRs) 13.6 (6.0, 21.3)

Stationary emergency refuge chambers 28.3 (18.9, 37.7)

Mobile emergency refuge chambers 13.8 (6.2, 21.3)

Sealing materials 76.3 (69.0, 83.6)

Cached water/food supplies 83.4 (76.5, 90.3)

First aid kits 89.4 (82.9, 95.9)

Defibrillator 44.1 (31.2, 57.0)

None of the above DSU DSU

Other DSU DSU

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted; data were collected prior to the 

effective date (March 2, 2009) of the Mine Safety and Health Administration’s (MSHA) final rule for 

refuge alternatives in underground coal mines. 

Table 74. Escape Aids at Underground Coal Mines 

Response

Percentage 

of Mines 95% CI

Lifelines 66.0 (57.3, 74.7)

Directional lifelines 87.5 (82.0, 93.1)

Signage 70.6 (62.2, 78.9)

Colored reflectors 87.9 (82.8, 92.9)

Lighting 16.9 (9.3, 24.6)

Strobe lights 18.3 (9.8, 26.8)

None of the above DSU DSU

Other 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

 
82 

 
83 

 

Mine Statistics for Surface 

Coal Mines 
84 
85 

Summary of Mine Statistics for Surface Coal Mines 

The data for training and non-English languages can be found in Tables 75–78. For 

surface coal mines, the weighted survey estimates indicate that annual miner refresher training is 

conducted more often by an outside trainer (70.1 percent) compared to the mine’s own 

employees (65.9 percent). However, newly hired inexperienced and experienced miner training 

is more often conducted by the mine’s own employees (55.2 percent and 70.1 percent, 

respectively). Lectures (98.2 percent), written materials (88.1 percent), and videos (87.2 percent) 

are the top three methods and materials used for training. Estimates from the survey indicate that 

51.1 percent of surface coal mines have employee safety meetings once a week. Approximately 

two percent of surface coal mine employees use a language other than English. 

Tables 79 and 80 present the national estimates for work schedules and shift work. The 

average number of hours worked per week is 49.2 for production workers, 45.9 for production 

support workers, and 46.4 for preparation plant/mill workers. The majority of surface coal mines 

operate two shifts per day for production workers (60.5 percent) and preparation plant/mill 

workers (49.9 percent) and one shift per day for production support workers (51.5 percent). 

National estimates for independent contractor employees are presented in Table 81. 

During a typical week, surface coal mines use independent contractor employees for various 

types of work including: material handling (32.4 percent); drilling and blasting (23.0 percent); 

construction or reconstruction of mine facilities (21.6 percent); and equipment service or repair 

of equipment on mine property (19.7 percent). 

 

Tables 82–85 present national estimates for safety, communication, and rescue measures. 

Cell phones (90.7 percent) are the most frequently used communication system followed by 

hand-held two-way radios (63.6 percent), and dedicated telephones (48.1 percent). Sixty-one 

percent of surface coal mines use telephones for emergency early warnings. Approximately 10 

percent of surface coal mines report having their own mine rescue team composed of about 13 

team members. The majority of mine rescue teams train once a month (76.9 percent). 
86 

Table 75. Miner Training Within the Past 12 Months at Surface Coal Mines 

Training Conducted by

Percentage 

of Mines 95% CI

Mine employees

Annual miner refresher 65.9 (56.1, 75.7)

Newly hired inexperienced miner 55.2 (43.8, 66.6)

Newly hired experienced miner 70.1 (53.2, 86.9)

 

Outside trainer

Annual miner refresher 70.1 (60.3, 79.9)

Newly hired inexperienced miner 31.6 (21.2, 42.1)

Newly hired experienced miner 32.4 (15.3, 49.5)

 

Outside contract trainer

Annual miner refresher 72.3 (61.7, 82.9)

Newly hired inexperienced miner 77.2 (58.3, 96.1)

Newly hired experienced miner 83.4 (65.1, 100.0)

 

Outside state grantee

Annual miner refresher 21.3 (11.2, 31.4)

Newly hired inexperienced miner 24.9 (9.9, 40.0)

Newly hired experienced miner DSU DSU

 

Outside other trainer

Annual miner refresher 14.1 (7.9, 20.2)

Newly hired inexperienced miner DSU DSU

Newly hired experienced miner DSU DSU

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 76. Frequency of Periodic Safety Meetings at Surface Coal Mines 

Response

Percentage 

of Mines 95% CI

Less than once a year DSU DSU

Annually DSU DSU

Less than once a month 8.1 (0.6, 15.5)

Once a month 13.3 (5.5, 21.1)

Once every 2 weeks 6.2 (0.0, 14.0)

Once a week 51.1 (39.0, 63.3)

Several times a week 10.0 (0.8, 19.3)

Daily 7.8 (1.2, 14.4)

Abbreviation: DSU, data suppressed. Note: Data are national estimates.
87 

Table 77. Employee Safety Training Materials and Methods at Surface Coal Mines 

Response

Percentage 

of Mines 95% CI

Lectures 98.2 (95.7, 100.0)

Written materials 88.1 (80.2, 96.1)

Videos 87.2 (77.3, 97.1)

Self-guided interactive computer programs 4.5 (0.4, 8.5)

Demonstrations 73.4 (59.1, 87.7)

Hands-on training exercises 73.7 (59.2, 88.3)

Group exercises (role playing, games, problem solving) 48.4 (36.0, 60.8)

Classroom simulations (e.g., virtual reality) 22.9 (13.0, 32.7)

Worksite simulations 34.6 (21.1, 48.1)

Narrative storytelling 44.0 (28.1, 59.9)

Other 4.7 (0.0, 9.6)

Notes: Data are national estimates; multiple responses permitted. 

Table 78. Non-English Languages at Surface Coal Mines 

Response Percentage 95% CI

Employees use a language other than English to 

communicate

1.9 (0.0, 4.9)

 

Mining operations provide training materials, signs, or 

written materials, in language(s) other than English

8.0 (0.0, 16.6)

Language(s) provided1

Spanish 100.0 NA

Other 0.0 NA

 

Helpful to have training materials, signs, or written 

materials in other languages, in addition to those 

already provided

DSU DSU

 

Helpful to have training materials, signs, or written 

materials in language(s) other than English 

DSU DSU

1

Multiple responses permitted. Abbreviations: DSU, data suppressed; NA, not applicable. 

Note: Data are national estimates. 
88 

Table 79. Work Schedules at Surface Coal Mines 

Response

Production 

Workers 95% CI

Production 

Support 

Workers 95% CI

Preparation 

Plant/Mill 

Workers 95% CI

Scheduled days per week (average) 5.6 (5.4, 5.8) 5.4 (5.2, 5.6) 5.1 (4.9, 5.4)Scheduled hours per day (average) 9.6 (9.0, 10.3) 9.5 (8.8, 10.1) 9.9 (9.4, 10.4)

Actual hours worked per week 

(average)

49.2 (45.2, 53.2) 45.9 (40.6, 51.2) 46.4 (33.4, 59.3)

Work crews change shifts at active 

mining site (percentage)

24.2 (11.6, 36.8) 15.8 (7.2, 24.4) NA NA

Average time spent traveling to and 

from active mining site while being paid (hours)

 1.8 (1.6, 2.0) 1.7 (1.5, 1.9) NA NA

Abbreviation: NA, not applicable. Note: Data are national estimates. 
89 

Table 80. Shift Work Schedules at Surface Coal Mines 

Response

Production 

Workers

 Percentage 

of Mines 95% CI

Production 

Support 

Workers 

Percentage 

of Mines 95% CI

Preparation 

Plant/Mill 

Workers 

Percentage 

of Mines 95% CI

Number of shifts per day 

1 shift 36.2 (24.7, 47.6) 51.5 (37.8, 65.2) 27.2 (5.8, 48.7)

2 shifts 60.5 (48.7, 72.3) 40.8 (26.9, 54.7) 49.9 (29.0, 70.8)3 shifts DSU DSU DSU DSU 22.3 (11.0, 33.6)

4 shifts DSU DSU DSU DSU DSU DSU

Rotating shifts 20.9 (11.3, 30.4) 18.2 (8.4, 28.0) 22.6 (10.6, 34.6)Frequency workers rotate shifts

Weekly 88.9 (76.1, 100.0) 90.7 (77.6, 100.0) 52.8 (11.9, 93.7)

Twice a month DSU DSU 0.0 NA DSU DSU

Monthly 0.0 NA 0.0 NA DSU DSUOther DSU DSU DSU DSU DSU DSU

Direction the shift rotates

Clockwise 

(day—afternoon—night)

69.3 (47.6, 91.0) 68.5 (37.9, 99.1) 59.0 (16.2, 100.0)

Counterclockwise 

(night—afternoon—day)

DSU DSU DSU DSU DSU DSU

Other 24.8 (4.5, 45.2) DSU DSU DSU DSU

Unique work shifts 13.8 (3.5, 24.2) 12.4 (3.1, 21.8) 10.5 (3.4, 17.6)

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
90 

Table 81. Activities of Independent Contractor Employees During the Reporting Week at Surface Coal Mines 

Response

Percentage 

of Mines 

Reporting 

Contractors 95% CI

Average 

Number of 

Contractor 

Employees 95% CI

Average 

Total 

Hours 95% CI

Mine development DSU DSU DSU DSU DSU DSUConstruction or reconstruction of 

mine facilities

21.6 (14.0, 29.2) 16.9 (0.0, 33.8) 641.0 (0.0, 1,320.3)

Demolition of mine facilities 0.0 NA NA NA NA NA

Construction of dams DSU DSU DSU DSU DSU DSU

Excavation or earthmoving 

activities (involving mobile equipment)

11.0 (4.7, 17.4) 13.2 (7.8, 18.5) 500.8 (194.4, 807.2)

Equipment installation DSU DSU DSU DSU DSU DSU

Equipment service or repair of 

equipment on mine property (exceeding 5 consecutive days)

19.7 (10.0, 29.4) 4.0 (2.6, 5.4) 155.7 (89.4, 222.1)

Material handling (within mine 

property)

32.4 (21.8, 43.0) 9.5 (5.5, 13.5) 222.6 (103.4, 341.8)

Drilling and blasting 23.0 (15.0, 31.0) 2.7 (1.8, 3.7) 80.8 (32.3, 129.2)

Production support work DSU DSU DSU DSU DSU DSU

Mineral extraction 0.0 NA NA NA NA NA

Other work 4.8 (0.0, 10.8) 4.4 (0.0, 16.0) 120.6 (0.0, 530.2)

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
91 

Table 82. Communication Devices and Systems at Surface Coal Mines 

Response

Percentage 

of Mines 95% CI

Dedicated telephones 48.1 (35.5, 60.7)

Mine page phones 20.2 (10.6, 29.8)

Trolley phones 0.0 NA

Shaft or hoist phones NA NA

Cell phones 90.7 (82.7, 98.8)

Voice over internet protocol (VOIP) phones 0.0 NA

Hand-held two-way radios 63.6 (48.8, 78.4)

Wireless paging devices 10.6 (2.3, 18.9)

Leaky feeder communications system (not running a 

PED)

DSU DSU

Personal emergency device (PED) cap lamp/pager 0.0 NA

Through-the-Earth (TTE) technology (other than a PED) 0.0 NA

Inductive coupled radios DSU DSU

Ethernet 11.2 (5.7, 16.7)

TRACKER tagging system 0.0 NA

Longwall face communication systems NA NA

None of the above DSU DSU

Other 23.0 (11.4, 34.5)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 83. Personal Locators, Trackers, and Devices at Surface Coal Mines 

Response

Percentage 

of Mines 95% CI

Electronic or computerized tagging or tracking 0.0 NA

Tag boards 4.2 (0.2, 8.3)

Reflective vests/clothing 41.2 (26.8, 55.6)

Chemical light sticks 6.5 (0.7, 12.2)

Lighted vests 0.0 NA

Laser lights/pointers 0.0 NA

Strobe lights 23.9 (12.3, 35.5)

None of the above 44.7 (30.4, 59.0)

Other DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

 
92 

Table 84. Emergency Early Warning Methods at Surface Coal Mines 

Response

Percentage 

of Mines 95% CI

Stench gas 0.0 NA

Audible systems 35.4 (25.8, 44.9)

Visual systems 17.9 (7.3, 28.4)

Pager phones 18.3 (8.5, 28.2)

Telephones 60.7 (48.2, 73.1)

Messengers 9.3 (2.4, 16.3)

Electronic personal communication systems DSU DSU

None of the above 27.8 (18.4, 37.2)

Other 8.2 (1.8, 14.6)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 85. Rescue Teams at Surface Coal Mines 

Response

Percentage 

of Mines 95% CI

Mine has own rescue team 9.7 (4.2, 15.2)

Average number of rescue team members 12.8 (8.5, 17.2)

 

Frequency of team training

Less than once a year 0.0 NA

Annually DSU DSU

Less than once a month 0.0 NA

Once a month 76.9 (44.6, 100.0)

Once every 2 weeks 0.0 NA

Once a week DSU DSU

Other time interval 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 

 
93 

 

Mine Statistics for 

Metal Mines 
94 
95 

Summary of Mine Statistics for Metal Mines 

The data for training and non-English languages can be found in Tables 86–89. For the 

U.S. metal mining industry, the weighted survey estimates indicate that more training is 

conducted by the mine’s employees including: annual refresher training (78.1 percent); newly 

hired inexperienced miner training (72.0 percent); and newly hired experienced miner training 

(70.7 percent) when compared to the mine’s use of outside trainers. Lectures (92.1 percent), 

written materials (87.8 percent), and videos (80.8 percent) are the top three methods and 

materials used for training. Estimates from the survey indicate that 39.8 percent of all metal 

mines have daily employee safety meetings. Approximately four percent of metal mine 

employees use a language other than English. 

 Tables 90 and 91 present the national estimates for work schedules and shift work. The 

average number of hours worked per week is 40.1 for production workers, 39.5 for production 

support workers, and 43.2 for preparation plant/mill workers. The majority of metal mines 

operate two shifts per day for production workers (54.7 percent) and preparation plant/mill 

workers (55.2 percent) and one shift per day for production support workers (57.2 percent). 

National estimates for independent contractor employees are presented in Table 92. 

During a typical week, metal mines use independent contractor employees for various types of 

work including: equipment service or repair of equipment on mine property (28.0 percent); 

construction or reconstruction of mine facilities (24.3 percent); excavation or earth moving 

activities (23.0 percent); and drilling and blasting (21.8 percent). 

 

Tables 93–96 present national estimates for safety, communication, and rescue measures. 

Hand-held two-way radios (74.3 percent) are the most frequently used communication system 

followed by cell phones (70.6 percent), and dedicated telephones (61.1 percent). Reflective 

vests/clothing (46.0 percent) and tag boards (43.4 percent) are the most frequently used personal 

locators/trackers in metal mines. Forty-four percent of metal mines use audible systems for 

emergency early warnings. Thirty-six percent of these mines report having their own mine 

rescue team composed of approximately 20 team members. The majority of mine rescue teams 

train once a month (65.5 percent). 

 
96 

Table 86. Miner Training Within the Past 12 Months at Metal Mines 

Training Conducted by

Percentage 

of Mines 95% CI

Mine employees

Annual miner refresher 78.1 (67.3, 89.0)

Newly hired inexperienced miner 72.0 (58.6, 85.4)

Newly hired experienced miner 70.7 (58.2, 83.1)

 

Outside trainer

Annual miner refresher 44.2 (31.5, 56.8)

Newly hired inexperienced miner 32.5 (19.3, 45.8)

Newly hired experienced miner 22.4 (12.7, 32.2)

 

Outside contract trainer

Annual miner refresher 58.3 (41.7, 74.9)

Newly hired inexperienced miner 65.8 (44.3, 87.2)

Newly hired experienced miner 75.4 (53.6, 97.2)

 

Outside state grantee

Annual miner refresher 39.8 (24.0, 55.7)

Newly hired inexperienced miner 34.2 (12.8, 55.7)

Newly hired experienced miner DSU DSU

 

Outside other trainer

Annual miner refresher DSU DSU

Newly hired inexperienced miner 0.0 NA

Newly hired experienced miner DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 87. Frequency of Periodic Safety Meetings at Metal Mines 

Response

Percentage 

of Mines 95% CI

Less than once a year DSU DSU

Annually 0.0 NA

Less than once a month DSU DSU

Once a month 11.5 (5.9, 17.2)

Once every 2 weeks DSU DSU

Once a week 33.2 (22.2, 44.3)

Several times a week 10.1 (2.8, 17.4)

Daily 39.8 (27.3, 52.3)

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
97 

Table 88. Employee Safety Training Materials and Methods at Metal Mines 

Response

Percentage 

of Mines 95% CI

Lectures 92.1 (86.2, 98.1)

Written materials 87.8 (79.6, 95.9)

Videos 80.8 (72.1, 89.5)

Self-guided interactive computer programs 21.6 (12.9, 30.3)

Demonstrations 70.2 (59.9, 80.4)

Hands-on training exercises 78.2 (68.4, 88.1)

Group exercises (role playing, games, problem solving) 39.0 (25.8, 52.1)

Classroom simulations (e.g., virtual reality) 19.3 (10.5, 28.1)

Worksite simulations 32.3 (21.5, 43.2)

Narrative storytelling 50.3 (38.5, 62.2)

Other 10.5 (3.6, 17.4)

Notes: Data are national estimates; multiple responses permitted. 

Table 89. Non-English Languages at Metal Mines 

Response Percentage 95% CI

Employees use a language other than English to 

communicate

3.8 (0.3, 7.3)

 

Mining operations provide training materials, signs, or 

written materials, in language(s) other than English

18.6 (9.4, 27.9)

Language(s) provided1

Spanish 100.0 NA

Other 0.0 NA

 

Helpful to have training materials, signs, or written 

materials in other languages, in addition to those 

already provided

DSU DSU

 

Helpful to have training materials, signs, or written 

materials in language(s) other than English 

15.7 (5.3, 26.0)

1

Multiple responses permitted. Abbreviations: DSU, data suppressed; NA, not applicable. 

Note: Data are national estimates. 

 
98 

Table 90. Work Schedules at Metal Mines 

Response

Production 

Workers 95% CI

Production 

Support 

Workers 95% CI

Preparation 

Plant/Mill 

Workers 95% CI

Scheduled days per week (average) 4.8 (4.4, 5.1) 4.8 (4.5, 5.0) 4.9 (4.4, 5.3)Scheduled hours per day (average) 9.8 (9.1, 10.4) 9.8 (8.9, 10.8) 9.7 (9.0, 10.4)

Actual hours worked per week 

(average)

40.1 (35.1, 45.1) 39.5 (36.4, 42.7) 43.2 (38.7, 47.7)

Work crews change shifts at active 

mining site (percentage)

26.1 (14.5, 37.7) 10.5 (2.9, 18.2) NA NA

Average time spent traveling to and 

from active mining site while being paid (hours)

1.8 (1.6, 2.0) 1.7 (1.5, 1.9) NA NA

Abbreviation: NA, not applicable. Note: Data are national estimates. 
99 

Table 91. Shift Work Schedules at Metal Mines 

Response

Production 

Workers

 Percentage 

of Mines 95% CI

Production 

Support 

Workers 

Percentage 

of Mines 95% CI

Preparation 

Plant/Mill 

Workers 

Percentage 

of Mines 95% CI

Number of shifts per day 

1 shift 35.3 (20.6, 50.0) 57.2 (45.0, 69.4) 27.4 (14.8, 40.0)

2 shifts 54.7 (40.4, 69.1) 34.8 (22.2, 47.3) 55.2 (39.8, 70.5)3 shifts 10.0 (2.3, 17.7) 8.0 (1.0, 15.0) 17.4 (5.5, 29.3)

4 shifts 0.0 NA 0.0 NA 0.0 NA

Rotating shifts 59.3 (45.6, 73.0) 42.2 (30.4, 54.0) 72.4 (60.1, 84.8)Frequency workers rotate shifts

Weekly 59.5 (42.5, 76.5) 45.1 (24.6, 65.6) 57.4 (39.1, 75.7)

Twice a month 17.0 (4.3, 29.8) 28.9 (9.7, 48.0) DSU DSU

Monthly 0.0 NA DSU DSU DSU DSU

Other 23.5 (8.9, 38.1) 22.5 (7.4, 37.7) 22.3 (8.0, 36.6)

Direction the shift rotates

Clockwise 

(day—afternoon—night)

58.2 (41.2, 75.1) 47.9 (27.0, 68.9) 49.5 (29.7, 69.2)

Counterclockwise 

(night—afternoon—day)

DSU DSU DSU DSU DSU DSU

Other 32.9 (16.7, 49.1) 41.1 (20.5, 61.7) 33.3 (16.7, 49.8)

Unique work shifts 27.7 (15.4, 40.0) 14.0 (5.5, 22.6) 13.7 (4.3, 23.1)

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
100 

Table 92. Activities of Independent Contractor Employees During the Reporting Week at Metal Mines 

Response 

Percentage 

of Mines 

Reporting 

Contractors 95% CI

Average 

Number of 

Contractor 

Employees 95% CI

Average 

Total 

Hours 95% CI

Mine development DSU DSU DSU DSU DSU DSUConstruction or reconstruction of 

mine facilities 

24.3 (14.7, 33.8) 65.9 (28.8, 103.0) 2,245.5 (849.0, 3641.9)

Demolition of mine facilities DSU DSU DSU DSU DSU DSUConstruction of dams DSU DSU DSU DSU DSU DSUExcavation or earthmoving 

activities (involving mobile equipment) 

23.0 (12.0, 34.1) 18.6 (9.2, 28.0) 663.2 (273.3, 1,053.0)

Equipment installation 8.4 (1.4, 15.4) 33.7 (0.0, 73.5) 1,643.7 (0.0, 3,644.1)Equipment service or repair of 

equipment on mine property (exceeding 5 consecutive days) 

28.0 (18.7, 37.2) 40.1 (0.0, 99.3) 771.9 (0.0, 1,646.7)

Material handling (within mine 

property) 

15.2 (6.4, 24.0) 20.4 (5.7, 35.2) 647.7 (22.1, 1273.2)

Drilling and blasting 21.8 (12.6, 30.9) 18.9 (1.2, 36.5) 726.8 (0.0, 1,496.6)Production support work DSU DSU DSU DSU DSU DSU

Mineral extraction DSU DSU DSU DSU DSU DSUOther work 10.3 (3.2, 17.5) 27.2 (0.0, 55.1) 1069.4 (0.0, 2,204.6)

Abbreviation: DSU, data suppressed. Note: Data are national estimates. 
101 

Table 93. Communication Devices and Systems at Metal Mines 

Response

Percentage 

of Mines 95% CI

Dedicated telephones 61.1 (50.2, 72.1)

Mine page phones 42.0 (32.9, 51.2)

Trolley phones 0.0 NA

Shaft or hoist phones DSU DSU

Cell phones 70.6 (60.7, 80.4)

Voice over internet protocol (VOIP) phones 14.6 (6.8, 22.4)

Hand-held two-way radios 74.3 (63.5, 85.0)

Wireless paging devices 13.8 (6.9, 20.7)

Leaky feeder communications system (not running a 

PED)

23.7 (16.6, 30.7)

Personal emergency device (PED) cap lamp/pager DSU DSU

Through-the-Earth (TTE) technology (other than a PED) DSU DSU

Inductive coupled radios 0.0 NA

Ethernet 12.8 (4.3, 21.3)

TRACKER tagging system DSU DSU

Longwall face communication systems NA NA

None of the above 0.0 NA

Other DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 94. Personal Locators, Trackers, and Devices at Metal Mines 

Response

Percentage 

of Mines 95% CI

Electronic or computerized tagging or tracking DSU DSU

Tag boards 43.4 (36.3, 50.4)

Reflective vests/clothing 46.0 (34.7, 57.3)

Chemical light sticks 0.0 NA

Lighted vests DSU DSU

Laser lights/pointers DSU DSU

Strobe lights 19.3 (10.2, 28.4)

None of the above 39.0 (31.2, 46.8)

Other 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

 
102 

Table 95. Emergency Early Warning Methods at Metal Mines 

Response

Percentage 

of Mines 95% CI

Stench gas 28.0 (19.4, 36.6)

Audible systems 44.2 (33.2, 55.3)

Visual systems 15.9 (7.1, 24.7)

Pager phones 36.4 (27.2, 45.5)

Telephones 40.8 (29.3, 52.3)

Messengers 13.3 (5.2, 21.5)

Electronic personal communication systems 0.0 NA

None of the above 17.2 (9.7, 24.6)

Other 23.5 (12.1, 34.8)

Abbreviation: NA, not applicable. Notes: Data are national estimates; multiple responses permitted. 

Table 96. Rescue Teams at Metal Mines 

Response

Percentage 

of Mines 95% CI

Mine has own rescue team 36.3 (25.9, 46.7)

Average number of rescue team members 20.3 (15.4, 25.1)

 

Frequency of team training

Less than once a year 0.0 NA

Annually DSU DSU

Less than once a month DSU DSU

Once a month 65.5 (46.2, 84.8)

Once every 2 weeks DSU DSU

Once a week DSU DSU

Other time interval 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 

 
103 

Mine Statistics for 

Underground Metal Mines 
104 
105 

Summary of Mine Statistics for Underground Metal Mines 

The data for training and non-English languages can be found in Tables 97–100. For 

underground metal mines, the weighted survey estimates indicate that more training is conducted 

by the mine’s employees including: annual refresher training (95.9 percent), newly hired 

inexperienced miner training (86.0 percent), and newly hired experienced miner training (86.0 

percent) when compared to the mine’s use of outside trainers. Lectures (100.0 percent), written 

materials (85.5 percent), and hands-on training exercises (81.4 percent) are the top three methods 

and materials used for training. Estimates from the survey indicate that 41.3 percent of 

underground metal mines have daily safety meetings. Approximately seven percent of 

underground metal mine employees use a language other than English. 

 Tables 101 and 102 present the national estimates for work schedules and shift work. 

The average number of hours worked per week is 40.0 for production workers, 37.6 for 

production support workers, and 39.9 for preparation plant/mill workers. The majority of 

underground metal mines operate two shifts per day for production workers (74.2 percent) and 

preparation plant/mill workers (54.5 percent) and one shift per day for production support 

workers (50.1 percent). 

National estimates for independent contractor employees are presented in Table 103. 

During a typical week, underground metal mines report using independent contractor employees 

for equipment service or repair of equipment on mine property (31.1 percent). The other data in 

this table have all been suppressed due to a survey count of less than five responses. 

 

Tables 104–109 present national estimates for safety, communication, and rescue 

measures. Mine page phones (80.6 percent) are the most frequently used communication system 

followed by a leaky feeder communication system (64.6 percent), dedicated telephones (50.2 

percent), and hand-held two-way radios (50.2 percent). Tag boards (100.0 percent) and 

reflective vests/clothing (66.0 percent) are the most frequently used personal locators/trackers in 

underground metal mines. Signage (91.8 percent) and colored reflectors (43.0 percent) are the 

most frequently reported escape aids. First aid kits (91.8 percent), belt-worn self-contained selfrescuers (SCSRs) (54.0 percent), and defibrillators (54.0 percent) are the top three emergency 

equipment and supplies found in these mines. Seventy-eight percent of underground mines use 

pager phones for emergency early warnings. Approximately 47 percent of underground metal 

mines report having their own mine rescue team composed of 16 team members. The majority 

of mine rescue teams train once a month (63.1 percent).
106 

Table 97. Miner Training Within the Past 12 Months at Underground Metal Mines 

Training Conducted by

Percentage 

of Mines 95% CI

Mine employees

Annual miner refresher 95.9 (88.0, 100.0)

Newly hired inexperienced miner 86.0 (70.9, 100.0)

Newly hired experienced miner 86.0 (71.6, 100.0)

 

Outside trainer

Annual miner refresher 34.4 (11.4, 57.3)

Newly hired inexperienced miner 30.9 (9.3, 52.5)

Newly hired experienced miner 25.7 (7.7, 43.7)

 

Outside contract trainer

Annual miner refresher 76.1 (48.4, 100.0)

Newly hired inexperienced miner 86.7 (67.3, 100.0)

Newly hired experienced miner 100.0 NA

 

Outside state grantee

Annual miner refresher DSU DSU

Newly hired inexperienced miner DSU DSU

Newly hired experienced miner 0.0 NA

 

Outside other trainer

Annual miner refresher 0.0 NA

Newly hired inexperienced miner 0.0 NA

Newly hired experienced miner 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 98. Frequency of Periodic Safety Meetings at Underground Metal Mines 

Response

Percentage 

of Mines 95% CI

Less than once a year 0.0 NA

Annually 0.0 NA

Less than once a month 0.0 NA

Once a month DSU DSU

Once every 2 weeks 0.0 NA

Once a week 40.2 (18.9, 61.4)

Several times a week DSU DSU

Daily 41.3 (21.3, 61.3)

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
107 

Table 99. Employee Safety Training Materials and Methods at Underground Metal Mines 

Response

Percentage 

of Mines 95% CI

Lectures 100.0 NA

Written materials 85.5 (69.7, 100.0)

Videos 58.5 (39.5, 77.5)

Self-guided interactive computer programs DSU DSU

Demonstrations 77.3 (61.4, 93.3)

Hands-on training exercises 81.4 (63.8, 99.1)

Group exercises (role playing, games, problem solving) 31.3 (8.8, 53.8)

Classroom simulations (e.g., virtual reality) DSU DSU

Worksite simulations 23.3 (4.6, 42.1)

Narrative storytelling 50.6 (27.9, 73.3)

Other DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 100. Non-English Languages at Underground Metal Mines 

Response Percentage 95% CI

Employees use a language other than English to 

communicate

7.4 (0.0, 16.0)

 

Mining operations provide training materials, signs, or 

written materials, in language(s) other than English

22.3 (4.5, 40.0)

Which Language(s) are provided1

Spanish 100.0 NA

Other 0.0 NA

 

Helpful to have training materials, signs, or written 

materials in other languages, in addition to those 

already provided

DSU DSU

 

Helpful to have training materials, signs, or written 

materials in language(s) other than English 

DSU DSU

1

Multiple responses permitted. Abbreviations: DSU, data suppressed; NA, not applicable. 

Note: Data are national estimates. 
108 

Table 101. Work Schedules at Underground Metal Mines 

Response

Production 

Workers 95% CI

Production 

Support 

Workers 95% CI

Preparation 

Plant/Mill 

Workers 95% CI

Scheduled days per week (average) 5.0 (4.3, 5.6) 4.7 (4.3, 5.1) 4.9 (4.3, 5.5)Scheduled hours per day (average) 10.3 (9.8, 10.9) 9.6 (9.0, 10.2) 9.7 (8.7, 10.8)

Actual hours worked per week 

(average)

40.0 (32.2, 47.7) 37.6 (31.2, 44.0) 39.9 (27.9, 51.9)

Work crews change shifts at active 

mining site (percentage)

DSU DSU DSU DSU NA NA

Average time spent traveling to and 

from active mining site while being paid (hours)

NA NA 2.0 (1.9, 2.0) NA NA

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
109 

Table 102. Shift Work Schedules at Underground Metal Mines 

Response

Production 

Workers

 Percentage 

of Mines 95% CI

Production 

Support 

Workers 

Percentage 

of Mines 95% CI

Preparation 

Plant/Mill 

Workers 

Percentage 

of Mines 95% CI

Number of shifts per day

1 shift DSU DSU 50.1 (30.6, 69.6) DSU DSU

2 shifts 74.2 (54.5, 93.9) 44.2 (23.8, 64.7) 54.5 (24.9, 84.2)

3 shifts DSU DSU DSU DSU DSU DSU

4 shifts 0.0 NA 0.0 NA 0.0 NA

Rotating shifts 80.4 (63.0, 97.8) 56.2 (38.0, 74.5) 65.4 (38.8, 92.1)Frequency workers rotate shifts

Weekly 59.5 (33.2, 85.7) 47.3 (15.4, 79.1) DSU DSU

Twice a month DSU DSU DSU DSU DSU DSU

Monthly 0.0 NA 0.0 NA DSU DSU

Other DSU DSU DSU DSU 0.0 NA

Direction the shift rotates

Clockwise 

(day—afternoon—night)

67.2 (41.6, 92.8) 46.0 (16.1, 75.9) 66.7 (31.4, 100.0)

Counterclockwise 

(night—afternoon—day)

DSU DSU DSU DSU DSU DSU

Other DSU DSU DSU DSU DSU DSU

Unique work shifts DSU DSU DSU DSU 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
110 

Table 103. Activities of Independent Contractor Employees During the Reporting Week at Underground Metal Mines 

Response

Percentage 

of Mines 

Reporting 

Contractors 95% CI

Average 

Number of 

Contractor 

Employees 95% CI

Average 

Total 

Hours 95% CI

Mine development DSU DSU DSU DSU DSU DSUConstruction or reconstruction of 

mine facilities

DSU DSU DSU DSU DSU DSU

Demolition of mine facilities 0.0 NA NA NA NA NA

Construction of dams DSU DSU DSU DSU DSU DSU

Excavation or earthmoving 

activities (involving mobile equipment)

DSU DSU DSU DSU DSU DSU

Equipment installation DSU DSU DSU DSU DSU DSU

Equipment service or repair of 

equipment on mine property (exceeding 5 consecutive days)

31.1 (14.6, 47.6) 4.3 (0.3, 8.3) 213.0 (0.0, 527.6)

Material handling (within mine 

property)

DSU DSU DSU DSU DSU DSU

Drilling and blasting DSU DSU DSU DSU DSU DSUProduction support work DSU DSU DSU DSU DSU DSU

Mineral extraction DSU DSU DSU DSU DSU DSUOther work DSU DSU DSU DSU DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates.
111 

Table 104. Communication Devices and Systems at Underground Metal Mines 

Response

Percentage 

of Mines 95% CI

Dedicated telephones 50.2 (27.1, 73.3)

Mine page phones 80.6 (65.4. 95.9)

Trolley phones 0.0 NA

Shaft or hoist phones DSU DSU

Cell phones 48.7 (25.7, 71.7)

Voice over internet protocol (VOIP) phones DSU DSU

Hand-held two-way radios 50.2 (28.3, 72.1)

Wireless paging devices 0.0 NA

Leaky feeder communications system (not running a 

PED)

64.6 (46.5, 82.8)

Personal emergency device (PED) cap lamp/pager DSU DSU

Through-the-Earth (TTE) technology (other than a PED) 0.0 NA

Inductive coupled radios 0.0 NA

Ethernet DSU DSU

TRACKER tagging system DSU DSU

Longwall face communication systems NA NA

None of the above 0.0 NA

Other 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 105. Personal Locators, Trackers, and Devices at Underground Metal Mines 

Response

Percentage 

of Mines 95% CI

Electronic or computerized tagging or tracking 0.0 NA

Tag boards 100.0 NA

Reflective vests/clothing 66.0 (43.6, 88.4)

Chemical light sticks 0.0 NA

Lighted vests DSU DSU

Laser lights/pointers DSU DSU

Strobe lights DSU DSU

None of the above 0.0 NA

Other 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

 
112 

Table 106. Emergency Early Warning Methods at Underground Metal Mines 

Response

Percentage 

of Mines 95% CI

Stench gas 75.3 (53.5, 97.1)

Audible systems 24.7 (5.6, 43.8)

Visual systems 0.0 NA

Pager phones 77.9 (60.2, 95.6)

Telephones 25.9 (8.4, 43.4)

Messengers DSU DSU

Electronic personal communication systems 0.0 NA

None of the above 0.0 NA

Other 29.2 (8.2, 50.3)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 107. Rescue Teams at Underground Metal Mines 

Response

Percentage 

of Mines 95% CI

Mine has own rescue team 47.1 (29.2, 65.0)

Average number of rescue team members 15.6 (9.2, 22.0)

 

Frequency of team training

Less than once a year 0.0 NA

Annually DSU DSU

Less than once a month DSU DSU

Once a month 63.1 (30.5, 95.8)

Once every 2 weeks DSU DSU

Once a week 0.0 NA

Other time interval 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
113 

Table 108. Emergency Equipment and Supplies at Underground Metal Mines 

Response

Percentage 

of Mines 95% CI

Belt-worn self-contained self-rescuers (SCSRs) 54.0 (33.6, 74.4)

Cached self-contained self-rescuers (SCSRs) DSU DSU

Filter self-rescuers (FSRs) 37.8 (18.2, 57.4)

Stationary emergency refuge chambers 49.2 (27.3, 71.2)

Mobile emergency refuge chambers DSU DSU

Sealing materials 34.8 (10.7, 58.8)

Cached water/food supplies 39.3 (18.8, 59.8)

First aid kits 91.8 (80.4, 100.0)

Defibrillator 54.0 (32.2, 75.8)

None of the above DSU DSU

Other DSU DSU

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 109. Escape Aids at Underground Metal Mines 

Response

Percentage 

of Mines 95% CI

Lifelines DSU DSU

Directional lifelines 0.0 NA

Signage 91.8 (80.4, 100.0)

Colored reflectors 43.0 (24.0, 62.0)

Lighting DSU DSU

Strobe lights 0.0 NA

None of the above DSU DSU

Other DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

 
114 

 
115 

 

Mine Statistics for Surface 

Metal Mines 
116 
117 

Summary of Mine Statistics for Surface Metal Mines 

The data for training and non-English languages can be found in Tables 110–113. For 

surface metal mines, the weighted survey estimates indicate that more training is conducted by 

the mine’s employees including: annual refresher training (68.5 percent); newly hired 

inexperienced miner training (64.4 percent); and newly hired experienced miner training (62.4 

percent) when compared to the mine’s use of outside trainers. Videos (92.9 percent), written 

materials (89.0 percent), and lectures (87.9 percent) are the top three methods and materials used 

for training. Estimates from the survey indicate that 39.0 percent of surface metal mines have 

daily employee safety meetings. Approximately two percent of surface metal mine employees 

use a language other than English. 

Tables 114 and 115 present the national estimates for work schedules and shift work. 

The average number of hours worked per week is 40.2 for production workers, 40.8 for 

production support workers, and 44.7 for preparation plant/mill workers. The majority of surface 

metal mines operate one shift per day for production workers (44.2 percent) and production 

support workers (61.6 percent) and two shifts per day for preparation plant/mill workers (55.5 

percent). 

National estimates for independent contractor employees are presented in Table 116. 

During a typical week, surface metal mines use independent contractor employees for various 

types of work including: construction or reconstruction of mine facilities (30.2 percent); 

equipment service or repair of equipment on mine property (26.3 percent); excavation or 

earthmoving activities (24.5 percent), and drilling and blasting (22.3 percent). 

 

Tables 117–120 present national estimates for safety, communication, and rescue 

measures. Hand-held two-way radios (87.0 percent) are the most frequently used 

communication system followed by cell phones (82.2 percent), and dedicated telephones (66.9 

percent). Fifty-four percent of surface metal mines use audible systems for emergency early 

warnings. Approximately 31 percent of surface metal mines report having their own mine rescue 

team composed of about 24 team members. The majority of mine rescue teams train once a 

month (67.4 percent). 
118 

Table 110. Miner Training Within the Past 12 Months at Surface Metal Mines 

Training Conducted by

Percentage 

of Mines 95% CI

Mine employees

Annual miner refresher 68.5 (52.8, 84.2)

Newly hired inexperienced miner 64.4 (45.7, 83.1)

Newly hired experienced miner 62.4 (45.0, 79.8)

 

Outside trainer

Annual miner refresher 49.5 (34.7, 64.3)

Newly hired inexperienced miner 33.4 (16.8, 50.0)

Newly hired experienced miner 20.7 (9.2, 32.1)

 

Outside contract trainer

Annual miner refresher 51.6 (31.6, 71.6)

Newly hired inexperienced miner 55.2 (26.1, 84.4)

Newly hired experienced miner 58.8 (25.7, 92.0)

 

Outside state grantee

Annual miner refresher 40.1 (21.4, 58.8)

Newly hired inexperienced miner 44.8 (15.6, 73.9)

Newly hired experienced miner DSU DSU

 

Outside other trainer

Annual miner refresher DSU DSU

Newly hired inexperienced miner 0.0 NA

Newly hired experienced miner DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 111. Frequency of Periodic Safety Meetings at Surface Metal Mines 

Response

Percentage 

of Mines 95% CI

Less than once a year DSU DSU

Annually 0.0 NA

Less than once a month DSU DSU

Once a month 15.6 (8.1, 23.1)

Once every 2 weeks DSU DSU

Once a week 29.5 (16.7, 42.2)

Several times a week DSU DSU

Daily 39.0 (23.1, 54.9)

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
119 

Table 112. Employee Safety Training Materials and Methods at Surface Metal Mines 

Response

Percentage 

of Mines 95% CI

Lectures 87.9 (78.8, 97.0)

Written materials 89.0 (79.8, 98.2)

Videos 92.9 (85.5, 100.0)

Self-guided interactive computer programs 31.1 (18.5, 43.7)

Demonstrations 66.3 (53.1, 79.5)

Hands-on training exercises 76.5 (64.8, 88.3)

Group exercises (role playing, games, problem solving) 43.1 (26.7, 59.5)

Classroom simulations (e.g., virtual reality) 22.5 (11.2, 33.7)

Worksite simulations 37.2 (23.9, 50.6)

Narrative storytelling 50.2 (36.6, 63.8)

Other 13.4 (4.0, 22.8)

Notes: Data are national estimates; multiple responses permitted. 

Table 113. Non-English Languages at Surface Metal Mines 

Response Percentage 95% CI

Employees use a language other than English to 

communicate

1.9 (0.0, 4.5)

 

Mining operations provide training materials, signs, or 

written materials, in language(s) other than English

16.6 (6.4, 26.9)

Which Language(s) are provided1

Spanish 100.0 NA

Other 0.0 NA

 

Helpful to have training materials, signs, or written 

materials in other languages, in addition to those 

already provided

0.0 NA

 

Helpful to have training materials, signs, or written 

materials in language(s) other than English 

DSU DSU

1

Multiple responses permitted. Abbreviations: DSU, data suppressed; NA, not applicable. 

Note: Data are national estimates. 
120 

Table 114. Work Schedules at Surface Metal Mines 

Response

Production 

Workers 95% CI

Production 

Support 

Workers 95% CI

Preparation 

Plant/Mill 

Workers 95% CI

Scheduled days per week (average) 4.7 (4.2, 5.1) 4.8 (4.4, 5.1) 4.9 (4.3, 5.5)Scheduled hours per day (average) 9.5 (8.5, 10.4) 9.9 (8.4, 11.4) 9.7 (8.8, 10.6)

Actual hours worked per week 

(average)

40.2 (33.6, 46.8) 40.8 (37.6, 44.0) 44.7 (40.8, 48.6)

Work crews change shifts at active 

mining site (percentage)

31.1 (16.4, 45.9) 14.4 (3.3, 25.4) NA NA

Average time spent traveling to and 

from active mining site while being paid (hours)

1.7 (1.4, 1.9) 1.5 (1.2, 1.9) NA NA

Abbreviation: NA, not applicable. Note: Data are national estimates. 
121 

Table 115. Shift Work Schedules at Surface Metal Mines 

Response

Production 

Workers

 Percentage 

of Mines 95% CI

Production 

Support 

Workers 

Percentage 

of Mines 95% CI

Preparation 

Plant/Mill 

Workers 

Percentage 

of Mines 95% CI

Number of shifts per day

1 shift 44.2 (24.4, 64.1) 61.6 (46.0, 77.3) 24.2 (10.3, 38.0)

2 shifts 43.6 (25.3, 62.0) 28.8 (13.0, 44.6) 55.5 (37.4, 73.5)3 shifts 12.1 (1.6, 22.7) DSU DSU 20.4 (5.4, 35.4)

4 shifts 0.0 NA 0.0 NA 0.0 NA

Rotating shifts 47.2 (29.8, 64.7) 33.4 (18.4, 48.4) 75.6 (62.2, 88.9)Frequency workers rotate shifts

Weekly 59.5 (37.6, 81.4) 42.9 (16.2, 69.6) 60.3 (39.7, 80.8)

Twice a month DSU DSU DSU DSU DSU DSU

Monthly 0.0 NA DSU DSU DSU DSUOther 30.4 (10.5, 50.3) 35.7 (12.1, 59.3) 31.0 (11.9, 50.1)

Direction the shift rotates

Clockwise 

(day—afternoon—night)

49.4 (27.0, 71.8) 50.0 (20.0, 80.0) 42.7 (20.1, 65.4)

Counterclockwise 

(night—afternoon—day)

DSU DSU 0.0 NA DSU DSU

Other 40.5 (18.6, 62.4) 50.0 (20.0, 80.0) 39.7 (20.2, 59.2)

Unique work shifts 29.7 (14.2, 45.2) DSU DSU 19.9 (6.3, 33.4)

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
122 

Table 116. Activities of Independent Contractor Employees During the Reporting Week at Surface Metal Mines 

Response

Percentage 

of Mines 

Reporting 

Contractors 95% CI

Average 

Number of 

Contractor 

Employees 95% CI

Average 

Total 

Hours 95% CI

Mine development DSU DSU DSU DSU DSU DSUConstruction or reconstruction of 

mine facilities

30.2 (16.9, 43.4) 68.6 (27.1, 110.1) 2,613.6 (948.0, 4,279.1)

Demolition of mine facilities DSU DSU DSU DSU DSU DSU

Construction of dams 0.0 NA NA NA NA NA

Excavation or earthmoving 

activities (involving mobile equipment)

24.5 (11.1, 37.9) 19.6 (8.2, 31.0) 639.1 (188.5, 1,089.8)

Equipment installation 9.8 (1.0, 18.6) 43.3 (0.0, 88.4) 2,112.2 (0.0, 4,398.7)

Equipment service or repair of 

equipment on mine property (exceeding 5 consecutive days)

26.3 (15.1, 37.4) 63.0 (0.0, 155.6) 1,131.2 (0.0, 2,488.8)

Material handling (within mine 

property)

15.0 (4.4, 25.6) 29.9 (9.6, 50.1) 970.5 (67.1, 1,873.8)

Drilling and blasting 22.3 (11.0, 33.6) 21.7 (0.0, 46.8) 798.3 (0.0, 1,894.4)Production support work DSU DSU DSU DSU DSU DSU

Mineral extraction 0.0 NA NA NA NA NA

Other work DSU DSU DSU DSU DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
123 

Table 117. Communication Devices and Systems at Surface Metal Mines 

Response

Percentage 

of Mines 95% CI

Dedicated telephones 66.9 (55.1, 78.8)

Mine page phones 21.6 (10.3, 32.8)

Trolley phones 0.0 NA

Shaft or hoist phones NA NA

Cell phones 82.2 (73.2, 91.2)

Voice over internet protocol (VOIP) phones 15.5 (5.7, 25.3)

Hand-held two-way radios 87.0 (75.2, 98.8)

Wireless paging devices 21.1 (10.5, 31.8)

Leaky feeder communications system (not running a 

PED)

DSU DSU

Personal emergency device (PED) cap lamp/pager DSU DSU

Through-the-Earth (TTE) technology (other than a PED) DSU DSU

Inductive coupled radios 0.0 NA

Ethernet 13.8 (3.7, 24.0)

TRACKER tagging system 0.0 NA

Longwall face communication systems NA NA

None of the above 0.0 NA

Other DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 118. Personal Locators, Trackers, and Devices at Surface Metal Mines 

Response

Percentage 

of Mines 95% CI

Electronic or computerized tagging or tracking DSU DSU

Tag boards 12.6 (3.1, 22.2)

Reflective vests/clothing 35.2 (23.3, 47.1)

Chemical light sticks 0.0 NA

Lighted vests DSU DSU

Laser lights/pointers DSU DSU

Strobe lights 19.3 (8.1, 30.5)

None of the above 60.2 (49.5, 70.8)

Other 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

 
124 

Table 119. Emergency Early Warning Methods at Surface Metal Mines 

Response

Percentage 

of Mines 95% CI

Stench gas DSU DSU

Audible systems 54.2 (40.3, 68.0)

Visual systems 23.9 (10.6, 37.3)

Pager phones 15.3 (5.3, 25.3)

Telephones 48.4 (33.3, 63.5)

Messengers 9.8 (1.0, 18.6)

Electronic personal communication systems 0.0 NA

None of the above 25.9 (14.7, 37.1)

Other 20.6 (7.1, 34.0)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 120. Rescue Teams at Surface Metal Mines 

Response

Percentage 

of Mines 95% CI

Mine has own rescue team 30.6 (18.1, 43.2)

Average number of rescue team members 24.1 (17.1, 31.1)

Frequency of team training

Less than once a year 0.0 NA

Annually DSU DSU

Less than once a month DSU DSU

Once a month 67.4 (44.1, 90.7)

Once every 2 weeks DSU DSU

Once a week DSU DSU

Other time interval 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 

 
125 

 

Mine Statistics for 

Nonmetal Mines 
126 

 
127 

Summary of Mine Statistics for Nonmetal Mines 

The data for training and non-English languages can be found in Tables 121–124. For 

the U.S. nonmetal mining industry, the weighted survey estimates indicate that more training is 

conducted by the mine’s employees including: annual refresher training (73.2 percent); newly 

hired inexperienced miner training (59.8 percent); and newly hired experienced miner training 

(46.3 percent) when compared to the mine’s use of outside trainers. Lectures (93.5 percent), 

written materials (87.5 percent) and videos (77.4 percent) are the top three methods and materials 

used for training. Estimates from the survey indicate that 34.0 percent of all nonmetal mines 

have employee safety meetings once a month. Overall, approximately nine percent of nonmetal 

mine employees use a language other than English. 

 Tables 125 and 126 present the national estimates for work schedules and shift work. The 

average number of hours worked per week is 36.3 for production workers, 37.8 for production 

support workers, and 40.3 for preparation plant/mill workers. The majority of nonmetal mines 

operate one shift per day (71.3 percent for production workers, 69.7 percent for production 

support workers, and 34.6 percent for preparation plant/mill workers). 

National estimates for independent contractor employees are presented in Table 127. 

During a typical week, nonmetal mines use independent contractor employees for various types 

of work including: construction or reconstruction of mine facilities (14.7 percent); excavation or 

earthmoving activities (12.9 percent); material handling (12.6 percent); and mineral extraction 

(8.5 percent). 

 

Tables 128–131 present national estimates for safety, communication, and rescue 

measures. Cell phones (80.9 percent) are the most frequently used communication system 

followed by hand-held two-way radios (69.3 percent), and dedicated telephones (42.7 percent). 

Forty-six percent of nonmetal mines use telephones for emergency early warnings. Twelve 

percent of nonmetal mines report having their own mine rescue team composed of approximately 

11 team members. The majority of mine rescue teams train on an annual basis (50.8 percent). 

 
128 

Table 121. Miner Training Within the Past 12 Months at Nonmetal Mines 

Training Conducted by

Percentage 

of Mines 95% CI

Mine employees

Annual miner refresher 73.2 (63.7, 82.6)

Newly hired inexperienced miner 59.8 (48.3, 71.3)

Newly hired experienced miner 46.3 (37.2, 55.5)

 

Outside trainer

Annual miner refresher 46.8 (37.8, 55.9)

Newly hired inexperienced miner 14.2 (9.8, 18.6)

Newly hired experienced miner 10.6 (6.9, 14.3)

 

Outside contract trainer

Annual miner refresher 29.9 (17.2, 42.7)

Newly hired inexperienced miner 44.4 (21.1, 67.7)

Newly hired experienced miner 36.7 (5.6, 67.9)

 

Outside state grantee

Annual miner refresher 63.7 (51.2, 76.2)

Newly hired inexperienced miner 64.6 (43.7, 85.5)

Newly hired experienced miner 50.9 (30.3, 71.6)

 

Outside other trainer

Annual miner refresher 13.4 (4.9, 22.0)

Newly hired inexperienced miner 0.0 NA

Newly hired experienced miner DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 122. Frequency of Periodic Safety Meetings at Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Less than once a year DSU DSU

Annually DSU DSU

Less than once a month 6.9 (3.2, 10.7)

Once a month 34.0 (23.2, 44.7)

Once every 2 weeks 4.4 (0.8, 8.1)

Once a week 24.9 (16.1, 33.7)

Several times a week 8.0 (3.3, 12.8)

Daily 16.2 (8.5, 24.0)

Abbreviation: DSU, data suppressed. Notes: Data are national estimates. 
129 

Table 123. Employee Safety Training Materials and Methods at Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Lectures 93.5 (90.1, 96.8)

Written materials 87.5 (81.7, 93.3)

Videos 77.4 (68.4, 86.4)

Self-guided interactive computer programs 13.8 (7.1, 20.6)

Demonstrations 62.9 (50.9, 74.9)

Hands-on training exercises 62.1 (55.9, 68.3)

Group exercises (role playing, games, problem solving) 30.4 (21.6, 39.2)

Classroom simulations (e.g., virtual reality) 12.9 (6.9, 18.9)

Worksite simulations 33.9 (24.6, 43.3)

Narrative storytelling 39.4 (30.0, 48.7)

Other 5.1 (0.6, 9.6)

Notes: Data are national estimates; multiple responses permitted. 

Table 124. Non-English Languages at Nonmetal Mines 

Response Percentage 95% CI

Employees use a language other than English to 

communicate

9.3 (4.9, 13.6)

 

Mining operations provide training materials, signs, or 

written materials, in language(s) other than English

22.1 (11.9, 32.2)

Which Language(s) are provided1

Spanish 100.0 NA

Other DSU DSU

 

Helpful to have training materials, signs, or written 

materials in other languages, in addition to those 

already provided

17.9 (4.7, 31.1)

 

Helpful to have training materials, signs, or written 

materials in language(s) other than English 

9.7 (4.1, 15.3)

1

Multiple responses permitted. Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; 
130 

Table 125. Work Schedules at Nonmetal Mines 

Response

Production 

Workers 95% CI

Production 

Support 

Workers 95% CI

Preparation 

Plant/Mill 

Workers 95% CI

Scheduled days per week (average) 4.7 (4.5, 5.0) 4.9 (4.7, 5.1) 4.8 (4.5, 5.0)Scheduled hours per day (average) 8.9 (8.6, 9.2) 8.5 (8.2, 8.7) 9.4 (8.3, 10.4)

Actual hours worked per week 

(average)

36.3 (33.2, 39.4) 37.8 (35.9, 39.7) 40.3 (37.5, 43.1)

Work crews change shifts at active 

mining site (percentage)

9.9 (4.3, 15.5) 13.0 (4.7, 21.4) NA NA

Average time spent traveling to and 

from active mining site while being paid (hours)

1.7 (1.6, 1.8) 1.7 (1.5, 1.8) NA NA

Abbreviation: NA, not applicable. Note: Data are national estimates. 
131 

Table 126. Shift Work Schedules at Nonmetal Mines 

Response

Production 

Workers

 Percentage 

of Mines 95% CI

Production 

Support 

Workers 

Percentage 

of Mines 95% CI

Preparation 

Plant/Mill 

Workers 

Percentage 

of Mines 95% CI

Number of shifts per day

1 shift 71.3 (62.8, 79.8) 69.7 (59.1, 80.2) 34.6 (21.4, 47.7)

2 shifts 17.6 (10.6, 24.5) 12.9 (6.6, 19.2) 30.7 (17.6, 43.7)

3 shifts 10.2 (4.8, 15.5) 16.5 (9.3, 23.7) 33.4 (23.0, 43.7)4 shifts DSU DSU DSU DSU DSU DSU

Rotating shifts 15.1 (8.1, 22.1) 17.7 (7.5, 28.0) 36.8 (25.3, 48.2)Frequency workers rotate shifts

Weekly 45.3 (25.6, 65.0) 65.0 (45.8, 84.3) 65.4 (49.5, 81.4)

Twice a month 37.7 (16.4, 59.0) DSU DSU 23.4 (8.2, 38.5)

Monthly DSU DSU 0.0 NA DSU DSU

Other DSU DSU DSU DSU DSU DSU

Direction the shift rotates

Clockwise 

(day—afternoon—night)

68.6 (49.2, 87.9) 60.2 (37.2, 83.1) 58.4 (37.5, 79.4)

Counterclockwise 

(night—afternoon—day)

DSU DSU 29.1 (7.0, 51.3) 24.1 (4.9, 43.2)

Other DSU DSU DSU DSU 17.5 (4.0, 31.0)

Unique work shifts 8.6 (4.2, 13.0) 8.1 (2.5, 13.8) 16.7 (8.8, 24.6)

Abbreviations: DSU, data suppressed; NA, not applicable. Notes: Data are national estimates. 
132 

Table 127. Activities of Independent Contractor Employees During the Reporting Week at Nonmetal Mines 

Response 

Percentage 

of Mines 

Reporting 

Contractors 95% CI

Average 

Number of 

Contractor 

employees 95% CI

Average 

Total 

Hours 95% CI

Mine development DSU DSU DSU DSU DSU DSUConstruction or reconstruction of 

mine facilities 

14.7 (8.6, 20.8) 3.5 (2.0, 5.0) 100.4 (43.9, 157.0)

Demolition of mine facilities 0.0 NA NA NA NA NAConstruction of dams 0.0 NA NA NA NA NAExcavation or earthmoving 

activities (involving mobile equipment) 

12.9 (5.6, 20.1) 13.5 (3.8, 23.3) 490.4 (189.0, 791.8)

Equipment installation 5.5 (2.1, 9.0) 3.2 (2.6, 3.8) 126.5 (67.0, 185.9)Equipment service or repair of 

equipment on mine property (exceeding 5 consecutive days) 

7.1 (3.6, 10.6) 6.9 (1.6, 12.1) 254.2 (68.1, 440.2)

Material handling (within mine 

property) 

12.6 (7.7, 17.5) 7.9 (3.4, 12.4) 302.0 (92.5, 511.6)

Drilling and blasting 7.6 (2.7, 12.6) 6.0 (0.7, 11.3) 47.7 (7.0, 88.3)Production support work 2.8 (0.8, 4.7) 2.9 (0.6, 5.3) 47.6 (0.0, 100.4)Mineral extraction 8.5 (3.3, 13.7) 3.3 (2.3, 4.2) 100.9 (50.7, 151.2)Other work DSU DSU DSU DSU DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. Notes: Data are national estimates. 
133 

Table 128. Communication Devices and Systems at Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Dedicated telephones 42.7 (31.8, 53.7)

Mine page phones 10.2 (6.1, 14.3)

Trolley phones 0.0 NA

Shaft or hoist phones 3.0 (1.8, 4.2)

Cell phones 80.9 (72.2, 89.7)

Voice over internet protocol (VOIP) phones 1.8 (0.3, 3.4)

Hand-held two-way radios 69.3 (61.9, 76.6)

Wireless paging devices 6.1 (2.0, 10.2)

Leaky feeder communications system (not running a 

PED)

1.5 (0.2, 2.8)

Personal emergency device (PED) cap lamp/pager DSU DSU

Through-the-Earth (TTE) technology (other than a PED) 0.0 NA

Inductive coupled radios DSU DSU

Ethernet 7.3 (1.9, 12.6)

TRACKER tagging system DSU DSU

Longwall face communication systems NA NA

None of the above DSU DSU

Other 7.5 (2.4, 12.6)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 129. Personal Locators, Trackers, and Devices at Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Electronic or computerized tagging or tracking DSU DSU

Tag boards 6.9 (5.0, 8.8)

Reflective vests/clothing 25.6 (18.4, 32.7)

Chemical light sticks 0.0 NA

Lighted vests 0.0 NA

Laser lights/pointers 0.0 NA

Strobe lights 8.0 (2.5, 13.5)

None of the above 63.8 (55.0, 72.5)

Other 6.1 (1.5, 10.7)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

 
134 

Table 130. Emergency Early Warning Methods at Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Stench gas DSU DSU

Audible systems 32.9 (23.1, 42.6)

Visual systems 13.4 (8.7, 18.1)

Pager phones 10.0 (4.7, 15.3)

Telephones 45.6 (33.8, 57.5)

Messengers 14.1 (7.5, 20.8)

Electronic personal communication systems DSU DSU

None of the above 28.9 (20.8, 37.0)

Other 11.1 (6.6, 15.7)

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 131. Rescue Teams at Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Mine has own rescue team 12.1 (7.7, 16.5)

Average number of rescue team members 11.2 (6.2, 16.2)

 

Frequency of team training

Less than once a year 0.0 NA

Annually 50.8 (28.4, 73.3)

Less than once a month DSU DSU

Once a month 40.4 (20.7, 60.1)

Once every 2 weeks 0.0 NA

Once a week 0.0 NA

Other time interval 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. Notes: Data are national estimates. 

 
135 

 

Mine Statistics for 

Underground 

Nonmetal Mines 
136 
137 

Summary Mine Statistics for Underground Nonmetal Mines 

The data for training and non-English languages can be found in Tables 132–135. For 

underground nonmetal mines, the weighted survey estimates indicate that more training is 

conducted by the mine’s employees for annual refresher training (82.2 percent), when compared 

to the mine’s use of outside trainers. No comparisons are possible for newly hired inexperienced 

and experienced miner training due to the need to suppress data (i.e., the survey count was less 

than five responses). Lectures (100.0 percent), written materials (90.8 percent), and 

demonstrations (85.3 percent) are the top three methods and materials used for training. 

Estimates from the survey indicate that 33.3 percent of underground nonmetal mines have daily 

safety meetings. Approximately four percent of underground nonmetal mine employees use a 

language other than English. 

 Tables 136 and 137 present the national estimates for work schedules and shift work. 

The average number of hours worked per week is 34.1 for production workers, 36.8 for 

production support workers, and 35.4 for preparation plant/mill workers. The majority of 

underground nonmetal mines operate two shifts per day for production workers (38.6 percent), 

one shift per day for production support workers (52.7 percent), and three shifts per day for 

preparation plant/mill workers (48.4 percent). 

National estimates for independent contractor employees are presented in Table 138. 

During a typical week, underground nonmetal mines use independent contractor employees for 

various types of work including: construction or reconstruction of mine facilities (33.6 percent) 

and equipment service or repair of equipment on mine property (23.3 percent). Most of the other 

data in this table have been suppressed due to a survey count of less than five responses. 

 

Tables 139–144 present national estimates for safety, communication, and rescue 

measures. Hand-held two-way radios (76.9 percent) are the most frequently used 

communication system followed by mine page phones (72.2 percent) and dedicated telephones 

(71.7 percent). Tag boards (95.3 percent) and reflective vests/clothing (43.1 percent) are the 

most frequently used personal locators/trackers in underground nonmetal mines. Colored 

reflectors (76.1 percent) and signage (75.6 percent) are the most frequently reported escape aids. 

First aid kits (95.3 percent), defibrillators (67.8 percent), and filter self-rescuers (66.4 percent) 

are the top three emergency equipment and supplies found in these mines. Seventy-two percent 

of underground nonmetal mines use visual systems for emergency early warnings. 

Approximately 67 percent of underground nonmetal mines report having their own mine rescue 

team composed of 10 team members. The majority of mine rescue teams train once a month 

(92.5 percent). 
138 

Table 132. Miner Training Within the Past 12 Months at Underground Nonmetal Mines 

Training Conducted by

Percentage 

of Mines 95% CI

Mine employees

Annual miner refresher 82.2 (68.8, 95.6)

Newly hired inexperienced miner 81.4 (64.7, 98.1)

Newly hired experienced miner 58.0 (37.4, 78.7)

 

Outside trainer

Annual miner refresher 37.0 (17.1, 56.9)

Newly hired inexperienced miner DSU DSU

Newly hired experienced miner DSU DSU

 

Outside contract trainer

Annual miner refresher DSU DSU

Newly hired inexperienced miner DSU DSU

Newly hired experienced miner DSU DSU

 

Outside state grantee

Annual miner refresher 73.0 (48.4, 97.5)

Newly hired inexperienced miner DSU DSU

Newly hired experienced miner DSU DSU

 

Outside other trainer

Annual miner refresher DSU DSU

Newly hired inexperienced miner DSU DSU

Newly hired experienced miner DSU DSU

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 133. Frequency of Periodic Safety Meetings at Underground Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Less than once a year 0.0 NA

Annually 0.0 NA

Less than once a month DSU DSU

Once a month DSU DSU

Once every 2 weeks DSU DSU

Once a week 23.6 (3.8, 43.4)

Several times a week DSU DSU

Daily 33.3 (13.7, 53.0)

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
139 

Table 134. Employee Safety Training Materials and Methods at 

Underground Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Lectures 100.0 NA

Written materials 90.8 (80.7, 100.0)

Videos 76.1 (56.4, 95.8)

Self-guided interactive computer programs DSU DSU

Demonstrations 85.3 (71.7, 98.9)

Hands-on training exercises 81.1 (66.0, 96.2)

Group exercises (role playing, games, problem solving) 38.1 (15.0, 61.1)

Classroom simulations (e.g., virtual reality) DSU DSU

Worksite simulations 38.6 (20.0, 57.2)

Narrative storytelling 38.9 (20.2, 57.6)

Other 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 135. Non-English Languages at Underground Nonmetal Mines 

Response Percentage 95% CI

Employees use a language other than English to 

communicate

4.1 (0.0, 11.1)

 

Mining operations provide training materials, signs, or 

written materials, in language(s) other than English

DSU DSU

Which Language(s) are provided1

Spanish DSU DSU

Other DSU DSU

 

Helpful to have training materials, signs, or written 

materials in other languages, in addition to those 

already provided

DSU DSU

 

Helpful to have training materials, signs, or written 

materials in language(s) other than English 

DSU DSU

1

Multiple responses permitted. Abbreviation: DSU, data suppressed. 

Note: Data are national estimates. 
140 

Table 136. Work Schedules at Underground Nonmetal Mines 

Response

Production 

Workers 95% CI

Production 

Support 

Workers 95% CI

Preparation 

Plant/Mill 

Workers 95% CI

Scheduled days per week (average) 4.8 (4.3, 5.2) 5.1 (4.9, 5.3) 4.8 (4.2, 5.4)Scheduled hours per day (average) 8.5 (7.7, 9.3) 8.8 (8.4, 9.2) 8.9 (8.2, 9.6)

Actual hours worked per week 

(average)

34.1 (26.0, 42.1) 36.8 (27.5, 46.0) 35.4 (26.8, 44.0)

Work crews change shifts at active 

mining site (percentage)

DSU DSU DSU DSU NA NA

Average time spent traveling to and 

from active mining site while being paid (hours)

1.8 (1.6, 2.0) 1.7 (1.4, 2.0) NA NA

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
141 

Table 137. Shift Work Schedules at Underground Nonmetal Mines 

Response

Production 

Workers

 Percentage 

of Mines 95% CI

Production 

Support 

Workers 

Percentage 

of Mines 95% CI

Preparation 

Plant/Mill 

Workers 

Percentage 

of Mines 95% CI

Number of shifts per day

1 shift 36.4 (16.4, 56.4) 52.7 (26.2, 79.3) DSU DSU

2 shifts 38.6 (17.7, 59.5) 28.8 (8.3, 49.2) 34.8 (11.9, 57.7)

3 shifts 25.0 (6.5, 43.5) DSU DSU 48.4 (24.4, 72.5)

4 shifts 0.0 NA 0.0 NA 0.0 NA

Rotating shifts 25.0 (7.6, 42.4) DSU DSU 30.7 (10.7, 50.7)Frequency workers rotate shifts

Weekly DSU DSU DSU DSU 100.0 NA

Twice a month DSU DSU DSU DSU 0.0 NAMonthly 0.0 NA DSU DSU 0.0 NAOther 0.0 NA DSU DSU 0.0 NA

Direction the shift rotates

Clockwise 

(day—afternoon—night)

DSU DSU DSU DSU DSU DSU

Counterclockwise

 (night—afternoon—day)

DSU DSU DSU DSU DSU DSU

Other DSU DSU DSU DSU DSU DSU

Unique work shifts DSU DSU DSU DSU DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates.
142 

Table 138. Activities of Independent Contractor Employees During the Reporting Week at Underground Nonmetal Mines 

Response

Percentage 

of Mines 

Reporting 

Contractors 95% CI

Average 

Number of 

Contractor 

Employees 95% CI

Average 

Total 

Hours 95% CI

Mine development DSU DSU DSU DSU DSU DSUConstruction or reconstruction of 

mine facilities

33.6 (14.1, 53.1) 6.1 (2.6, 9.6) 171.6 (74.3, 268.8)

Demolition of mine facilities 0.0 NA NA NA NA NA

Construction of dams 0.0 NA NA NA NA NAExcavation or earthmoving 

activities (involving mobile equipment)

0.0 NA NA NA NA NA

Equipment installation DSU DSU DSU DSU DSU DSU

Equipment service or repair of 

equipment on mine property (exceeding 5 consecutive days)

23.3 (10.2, 36.4) 3.4 (1.7, 5.0) 99.0 (40.2, 157.9)

Material handling (within mine 

property)

DSU DSU DSU DSU DSU DSU

Drilling and blasting DSU DSU DSU DSU DSU DSU

Production support work DSU DSU DSU DSU DSU DSUMineral extraction DSU DSU DSU DSU DSU DSU

Other work DSU DSU DSU DSU DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
143 

Table 139. Communication Devices and Systems at Underground Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Dedicated telephones 71.7 (51.2, 92.1)

Mine page phones 72.2 (53.7, 90.7)

Trolley phones 0.0 NA

Shaft or hoist phones 47.8 (26.0, 69.6)

Cell phones 56.7 (38.8, 74.6)

Voice over internet protocol (VOIP) phones DSU DSU

Hand-held two-way radios 76.9 (62.4, 91.5)

Wireless paging devices 0.0 NA

Leaky feeder communications system (not running a 

PED)

24.4 (2.7, 46.2)

Personal emergency device (PED) cap lamp/pager DSU DSU

Through-the-Earth (TTE) technology (other than a PED) 0.0 NA

Inductive coupled radios DSU DSU

Ethernet DSU DSU

TRACKER tagging system DSU DSU

Longwall face communication systems NA NA

None of the above 0.0 NA

Other 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 140. Personal Locators, Trackers, and Devices at Underground Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Electronic or computerized tagging or tracking DSU DSU

Tag boards 95.3 (89.0, 100.0)

Reflective vests/clothing 43.1 (20.9, 65.2)

Chemical light sticks 0.0 NA

Lighted vests 0.0 NA

Laser lights/pointers 0.0 NA

Strobe lights DSU DSU

None of the above 0.0 NA

Other DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

 
144 

Table 141. Emergency Early Warning Methods at Underground Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Stench gas DSU DSU

Audible systems 42.5 (22.1, 62.9)

Visual systems 71.7 (51.8, 91.6)

Pager phones 48.3 (27.5, 69.2)

Telephones 57.0 (35.0, 78.9)

Messengers 23.3 (6.1, 40.6)

Electronic personal communication systems DSU DSU

None of the above DSU DSU

Other DSU DSU

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 142. Rescue Teams at Underground Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Mine has own rescue team 66.7 (45.5, 87.8)

Average number of rescue team members 9.9 (7.7, 12.2)

Frequency of team training

Less than once a year 0.0 NA

Annually 0.0 NA

Less than once a month DSU DSU

Once a month 92.5 (79.3, 100.0)

Once every 2 weeks 0.0 NA

Once a week 0.0 NA

Other time interval 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 

 
145 

Table 143. Emergency Equipment and Supplies at Underground Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Belt-worn self-contained self-rescuers (SCSRs) 38.3 (17.5, 59.1)

Cached self-contained self-rescuers (SCSRs) DSU DSU

Filter self-rescuers (FSRs) 66.4 (48.3, 84.5)

Stationary emergency refuge chambers 24.7 (6.3, 43.1)

Mobile emergency refuge chambers 0.0 NA

Sealing materials 24.4 (2.9, 46.0)

Cached water/food supplies 34.2 (15.2, 53.1)

First aid kits 95.3 (86.4, 100.0)

Defibrillator 67.8 (43.5, 92.0)

None of the above 0.0 NA

Other DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 144. Escape Aids at Underground Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Lifelines DSU DSU

Directional lifelines 0.0 NA

Signage 75.6 (59.8, 91.3)

Colored reflectors 76.1 (55.5, 96.8)

Lighting 37.5 (16.7, 58.3)

Strobe lights DSU DSU

None of the above 0.0 NA

Other 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

 
146 

 
147 

 

Mine Statistics for Surface 

Nonmetal Mines 
148 
149 

Summary of Mine Statistics for Surface Nonmetal Mines 

The data for training and non-English languages can be found in Tables 145–148. For 

surface nonmetal mines, the weighted survey estimates indicate that more training is conducted 

by the mine’s employees including: annual refresher training (72.6 percent), newly hired 

inexperienced miner training (58.4 percent), and newly hired experienced miner training (45.5 

percent) when compared to the mine’s use of outside trainers. Lectures (93.1 percent), written 

materials (87.3 percent), and videos (77.5 percent) are the top three methods and materials used 

for training. Estimates from the survey indicate that 35.0 percent of surface nonmetal mines 

have employee safety meetings once a month. Approximately 10 percent of surface nonmetal 

mine employees use a language other than English. 

Tables 149 and 150 present the national estimates for work schedules and shift work. 

The average number of hours worked per week is 36.5 for production workers, 37.9 for 

production support workers, and 40.9 for preparation plant/mill workers. The majority of surface 

nonmetal mines operate one shift per day (74.7 percent for production workers, 70.9 percent for 

production support workers, and 36.6 percent for preparation plant/mill workers). 

National estimates for independent contractor employees are presented in Table 151. 

During a typical week, surface nonmetal mines use independent contractor employees for 

various types of work including: excavation or earthmoving activities (13.7 percent), 

construction or reconstruction of mine facilities (13.4 percent), material handling (12.8 percent), 

and mineral extraction (8.1 percent). 

 

Tables 152–155 present national estimates for safety, communication, and rescue 

measures. Cell phones (82.6 percent) are the most frequently used communication system 

followed by hand-held two-way radios (68.7 percent), and dedicated telephones (40.8 percent). 

Forty-five percent of surface nonmetal mines use telephones for emergency early warnings. 

Approximately nine percent of surface nonmetal mines report having their own mine rescue team 

composed of about 12 team members. The majority of mine rescue teams train on an annual 

basis (81.9 percent). 

 
150 

Table 145. Miner Training Within the Past 12 Months at Surface Nonmetal Mines 

Training Conducted by

Percentage 

of Mines 95% CI

Mine employees

Annual miner refresher 72.6 (62.5, 82.6)

Newly hired inexperienced miner 58.4 (46.2, 70.5)

Newly hired experienced miner 45.5 (35.9, 55.2)

 

Outside trainer

Annual miner refresher 47.5 (38.0, 57.0)

Newly hired inexperienced miner 13.9 (9.2, 18.5)

Newly hired experienced miner 10.4 (6.6, 14.2)

 

Outside contract trainer

Annual miner refresher 30.8 (17.4, 44.1)

Newly hired inexperienced miner 46.0 (21.0, 71.0)

Newly hired experienced miner DSU DSU

 

Outside state grantee

Annual miner refresher 63.2 (50.1, 76.3)

Newly hired inexperienced miner 63.8 (41.5, 86.2)

Newly hired experienced miner 52.7 (30.5, 74.9)

 

Outside other trainer

Annual miner refresher 13.4 (4.5, 22.4)

Newly hired inexperienced miner 0.0 NA

Newly hired experienced miner DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 146. Frequency of Periodic Safety Meetings at Surface Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Less than once a year DSU DSU

Annually DSU DSU

Less than once a month 7.1 (3.2, 11.0)

Once a month 35.0 (23.5, 46.5)

Once every 2 weeks 4.4 (0.6, 8.2)

Once a week 25.0 (15.7, 34.2)

Several times a week 7.5 (2.6, 12.5)

Daily 15.1 (6.9, 23.3)

Abbreviation: DSU, data suppressed. Note: Data are national estimates.
151 

Table 147. Employee Safety Training Materials and Methods at Surface Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Lectures 93.1 (89.5, 96.6)

Written materials 87.3 (81.2, 93.5)

Videos 77.5 (67.9, 87.0)

Self-guided interactive computer programs 13.8 (6.7, 20.9)

Demonstrations 61.4 (48.7, 74.2)

Hands-on training exercises 60.8 (54.3, 67.4)

Group exercises (role playing, games, problem solving) 29.9 (20.7, 39.1)

Classroom simulations (e.g., virtual reality) 12.5 (6.2, 18.8)

Worksite simulations 33.6 (23.7, 43.6)

Narrative storytelling 39.4 (29.5, 49.3)

Other 5.5 (0.7, 10.2)

Notes: Data are national estimates; multiple responses permitted. 

Table 148. Non-English Languages at Surface Nonmetal Mines 

Response Percentage 95% CI

Employees use a language other than English to 

communicate

9.6 (4.9, 14.3)

 

Mining operations provide training materials, signs, or 

written materials, in language(s) other than English

22.6 (11.8, 33.3)

Which Language(s) are provided1

Spanish 100.0 NA

Other DSU DSU

 

Helpful to have training materials, signs, or written 

materials in other languages, in addition to those 

already provided

17.2 (3.7, 30.7)

 

Helpful to have training materials, signs, or written 

materials in language(s) other than English 

10.0 (4.1, 15.9)

1

Multiple responses permitted. Abbreviations: DSU, data suppressed; NA, not applicable. 

Note: Data are national estimates. 
152 

Table 149. Work Schedules at Surface Nonmetal Mines 

Response

Production 

Workers 95% CI

Production 

Support 

Workers 95% CI

Preparation 

Plant/Mill 

Workers 95% CI

Scheduled days per week (average) 4.7 (4.4, 5.0) 4.9 (4.7, 5.1) 4.8 (4.5, 5.0)Scheduled hours per day (average) 8.9 (8.6, 9.2) 8.5 (8.2, 8.7) 9.4 (8.3, 10.6)

Actual hours worked per week 

(average)

36.5 (33.2, 39.8) 37.9 (36.0, 39.8) 40.9 (37.9, 43.8)

Work crews change shifts at active 

mining site (percentage)

9.4 (3.4, 15.3) 13.6 (4.6, 22.5) NA NA

Average time spent traveling to and 

from active mining site while being paid (hours)

1.7 (1.6, 1.8) 1.7 (1.5, 1.8) NA NA

Abbreviation: NA, not applicable. Note: Data are national estimates. 
153 

Table 150. Shift Work Schedules at Surface Nonmetal Mines 

Response

Production 

Workers

 Percentage 

of Mines 95% CI

Production 

Support 

Workers 

Percentage 

of Mines 95% CI

Preparation 

Plant/Mill 

Workers 

Percentage 

of Mines 95% CI

Number of shifts per day

1 shift 74.7 (65.5, 83.8) 70.9 (59.9, 82.0) 36.6 (22.2, 50.9)

2 shifts 15.6 (8.2, 22.9) 11.7 (5.1, 18.3) 30.2 (16.0, 44.4)

3 shifts 8.7 (3.1, 14.4) 16.4 (8.7, 24.0) 31.7 (20.5, 42.8)4 shifts DSU DSU DSU DSU DSU DSU

Rotating shifts 14.2 (6.7, 21.7) 18.6 (7.6, 29.6) 37.4 (24.9, 50.0)Frequency workers rotate shifts

Weekly 39.4 (18.3, 60.6) 64.2 (44.5, 83.8) 62.3 (45.1, 79.6)

Twice a month 40.7 (16.8, 64.6) DSU DSU 25.5 (9.0, 42.0)

Monthly DSU DSU 0.0 NA DSU DSU

Other DSU DSU DSU DSU DSU DSU

Direction the shift rotates

Clockwise 

(day—afternoon—night)

73.4 (52.8, 94.0) 61.7 (38.5, 84.8) 60.1 (37.7, 82.5)

Counterclockwise

 (night—afternoon—day)

DSU DSU 27.4 (5.2, 49.5) 22.6 (2.2, 43.0)

Other DSU DSU DSU DSU 17.3 (2.8, 31.7)

Unique work shifts 8.0 (3.4, 12.6) 7.8 (1.9, 13.8) 16.6 (8.0, 25.1)

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
154 

Table 151. Activities of Independent Contractor Employees During the Reporting Week at Surface Nonmetal Mines 

Response

Percentage 

of Mines 

Reporting 

Contractors 95% CI

Average 

Number of 

Contractor 

Employees 95% CI

Average 

Total 

Hours 95% CI

Mine development DSU DSU DSU DSU DSU DSUConstruction or reconstruction of 

mine facilities

13.4 (7.1, 19.8) 3.1 (1.5, 4.7) 88.7 (25.8, 151.7)

Demolition of mine facilities 0.0 NA NA NA NA NA

Construction of dams 0.0 NA NA NA NA NAExcavation or earthmoving 

activities (involving mobile equipment)

13.7 (5.9, 21.4) 13.5 (3.8, 23.3) 490.4 (189.0, 791.8)

Equipment installation 5.3 (1.7, 8.8) 3.2 (2.6, 3.9) 135.5 (70.3, 200.6)

Equipment service or repair of 

equipment on mine property (exceeding 5 consecutive days)

6.0 (2.4, 9.7) 7.8 (1.1, 14.4) 293.6 (58.4, 528.8)

Material handling (within mine 

property)

12.8 (7.6, 18.0) 8.2 (3.5, 12.8) 313.9 (95.1, 532.8)

Drilling and blasting 7.5 (2.3, 12.7) 6.3 (0.5, 12.0) 50.7 (6.3, 95.1)Production support work DSU DSU DSU DSU DSU DSU

Mineral extraction 8.1 (2.7, 13.6) 3.3 (2.2, 4.4) 109.7 (56.7, 162.8)

Other work DSU DSU DSU DSU DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
155 

Table 152. Communication Devices and Systems at Surface Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Dedicated telephones 40.8 (29.3, 52.3)

Mine page phones 6.0 (2.0, 10.0)

Trolley phones 0.0 NA

Shaft or hoist phones NA NA

Cell phones 82.6 (73.3, 91.8)

Voice over internet protocol (VOIP) phones DSU DSU

Hand-held two-way radios 68.7 (61.0, 76.5)

Wireless paging devices 6.5 (2.1, 10.9)

Leaky feeder communications system (not running a 

PED)

0.0 NA

Personal emergency device (PED) cap lamp/pager DSU DSU

Through-the-Earth (TTE) technology (other than a PED) 0.0 NA

Inductive coupled radios 0.0 NA

Ethernet 7.1 (1.4, 12.8)

TRACKER tagging system 0.0 NA

Longwall face communication systems NA NA

None of the above DSU DSU

Other 8.0 (2.5, 13.5)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 153. Personal Locators, Trackers, and Devices at Surface Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Electronic or computerized tagging or tracking DSU DSU

Tag boards DSU DSU

Reflective vests/clothing 24.3 (16.8, 31.8)

Chemical light sticks 0.0 NA

Lighted vests 0.0 NA

Laser lights/pointers 0.0 NA

Strobe lights 7.5 (1.8, 13.3)

None of the above 68.2 (59.0, 77.4)

Other 6.2 (1.3, 11.1)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

 
156 

Table 154. Emergency Early Warning Methods at Surface Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Stench gas 0.0 NA

Audible systems 32.2 (21.9, 42.5)

Visual systems 9.4 (4.7, 14.2)

Pager phones 7.4 (1.8, 13.1)

Telephones 44.9 (32.4, 57.4)

Messengers 13.5 (6.5, 20.5)

Electronic personal communication systems DSU DSU

None of the above 30.5 (22.0, 39.1)

Other 11.6 (6.7, 16.4)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 155. Rescue Teams at Surface Nonmetal Mines 

Response

Percentage 

of Mines 95% CI

Mine has own rescue team 8.5 (4.0, 13.0)

Average number of rescue team members 11.9 (4.2, 19.5)

Frequency of team training

Less than once a year 0.0 NA

Annually 81.9 (60.3, 100.0)

Less than once a month DSU DSU

Once a month DSU DSU

Once every 2 weeks 0.0 NA

Once a week 0.0 NA

Other time interval 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 

 
157 

 

Mine Statistics for 

Stone Mines 
158 
159 

Summary of Mine Statistics for Stone Mines 

The data for training and non-English languages can be found in Tables 156–159. For 

the U.S. stone mining industry, the weighted survey estimates indicate that more training is 

conducted by the mine’s employees including: annual refresher training (75.0 percent); newly 

hired inexperienced miner training (75.1 percent); and newly hired experienced miner training 

(66.0 percent) when compared to the mine’s use of outside trainers. Lectures (91.1 percent), 

written materials (88.8 percent) and videos (82.3 percent) are the top three methods and materials 

used for training. Estimates from the survey indicate that 46.0 percent of all mines have 

employee safety meetings once a week. Overall, approximately 12 percent of mine employees 

use a language other than English. 

 Tables 160 and 161 present the national estimates for work schedules and shift work. The 

average number of hours worked per week is 40.6 for production workers, 41.5 for production 

support workers, and 42.5 for preparation plant/mill workers. The majority of stone mines 

operate one shift per day (81.7 percent for production workers, 86.0 percent for production 

support workers, and 80.0 percent for preparation plant/mill workers). 

National estimates for independent contractor employees are presented in Table 162. 

During a typical week, stone mines use independent contractor employees for various types of 

work including: drilling and blasting (25.4 percent); construction or reconstruction of mine 

facilities (10.5 percent); equipment service or repair of equipment on mine property (8.3 

percent); and excavation or earthmoving activities (5.4 percent). 

 

Tables 163–166 present national estimates for safety, communication, and rescue 

measures. Cell phones (86.0 percent) are the most frequently used communication system 

followed by hand-held two-way radios (61.8 percent), and dedicated telephones (48.2 percent). 

Forty-nine percent of stone mines use telephones for emergency early warnings. Eight percent 

of stone mines report having their own mine rescue team composed of approximately seven team 

members. The majority of mine rescue teams train on an annual basis (82.7 percent). 
160 

Table 156. Miner Training Within the Past 12 Months at Stone Mines 

Training Conducted by

Percentage 

of Mines 95% CI

Mine employees

Annual miner refresher 75.0 (67.7, 82.2)

Newly hired inexperienced miner 75.1 (68.1, 82.0)

Newly hired experienced miner 66.0 (58.4, 73.7)

 

Outside trainer

Annual miner refresher 49.2 (40.0, 58.5)

Newly hired inexperienced miner 18.5 (10.5, 26.5)

Newly hired experienced miner 15.9 (9.0, 22.9)

 

Outside contract trainer

Annual miner refresher 59.1 (49.5, 68.6)

Newly hired inexperienced miner 65.3 (41.3, 89.3)

Newly hired experienced miner 77.4 (63.2, 91.5)

 

Outside state grantee

Annual miner refresher 29.2 (15.8, 42.6)

Newly hired inexperienced miner 25.0 (0.0, 50.8)

Newly hired experienced miner 16.7 (2.3, 31.1)

 

Outside other trainer

Annual miner refresher 11.8 (4.7, 18.9)

Newly hired inexperienced miner DSU DSU

Newly hired experienced miner DSU DSU

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 157. Frequency of Periodic Safety Meetings at Stone Mines 

Response

Percentage 

of Mines 95% CI

Less than once a year 0.0 NA

Annually DSU DSU

Less than once a month 10.7 (7.3, 14.0)

Once a month 17.0 (10.4, 23.6)

Once every 2 weeks 6.8 (2.7, 11.0)

Once a week 46.0 (33.9, 58.1)

Several times a week 5.9 (2.6, 9.1)

Daily 12.0 (3.1, 20.8)

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
161 

Table 158. Employee Safety Training Materials and Methods at Stone Mines 

Response

Percentage 

of Mines 95% CI

Lectures 91.1 (85.7, 96.5)

Written materials 88.8 (80.4, 97.2)

Videos 82.3 (76.2, 88.4)

Self-guided interactive computer programs 16.7 (10.7, 22.6)

Demonstrations 71.7 (61.4, 81.9)

Hands-on training exercises 66.1 (59.9, 72.3)

Group exercises (role playing, games, problem solving) 39.5 (32.5, 46.6)

Classroom simulations (e.g., virtual reality) 7.8 (4.0, 11.6)

Worksite simulations 31.9 (25.5, 38.3)

Narrative storytelling 54.2 (46.3, 62.1)

Other 3.6 (1.1, 6.0)

Notes: Data are national estimates; multiple responses permitted. 

Table 159. Non-English Languages at Stone Mines 

Response Percentage 95% CI

Employees use a language other than English to 

communicate

11.8 (5.6, 18.1)

 

Mining operations provide training materials, signs, or 

written materials, in language(s) other than English

32.9 (22.8, 43.0)

Which Language(s) are provided1

Spanish 100.0 NA

Other DSU DSU

 

Helpful to have training materials, signs, or written 

materials in other languages, in addition to those 

already provided

36.0 (16.6, 55.4)

 

Helpful to have training materials, signs, or written 

materials in language(s) other than English 

13.1 (6.7, 19.4)

1

Multiple responses permitted. Abbreviations: DSU, data suppressed; NA, not applicable. 

Note: Data are national estimates. 
162 

Table 160. Work Schedules at Stone Mines 

Response

Production 

Workers 95% CI

Production 

Support 

Workers 95% CI

Preparation 

Plant/Mill 

Workers 95% CI

Scheduled days per week (average) 4.9 (4.9, 5.0) 5.0 (5.0, 5.1) 4.9 (4.8, 5.1)Scheduled hours per day (average) 9.0 (8.8, 9.3) 10.3 (8.6, 12.0) 9.1 (8.7, 9.5)

Actual hours worked per week 

(average)

40.6 (38.7, 42.6) 41.5 (38.3, 44.6) 42.5 (38.9, 46.1)

Work crews change shifts at active 

mining site (percentage)

8.3 (5.1, 11.4) 5.6 (1.7, 9.5) NA NA

Average time spent traveling to and 

from active mining site while being paid (hours)

1.5 (1.3, 1.6) 1.5 (1.4, 1.7) NA NA

Abbreviation: NA, not applicable. Note: Data are national estimates. 
163 

Table 161. Shift Work Schedules at Stone Mines 

Response

Production 

Workers

 Percentage 

of Mines 95% CI

Production 

Support 

Workers 

Percentage 

of Mines 95% CI

Preparation 

Plant/Mill 

Workers 

Percentage 

of Mines 95% CI

Number of shifts per day

1 shift 81.7 (76.9, 86.5) 86.0 (79.7, 92.3) 80.0 (74.3, 85.8)

2 shifts 15.9 (10.7, 21.1) 10.6 (4.4, 16.8) 13.1 (6.9, 19.2)

3 shifts 2.3 (0.3, 4.2) 3.4 (1.8, 5.0) 5.2 (3.1, 7.2)

4 shifts DSU DSU 0.0 NA DSU DSU

Rotating shifts 3.3 (0.8, 5.9) 2.5 (1.2, 3.8) 4.0 (2.1, 5.9)Frequency workers rotate shifts

Weekly 90.3 (78.7, 100.0) 83.8 (63.1, 100.0) 70.9 (44.0, 97.9)

Twice a month DSU DSU DSU DSU 0.0 NA

Monthly 0.0 NA DSU DSU DSU DSU

Other 0.0 NA 0.0 NA DSU DSU

Direction the shift rotates

Clockwise

 (day—afternoon—night)

78.1 (58.8, 97.4) 67.8 (42.2, 93.4) 83.5 (63.3, 100.0)

Counterclockwise

 (night—afternoon—day)

DSU DSU DSU DSU DSU DSU

Other DSU DSU DSU DSU DSU DSU

Unique work shifts 1.6 (0.5, 2.7) 0.9 (0.1, 1.8) DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
164 

Table 162. Activities of Independent Contractor Employees During the Reporting Week at Stone Mines 

Response 

Percentage 

of Mines 

Reporting 

Contractors 95% CI

Average 

Number of 

Contractor 

Employees 95% CI

Average 

Total 

Hours 95% CI

Mine development 3.0 (0.2, 5.8) 3.0 (1.1, 4.9) 49.9 (36.4, 63.5)Construction or reconstruction of 

mine facilities 

10.5 (5.2, 15.9) 9.2 (1.3, 17.1) 121.0 (8.4, 233.6)

Demolition of mine facilities DSU DSU DSU DSU DSU DSU

Construction of dams 0.0 NA NA NA NA NA

Excavation or earthmoving 

activities (involving mobile equipment) 

5.4 (2.3, 8.6) 4.4 (2.5, 6.2) 94.8 (46.7, 142.8)

Equipment installation 2.8 (0.2, 5.3) 2.0 (1.2, 2.9) 28.6 (13.0, 44.3)Equipment service or repair of 

equipment on mine property (exceeding 5 consecutive days) 

8.3 (4.7, 11.9) 2.2 (1.5, 2.8) 37.1 (18.0, 56.2)

Material handling (within mine 

property) 

3.4 (0.0, 7.2) 4.1 (0.2, 8.0) 73.5 (44.2, 102.7)

Drilling and blasting 25.4 (19.9, 30.8) 2.3 (1.9, 2.6) 36.2 (27.0, 45.3)Production support work 2.0 (0.2, 3.7) 4.0 (1.3, 6.6) 77.1 (17.0, 137.2)Mineral extraction DSU DSU DSU DSU DSU DSU

Other work DSU DSU DSU DSU DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
165 

Table 163. Communication Devices and Systems at Stone Mines 

Response

Percentage 

of Mines 95% CI

Dedicated telephones 48.2 (39.7, 56.6)

Mine page phones 2.4 (1.3, 3.5)

Trolley phones 0.0 NA

Shaft or hoist phones DSU DSU

Cell phones 86.0 (79.6, 92.5)

Voice over internet protocol (VOIP) phones DSU DSU

Hand-held two-way radios 61.8 (49.4, 74.2)

Wireless paging devices 3.3 (0.7, 6.0)

Leaky feeder communications system (not running a 

PED)

0.6 (0.1, 1.0)

Personal emergency device (PED) cap lamp/pager 0.0 NA

Through-the-Earth (TTE) technology (other than a PED) DSU DSU

Inductive coupled radios DSU DSU

Ethernet 3.6 (2.3, 4.9)

TRACKER tagging system 0.0 NA

Longwall face communication systems NA NA

None of the above DSU DSU

Other 22.4 (14.9, 30.0)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 164. Personal Locators, Trackers, and Devices at Stone Mines 

Response

Percentage 

of Mines 95% CI

Electronic or computerized tagging or tracking DSU DSU

Tag boards 6.2 (3.3, 9.0)

Reflective vests/clothing 30.6 (20.3, 41.0)

Chemical light sticks DSU DSU

Lighted vests DSU DSU

Laser lights/pointers 0.0 NA

Strobe lights 9.5 (3.1, 15.9)

None of the above 63.2 (53.0, 73.4)

Other 6.6 (2.4, 10.9)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

 
166 

Table 165. Emergency Early Warning Methods at Stone Mines 

Response

Percentage 

of Mines 95% CI

Stench gas DSU DSU

Audible systems 34.2 (26.8, 41.7)

Visual systems 14.3 (9.4, 19.1)

Pager phones 3.2 (0.4, 6.0)

Telephones 48.5 (41.0, 56.1)

Messengers 18.2 (11.0, 25.4)

Electronic personal communication systems DSU DSU

None of the above 20.4 (15.2, 25.7)

Other 20.1 (11.6, 28.7)

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 166. Rescue Teams at Stone Mines 

Response

Percentage 

of Mines 95% CI

Mine has own rescue team 7.6 (1.3, 14.0)

Average number of rescue team members 6.6 (3.6, 9.6)

Frequency of team training

Less than once a year DSU DSU

Annually 82.7 (57.0, 100.0)

Less than once a month DSU DSU

Once a month DSU DSU

Once every 2 weeks 0.0 NA

Once a week 0.0 NA

Other time interval 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 

 
167 

Mine Statistics for 

Underground Stone Mines 
168 
169 

Summary of Mine Statistics for Underground Stone Mines 

The data for training and non-English languages can be found in Tables 167–170. For 

underground stone mines, the weighted survey estimates indicate that more training is conducted 

by the mine’s employees including: annual refresher training (75.0 percent), newly hired 

inexperienced miner training (74.9 percent), and newly hired experienced miner training (78.0 

percent) when compared to the mine’s use of outside trainers. Lectures (93.9 percent), written 

materials (93.5 percent), and videos (86.3 percent) are the top three methods and materials used 

for training. Estimates from the survey indicate that 39.4 percent of underground stone mines 

have safety meetings once a week. Approximately seven percent of underground stone mine 

employees use a language other than English. 

Tables 171 and 172 present the national estimates for work schedules and shift work. 

The average number of hours worked per week is 45.8 for production workers, 45.2 for 

production support workers, and 47.7 for preparation plant/mill workers. The majority of 

underground stone mines operate one shift per day (75.1 percent for production workers, 89.6 

percent for production support workers, and 72.0 percent for preparation plant/mill workers). 

National estimates for independent contractor employees are presented in Table 173. 

During a typical week, underground stone mines use independent contractor employees for 

equipment service or repair of equipment on mine property (17.2 percent). The other data in this 

table have been suppressed due to a survey count of less than five responses. 

 

Tables 174–179 present national estimates for safety, communication, and rescue 

measures. Hand-held two-way radios (84.3 percent) are the most frequently used 

communication system followed by dedicated telephones (67.0 percent), and cell phones (58.9 

percent). Tag boards (96.6 percent) and reflective vests/clothing (57.6 percent) are the most 

frequently used personal locators/trackers in underground stone mines. Signage (83.2 percent) 

and colored reflectors (60.5 percent) are the most frequently reported escape aids. First aid kits 

(82.3 percent), filter self-rescuers (60.9 percent), and belt-worn self-contained self-rescuers 

(SCSRs) (46.0 percent) are the top three emergency equipment and supplies found in these 

mines. Eighty-two percent of underground stone mines use visual systems for emergency early 

warnings. Approximately 18 percent of underground stone mines report having their own mine 

rescue team composed of 26 team members. The frequency of rescue teams training data have 

been suppressed due to a survey count of less than five responses. 

 
170 

Table 167. Miner Training Within the Past 12 Months at Underground Stone Mines 

Training Conducted by

Percentage 

of Mines 95% CI

Mine employees

Annual miner refresher 75.0 (58.3, 91.6)

Newly hired inexperienced miner 74.9 (60.1, 89.6)

Newly hired experienced miner 78.0 (63.3, 92.8)

 

Outside trainer

Annual miner refresher 51.7 (33.1, 70.3)

Newly hired inexperienced miner 34.6 (18.7, 50.6)

Newly hired experienced miner 21.3 (5.8, 36.7)

 

Outside contract trainer

Annual miner refresher 61.2 (40.1, 82.4)

Newly hired inexperienced miner 70.8 (47.1, 94.5)

Newly hired experienced miner DSU DSU

 

Outside state grantee

Annual miner refresher 25.2 (6.1, 44.2)

Newly hired inexperienced miner DSU DSU

Newly hired experienced miner DSU DSU

 

Outside other trainer

Annual miner refresher DSU DSU

Newly hired inexperienced miner DSU DSU

Newly hired experienced miner DSU DSU

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 168. Frequency of Periodic Safety Meetings at Underground Stone Mines 

Response

Percentage 

of Mines 95% CI

Less than once a year 0.0 NA

Annually DSU DSU

Less than once a month DSU DSU

Once a month 35.0 (16.5, 53.6)

Once every 2 weeks DSU DSU

Once a week 39.4 (22.7, 56.1)

Several times a week 0.0 NA

Daily DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates.
171 

Table 169. Employee Safety Training Materials and Methods at 

Underground Stone Mines 

Response

Percentage 

of Mines 95% CI

Lectures 93.9 (86.8, 100.0)

Written materials 93.5 (84.5, 100.0)

Videos 86.3 (73.4, 99.1)

Self-guided interactive computer programs 15.7 (4.9, 26.5)

Demonstrations 82.9 (69.5, 96.2)

Hands-on training exercises 63.9 (45.6, 82.2)

Group exercises (role playing, games, problem solving) 34.1 (13.0, 55.1)

Classroom simulations (e.g., virtual reality) 24.1 (13.0, 35.3)

Worksite simulations 45.8 (30.6, 61.0)

Narrative storytelling 65.8 (52.9, 78.7)

Other DSU DSU

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 170. Non-English Languages at Underground Stone Mines 

Response Percentage 95% CI

Employees use a language other than English to 

communicate

7.4 (0.0, 15.1)

 

Mining operations provide training materials, signs, or 

written materials, in language(s) other than English

22.3 (4.7, 39.9)

Which Language(s) are provided1

Spanish 100.0 NA

Other 0.0 NA

 

Helpful to have training materials, signs, or written 

materials in other languages, in addition to those 

already provided

DSU DSU

 

Helpful to have training materials, signs, or written 

materials in language(s) other than English 

DSU DSU

1

Multiple responses permitted. Abbreviations: DSU, data suppressed; NA, not applicable. 

Note: Data are national estimates. 
172 

Table 171. Work Schedules at Underground Stone Mines 

Response

Production 

Workers 95% CI

Production 

Support 

Workers 95% CI

Preparation 

Plant/Mill 

Workers 95% CI

Scheduled days per week (average) 4.9 (4.7, 5.1) 5.1 (4.9, 5.3) 5.0 (4.6, 5.4)Scheduled hours per day (average) 9.5 (9.2, 9.9) 9.4 (9.1, 9.8) 9.8 (9.4, 10.1)

Actual hours worked per week 

(average)

45.8 (41.6, 50.0) 45.2 (41.3, 49.2) 47.7 (42.8, 52.6)

Work crews change shifts at active 

mining site (percentage)

18.5 (3.8, 33.2) DSU DSU NA NA

Average time spent traveling to and 

from active mining site while being paid (hours)

1.5 (1.2, 1.8) 1.6 (1.3, 1.9) NA NA

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
173 

Table 172. Shift Work Schedules at Underground Stone Mines 

Response

Production 

Workers

 Percentage 

of Mines 95% CI

Production 

Support 

Workers 

Percentage 

of Mines 95% CI

Preparation 

Plant/Mill 

Workers 

Percentage 

of Mines 95% CI

Number of shifts per day

1 shift 75.1 (61.4, 88.9) 89.6 (78.3, 100.0) 72.0 (56.1, 88.0)

2 shifts 21.1 (10.5, 31.8) DSU DSU DSU DSU

3 shifts DSU DSU DSU DSU DSU DSU4 shifts 0.0 NA 0.0 NA 0.0 NA

Rotating shifts DSU DSU DSU DSU DSU DSUFrequency workers rotate shifts

Weekly DSU DSU DSU DSU DSU DSU

Twice a month DSU DSU DSU DSU DSU DSUMonthly DSU DSU DSU DSU DSU DSUOther DSU DSU DSU DSU DSU DSU

Direction the shift rotates

Clockwise 

(day—afternoon—night)

DSU DSU DSU DSU DSU DSU

Counterclockwise

 (night—afternoon—day)

DSU DSU DSU DSU DSU DSU

Other DSU DSU DSU DSU DSU DSU

Unique work shifts 0.0 NA DSU DSU 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. .
174 

Table 173. Activities of Independent Contractor Employees During the Reporting Week at Underground Stone Mines 

Response

Percentage 

of Mines 

Reporting 

Contractors 95% CI

Average 

Number of 

Contractor 

Employees 95% CI

Average 

Total 

Hours 95% CI

Mine development DSU DSU DSU DSU DSU DSUConstruction or reconstruction of 

mine facilities

DSU DSU DSU DSU DSU DSU

Demolition of mine facilities 0.0 NA NA NA NA NA

Construction of dams 0.0 NA NA NA NA NAExcavation or earthmoving 

activities (involving mobile equipment)

DSU DSU DSU DSU DSU DSU

Equipment installation 0.0 NA NA NA NA NA

Equipment service or repair of 

equipment on mine property (exceeding 5 consecutive days)

17.2 (3.8, 30.6) 2.2 (1.4, 3.1) 24.9 (15.2, 34.6)

Material handling (within mine 

property)

DSU DSU DSU DSU DSU DSU

Drilling and blasting DSU DSU DSU DSU DSU DSUProduction support work DSU DSU DSU DSU DSU DSUMineral extraction 0.0 NA NA NA NA NA

Other work 0.0 NA NA NA NA NA

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
175 

Table 174. Communication Devices and Systems at Underground Stone Mines 

Response

Percentage 

of Mines 95% CI

Dedicated telephones 67.0 (49.6, 84.4)

Mine page phones 39.9 (22.3, 57.5)

Trolley phones 0.0 NA

Shaft or hoist phones DSU DSU

Cell phones 58.9 (36.9, 80.9)

Voice over internet protocol (VOIP) phones 0.0 NA

Hand-held two-way radios 84.3 (68.6, 100.0)

Wireless paging devices DSU DSU

Leaky feeder communications system (not running a 

PED)

20.6 (5.7, 35.6)

Personal emergency device (PED) cap lamp/pager 0.0 NA

Through-the-Earth (TTE) technology (other than a PED) DSU DSU

Inductive coupled radios 0.0 NA

Ethernet 0.0 NA

TRACKER tagging system 0.0 NA

Longwall face communication systems NA NA

None of the above 0.0 NA

Other 24.7 (10.9, 38.5)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 175. Personal Locators, Trackers, and Devices at Underground Stone Mines 

Response

Percentage 

of Mines 95% CI

Electronic or computerized tagging or tracking 0.0 NA

Tag boards 96.6 (91.5, 100.0)

Reflective vests/clothing 57.6 (39.9, 75.2)

Chemical light sticks DSU DSU

Lighted vests 0.0 NA

Laser lights/pointers 0.0 NA

Strobe lights 40.3 (22.2, 58.5)

None of the above 0.0 NA

Other DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

 
176 

Table 176. Emergency Early Warning Methods at Underground Stone Mines 

Response

Percentage 

of Mines 95% CI

Stench gas DSU DSU

Audible systems 58.8 (42.4, 75.2)

Visual systems 81.8 (73.6, 90.0)

Pager phones DSU DSU

Telephones 38.1 (18.8, 57.3)

Messengers 37.8 (20.2, 55.3)

Electronic personal communication systems DSU DSU

None of the above 0.0 NA

Other 25.6 (6.5, 44.6)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 177. Rescue Teams at Underground Stone Mines 

Response

Percentage 

of Mines 95% CI

Mine has own rescue team 18.2 (6.3, 30.1)

Average number of rescue team members 26.1 (10.8, 41.5)

Frequency of team training

Less than once a year 0.0 NA

Annually DSU DSU

Less than once a month DSU DSU

Once a month DSU DSU

Once every 2 weeks 0.0 NA

Once a week 0.0 NA

Other time interval 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
177 

Table 178. Emergency Equipment and Supplies at Underground Stone Mines 

Response

Percentage 

of Mines 95% CI

Belt-worn self-contained self-rescuers (SCSRs) 46.0 (28.9, 63.1)

Cached self-contained self-rescuers (SCSRs) DSU DSU

Filter self-rescuers (FSRs) 60.9 (44.9, 76.8)

Stationary emergency refuge chambers DSU DSU

Mobile emergency refuge chambers DSU DSU

Sealing materials 0.0 NA

Cached water/food supplies DSU DSU

First aid kits 82.3 (70.6, 94.0)

Defibrillator 35.0 (18.8, 51.1)

None of the above 0.0 NA

Other DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 179. Escape Aids at Underground Stone Mines 

Response

Percentage 

of Mines 95% CI

Lifelines DSU DSU

Directional lifelines 0.0 NA

Signage 83.2 (69.5, 96.8)

Colored reflectors 60.5 (44.4, 76.5)

Lighting 37.3 (18.0, 56.7)

Strobe lights 21.0 (5.0, 37.1)

None of the above 0.0 NA

Other 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

 
178 

 
179 

 

Mine Statistics for Surface 

Stone Mines 
180 
181 

Summary of Mine Statistics for Surface Stone Mines 

The data for training and non-English languages can be found in Tables 180–183. For 

surface stone mines, the weighted survey estimates indicate that more training is conducted by 

the mine’s employees including: annual refresher training (75.0 percent), newly hired 

inexperienced miner training (75.1 percent), and newly hired experienced miner training (65.7 

percent) when compared to the mine’s use of outside trainers. Lectures (91.0 percent), written 

materials (88.7 percent), and videos (82.2 percent) are the top three methods and materials used 

for training. Estimates from the survey indicate that 46.2 percent of surface stone mines have 

employee safety meetings once a week. Approximately 12 percent of surface stone mine 

employees use a language other than English. 

Tables 184 and 185 present the national estimates for work schedules and shift work. 

The average number of hours worked per week is 40.5 for production workers, 41.3 for 

production support workers, and 42.3 for preparation plant/mill workers. The majority of surface 

stone mines operate one shift per day (81.9 percent for production workers, 85.9 percent for 

production support workers, and 80.4 percent for preparation plant/mill workers). 

National estimates for independent contractor employees are presented in Table 186. 

During a typical week, surface stone mines use independent contractor employees for various 

types of work including: drilling and blasting (25.7 percent), construction or reconstruction of 

mine facilities (10.7 percent), equipment service or repair of equipment on mine property (8.1 

percent), and excavation or earthmoving activities (5.4 percent). 

 

Tables 187–190 present national estimates for safety, communication, and rescue 

measures. Cell phones (86.8 percent) are the most frequently used communication system 

followed by hand-held two-way radios (61.2 percent) and dedicated telephones (47.7 percent). 

Forty-nine percent of surface stone mines use telephones for emergency early warnings. 

Approximately seven percent of surface stone mines report having their own mine rescue team 

composed of about five team members. The majority of mine rescue teams train on an annual 

basis (84.2 percent).
182 

Table 180. Miner Training Within the Past 12 Months at Surface Stone Mines 

Training Conducted by

Percentage 

of Mines 95% CI

Mine employees

Annual miner refresher 75.0 (67.5, 82.4)

Newly hired inexperienced miner 75.1 (68.0, 82.2)

Newly hired experienced miner 65.7 (57.9, 73.6)

 

Outside trainer

Annual miner refresher 49.2 (39.7, 58.7)

Newly hired inexperienced miner 18.1 (9.8, 26.3)

Newly hired experienced miner 15.8 (8.6, 23.0)

 

Outside contract trainer

Annual miner refresher 59.0 (49.2, 68.8)

Newly hired inexperienced miner 65.0 (39.6, 90.4)

Newly hired experienced miner 78.3 (63.6, 93.1)

 

Outside state grantee

Annual miner refresher 29.3 (15.5, 43.0)

Newly hired inexperienced miner 25.3 (0.0, 52.5)

Newly hired experienced miner DSU DSU

 

Outside other trainer

Annual miner refresher 11.4 (4.2, 18.7)

Newly hired inexperienced miner DSU DSU

Newly hired experienced miner DSU DSU

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 181. Frequency of Periodic Safety Meetings at Surface Stone Mines 

Response

Percentage 

of Mines 95% CI

Less than once a year 0.0 NA

Annually DSU DSU

Less than once a month 10.8 (7.3, 14.2)

Once a month 16.5 (9.7, 23.2)

Once every 2 weeks 6.9 (2.7, 11.2)

Once a week 46.2 (33.8, 58.6)

Several times a week 6.0 (2.7, 9.3)

Daily 12.0 (2.9, 21.1)

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates.
183 

Table 182. Employee Safety Training Materials and Methods at Surface Stone Mines 

Response

Percentage 

of Mines 95% CI

Lectures 91.0 (85.5, 96.5)

Written materials 88.7 (80.1, 97.3)

Videos 82.2 (75.9, 88.5)

Self-guided interactive computer programs 16.7 (10.6, 22.8)

Demonstrations 71.4 (60.8, 81.9)

Hands-on training exercises 66.1 (59.8, 72.5)

Group exercises (role playing, games, problem solving) 39.7 (32.5, 46.9)

Classroom simulations (e.g., virtual reality) 7.4 (3.4, 11.3)

Worksite simulations 31.5 (25.0, 38.1)

Narrative storytelling 53.9 (45.7, 62.0)

Other 3.6 (1.0, 6.1)

Notes: Data are national estimates; multiple responses permitted. 

Table 183. Non-English Languages at Surface Stone Mines 

Response Percentage 95% CI

Employees use a language other than English to 

communicate

12.0 (5.5, 18.4)

 

Mining operations provide training materials, signs, or 

written materials, in language(s) other than English

33.2 (22.9, 43.6)

Which Language(s) are provided1

Spanish 100.0 NA

Other DSU DSU

 

Helpful to have training materials, signs, or written 

materials in other languages, in addition to those 

already provided

36.4 (16.7, 56.0)

 

Helpful to have training materials, signs, or written 

materials in language(s) other than English 

13.1 (6.5, 19.7)

1

Multiple responses permitted. Abbreviations: DSU, data suppressed; NA, not applicable. 

Note: Data are national estimates. 
184 

Table 184. Work Schedules at Surface Stone Mines 

Response

Production 

Workers 95% CI

Production 

Support 

Workers 95% CI

Preparation 

Plant/Mill 

Workers 95% CI

Scheduled days per week (average) 4.9 (4.9, 5.0) 5.0 (5.0, 5.1) 4.9 (4.8, 5.1)Scheduled hours per day (average) 9.0 (8.7, 9.3) 10.4 (8.6, 12.1) 9.0 (8.6, 9.4)

Actual hours worked per week 

(average)

40.5 (38.5, 42.5) 41.3 (38.0, 44.6) 42.3 (38.6, 46.0)

Work crews change shifts at active 

mining site (percentage)

8.0 (4.8, 11.2) 5.6 (1.5, 9.6) NA NA

Average time spent traveling to and 

from active mining site while being paid (hours)

1.5 (1.3, 1.6) 1.5 (1.4, 1.7) NA NA

Abbreviation: NA, not applicable. Note: Data are national estimates. 
185 

Table 185. Shift Work Schedules at Surface Stone Mines 

Response

Production 

Workers

 Percentage 

of Mines 95% CI

Production 

Support 

Workers 

Percentage 

of Mines 95% CI

Preparation 

Plant/Mill 

Workers 

Percentage 

of Mines 95% CI

Number of shifts per day

1 shift 81.9 (76.9, 86.8) 85.9 (79.3, 92.4) 80.4 (74.5, 86.3)

2 shifts 15.8 (10.4, 21.1) 10.8 (4.3, 17.2) 12.7 (6.4, 19.1)

3 shifts 2.2 (0.2, 4.2) 3.4 (1.7, 5.0) 5.1 (3.0, 7.2)

4 shifts DSU DSU 0.0 NA DSU DSU

Rotating shifts 3.2 (0.6, 5.7) 2.5 (1.2, 3.9) 3.9 (2.0, 5.9)Frequency workers rotate shifts

Weekly 94.9 (85.1, 100.0) 83.3 (61.9, 100.0) 69.1 (40.3, 97.8)

Twice a month DSU DSU DSU DSU 0.0 NA

Monthly 0.0 NA DSU DSU DSU DSU

Other 0.0 NA 0.0 NA DSU DSU

Direction the shift rotates

Clockwise

 (day—afternoon—night)

79.7 (59.9, 99.5) 66.8 (40.4, 93.2) 84.4 (63.1, 100.0)

Counterclockwise

 (night—afternoon—day)

DSU DSU DSU DSU 0.0 NA

Other DSU DSU DSU DSU DSU DSU

Unique work shifts 1.7 (0.5, 2.8) DSU DSU DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
186 

Table 186. Activities of Independent Contractor Employees During the Reporting Week at Surface Stone Mines 

Response

Percentage 

of Mines 

Reporting 

Contractors 95% CI

Average 

Number of 

Contractor 

Employees 95% CI

Average 

Total 

Hours 95% CI

Mine development DSU DSU DSU DSU DSU DSUConstruction or reconstruction of 

mine facilities

10.7 (5.2, 16.1) 9.3 (1.3, 17.3) 122.2 (7.5, 236.8)

Demolition of mine facilities DSU DSU DSU DSU DSU DSU

Construction of dams 0.0 NA NA NA NA NA

Excavation or earthmoving 

activities (involving mobile equipment)

5.4 (2.2, 8.6) 4.3 (2.4, 6.2) 87.0 (42.0, 132.1)

Equipment installation 2.8 (0.2, 5.5) 2.0 (1.2, 2.9) 28.6 (13.0, 44.3)Equipment service or repair of 

equipment on mine property (exceeding 5 consecutive days)

8.1 (4.4, 11.7) 2.2 (1.5, 2.9) 37.8 (17.4, 58.1)

Material handling (within mine 

property)

3.4 (0.0, 7.3) 4.2 (0.2, 8.2) 74.0 (44.0, 104.1)

Drilling and blasting 25.7 (20.1, 31.3) 2.3 (1.9, 2.6) 36.0 (26.7, 45.3)Production support work 1.8 (0.1, 3.6) 3.8 (1.0, 6.7) 69.3 (8.8, 129.8)Mineral extraction DSU DSU DSU DSU DSU DSU

Other work DSU DSU DSU DSU DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
187 

Table 187. Communication Devices and Systems at Surface Stone Mines 

Response

Percentage 

of Mines 95% CI

Dedicated telephones 47.7 (39.0, 56.4)

Mine page phones 1.4 (0.3, 2.4)

Trolley phones 0.0 NA

Shaft or hoist phones NA NA

Cell phones 86.8 (80.2, 93.3)

Voice over internet protocol (VOIP) phones DSU DSU

Hand-held two-way radios 61.2 (48.5, 73.9)

Wireless paging devices 3.3 (0.6, 6.1)

Leaky feeder communications system (not running a 

PED)

0.0 NA

Personal emergency device (PED) cap lamp/pager 0.0 NA

Through-the-Earth (TTE) technology (other than a PED) 0.0 NA

Inductive coupled radios DSU DSU

Ethernet 3.7 (2.4, 5.0)

TRACKER tagging system 0.0 NA

Longwall face communication systems NA NA

None of the above DSU DSU

Other 22.4 (14.7, 30.1)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 188. Personal Locators, Trackers, and Devices at Surface Stone Mines 

Response

Percentage 

of Mines 95% CI

Electronic or computerized tagging or tracking DSU DSU

Tag boards DSU DSU

Reflective vests/clothing 29.9 (19.2, 40.5)

Chemical light sticks DSU DSU

Lighted vests DSU DSU

Laser lights/pointers 0.0 NA

Strobe lights 8.6 (2.1, 15.2)

None of the above 65.0 (54.5, 75.4)

Other 6.7 (2.3, 11.2)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

 
188 

Table 189. Emergency Early Warning Methods at Surface Stone Mines 

Response

Percentage 

of Mines 95% CI

Stench gas 0.0 NA

Audible systems 33.5 (25.9, 41.2)

Visual systems 12.4 (7.4, 17.4)

Pager phones 2.9 (0.0, 5.8)

Telephones 48.8 (41.1, 56.6)

Messengers 17.6 (10.2, 25.0)

Electronic personal communication systems DSU DSU

None of the above 21.0 (15.6, 26.4)

Other 20.0 (11.2, 28.8)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 190. Rescue Teams at Surface Stone Mines 

Response

Percentage 

of Mines 95% CI

Mine has own rescue team 7.3 (0.8, 13.9)

Average number of rescue team members 5.3 (3.6, 6.9)

Frequency of team training

Less than once a year DSU DSU

Annually 84.2 (57.7, 100.0)

Less than once a month 0.0 NA

Once a month DSU DSU

Once every 2 weeks 0.0 NA

Once a week 0.0 NA

Other time interval 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 

 
189 

Mine Statistics for 

Sand and Gravel Mines 
190 
191 

Summary of Mine Statistics for Sand and Gravel Mines 

The data for training and non-English languages can be found in Tables 191–194. For 

the U.S. sand and gravel mining industry, the weighted survey estimates indicate that more 

training is conducted by the mine’s employees including: annual refresher training (67.8 

percent); newly hired inexperienced miner training (59.0 percent); and newly hired experienced 

miner training (54.5 percent) when compared to the mine’s use of outside trainers. Lectures 

(81.9 percent), written materials (81.0 percent) and videos (74.5 percent) are the top three 

methods and materials used for training. Estimates from the survey indicate that 35.1 percent of 

all sand and gravel mines have employee safety meetings once a week. Overall, approximately 

six percent of mine employees use a language other than English. 

 Tables 195 and 196 present the national estimates for work schedules and shift work. The 

average number of hours worked per week is 36.8 for production workers, 35.3 for production 

support workers, and 31.7 for preparation plant/mill workers. The majority of sand and gravel 

mines operate one shift per day (84.8 percent for production workers, 89.0 percent for production 

support workers, and 79.2 percent for preparation plant/mill workers). 

National estimates for independent contractor employees are presented in Table 197. 

During a typical week, sand and gravel mines use independent contractor employees for various 

types of work including: equipment service or repair of equipment on mine property (4.6 

percent); construction or reconstruction of mine facilities (4.4 percent); excavation or 

earthmoving activities (3.2 percent); and equipment installation (1.8 percent). 

 

Tables 198–201 present national estimates for safety, communication, and rescue 

measures. Cell phones (95.3 percent) are the most frequently used communication system 

followed by hand-held two-way radios (62.0 percent), and dedicated telephones (30.9 percent). 

Forty-seven percent of sand and gravel mines use telephones for emergency early warnings. 

Five percent of sand and gravel mines report having their own mine rescue team composed of 

approximately three team members. The majority of mine rescue teams train on an annual basis 

(81.2 percent). 

 
192 

Table 191. Miner Training Within the Past 12 Months at Sand and Gravel Mines 

Training Conducted by

Percentage 

of Mines 95% CI

Mine employees

Annual miner refresher 67.8 (62.1, 73.4)

Newly hired inexperienced miner 59.0 (51.9, 66.0)

Newly hired experienced miner 54.5 (48.8, 60.2)

 

Outside trainer

Annual miner refresher 63.6 (55.3, 71.9)

Newly hired inexperienced miner 16.6 (13.4, 19.9)

Newly hired experienced miner 12.4 (4.9, 19.9)

 

Outside contract trainer

Annual miner refresher 42.2 (33.0, 51.4)

Newly hired inexperienced miner 45.0 (26.8, 63.2)

Newly hired experienced miner 46.3 (26.9, 65.7)

 

Outside state grantee

Annual miner refresher 41.5 (26.6, 56.4)

Newly hired inexperienced miner 52.6 (21.9, 83.3)

Newly hired experienced miner 50.1 (5.7, 94.5)

 

Outside other trainer

Annual miner refresher 21.5 (14.0, 29.0)

Newly hired inexperienced miner DSU DSU

Newly hired experienced miner DSU DSU

Abbreviation: DSU, data suppressed. 

Notes: Data are national estimates; multiple responses permitted. 

Table 192. Frequency of Periodic Safety Meetings at Sand and Gravel Mines 

Response

Percentage 

of Mines 95% CI

Less than once a year DSU DSU

Annually 8.6 (4.4, 12.8)

Less than once a month 8.9 (4.4, 13.4)

Once a month 25.8 (18.5, 33.2)

Once every 2 weeks 7.3 (2.5, 12.1)

Once a week 35.1 (25.3, 44.9)

Several times a week 5.6 (2.5, 8.8)

Daily 5.3 (1.0, 9.7)

Abbreviation: DSU, data suppressed. Note: Data are national estimates.
193 

Table 193. Employee Safety Training Materials and Methods at Sand and Gravel Mines 

Response

Percentage 

of Mines 95% CI

Lectures 81.9 (77.1, 86.6)

Written materials 81.0 (75.5, 86.6)

Videos 74.5 (70.7, 78.4)

Self-guided interactive computer programs 20.8 (12.2, 29.4)

Demonstrations 52.9 (41.9, 63.8)

Hands-on training exercises 62.0 (53.9, 70.2)

Group exercises (role playing, games, problem solving) 24.3 (19.2, 29.4)

Classroom simulations (e.g., virtual reality) 11.5 (7.4, 15.6)

Worksite simulations 31.3 (23.5, 39.0)

Narrative storytelling 41.8 (33.0, 50.7)

Other 2.1 (0.0, 4.2)

Notes: Data are national estimates; multiple responses permitted. 

Table 194. Non-English Languages at Sand and Gravel Mines 

Response Percentage 95% CI

Employees use a language other than English to 

communicate

5.7 (2.6, 8.7)

 

Mining operations provide training materials, signs, or 

written materials, in language(s) other than English

15.3 (9.3, 21.2)

Which Language(s) are provided1

Spanish 100.0 NA

Other 0.0 NA

 

Helpful to have training materials, signs, or written 

materials in other languages, in addition to those 

already provided

33.9 (13.3, 54.4)

 

Helpful to have training materials, signs, or written 

materials in language(s) other than English 

9.8 (6.0, 13.7)

1

Multiple responses permitted. Abbreviation: NA, not applicable. 

Note: Data are national estimates. 
194 

Table 195. Work Schedules at Sand and Gravel Mines 

Response

Production 

Workers 95% CI

Production 

Support 

Workers 95% CI

Preparation 

Plant/Mill 

Workers 95% CI

Scheduled days per week (average) 4.6 (4.5, 4.7) 4.7 (4.5, 4.8) 4.7 (4.5, 4.9)Scheduled hours per day (average) 9.1 (8.8, 9.3) 9.5 (7.8, 11.2) 8.8 (7.7, 9.9)

Actual hours worked per week 

(average)

36.8 (33.8, 39.8) 35.3 (32.2, 38.3) 31.7 (22.5, 41.0)

Work crews change shifts at active 

mining site (percentage)

9.0 (5.5, 12.4) 11.4 (6.0, 16.8) NA NA

Average time spent traveling to and 

from active mining site while being paid (hours)

1.6 (1.5, 1.8) 1.6 (1.4, 1.8) NA NA

Abbreviation: NA, not applicable. Note: Data are national estimates. 
195 

Table 196. Shift Work Schedules at Sand and Gravel Mines 

Response

Production 

Workers

 Percentage 

of Mines 95% CI

Production 

Support 

Workers 

Percentage 

of Mines 95% CI

Preparation 

Plant/Mill 

Workers 

Percentage 

of Mines 95% CI

Number of shifts per day

1 shift 84.8 (79.5, 90.0) 89.0 (82.6, 95.5) 79.2 (63.5, 94.9)

2 shifts 12.0 (6.9, 17.1) 10.2 (4.2, 16.2) 18.0 (4.2, 31.7)

3 shifts DSU DSU DSU DSU DSU DSU

4 shifts DSU DSU 0.0 NA 0.0 NA

Rotating shifts 3.6 (0.1, 7.1) DSU DSU DSU DSUFrequency workers rotate shifts

Weekly DSU DSU DSU DSU DSU DSU

Twice a month DSU DSU DSU DSU DSU DSUMonthly DSU DSU DSU DSU DSU DSUOther 0.0 NA DSU DSU DSU DSU

Direction the shift rotates

Clockwise 

(day—afternoon—night)

100.0 NA DSU DSU DSU DSU

Counterclockwise 

(night—afternoon—day)

0.0 NA DSU DSU DSU DSU

Other 0.0 NA DSU DSU DSU DSU

Unique work shifts DSU DSU DSU DSU 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
196 

Table 197. Activities of Independent Contractor Employees During the Reporting Week at Sand and Gravel Mines 

Response 

Percentage 

of Mines 

Reporting 

Contractors 95% CI

Average 

Number of 

Contractor 

Employees 95% CI

Average 

Total Hours 95% CI

Mine development DSU DSU DSU DSU DSU DSUConstruction or reconstruction of 

mine facilities 

4.4 (0.9, 7.9) 2.0 (1.6, 2.5) 30.9 (12.0, 49.8)

Demolition of mine facilities 0.0 NA NA NA NA NA

Construction of dams DSU DSU DSU DSU DSU DSUExcavation or earthmoving 

activities (involving mobile equipment) 

3.2 (0.2, 6.2) 1.1 (0.9, 1.3) 44.0 (29.6, 58.4)

Equipment installation 1.8 (0.0, 3.8) 1.5 (0.8, 2.2) 41.3 (24.6, 58.0)Equipment service or repair of 

equipment on mine property (exceeding 5 consecutive days) 

4.6 (1.8, 7.4) 1.7 (1.0, 2.5) 46.3 (6.0, 86.6)

Material handling (within mine 

property) 

DSU DSU DSU DSU DSU DSU

Drilling and blasting 0.7 (0.0, 1.8) 3.1 (2.1, 4.1) 33.3 (9.2, 57.4)Production support work DSU DSU DSU DSU DSU DSUMineral extraction DSU DSU DSU DSU DSU DSUOther work DSU DSU DSU DSU DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 
197 

Table 198. Communication Devices and Systems at Sand and Gravel Mines 

Response

Percentage 

of Mines 95% CI

Dedicated telephones 30.9 (21.8, 40.0)

Mine page phones 2.8 (0.0, 5.8)

Trolley phones 0.0 NA

Shaft or hoist phones NA NA

Cell phones 95.3 (91.6, 99.0)

Voice over internet protocol (VOIP) phones DSU DSU

Hand-held two-way radios 62.0 (56.0, 67.9)

Wireless paging devices 3.9 (0.6, 7.1)

Leaky feeder communications system (not running a 

PED)

0.0 NA

Personal emergency device (PED) cap lamp/pager DSU DSU

Through-the-Earth (TTE) technology (other than a PED) 0.0 NA

Inductive coupled radios DSU DSU

Ethernet 1.6 (0.0, 3.8)

TRACKER tagging system DSU DSU

Longwall face communication systems NA NA

None of the above 0.0 NA

Other 19.1 (11.0, 27.2)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 199. Personal Locators, Trackers, and Devices at Sand and Gravel Mines 

Response

Percentage 

of Mines 95% CI

Electronic or computerized tagging or tracking DSU DSU

Tag boards DSU DSU

Reflective vests/clothing 36.9 (24.5, 49.3)

Chemical light sticks DSU DSU

Lighted vests DSU DSU

Laser lights/pointers 0.0 NA

Strobe lights 8.9 (3.3, 14.5)

None of the above 58.0 (45.1, 71.0)

Other DSU DSU

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

 
198 

Table 200. Emergency Early Warning Methods at Sand and Gravel Mines 

Response

Percentage 

of Mines 95% CI

Stench gas 0.0 NA

Audible systems 24.3 (19.1, 29.5)

Visual systems 12.0 (5.8, 18.2)

Pager phones 2.5 (0.0, 5.4)

Telephones 46.9 (40.5, 53.3)

Messengers 12.0 (1.2, 22.8)

Electronic personal communication systems DSU DSU

None of the above 32.2 (21.6, 42.8)

Other 16.4 (10.7, 22.0)

Abbreviations: DSU, data suppressed; NA, not applicable. 

Notes: Data are national estimates; multiple responses permitted. 

Table 201. Rescue Teams at Sand and Gravel Mines 

Response

Percentage 

of Mines 95% CI

Mine has own rescue team 4.6 (0.0, 9.3)

Average number of rescue team members 2.7 (2.3, 3.0)

 

Frequency of team training

Less than once a year DSU DSU

Annually 81.2 (33.9, 100.0)

Less than once a month 0.0 NA

Once a month 0.0 NA

Once every 2 weeks 0.0 NA

Once a week 0.0 NA

Other time interval 0.0 NA

Abbreviations: DSU, data suppressed; NA, not applicable. Note: Data are national estimates. 

 
199 

Acknowledgements 

The authors extend their appreciation to the reviewers for their thoughtful and insightful 

comments. We acknowledge the contributions of: Jefferey L. Burgess, M.D., M.P.H., University 

of Arizona, Jeffery H. Kravitz, Ph.D., Mine Safety and Health Administration, Elaine N. 

Rubinstein, Ph.D., University of Pittsburgh, John P. Sestito and William K. Sieber, National 

Institute for Occupational Safety and Health, and Bruce Watzman, National Mining Association. 

Additionally, we appreciate the contributions of our numerous colleagues at the Office of 

Mine Safety and Health Research. In particular, Audrey Podlesny for preparing the maps, 

Michael J. Brnich, Jr., Albert H. Cook, Nathan T. Lowe, Mary Ellen Nelson, Robert H. Peters, 

and Charles Vaught (retired) for their invaluable advice regarding the coding of the mining 

industry job titles, Joseph Schall and Candace A. Wolf for their editorial assistance, Donna Opfer 

and Brittney Warnick for their formatting assistance, Genny Lohr for her work on 508 

Compliance, and David Beshero for the cover design. 

Finally, the authors gratefully acknowledge the survey respondents in the coal, metal, 

nonmetal, stone, and sand and gravel mining sectors. Thank you for your time and effort in 

completing this survey. 
200 

 
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203 

Appendices 
204 

 
205 

Appendix A. Questionnaire Booklet 
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225 
226 
227 
228 
229 

Appendix B. Questions and Answers Brochure 

 
230 
231 

 
232 
233 

Appendix C. MSHA Form 7000-2: Quarterly Mine Employment 

and Coal Production Report 

 
234 

 
235 

 
236 

 
237 

Appendix D. Standard Industrial Classification (SIC) for 

Active Mines in 2007 
238 
239 

Coal Mining Sector 

Anthracite Coal 

Bituminous Coal 

Metal Mining Sector 

Alumina (Mill) 

Aluminum Ore 

Beryl 

Chromite 

Copper Ore 

Gold (Lode and Placer) 

Iron Ore 

Lead and/or Zinc Ore 

Manganese 

Metal Ores, NEC 

Molybdenum 

Platinum Group 

Rare Earths 

Silver Ores 

Titanium 

Uranium 

Uranium – Vanadium Ores 

Vanadium 

Zircon 

Nonmetal Mining Sector 

Aplite 

Barite 

Boron Materials 

Brucite 

Chemical and Fertilizer, NEC 

Clay (Common) 

Clay (Fire) 

Clay, Ceramic and Refractory, NEC 

Feldspar 

Fluorspar 

Gemstones 

Gilsonite 

Gypsum 

Kyanite 

Abbreviation: NEC, not elsewhere classified 

Nonmetal Mining Sector (Cont.) 

Leonardite 

Magnesite 

Mica 

Nonmetallic Minerals, NEC 

Oil Sand 

Oil Shale 

Perlite 

Phosphate Rock 

Pigment Mineral 

Potash 

Potash, Soda, & Borate Minerals, NEC 

Pumice 

Salt (Evaporated) 

Salt (Rock) 

Shale (Common) 

Sodium Compounds 

Talc, Soapstone, & Pyrophyllite 

Trona 

Vermiculite 

Stone Mining Sector 

Cement 

Granite (Crushed & Broken) 

Granite (Dimension) 

Lime 

Limestone (Crushed & Broken) 

Limestone (Dimension) 

Marble (Crushed & Broken) 

Marble (Dimension) 

Sandstone (Crushed & Broken) 

Sandstone (Dimension) 

Slate (Crushed & Broken) 

Slate (Dimension) 

Stone, Crushed & Broken, NEC 

Stone, Dimension, NEC 

Traprock (Crushed & Broken) 

Traprock (Dimension) 

Sand and Gravel Mining Sector 

Sand and Gravel 
240 
241 

Appendix E. Stratification and Sample Size Guidelines 

 
242 

 
243 

Stratification 

The cum f rule is often suggested for use in forming strata for surveys of businesses, 

which typically have a large number of small businesses with very few employees and a small 

number of large businesses with quite substantial payrolls [Cochran 1977]. Using this approach, 

strata that have approximately equal sizes in terms of the square root of the size measure are 

established. The cum f rule was used in determining the initial size-based strata for each 

mining sector with an assumption of about 4–5 strata per sector for underground mines and for 

surface mines. Except for sand and gravel mines, the large mines account for 25 percent or more 

of total employment. These initial stratum definitions for each commodity varied somewhat 

across mining sectors but were similar. 

The next step in stratum formation was to recognize that data from the five mining 

sectors would be combined to study mining as a whole. Using common definitions for strata 

across the five sectors facilitated these combined analyses. The initial stratum definitions were 

compared to determine a common stratification approach. The stratum definitions that met the 

needs for all five commodities were formed by the cross of underground versus surface mines 

with these size groupings of employees: 1–9, 10–25, 26–50, 51–75, 76–100, 101–250, and 251 

and up. 

Sample Size 

To determine the stratum sample sizes, the precision of percentage estimates under 

various sample sizes was considered. Table E-1 presents the half-length of confidence intervals 

around an estimated percentage Pˆ under various sample size and design effects and assuming 

large population sizes. For this table, the confidence interval was approximated for design 

purposes as: 

P z Var (P ) 1- ˆ ˆ   (1) 

Here z1- is the value of the critical point x at which the normal cumulative distribution 

function equals 1-, and ) ˆ Var (P is the variance of Pˆ . The half-length HL is: 

HL = z Var (P) 1- ˆ  (2) 

That is, Pˆ can be expected to fall within the range [PHL, P+HL] with 95 percent 

confidence for the indicated sample sizes. 

To determine these half-lengths of confidence intervals, there is a need to estimate the 

variance of the estimated percentage Pˆ . Ignoring finite population correction factors, Table E-1 

models the variance for an estimated percentage Pˆ as: 
244 

DEFF

n

P ( - P ) Var (P) = 100 ˆ (3) 

where n is the sample size, P is the percentage being estimated, and DEFF is the design effect. 

The design effect for a survey estimate is defined to be the ratio of the statistic under the actual 

design divided by the variance that would have been achieved from a simple random sample of 

the same size. The design effect represents the cumulative effect of design components such as 

stratification, unequal weighting, and clustering, and varies with each design. The design effects 

for this survey were estimated to be about 1.00 for mine-level and employee-level estimates 

within strata. Crosscutting estimates were likely to have larger design effects, particularly for 

employee-level estimates. The design effect differs from 1.00 for the crosscutting estimates due 

to the variation in sampling rates used across strata. Fortunately, these crosscutting estimates 

often have large sampler sizes due to combining samples across strata. 

Sample sizes were set with the guideline that the precision for stratum estimates was 

constrained as that shown for sample sizes of 100 in Table E-1. Some mine strata have very 

small population sizes and some mining sectors are small overall. In such situations, the variance 

as given in equation (3) is reduced by the factor(N  n) /(N  1) , where n is the sample size and 

N is the population size. Rather than create versions of Table E-1 for all possible population 

sizes, finite-population-corrected (fpc) sample sizes were developed. An actual sample size of n

for a population of size N is equivalent to the precision achieved with a sample size of 

N n

n N n    ( 1)

from a population so large that fpc effects are ignorable. Initial sample sizes were set for each 

stratum so that the finite-population-corrected sample size was about 100 and then inflated to 

account for a projected 80 percent response rate. These initial sample sizes were then adjusted to 

prevent excessive variations in the sampling rates across strata for mines and for employees. 

Besides the number of mines selected, the employee sample size is affected by the 

eligibility and response rates for mines and the average number of employees sampled per mine. 

The average number of employees sampled per mine would be about 20 except for the smallest 

stratum where approximately 5 employees would tend to be sampled. It was assumed that 80 

percent of all eligible mines would respond, providing both mine-level and employee-level data. 

For sample design purposes, the assumption was made that a variable percentage of mines would 

be eligible for the survey, depending upon employment size. An eligibility rate of 85 percent was 

assumed for mines with 1–9 employees. These mines are most likely to shut down operations or 

go out of business. An eligibility rate of 90 percent was assumed for mines with 10–50 

employees, and 95 percent for mines with 51–100 employees. For very large mines with 

employment of more than 100, an eligibility rate of 99 percent was assumed, as they should be 

most stable in terms of their operations. 

In designing the commodity samples, an effort was made to minimize the design effects 

for mine-level and employee-level analyses. In particular, the goal was to achieve design effects 

of 1.0 for within-stratum estimates and design effects of 2.0 or less for crosscutting estimates. 

Following standard practice, the design effect DEFF was modeled as the product of the design 

effect associated with unequal weighting Dw and the design effect for clustering Dc, that is 

* . DEFF Dw Dc A simple random sample has both design effect components equal to one—

therefore DEFF=1. 
245 

Both mine-level and employee-level estimates could potentially be subject to an unequal 

weighting effect greater than one, particularly for crosscutting estimates that combine data from 

multiple strata. The design effect for unequal weighting can be estimated as: 

2

1

1

2





 















n

i

i

n

i

i

w

W

n W

D (4) 

where n is the total sample size and Wi is the weight for the i

th observation. When the weights 

(the inverse of the selection probabilities) are equal for all selections, Dw = 1. For mines, Dw = 1 

within all strata for the proposed designs and was often only slightly greater than one across 

strata. For employees, Dw = 1 except for the two largest strata that collapsed employee size 

categories. These strata tended to have all mines selected with certainty, so the only way to 

reduce Dw was to increase the number of employees sampled per mine from 25 to 50. Adjusting 

the sample size for the very large mines could even out the employee-level weights within these 

strata and across strata. However, the increase in employee sample size also increased the burden 

for the mine respondent and increased the design effect for clustering. 

The design effect associated with clustering measures the loss of precision of a clustered 

sample as compared with a simple random sample. Clustered samples tend to have less precision 

than simple random samples of the same size, because units within the same cluster usually are 

more homogeneous than units from different clusters. The design effect for clustering can be 

estimated as: 

 D 1 (b 1) c  (5) 

where ρ is the intracluster correlation coefficient and b is the cluster size. Because stratified 

simple random sampling would be used to select mines, the mines would not be clustered (b = 1) 

and mine-level estimates would not be subject to a clustering effect (Dc = 1). However, multiple 

employees would be selected from each mine, so employee-level estimates would be subject to a 

design effect due to clustering. For the purpose of modeling the clustering design effect, it was 

assumed that variable values for ρ be based upon the size of the mine. Employees within small 

mines with 1 to 50 employees were expected to be more homogeneous, so a value of ρ = 5 

percent was assumed. Medium size mines were assumed to be less homogeneous, so a value of 

ρ = 3 percent was assumed. Large mines with more than 100 employees were expected to be 

quite diverse, so a value of ρ = 1 percent was assumed. A value of ρ = 3 percent was assumed for 

estimates compiled across strata. 
246 

Table E-1. Half-Length of 95% Confidence Intervals in Percentage Points for Various 

Percentages Being Estimated for Domains of Various Sizes with Various Design Effects 

DEFF P 50 75 100 150 200 250 350 400 500

1.00 10 8 7 6 5 4 4 3 3 3

1.00 20 11 9 8 6 6 5 4 4 4

1.00 25 12 10 8 7 6 5 5 4 4

1.00 30 13 10 9 7 6 6 5 4 4

1.00 40 14 11 10 8 7 6 5 5 4

1.00 50 14 11 10 8 7 6 5 5 4

1.25 10 9 8 7 5 5 4 4 3 3

1.25 20 12 10 9 7 6 6 5 4 4

1.25 25 13 11 9 8 7 6 5 5 4

1.25 30 14 12 10 8 7 6 5 5 4

1.25 40 15 12 11 9 8 7 6 5 5

1.25 50 15 13 11 9 8 7 6 5 5

1.50 10 10 8 7 6 5 5 4 4 3

1.50 20 14 11 10 8 7 6 5 5 4

1.50 25 15 12 10 8 7 7 6 5 5

1.50 30 16 13 11 9 8 7 6 6 5

1.50 40 17 14 12 10 8 7 6 6 5

1.50 50 17 14 12 10 8 8 6 6 5

2.00 10 12 10 8 7 6 5 4 4 4

2.00 20 16 13 11 9 8 7 6 6 5

2.00 25 17 14 12 10 8 8 6 6 5

2.00 30 18 15 13 10 9 8 7 6 6

2.00 40 19 16 14 11 10 9 7 7 6

2.00 50 20 16 14 11 10 9 7 7 6

3.00 10 12 10 8 7 6 5 4 4 4

3.00 20 16 13 11 9 8 7 6 6 5

3.00 25 17 14 12 10 8 8 6 6 5

3.00 30 18 15 13 10 9 8 7 6 6

3.00 40 19 16 14 11 10 9 7 7 6

3.00 50 20 16 14 11 10 9 7 7 6

 
247 

Appendix F. Sample Size Allocation Using MSHA Data from 

the Second Quarter of 2002 

 
248 
249 

Table F-1. Sample Allocation for Underground Coal Mines 

Stratum

Number 

of 

Mines

Percentage 

of Total 

Mines

Number of 

Employees

Percentage 

of Total 

Employees

Sample 

Mines

Eligibility 

Rate

Response 

Rate

Responding 

Eligible 

Mines

1–9 102 19% 461 1% 56 85% 80% 3810–25 149 27% 2,589 7% 68 90% 80% 49

26–50 146 26% 5,206 15% 67 90% 80% 4851–75 49 9% 3,098 9% 35 95% 80% 2776–100 22 4% 1,917 5% 22 95% 80% 17101–250 49 9% 8,301 24% 49 99% 80% 39251+ 34 6% 13,477 38% 34 99% 80% 27

Total 551 100% 35,049 100% 331 244

Stratum

Employees 

Sampled Per Mine

Total 

Sample 

Employees

Nonresponse 

Adjusted 

Mine Weight

Average 

Employee 

Weight

Mine 

DEFF

Employee 

Dw

Employee 

ρ

Employee 

Dc

Employee 

DEFF

1–9 5 172 2.3 2.3 1.0 1.0 5% 1.2 1.210–25 17 851 2.7 2.7 1.0 1.0 5% 1.8 1.8

26–50 18 860 2.7 5.4 1.0 1.0 5% 1.8 1.851–75 21 561 1.8 5.3 1.0 1.0 3% 1.6 1.676–100 22 364 1.3 5.0 1.0 1.0 3% 1.6 1.6101–250 23 908 1.3 9.1 1.0 1.0 1% 1.2 1.3251+ 24 651 1.3 20.5 1.0 1.1 1% 1.2 1.3

Total 4,366 1.1 1.6 3% 1.5 2.5
250 

Table F-2. Sample Allocation for Surface Coal Mines 

Stratum

Number 

of 

Mines

Percentage 

of Total 

Mines

Number of 

Employees

Percentage 

of Total 

Employees

Sample 

Mines

Eligibility 

Rate

Response 

Rate

Responding 

Eligible 

Mines

1–9 518 46% 2,193 6% 101 85% 80% 6910–25 252 23% 4,166 12% 84 90% 80% 60

26–50 188 17% 6,860 19% 75 90% 80% 5451–75 58 5% 3,500 10% 36 95% 80% 2776–100 24 2% 2,068 6% 20 95% 80% 15101–250 52 5% 8,114 23% 52 99% 80% 41251+ 23 2% 8,823 25% 23 99% 80% 18

Total 1,115 100% 35,724 100% 391 285

Stratum

Employees 

Sampled Per Mine

Total 

Sample 

Employees

Nonresponse 

Adjusted 

Mine Weight

Average 

Employee 

Weight

Mine 

DEFF

Employee 

Dw

Employee 

ρ

Employee 

Dc

Employee 

DEFF

1–9 4 291 6.4 6.4 1.0 1.0 5% 1.2 1.210–25 17 1,000 3.8 3.8 1.0 1.0 5% 1.8 1.8

26–50 18 985 3.1 6.3 1.0 1.0 5% 1.9 1.9

51–-75 20 550 2.0 6.0 1.0 1.0 3% 1.6 1.676–100 22 327 1.5 6.0 1.0 1.0 3% 1.6 1.6101–250 23 935 1.3 8.6 1.0 1.1 1% 1.2 1.3251+ 25 461 1.3 19.0 1.0 1.1 1% 1.2 1.4

Total 4,549 1.3 1.4 5% 1.7 2.4
251 

Table F-3. Sample Allocation for Underground Metal Mines 

Stratum

Number 

of 

Mines

Percentage 

of Total 

Mines

Number of 

Employees

Percentage 

of Total 

Employees

Sample 

Mines

Eligibility 

Rate

Response 

Rate

Responding 

Eligible 

Mines

1–9 18 35% 92 2% 18 85% 80% 1210–25 7 14% 123 2% 7 90% 80% 5

26–50 4 8% 171 3% 4 90% 80% 351–75 2 4% 125 2% 2 95% 80% 276–100 3 6% 264 5% 3 95% 80% 2101–250 12 24% 1,844 36% 12 99% 80% 10251+ 5 10% 2,476 49% 5 99% 80% 4

Total 51 100% 5,095 100% 51 37

Stratum

Employees 

Sampled Per Mine

Total 

Sample 

Employees

Nonresponse 

Adjusted 

Mine Weight

Average 

Employee 

Weight

Mine 

DEFF

Employee 

Dw

Employee 

ρ

Employee 

Dc

Employee 

DEFF

1–9 5 63 1.3 1.3 1.0 1.0 5% 1.2 1.210–25 18 89 1.3 1.3 1.0 1.0 5% 1.8 1.8

26–50 21 62 1.3 2.5 1.0 1.0 5% 2.0 2.051–75 21 32 1.3 3.8 1.0 1.0 3% 1.6 1.676–100 22 50 1.3 5.0 1.0 1.0 3% 1.6 1.6101–250 23 222 1.3 8.2 1.0 1.1 1% 1.2 1.3

251+ 24 96 1.3 25.4 1.0 1.4 1% 1.2 1.7

Total 613 1.0 2.5 3% 1.5 3.7
252 

Table F-4. Sample Allocation for Surface Metal Mines 

Stratum

Number 

of 

Mines

Percentage 

of Total 

Mines

Number of 

Employees

Percentage 

of Total 

Employees

Sample 

Mines

Eligibility 

Rate

Response 

Rate

Responding 

Eligible 

Mines

1–9 54 34% 235 1% 54 85% 80% 3710–25 27 17% 438 2% 27 90% 80% 19

26–50 10 6% 356 2% 10 90% 80% 751–75 9 6% 591 3% 9 95% 80% 776–100 12 7% 1,094 5% 12 95% 80% 9101–250 19 12% 2,959 13% 19 99% 80% 15251+ 30 19% 17,703 76% 30 99% 80% 24

Total 161 100% 23,376 100% 161 118

Stratum

Employees 

Sampled Per Mine

Total 

Sample 

Employees

Nonresponse 

Adjusted 

Mine Weight

Average 

Employee 

Weight

Mine 

DEFF

Employee 

Dw

Employee 

ρ

Employee 

Dc

Employee 

DEFF

1–9 4 160 1.3 1.3 1.0 1.0 5% 1.2 1.210–25 16 315 1.3 1.3 1.0 1.0 5% 1.8 1.8

26–50 18 128 1.3 2.5 1.0 1.0 5% 1.8 1.851–75 22 150 1.3 3.8 1.0 1.0 3% 1.6 1.676–100 23 208 1.3 5.0 1.0 1.0 3% 1.7 1.7101–250 23 344 1.3 8.5 1.0 1.1 1% 1.2 1.3251+ 24 581 1.3 30.2 1.0 1.4 1% 1.2 1.7

Total 1,886 1.0 2.7 3% 1.4 3.9
253 

Table F-5. Sample Allocation for Underground Nonmetal Mines 

Stratum

Number 

of 

Mines

Percentage 

of Total 

Mines

Number of 

Employees

Percentage 

of Total 

Employees

Sample 

Mines

Eligibility 

Rate

Response 

Rate

Responding 

Eligible 

Mines

1–9 12 29% 50 1% 12 85% 80% 810–25 2 5% 38 1% 2 90% 80% 1

26–50 8 20% 290 6% 8 90% 80% 651–75 4 10% 232 5% 4 95% 80% 376–100 1 2% 80 2% 1 95% 80% 1101–250 9 22% 1,634 34% 9 99% 80% 7251+ 5 12% 2,431 51% 5 99% 80% 4

Total 41 100% 4,755 100% 41 30

Stratum

Employees 

Sampled Per Mine

Total 

Sample 

Employees

Nonresponse 

Adjusted 

Mine Weight

Average 

Employee 

Weight

Mine 

DEFF

Employee 

Dw

Employee 

ρ

Employee 

Dc

Employee 

DEFF

1–9 4 34 1.25 1.3 1.0 1.00 5% 1.2 1.210–25 19 27 1.25 1.3 1.0 1.00 5% 1.9 1.9

26–50 18 104 1.25 2.5 1.0 1.00 5% 1.9 1.9

51–75 19 59 1.25 3.8 1.0 1.00 3% 1.6 1.6

76–100 20 15 1.25 5.0 1.0 1.00 3% 1.6 1.6101–250 24 169 1.25 9.6 1.0 1.03 1% 1.2 1.3

251+ 24 96 1.25 25.1 1.0 1.26 1% 1.2 1.5

Total 504 1.0 2.18 3% 1.1 2.4
254 

Table F-6. Sample Allocation for Surface Nonmetal Mines 

Stratum

Number 

of 

Mines

Percentage 

of Total 

Mines

Number of 

Employees

Percentage 

of Total 

Employees

Sample 

Mines

Eligibility 

Rate

Response 

Rate

Responding 

Eligible 

Mines

1–9 347 53% 1,454 8% 92 85% 80% 6310–25 136 21% 2,094 12% 65 90% 80% 47

26–50 73 11% 2,768 15% 46 90% 80% 3351–75 45 7% 2,799 16% 34 95% 80% 2676–100 14 2% 1,191 7% 14 99% 80% 11101–250 25 4% 3,790 21% 25 99% 80% 20251+ 10 2% 3,785 21% 10 99% 80% 8

Total 650 100% 17,881 100% 286 207

Stratum

Employees 

Sampled Per Mine

Total 

Sample 

Employees

Nonresponse 

Adjusted 

Mine Weight

Average 

Employee 

Weight

Mine 

DEFF

Employee 

Dw

Employee 

ρ

Employee 

Dc

Employee 

DEFF

1–9 4 262 4.71 4.7 1.0 1.00 5% 1.2 1.210–25 15 721 2.62 2.6 1.0 1.00 5% 1.7 1.7

26–50 19 628 1.98 4.0 1.0 1.00 5% 1.9 1.951–75 21 536 1.65 5.0 1.0 1.00 3% 1.6 1.676–100 21 236 1.25 5.0 1.0 1.00 3% 1.6 1.6101–250 23 450 1.25 8.3 1.0 1.04 1% 1.2 1.3251+ 24 191 1.25 19.6 1.0 1.15 1% 1.2 1.4

Total 3023 1.2 1.65 3% 1.0 1.6
255 

Table F-7. Sample Allocation for Underground Stone Mines 

Stratum

Number 

of 

Mines

Percentage 

of Total 

Mines

Number of 

Employees

Percentage 

of Total 

Employees

Sample 

Mines

Eligibility 

Rate

Response 

Rate

Responding 

Eligible 

Mines

1–9 20 18% 102 3% 20 85% 80% 1410–25 48 43% 766 22% 35 90% 80% 25

26–50 28 25% 955 27% 23 90% 80% 1751–75 10 9% 610 17% 10 95% 80% 876–100 1 1% 91 3% 1 95% 80% 1101–250 3 3% 377 11% 3 99% 80% 2251+ 1 1% 637 18% 1 99% 80% 1

Total 111 100% 3,538 100% 93 67

Stratum

Employees 

Sampled Per Mine

Total 

Sample 

Employees

Nonresponse 

Adjusted 

Mine Weight

Average 

Employee 

Weight

Mine 

DEFF

Employee 

Dw

Employee 

ρ

Employee 

Dc

Employee 

DEFF

1–9 5 69 1.3 1.3 1.0 1.000 5% 1.2 1.210–25 16 402 1.7 1.7 1.0 1.000 5% 1.7 1.7

26–50 17 282 1.5 3.0 1.0 1.000 5% 1.8 1.851–75 20 155 1.3 3.8 1.0 1.000 3% 1.6 1.676–100 23 17 1.3 5.0 1.0 1.000 3% 1.7 1.7

101–250 22 53 1.3 7.1 1.0 1.007 1% 1.2 1.2251+ 25 19 1.3 32.5 1.0 1.000 1% 1.2 1.2

Total 998 1.0 2.710 3% 1.0 2.6
256 

Table F-8. Sample Allocation for Surface Stone Mines 

Stratum

Number 

of 

Mines

Percentage 

of Total 

Mines

Number of 

Employees

Percentage 

of Total 

Employees

Sample 

Mines

Eligibility 

Rate

Response 

Rate

Responding 

Eligible 

Mines

1–9 1,698 46% 8,067 11% 116 85% 80% 7910–25 1,304 35% 20,497 28% 114 90% 80% 82

26–50 402 11% 13,862 19% 95 90% 80% 6851–75 104 3% 6,356 9% 51 95% 80% 3976–100 54 1% 4,704 6% 35 95% 80% 27101–250 124 3% 17,528 24% 62 99% 80% 49251+ 6 0% 1,796 2% 6 99% 80% 5

Total 3,692 100% 72,810 100% 479 349

Stratum

Employees 

Sampled Per Mine

Total 

Sample 

Employees

Nonresponse 

Adjusted 

Mine Weight

Average 

Employee 

Weight

Mine 

DEFF

Employee 

Dw

Employee 

ρ

Employee 

Dc

Employee 

DEFF

1–9 5 375 18.3 18.3 1.0 1.000 5% 1.2 1.210–25 16 1,290 14.3 14.3 1.0 1.000 5% 1.7 1.7

26–50 17 1,179 5.3 10.6 1.0 1.000 5% 1.8 1.851–75 20 790 2.5 7.6 1.0 1.000 3% 1.6 1.6

76–100 22 579 1.9 7.7 1.0 1.000 3% 1.6 1.6101–250 23 1,126 2.5 15.4 1.0 1.046 1% 1.2 1.3

251+ 24 114 1.3 15.7 1.0 1.028 1% 1.2 1.3

Total 5,453 1.5 1.092 3% 1.0 1.1
257 

Table F-9. Sample Allocation for Sand and Gravel Mines 

Stratum

Number 

of 

Mines

Percentage 

of Total 

Mines

Number of 

Employees

Percentage 

of Total 

Employees

Sample 

Mines

Eligibility 

Rate

Response 

Rate

Responding 

Eligible 

Mines

1–3 2,589 42.6% 5,504 13.3% 119 85% 80% 814–6 1,572 25.9% 7,570 18.4% 80 85% 80% 54

7–9 748 12.3% 5,872 14.2% 37 85% 80% 2510–25 963 15.9% 13,995 33.9% 110 90% 80% 7926–50 168 2.8% 5,743 13.9% 70 95% 80% 5351–75 27 0.4% 1,607 3.9% 16 95% 80% 1276–100 3 0.0% 264 0.6% 3 99% 80% 2101–250 4 0.1% 683 1.7% 4 99% 80% 3251+ 0 0.0% 0 0.0% --- --- --- ---

Total 6,074 100.0% 41,238 100% 439 311

Stratum

Employees 

Sampled Per Mine

Total 

Sample 

Employees

Nonresponse 

Adjusted 

Mine Weight

Average 

Employee 

Weight

Mine 

DEFF

Employee 

Dw

Employee 

ρ

Employee 

Dc

Employee 

DEFF

1–3 2 172 27 27 1.00 1.00 5% 1.1 1.064–6 5 262 25 25 1.00 1.00 5% 1.2 1.19

7–9 8 198 25 25 1.00 1.00 5% 1.3 1.3410–25 15 1,151 11 11 1.00 1.00 5% 1.7 1.68

26–50 17 909 3 6 1.00 1.00 5% 1.8 1.80

51–75 20 241 2 6 1.00 1.00 3% 1.6 1.5776–100 22 52 1 5 1.00 1.00 3% 1.6 1.63

101–250 24 75 1 9 1.00 1.01 1% 1.2 1.24251+ --- --- --- --- --- --- --- --- ---

Total 3,060 1.35 1.37 5% 1.0 1.30
258 

 
259 

Appendix G. Critical Items from the Questionnaire 

 
260 

 
261 

National Survey of the Mining Population. 

Final List of Critical Items 

October 31, 2008 

Question Number Variable Name

M1a EMP_TRAIN_REF 

M1b EMP_TRAIN_INEXP 

M1c EMP_TRAIN_EXP 

M10 LANG_NON_ENG 

M11 MATS_NON_ENG 

M14 ADD_MATS_NON_ENG 

M16aa PROD_WORKERS 

SCH_DAYS_PROD 

M16ab SCH_HOURS_PROD 

M16ac ACT_HOURS_PROD 

M16ad CH_SHIFTS_PROD 

M16ae TRAV_HOURS_PROD 

TRAV_MINUTES_PROD 

M16ba PROD_SUP_WORKERS 

SCH_DAYS_PROD_SUP 

M16bb SCH_HOURS_PROD_SUP 

M16bc ACT_HOURS_PROD_SUP 

M16bd CH_SHIFTS_PROD_SUP 

M16be TRAV_HOURS_PROD_SUP 

TRAV_MINUTES_PROD_SUP 

M16ca PREP_WORKERS 

SCH_DAYS_PREP 

M16cb SCH_HOURS_PREP 

M16cc ACT_HOURS_PREP 

M17a PROD_WORKERS 

SHIFTS_DAY_PROD 

 
262 

Question Number Variable Name 

M17b PROD_SUP_WORKERS 

SHIFTS_DAY_PROD_SUP 

M17c PREP_WORKERS 

SHIFTS_DAY_PREP 

M23a USE_CONT_DEVELOP 

M23b USE_CONT_CONST 

M23c USE_CONT_DEMO 

M23d USE_CONT_DAMS 

M23e USE_CONT_EXCAV 

M23f USE_CONT_EQUIP 

M23g USE_CONT_EQUIP_SRV 

M23h USE_CONT_MATERIAL 

M23i USE_CONT_DRILL 

M23j USE_CONT_PROD 

M23k USE_CONT_MINERAL 

M23l USE_CONT_OTHER 

M24a NUM_CONT_DEVELOP 

M24b NUM_CONT_CONST 

M24c NUM_CONT_DEMO 

M24d NUM_CONT_DAMS 

M24e NUM_CONT_EXCAV 

M24f NUM_CONT_EQUIP 

M24g NUM_CONT_EQUIP_SRV 

M24h NUM_CONT_MATERIAL 

M24i NUM_CONT_DRILL 

M24j NUM_CONT_PROD 

M24k NUM_CONT_MINERAL 

M24l NUM_CONT_OTHER 

Step3 TOTAL_NUMBER 
263 

Question Number Variable Name 

E2 JOB_TITLE 

E3, 

TITLE_EXP_MNTHS 

TITLE_EXP_YRS 

E4, or 

THIS_MINE_MNTHS 

THIS_MINE_YRS 

E5 TOTAL_MINE_MNTHS 

TOTAL_MINE_YRS 

E7 WORK_LOCATE 

E8 GENDER 

E9 or LATINO 

E10 

RACE_INDIAN 

RACE_ASIAN 

RACE_BLACK RACE_HAWAIIAN 

RACE_WHITE 

 
264 
265 

Appendix H. Glossary of Mining Terms 

Unless otherwise noted, the source of the definitions in this Glossary is the Dictionary of Mining, 

Mineral, and Related Terms [American Geological Institute 1997].   
266 

   
267 

Active mining area. 1. The area, on and beneath land, related to the extraction, removal, or 

recovery of coal from its natural deposits. This term excludes coal preparation plants, areas 

associated with coal preparation plants, and post-mining areas. 2. The area in which active 

mining takes place relative also to extraction of metal ores, industrial minerals, and other 

minerals of economic value. 

Annual miner refresher training. Training given to all miners at least once a year consisting of 

8 hours of instruction reviewing the essentials of new miner training [30 CFR 48]. 

Cache. The place where provisions, safety or rescue equipment, ammunition, etc., are cached or 

hidden by trappers, miners, or prospectors, in unsettled regions 

Contractor. 1. The person who signs a contract to do certain specified work at a certain rate of 

payment. In mining, the contractor is an experienced miner or hard-heading miner. He or she 

employs other people and the work may proceed on a three-shift basis. 2. Mine worker 

undertaking special tasks on a contractual basis such as shaft sinking, development blasting, etc. 

Dedicated telephones. A type of wired communications devise used in mining operations to 

carry voice transmissions [NIOSH 2009]. 

Electronic or computerized tagging or tracking systems/devices. Technology designed to 

identify the location of miners in the event of a mine emergency. Miner tracking systems use 

wireless communications technology and can be integrated with communication networks 

[NIOSH 2009]. 

Escapeway. An opening through which the miners may leave the mine if the ordinary exit is 

obstructed. 

Face. The surface of an unbroken coal bed at the advancing end of the working place. 

Filter self-rescuers (FSRs). A type of gas mask for escape from underground mines which 

provides at least 1 hour of protection against carbon monoxide [30 CFR 75.2]. 

Flexalert (Mine Radio Systems, Canada). An emergency evacuation system that employs a low 

frequency electromagnetic field to convey information to miners wearing special cap lamp 

receivers. It is a one-way Through-the-Earth (TTE) transmission system [Schiffbauer et al n.d.]. 

Inductive coupled radios. A mining communication system that uses existing mine wires as a 

carrier for radio signals [30 CFR 49]. 

Leaky feeder communications system. A two-way radio system that features a base station on 

the surface that communicates with individual underground radio units, such as walkie-talkie 

radios. To allow radio frequencies to function underground, it is necessary to replace a standard 

surface antenna with a cable network. The cable is designed to “leak” signal, which allows radio 

transmissions to both leak from the cable and also enter the cable [Schiffbauer et al. n.d.]. 
268 

Lifelines. An emergency escape rope with directional cones designed to help evacuate an 

underground mine in the event of a fire or explosion leading employees to the slope and shaft 

rather than getting lost or confused [CAB Products n.d.]. 

Mill. A mineral treatment plant in which crushing, wet grinding, and further treatment of ore is 

conducted. A preparation facility within which metal ore is cleaned, concentrated, or otherwise 

processed before it is shipped to the customer, refiner, smelter, or manufacturer. 

Mine page phones. Self-contained battery-powered communication units that provide 

loudspeaker paging and handset party line conversation over a two-conductor telephone line 

[MSHA n.d.a]. 

New miner training. Mandatory training given to miners having no previous mining experience; 

includes instruction in the statutory rights of miners and their representatives, use of self-rescue 

devices and respiratory devices where appropriate, hazard recognition, emergency procedures, 

electrical hazards, first aid, walk-around training, and other health and safety aspects of the tasks 

to which the person will be assigned [30 CFR 46]. 

Personal Emergency Device (Mine Site Technologies, Australia). A one-way communication 

system featuring a belt-wearable device or paging receiver/cap lamp. The system generally 

consists of a transmitter capable of sending communications that can be received as a text 

message by miners [MSHA n.d.a]. 

Preparation plant. Any facility where coal is prepared for market, but by common usage it has 

come to mean a rather elaborate collection of facilities where coal is separated from its 

impurities, washed and sized, and loaded for shipment. 

Refuge chamber. An airtight, fire-resistant room in a mine used as a refuge in emergencies by 

miners unable to reach the surface. 

Rescue team. A team of workers, from five to eight strong, trained in the use of breathing 

apparatus and in rescue operations after colliery explosions or mine fires. 

Sealing Materials. Emergency supplies designed to rapidly, safely, and efficiently control 

underground mine fires by sealing off a section of the mine in order to reduce the exchange of 

oxygen to the fire. Materials should be readily available at the mine, should require minimum 

time for construction, should minimize air leakage into and out of the fire area, should be capable 

of withstanding explosion overpressures [Sapko et al. 2003]. 

Self-contained self-rescuer (SCSR). A respiratory device, usually worn on the belt by miners, 

used for the purpose of escape during mine fires and explosions. It provides the wearer with a 

closed-circuit supply of oxygen for a minimum of 10 minutes and up to 1 hour. 

Shaft. An excavation of limited area compared with its depth; made for finding or mining ore or 

coal; raising water, ore, rock, or coal; hoisting and lowering workers and material; or ventilating 

underground workings. 
269 

Stench. A substance with a distinctive, disagreeable odor put in the air current to warn 

underground workers of fire or other emergency; ethyl mercaptan is commonly used. 

Stoppings. Elongated extensible panels extending vertically from the floor to the roof of a 

passage in a mine. The panels impede the flow of air through the passageway except for a space 

at a side of the passageway because of irregularity of the side of the passageway. The stopping 

further has means for impeding the flow of air through the space comprising at least one side 

extension for the stopping [Kennedy and Kennedy 1984]. 

Tag boards. “This is a large square or rectangular board equipped with hooks. As miners enter 

the mine, they hang a brass identification tag on the board. This indicates they are in the mine. 

As they exit the mine, they remove the tag from the board to indicate they are no longer in the 

mine.” [Vaught 2008]. 

TeleMag (Transtek, United States). A wireless through-the-earth two-way voice and data 

communication system. It is a fixed station-to-station system [Schiffbauer et al. n.d.].

Through-the-Earth (TTE) technology. Communication system that is mainly limited to 

surface-to-underground. TTE requires no cabling between surface to underground and can be 

portable and worn on the person [Schiffbauer and Brune 2006]. 

 

Toolbox talks. Safety and health training discussions, often using materials developed by the 

Small Mine Office of MSHA or other organizations, that are primarily intended to educate 

mining operation workers about creating and maintaining safer working conditions [MSHA 

n.d.b].

TRACKER Tagging System (Mine Site Technologies, Australia). An underground tracking 

system developed specifically for use in underground mines and tunneling applications. The 

system tracks active tags carried by personnel or attached to vehicles and other equipment [Mine 

Site Technologies n.d.]. 

Trolley phones. A phone system that uses trolleywire-rail power circuit to carry 

communications. Signals are coupled to the trolley wire and modified trolley voltage operating 

power for communication circuits [Murphy and Parkinson 1978]. 

Voice Over Internet Protocol (VOIP) phones. A communications technology that allows you 

to make voice calls using a broadband Internet connection instead of a regular (or analog) phone 

line [FCC 2010]. 

Worksite simulations. Problem-solving exercises developed to support mine health and safety 

training. The exercises are designed to teach judgment and decision-making skills within two 

broad domains: (1) how miners respond to mine emergencies (e.g., first aid, self-rescue, and 

escape) and (2) how miners integrate safety concepts within the context and performance of 

routine production work [NIOSH 2001]. 
DHHS (NIOSH) Publication No. 2012-153

Delivering on the Nation’s promise:

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