PROCEEDINGS OF THE HUMAN FACTORS SOCIETY-30th ANNUAL MEETING- 1986

a c c i d e n t t.ype, n a t u r e of t h e i n j u r y , and p a r t of body i n j u r e d . Third, l i k e l y scenarios for each tool's associated i n j u r i e s were developed. T h i s paper r e p o r t s o n . the first comprehensive e v a l u a t i o n of hand t o o l a c c i d e n t d a t a r e l a t e d t o underground mining. A major emphasis of t h e s t u d y was t h e e s t a b l i s h m e n t of common and severe accident scenarios f o r the purpose of further empi r i ca 1 investigation.

Analysis of Hand T o o l U s e i n t h e Underground Mining I n d u s t r y S. A. Lavender, W. S . Marras, R. G . Lundquist, and T. H. Rockwell

The Ohio S t a t e U n i v e r s i t y ABSTRACT A research project that is sponsored by t h e Bureau of Mines, Department of I n t e r i o r and conducted by Ohio S t a t e U n i v e r s i t y i s a n a l y z i n g t h e a c c i d e n t s caused by hand t o o l s used i n the underground coal, m e t a l , and nonmetal mining industries. To d e s c r i b e t h e a c c i d e n t t y p e s and t h e r e s u l t i n g i n j u r i e s , a thorough s e a r c h w a s conducted of a computer d a t a base of mining-related accidents. After s o r t i n g f o r d a t a p e r t a i n i n g t o hand t o o l s , analyses w e r e c a r r i e d out t o determine l i k e l y s c e n a r i o s , and t h e i r p r o b a b i l i t y of occurrence, f o r the various hand tool injuries. This p r o j e c t , which summarized a c c i d e n t d a t a f o r a six-year p e r i o d , i s t h e f i r s t comprehensive e v a l u a t i o n of hand t o o l a c c i d e n t d a t a r e l a t e d t o underground mining. The method of accident classification, which i s based on a c c i d e n t type, p a r t of body i n j u r e d , and nature of t h e i n j u r y , allows assessment of t h e key components of t h e hand t o o l i n j u r y . Furthermore, t h i s a n a l y s i s , i n conjunction with the scenario development, provides d i r e c t i o n f o r f u t u r e r e s e a r c h i n t o hand t o o l ergonomics.

NF.THOD The d a t a f o r Underground mining a c c i d e n t s were o b t a i n e d from t h e d a t a base maintained by t h e Mine S a f e t y and Health A d m i n i s t r a t i o n (MSHA). Access t o t h e Bureau's computer system allowed e x h a u s t i v e s e a r c h i n g of MSHA's a c c i d e n t r e c o r d s between t h e y e a r s 1978 and 1983 f o r t h e underground c o a l , metal and nonmetal mining i n d u s t r i e s . For a l l t o o l s , key f i e l d s were used t o select a c c i d e n t r e c o r d s f o r underground work locations and f o r a p p r o p r i a t e mine worker a c t i v i t i e s . Hammer and a x e , jack, pry b a r , k n i f e , and wrench accidents required additional s p e c i f i c a t i o n f o r t h e key f i e l d s mining machine and s o u r c e of i n j u r y . Each record s e l e c t e d from the database contained the following f i e l d s : 1 ) Mine i d e n t i f i c a t i o n number, 2 ) Accident t y p e code, 3 ) Accident document number, 4 ) P a r t of body code, 5 ) Nature of i n j u r y code, 6 ) Source of i n j u r y code, and 7 ) Days l o s t from work. The mine i d e n t i f i c a t i o n number i s t h e 7 d i g i t code a s s i g n e d by MSHA. The a c c i d e n t type code w a s used t o s o r t d a t a i n t o 5 classes of a c c i d e n t s . The a c c i d e n t was c l a s s i f i e d an "Exertion" i n j u r y when i t w a s due t o o v e r e x e r t i o n i n l i f t i n g , pushing, p u l l i n g , throwing, o r wielding o b j e c t s . The "caught" type i n j u r y included a c c i d e n t s where t h e miner was (1)caught i n , under, between (a)moving and s t a t i o n a r y o b j e c t s , o r (b)two or more moving objects, (2)between collapsing material or b u i l d i n g s , o r (3)between in-running or meshing o b j e c t s . A "struck against" a c c i d e n t occurred when miners moved i n t o a s t a t i o n a r y o r mobile o b j e c t . "Struck- by" a c c i d e n t s occurred when miners were i n j u r e d from f a l l i n g ,

INTRODUCTION

A significant proportion of underground mining accidents are a t t r i b u t e d t o t h e u s e of hand t o o l s . Where a "hand t o o l " i s d e f i n e d as any t o o l c a r r i e d t o t h e work s i t e . To g a i n a n understanding of how hand t o o l use relates to reported i n j u r i e s, a d e s c r i p t i v e s t u d y was conducted. The o b j e c t i v e s were three-fold. F i r s t , the s t u d y i d e n t i f i e d hand t o o l s t h a t are major c o n t r i b u t o r s t o t h e accident statistics with respect t o accident frequency and l o s t t i m e . Second, t h e study described, using c o n d i t i o n a l p r o b a b i l i t i e s , t h e components of each tool's injuries with respect to

1419

PROCEEDINGS OF THE HUMAN FAC:TORS SOCIETY-30th ANNUAL MEETING-I986 f l y i n g , r o l l i n g , o r moving o b j e c t s . RESULTS AND DISCUSSION " F a l l s " included f a l l s from machines, v e h i c l e s , walkways, and work s u r f a c e s , C o n d i t i o n a l p r o b a b i l i t y trees w e r e o r f a l l s onto o r a g a i n s t o b j e c t s . constructed f o r a l l t o o l s i d e n t i f i e d a s c o n t r i b u t i n g t o t h e hand t o o l a c c i d e n t The t h i r d d a t a f i e l d contained t h e data. These t o o l s included s c a l i n g a c c i d e n t document number. This number b a r s , hammers and a x e s , pry bars, could be used t o o b t a i n a 1 t o 2 j a c k s , k n i v e s , and wrenches f o r c o a l sentence narrative describing the and metal- nonmetal (MNM) mining. accident. The fourth data field J a c k l e g d r i l l s used i n MNM mining, and contained a code f o r t h e p a r t of t h e s t o p e r s o r o t h e r pneumatic d r i l l s used body i n j u r e d . For t h e purposes of t h i s i n c o a l mining were a l s o included i n s t u d y , t h e s e codes were s o r t e d i n t o t h e hand t o o l a c c i d e n t a n a l y s i s . These f i v e anatomical u n i t s : head, t r u n k , a n a l y s e s were performed on annual d a t a a r m , l e g , and m u l t i p l e p a r t s . The l a s t c a t e g o r y w a s used when t h e i n d i v i d u a l f o r t h e y e a r s 1978 through 1983. s u f f e r e d s e v e r e i n j u r i e s t o more t h a n V a r i a t i o n s i n d a t a a s a f u n c t i o n of i n d i v i d u a l y e a r s probably reflected one body p a r t . The f i f t h d a t a f i e l d , which was t h e n a t u r e of t h e i n j u r y , yearly economic trends within the mining i n d u s t r i e s more than changes i n i d e n t i f i e d t h e i n j u r y i n terms of i t s t h e n a t u r e of t h e hand t o o l a c c i d e n t s . principal physical characteristics. Chi-square a n a l y s e s were performed t o The c l a s s i f i c a t i o n s included cuts, b r e a k s , tears, m u l t i p l e i n j u r i e s , and test t h e independence of t h e d a t a "other". The l a s t c a t e g o r y h e r e was p o p u l a t i o n from each i n d i v i d u a l year. These tests revealed there was used f o r t h e numerous p o s s i b l e i n j u r i e s s t a t i s t i c a l j u s t i f i c a t i o n i n combining n o t covered i n t h e previous four t h e d a t a from t h e i n d i v i d u a l y e a r s f o r categories. Again, the multiple all hand tools investigated. c a t e g o r y w a s used t o d e s c r i b e cases Therefore, f o r t h e purposes of t h i s where there were equally severe r e p o r t , only t h e d a t a pooled a c r o s s a l l injuries. Tears included strains, y e a r s w i l l be p r e s e n t e d and discussed. s p r a i n s , t w i s t e d body p a r t s , h e r n i a s , d i s l o c a t i o n s , and r u p t u r e d d i s c s i n t h e back. Table l a p r e s e n t s t h e 7 top-ranked t o o l s according t o l o s t t i m e f o r t h e The source of i n j u r y code, t h e coal mining industry. Table lb s i x t h d a t a f i e l d , w a s used f o r s o r t i n g p r e s e n t s t h e l o s t - t i m e rankings f o r t h e same t o o l s i n t h e m e t a l and nonmetal d a t a a s t o t h e t o o l t h a t caused t h e mining i n d u s t r i e s . The t o o l s ranking i n j u r y . The l a s t d a t a f i e l d , days l o s t h i g h i n l o s t t i m e are n o t n e c e s s a r i l y from work, provided a measure of accident severity. t h e most f r e q u e n t s o u r c e s of i n j u r y . T h i s r e s u l t shows t h e n e c e s s i t y of The d a t a were t h e n s o r t e d i n t o c o n s i d e r i n g both a c c i d e n t frequency and probability trees according t o t h e l o s t t i m e as dependent measures. As t o o l , a c c i d e n t t y p e , p a r t of body mentioned p r e v i o u s l y , t h e l a t e r measure i n j u r e d , and t h e n a t u r e of t h e i n j u r y . i s an i n d i c a t i o n of a c c i d e n t s e v e r i t y . The s t r u c t u r e of t h e p r o b a b i l i t y trees The d i s t r i b u t i o n of t h e l o s t t i m e i n provided a d e s c r i p t i o n of t h e t y p e s of t h e MNM mining i n d u s t r y demonstrates i n j u r i e s t h a t occprred along each t h a t t h e problem t o o l s a r e s c a l i n g branch, as w e l l a s t h e i r c o n d i t i o n a l b a r s . However, most of t h e l o s t time probability of occurrence. These i s d i s t r i b u t e d among t h e top 5 t o o l s i n conditional probabilities, and t h e t h e c o a l mining i n d u s t r y . T h i s r e s u l t accident narrative descriptions that indicates t h a t a t t e n t i o n should be were a v a i l a b l e through t h e d a t a b a s e given t o t h e s c a l i n g b a r s , j a c k s , pry were then used i n t h e development of b a r s , hammers and a x e s , and d r i l l s used accident scenarios. These s c e n a r i o s i n c o a l mining. I n m e t a l and nonmetal w e r e c o n s t r u c t e d f o r each t o o l to mining, however, further research d e s c r i b e t h o s e a c c i d e n t s t h a t were most should be d i r e c t e d almost e x c l u s i v e l y f r e q u e n t and most s e v e r e i n t e r m s of a t t h e j a c k l e g d r i l l and t h e s c a l i n g lost time. This s c e n a r i o was t h e n bar. compared with t h e a c c i d e n t n a r r a t i v e s f o r verification.

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PROCEEDINGS OF THE HUMAN FACTORS SOCIETY-30th ANNUAL MEETING-I986

TABLE la:

Lost-time r i s k a s s o c i a t e d w i t h t o o l u s e i n c o a l mining (1978 - 1983)

TOOL

N

....................... 1. 2. 3. 4. 5. 6. 7.

Scaling bar Jack Pry Bar IIammer/Axe Drills Wrench Knife

.-----------

760 1139 677 1104 555 430 840

TOTAL LOST DAYS

.-------

23601 22205 14065 11105 9717 5688 2258

AVERAGE DAYS PER ACCIDENT

% OF TOTAL LOST DAYS OF ALL HAND TOOL ACCIDENTS

----.__------_____--

31.05 19.50 20.75 10.05 17.51 13.20 2.69

26.63% 25.05% 15.87% 12.53% 10.96% 6.42% 2.55%

TABLE lb: Lost-time r i s k a s s o c i a t e d with t o o l use i n metal and nonmetal mining (1978 1983)

-

1. 2. 3. 4. 5. 6. 7.

Jackleg D r i l l S c a l i n g Bar Pry Bar HammerIAxe Wrench Knife Jack

1913 1033 397 405 189 162 61

18048 16546 2663 1so2 1170 304 283

Based on probability trees constructed f o r each t o o l , summary trees f o r t h e c o a l and MNM i n d u s t r i e s , f i g u r e s 1 and 2, can be compiled. These summary trees h i g h l i g h t t h e more f r e q u e n t and t h e more s e v e r e a c c i d e n t s f o r each t o o l i n each i n d u s t r y . I n the MNM mining ( f i g u r e l ) , t h e j a c k l e g d r i l l accounts f o r t h e most i n j u r i e s and t h e most days l o s t from work. The key i n j u r i e s r e s u l t from struck-by accidents to t h e l e g s , arms, and m u l t i p l e body p a r t s . The same i n j u r y t y p i f i e s s c a l i n g b a r a c c i d e n t s . When using a jackleg drill, exertion injuries to the trunk are f a i r l y f r e q u e n t and o f t e n severe.

9.43 16.02 6.69 4.69 6.16 1.87 4.64

44.11% 40.44% 6.51% 4.65% 2.86X 0.74% 0.69%

o r struck-by i n j u r i e s t o v a r i o u s body parts. I n t h e c a s e of j a c k and pry b a r i n j u r i e s , miners are o f t e n s t r u c k by t h e bar. Likewise, i n hammer i n j u r i e s miners of t e n s t r i k e themselves r a t h e r than t h e t a r g e t . The same d e s c r i p t i o n holds true f o r knife accidents. The wrench struck-by i n j u r y tends t o occur when t h e t o o l s l i p s from a b o l t . Table 2a shows t h e 5 most f r e q u e n t accident scenarllos f o r MNM mining. Table 2b shows t h e t o p 5 s c e n a r i o s f o r t h e same i n d u s t r y when ranked by l o s t time. Likewise, t a b l e s 3a and 3b r e p r e s e n t the- t o p s c e n a r i o s i n t h e c o a l mining i n d u s t r y f o r frequency and severity, respectively. These t a b l e s are u s e f u l when a t t r i b u t i n g causal factors to the data. Accident n a r r a t i v e s support t h e i d e a t h a t th e primary proximal c a u s e of struck-by a c c i d e n t s when u s i n g a s c a l i n g b a r o r

F i g u r e 2 i n d i c a t e s t h a t t h e key i n j u r y types occurring f o r a l l t o o l s used i n underground c o a l mining are e i t h e r e x e r t i o n i n j u r i e s t o t h e trunk,

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PROCEEDINGS OF THE HUMAN FACTORS SOCIETY-30th

jackleg drill is falling debris. Given the relatively small amount of time devoted to scaling, the likelihood of injury is high.

accidents. The causes may be related to the poor lighting, poor work site preparation, or even careless use of the tool. Before solutions can be proposed, further investigation, aimed at attributing appropriate causal factors, should be conducted. Knowledge of the secondary causes, whether they are environmental, design related, defects in tool production, or insufficient training, should guide the proposed solutions. Future efforts in this research project will be concentrated in this area. Through the use of task analyses, environmental data, and work site observations, we seek to advance our understanding of the hand tool problems in the underground mining industries.

The jackleg exertion injury is often related to pulling the drill out of the hole. Often the primary cause involves a stuck drill steel. Establishing the causal factors for the numerous jack and pry bar exertion injuries seen in the coal industry is more difficult. Several hypotheses have been proposed and future research will empirically evaluate their credibility. Injuries in the coal mining industry frequently involve struck-by

TABLE 2 a :

ANNUAL MEETING-1986

Top 5 accident scenarios in metal and nonmetal mining when ranked by frequency.

TOOL

INJURY TYPE

ACCIDENT FREOUENCY

LOST DAYS

-------------____---____________________---------------1. 2. 3. 4.

Jackleg Scaling Jackleg Jackleg 5 . Jackleg

Drill Bar Drill Drill Drill

TABLE 2b:

Top 5 accident scenarios in metal and nonmetal mining when ranked by lost time.

TOOL

Struckby-Arm-Cut Struckby-Arm-Cut Struckby-Leg-Cut Caught-Arm-Cut Exertion-Trunk-Tear

INJURY TYPE

357 190 175 166 148

ACCIDENT FREQUENCY

888 597 998 935 1467

LOST

DAYS

........................................................ 1. Scaling Jackleg Scaling Jackleg Jackleg

2. 3. 4. 5.

Bar Drill Bar Drill Drill

Struckby-Leg-Break Struckby-Leg-Break Struckby-Mult-Mult Exertion-Trunk-Tear Struckby-Mult-Mult

61 56 43 148

39

2893 2331 1621 1467 1439

TABLE 3a. Top 5 accident scenarios in coal nininp when ranked by frequency TOOL

1tIJUR.Y TYPE

ACCIPENT FREOIJEMCY

LOST DAYS

____________________-----------------------------------1. Knife Pammer/Axe Vammer/Axe Jack Knife

2. 3. 4. 5.

Struckby-Arm-Cut Struckby-Arm-Cut Struckby-Arm-Break Fxertion-Trunk-Tear Ctruckby-Leg-Cut

1422

601 316 304 277 197

1725 1966 3776 8257 45 1

PROCEEDINGS OF THE HUMAN FACTORS SOCIETY-30th ANNUAL MEETING- 1986

TABLE 3b:

Top 5 accident scenario& in coal mining when ranked by lost time.

ACCIDENT TOOL IMJURY TYPE FREQUENCY ----------------------------------------.--------1. Jack Exertion-Trunk-Tear 277 Exertion-Trunk-Tear 183 2. Pry Rar 3. Scaling Bar Struckby-Leg-Break 72 4 . Iiammer/Axe Struckby-Arm-Break 304 5 . Scaling Bar S t ruckby-Mu1 t-lhl t 33

LO ST DAYS

------8257

5168 3985 3776 3492 N

Leg

Fig. 1 Tree diagram of major

injury aomponents involved in n-etal-nonmetal mining.

STBY N=1193 TUL=11329

A

JLD N=1913 TDL=18048

/

I

Caught N=318 TDL=2126 x e r t i o n N=205 TDL=2360 F a ' l l N=152 TUL=1907

Sc Bar N=1033 TOL.16546

/ /

STBY Nu774 TDL=11334

r

Arm

277 70 470

3898 26 18 2311

Arm

290

1884

Trunk

161

1587

Mu l t

/

/Nu

TDL

Trunk

61

1164

Leg 1t Trunk Arm

226 96 83 236

4402 3207 1489 1394

219 53

978 29 1

58

464

I*-

\,lea"

\\ \

Arm

STBY N=312 TUL.1314 Ham/Axe N=405 TDL=1902

\\Knife

\

N=162 TDL=304

Jack N=61 TDL=283

Leg E x e r t i o n N=67 TDL=548

Trunk

STBY N=155 TDL.304

Ann

138

256

STBY N=37 TUL=123

Arm

16

104

Arm

17

101

aught N=17 TUL=101

Fiq 2 T r e e diagram of major injury c m p n & t s involved

E x e r t i o n N=324 TDL=9878 Struck Uy N=594 TDL=9236

Trunk N=294 TUL=9205

/A \Leg

S c a l i n g Bar N-760 TDL=23601

Struck By N=601 TUL=19796

Leg N=239 TDL=6763 N=67 TDL=5671 \Trunk N=94 TDL=4298

/M u l t

E x e r t i o n N=227 TUL.6648 Bar N=677 TDL=14065 Coal

Struck By N=347 TUL=5921

Trunk N=196 TDL=5372

\Ley

A m N=73 TDL.1349 ead N=142 TD L=165Y N=74 TUL=1909

Struck By N=9E3 TOL=7857

Arm N=721 TDL=6676

E x e r t i o n N=124 TDL=2808

Trunk N=91 TDL=2156

E x e r t i o n N=141 TUL=3691 Wrench N=430 TDL-56 K n i f e N=840 TDL=2258

Head N=172 TDL=1798 mi N=173 TUL=2248 N=151 TDL=2932

Trunk N=108 TDL=3230

Arm N=104 TDL=90D Struck By N.801

TDL=2215

1423

Arm N=601 TDL=1723