1 

AN ANALYSIS OF THE POTENTIAL OF ROOF SCREENING TO REDUCE WORKERS’ COMPENSATION COSTS 

S. M. Moore, National Institute for Occupational Safety and Health, Pittsburgh, PA 

J. Pollard, National Institute for Occupational Safety and Health, Pittsburgh, PA 

S. K. Bhatt, Consultant, Export, PA 

C. Mark, National Institute for Occupational Safety and Health, Pittsburgh, PA 

ABSTRACT 

Each year more than 400 coal miners are injured (fatal and nonfatal) by rock falling from between or around roof supports. Many of 

these injuries could be prevented by the installation of roof screen 

(wire mesh). However, many coal mines may be reluctant to use roof 

screen because of the added cost. The goal of this study was to 

determine the potential saving in workers’ compensation (WC)

premiums that could be achieved due to a reduction in rock fall injuries 

after roof screening. The WC rate-setting methods utilized by IL and 

KY were investigated in this study. Using actual data obtained from 

MSHA, national and state WC bodies and individual insurance 

companies (e.g. average cost per injury, loss cost rate, number of 

injuries per year, number of injuries preventable each year with roof 

screening), hypothetical mines (representing two mine sizes: 67 and 

150 employees) were constructed with realistic ranges for estimates of 

injuries and WC premium costs. Using each state’s actual WC ratesetting formulas, total savings in WC costs after a three-year period 

were determined. Across both states, savings in WC premiums 

ranged from 1.8% to 14.6% when injuries were reduced by 10% to 

20%. Additionally, an economic analysis was performed for an existing 

mine consisting of 67 employees. For this mine, the annual cost of a 

roof screening program was estimated at $240,000. If the screening 

prevented 13 “struck by” WC claims over a 3-year period at this mine, 

the reduction in WC premiums alone could pay for the entire screening 

program. 

INTRODUCTION 

More than 400 roof fall injuries are reported to MSHA each year. 

Nearly all of these injuries, which included six fatal injuries between 

2006 and 2008, are caused by rocks falling between and around roof 

supports. Technology is available to prevent the vast majority of these 

injuries and fatalities. Surface controls like straps, headers, and large 

roof bolt plates can help, but by far the most effective prevention 

technique is roof screen. Screen works best because it can cover up 

to 94% of the roof (Robertson et al., 2003). Screen also offers a first 

line of defense for roof bolter operators by confining or deflecting small 

rocks that can come loose during drilling or bolt installation. Numerous 

studies have now shown that mines that use screen routinely have 

much lower rates of “struck by” rock fall injuries. At a Maryland mine 

that the National Institute for Occupational Safety and Health (NIOSH) 

studied, there was an average of 14 roof fall injuries per year prior to 

their implementation of roof screening. The number of injuries was 

then tracked for 5 years following the implementation of roof screening 

and averaged 2.2 per year. NIOSH also studied an Illinois mine where 

there was an average of 8 injuries per year prior to roof screening. 

After implementing roof screening, the number of roof fall injuries was 

tracked for an additional 8 years. Over this 8 year period, the average 

number of injuries per year was only 0.25. Despite the fact that roof 

screening has obvious benefits to the health and safety of mine 

workers, some mining companies have yet to implement this safety 

measure due to concerns for the cost. However, by preventing injuries 

to the mine workers, roof screening has a direct impact on a mine’s 

workers’ compensation (WC) premiums. In fact, benefits in WC 

premiums may be so large that they can largely offset, or even exceed, 

the direct costs of a roof screening program. The goal of this study was 

to quantify the financial savings related to lower WC premiums that 

mining operations might expect after implementing roof screening as a 

method to reduce rock fall injuries. Estimates for WC premiums were 

determined before and after the simulated implementation of roof 

screening for hypothetical mines (representing two mine sizes: 67 and 

150 employees) in Illinois and Kentucky. 

METHODS AND RESULTS 

The WC rate-setting methods utilized by Illinois and Kentucky for 

experience rating plans were investigated. These states were selected 

because mines in the Illinois basin have higher rock fall injury rates 

than mines in other coal fields (Molinda et al., 2008). Mines in these 

states may be highly interested in reducing WC costs through various 

methodologies such as the one proposed in this study. 

WC Rate-Setting Calculations for NCCI States 

WC rate-setting functions may be performed by a State Insurance 

Fund or department of insurance. Some of these organizations 

designate these functions to rating bureaus or advisory organizations. 

The National Council on Compensation Insurance (NCCI) is the largest 

rating organization in the United States and provides services to some 

40 states. Both Illinois and Kentucky are NCCI states. Several types 

of rating plans exist whereby the general principles are similar (e.g. 

experience rating, manual rating). However, experience rating plans 

are the most common and are, therefore, the focus of this study. 

Experience rating plans encourage employers to reduce the frequency 

and severity of work-related injuries through economic incentives. 

According to NCCI, typically a company that has been paying $5,000 

average annual premium for the past few years or has paid $10,000 or 

more in a single recent year, qualifies to be experience rated. The 

experience period is usually three full policy years, ending one year 

prior to the effective date of the modification. Prior to 2008, Illinois 

mines used a different equation to arrive at the WC premium to be paid 

by each mine than they do today. However, since Illinois now employs 

the same equation as Kentucky, the currently used equation was 

implemented in both states for the purpose of this study. The NCCI 

formula used for the rating [NCCI 2003] are shown in Eqns 1 and 2. 

Primary 

Losses 

Stabilizing 

Values 

Ratable

Excess 

Total 

APL + (1 - WV) x EEL + 

+ BV 

WV x AEL Total A (1) 

EPL + (1 - WV) x EEL + 

+ BV 

WV x EEL Total B (2) 

Where, 

APL = Actual Primary Losses 

WV = Weighting Value 

EEL = Expected Excess Losses 

BV = Ballast Value 

AEL = Actual Excess Losses 

EPL = Expected Primary Losses 

The actual primary losses are the ultimate losses with each injury 

at a mine up to the primary limiting factor ($5,000). The expected 

primary losses are then determined by multiplying the D-ratio (obtained 
2 

using a table provided by NCCI (2003); this ratio determines the 

portion of a mine’s expected losses that are expected to be primary 

losses) by the expected losses, Eqn 3. The expected losses are 

determined by multiplying the expected loss rate (ELR – obtained 

using a table provided by NCCI; use classification 1016 for 

underground bituminous coal) by the payroll for the three years used in 

the rating. This value is then multiplied by 0.01 to put the number in 

terms per $100 of payroll. Expected excess losses are determined by 

subtracting the total expected primary losses from the total expected 

losses, Eqn 4. 

EPL=D-ratio x ELR x (3-year pay) x 0.01 (3) 

EEL=EL – EPL (4) 

The weighting value is obtained using a table from the NCCI 

Experience Rating Plan Manual and is based on the expected losses 

(Note: different tables exist for different states). The weighting value 

determines how much of the actual losses and expected excess losses 

are used in the experience rating. The weighting value increases as 

expected losses increase. The ballast value is a stabilized element 

designed to limit the effect of any single loss on the experience rating 

modification (MOD). It is added to both the actual primary losses and 

the expected primary losses. This value also increases as expected 

losses increase. 

MOD=Total A / Total B (5) 

Expected Savings with Roof Screening 

The rating period utilized for this study was 2001, 2002, and 2003 

yielding WC costs for the year 2005 (recall, the equation used from 

2008 onward for the state of Illinois will be implemented in this study 

since the former equation is no longer utilized). To demonstrate the 

expected amount of savings in WC premiums, hypothetical mines were 

created that are representative of mines that are experience rated in 

the United States. Two sizes of mines were used in the analysis, one 

with 67 employees and the other with 150 employees. Sixty-seven 

employees was chosen for the first mine since that was the number of 

employees at a mine NIOSH studied that performed a cost analysis for 

implementing roof screen (presented later; see Economics of Roof 

Screening). The second mine size was 150 since this would depict the 

cost savings that may be expected for some of the larger mines in 

these states. In order to estimate the savings in WC premiums that 

mines of this size would experience if they implemented roof 

screening, the following parameters were necessary: payroll for 2001, 

2002, and 2003; total number of injuries each of the three years; 

number of injuries that would have been prevented by implementing 

roof screening each of the three years; base loss cost rate in 2005; 

administrative fee multiplier applied by their insurance provider; and 

the ultimate losses associated with each injury. 

In 2005, loss cost rates for IL was $33.13 (effective 1/1/05) 

whereby $9.67 and $6.99 were for the state and federal black lung 

coverage, respectively leaving $16.47 subject to a MOD factor. (NCCI, 

2009) For KY the loss cost rate was $31.02 (effective 9/1/04) whereby 

$1.18 and $5.06 were for the state and federal black lung coverage 

leaving $24.78 subject to a MOD factor (NCCI, 2009).

Communications with NCCI and a large insurance provider in the state 

of KY (NCCI, 2009; Kentucky Employers Mutual Insurance, 2009) 

yielded information regarding typical administrative multipliers used by 

insurers in Illinois and Kentucky. The multipliers used for IL and KY 

were 1.46 and 1.115, respectively. To obtain the remaining 

parameters, several assumptions were made: 

• Payroll – The average mine worker salary in 2002 was 

determined to be $50,538 and $47,473 for IL and KY, respectively 

(U.S. Census Bureau, 2002). This salary was used to estimate 

the salaries in 2001 and 2003 by adjusting for 4.6% inflation 

between 2001-2002 and 2002-2003. An average salary of 

$51,000 and $47,000 was used for IL and KY, respectively. To 

determine the payroll this average salary was multiplied by the 

number of employees at the mine and then multiplied by three to 

account for the three calendar years of 2001, 2002, and 2003. 

• Total number of injuries – A sensitivity analysis was carried out 

where the total number of injuries over the three year period at 

both mines was defined as being 30%, 50%, and 70% of the 

number of employees. These percentages were based upon 

actual injury data reported to MSHA for experience rated mines in 

IL and KY which demonstrated that the total number of injuries at 

these mines ranged from 30%-70% of the total number of 

employees. Based on data obtained from NCCI, it was 

determined that more WC claims are submitted due to differences 

in what is considered a reportable injury. It was found that 1.4 

and 1.8 times as many claims were submitted to NCCI as were 

reported to MSHA for IL and KY, respectively. Therefore, the total 

number of injuries were then multiplied by these factors to get the 

total number of injuries used in this study. 

• Number of preventable injuries – The sensitivity analysis was 

extended to cases where 10%, 15%, and 20% of the estimated 

total number of injuries reported to NCCI were hypothetically 

prevented by roof screening. These percentages were based 

upon actual injury data reported to MSHA for experience rated 

mines in IL and KY. From these data, it was determined that the 

number of injuries deemed preventable by roof screening ranged 

from approximately 10%-20% of the total number of injuries 

reported to MSHA. (Injury narratives were read and the number 

of injuries that were considered preventable by roof screens was 

determined based upon the size of the rock(s) involved in the roof 

fall). 

• Ultimate losses per injury (actuarially determined amount; loss 

estimate at resolution of the claim based upon statistical trends 

for a specific state) – For both states, incurred losses and claims 

data were obtained from NCCI for underground coal mines and 

represented all experience rated coal mines. Using claim data 

from IL between 4/01 – 3/04, the average cost per claim was 

determined to be $28,449. For KY, claim data between 5/02 – 

4/04 yielded an average claim cost of $35,582. 

The demographics associated with each mine are shown in Table 

1 (see Appendix A)for IL and KY. The calculated parameters to obtain 

the WC cost with and without screening are shown in Table 2 (see 

Appendix A). The overall WC costs and savings when screen is 

implemented are shown in Table 3 (see Appendix A). The expected 

loss ratio used for IL was 10.21 and the discount ratio was 0.15 while 

these values were 12.9 and 0.17 for KY. The weighting value used for 

mines 1 to 9 was 0.40 and 0.56 for IL and KY, respectively, and 0.55 

and 0.67 for mines 10 to 18, respectively. Finally, the ballast value 

used for mines 1 to 9 was 133,125 and 133,900 for IL and KY, 

respectively, and 260,925 and 285,693 for mines 10 to 18, 

respectively. Again, all of these values are determined using tables 

provided by NCCI for each state. Figure 1 (see Appendix B) depicts 

the estimated percent savings in WC premiums. 

Economics of Screening 

In order to estimate what fraction of the costs associated with the 

implementation of roof screening would be offset by the reduction in 

WC premiums seen from reduced injuries, an economic analysis was 

performed. This analysis was performed for a room and pillar mine 

employing 67 people and producing 800,000 tons per year (Compton 

et al 2007). The mine operates two shifts per day with a single supersection employing two continuous miners and two roof bolters. It was 

assumed that adding roof screen did not decrease the footage of 

advance per shift as long as two roof bolters were being utilized. Other 

assumptions were: 

• The section advances 400 feet/shift in a 5-foot thick coal seam 

• Straps, costing $8 per piece, are currently installed in all headings 

and crosscuts 

• Screen installation requires an additional ten minutes per 40 feet 

of advance (Note: This additional time for screening affects the 

time to install roof support materials, but does not affect the time 

for cutting coal (production time) because that is done by the 

continuous mining machine in a different heading). 

• Screen costing $16 per piece, will replace the straps in 50% of the 

drivage 

• Labor cost (fully loaded) is $40/hour 

• Maintenance costs may be excluded as they are not normally 

required for screening 
3 

The incremental costs associated with the roof screening program 

can be calculated as follows: 

• Cost of screen = $2/ft. 

• Cost of labor to install screen = 0.25 minutes/ft with two roof 

bolter operators = $0.33/ft. 

• Cost of supplying screen to the section is approximately $0.10/ft. 

The total cost for installing screen is therefore approximately 

$2.43/ft or $0.58/ton. If screen is installed in 50% of the drivage, the 

cost per ton for the mine drops to $0.29/ton. If this one-section mine 

produces 800,000 tons annually, the yearly cost for the screen 

installation is $240,000. 

Mines 1 to 9 of KY have demographics that are a reasonable 

approximation to the mine that the economic analysis was performed 

from. For these mines, the annual savings in WC premiums ranged 

from $51,000 to $241,000. Therefore, it is possible that savings in WC 

premiums may entirely offset the cost of roof screening. 

However, it is important to consider the additional savings beyond 

those of WC premiums. “Struck By” injuries incur many other costs to 

a mining operation. There will be direct administrative costs to replace 

these injured workers, costs to train a new replacement worker, and 

production delays due to inexperienced workers on the continuous 

miner or roof bolter. A roof fall that causes an injury will also cause 

production delays due to MSHA inspection of the fall area and 

plan/operational changes made to accommodate MSHA requirements 

to prevent further “Struck By” accidents. “Struck By” injuries will have 

a negative effect on the morale of the entire underground work force 

and may make the miners question their own safety. There may also 

be legal costs linked to “Struck By” injuries such as fines or penalties 

related to reportable injuries, legal fees, possible “gross negligence” 

law suits, and an increase in overall insurance costs due to the 

negative impact on mine property injury statistics. It should also be 

noted that the costs discussed in this paper are from the employer’s 

perspective and not from a societal perspective which would also 

include the costs associated with pain and suffering of the mine worker 

and the consequences this would place on their families. 

The total economic benefits to a mine that installs roof screen as 

part of their regular mining cycle can therefore be substantial. A mine 

that installs roof screen during the mining cycle will see cost savings 

by: 

• Reducing cost of replacing injured workers, 

• Improving workforce morale and reducing turnover of face 

workers, 

• Reducing immediate requirements for spot bolting to support bolts 

that become loose due to deteriorating roof conditions, 

• Minimizing production losses due to clean-up and re-support of 

important belt, travel, and escape entries, 

• Reducing major roof falls by providing confinement between bolts 

and preventing unraveling up above bolt anchorage. 

DISCUSSION 

In this study, the methods utilized by IL, and KY to determine a 

mine’s WC premiums were detailed. Additionally, the WC savings 

incurred when roof screening is implemented were calculated for 18 

hypothetical mines in both IL and KY. The 18 mines represented a 

sensitivity analysis where the number of total injuries and the number 

of injuries that could have been prevented with roof screening were 

varied. This was done for a medium sized mine (67 employees) and 

for a larger mine (150 employees). It was demonstrated that reducing 

actual losses by a set dollar amount does not reduce WC premiums by 

that same dollar amount. However, across both states, savings in WC 

premiums ranged from 1.8% to 14.6% when injuries were reduced by 

10% to 20%. For mines with a larger number of employees, and thus 

a larger payroll, the percent savings in WC premiums was greater than 

that of a smaller mine with similar percentage improvement. Finally, a 

general cost estimate was generated for incorporating roof screening 

into a mines process for a real mine with 67 employees ($240,000). 

Thus, since this was for specific mine demographics, the cost may be 

more or less for other operations. 

There were several limitations to the current study. The mines 

utilized in the study were hypothetical as opposed to using real mine 

demographic and injury data. The total number of injuries and the 

preventable injuries at each hypothetical mine were based upon injury 

data obtained from the MSHA injury database in each state. Another 

limitation to the study was that, for each state, an average injury cost 

was used instead of determining the true injury costs associated with 

known injuries at a specific mine. The economic analysis of roof 

screening presented was only for one mine of 67 employees; however, 

these numbers were based on an actual mine giving them more 

validity than a completely hypothetical estimation of costs. Finally, it 

should be noted that large coal companies tend to purchase nonstandard WC policies. Specifically, there would be some type of risk 

sharing policy such as a large deductible or they may be self-insured 

and purchase an excess WC policy. For the latter case, the cost 

associated with every claim eliminated through roof screening is 

directly saved by the company. Additional savings would then be 

observed by the reduction in the MOD associated with the excess WC 

policy. 

The data presented in this study demonstrate that a savings in 

WC costs may be expected after roof screening for a three-year 

period. While the savings in WC is less than the value saved in direct 

injury costs, these savings are still substantial. Future studies, such as 

those conducted by Compton et al. (2007), should evaluate the 

methodology used for roof screening to assess the physical demands 

on the worker and suggest work station design to minimize these 

demands. In the future more detailed information on the application of 

WC rate-setting methods for IL, KY, and PA will be published in an 

Information Circular by NIOSH. 

ACKNOWLEDGEMENTS 

The authors thank Deno M. Pappas of NIOSH for assistance with 

the MSHA database on accident statistics and the National Council on 

Compensation Insurance, Rockwood Casualty Insurance Company, 

Kentucky Employers Mutual Insurance, and Petroleum Casualty 

Company for providing useful information on compensation insurance. 

REFERENCES 

Compton C., Gallagher S., Molinda G., Mark C. and Wilson G. [2007]. 

Roof Screening for Underground Coal Mines: Recent 

Developments. Proceedings of the 26th International Conference 

on Ground Control in Mining, Morgantown, WV, July 31-August 2, 

2007 pp. 270 – 276. 

Kentucky Employers Mutual Insurance [2009]. Personal 

Communications with Mike Prickett, Product Development 

Manager, October. 

National Council on Compensation Insurance, Inc. (NCCI) [2003]. 

Experience Rating Plan Manual. www.ncci.com. 

National Council on Compensation Insurance, Inc. (NCCI) [2009]. 

Personal Communications with Customer Service. Boca Raton, 

FL, September. 

National Council on Compensation Insurance, Inc. (NCCI) [2009]. 

Personal Communications with Karen Ayers, Director and 

Actuary, Actuarial and Economic Services Division, October. 

Molinda GM, Mark C, Pappas D, Klemetti T [2008]. Overview of 

ground control issues in the Illinois Basin. SME Transactions, vol. 

324, pp. 41-48 

Robertson S., Molinda G., Dolinar D, Pappas D. and Hinshaw G. 

[2003]. Best Practices and Bolting Machine Innovations for Roof 

Screening. SME Preprint No. 03-158. pp. 1-8 

U.S. Census Bureau [2002]. Economic Census. Mining Industry 

Series Report. Bituminous Coal Underground Mining. Pp. 1-8. 
4 

APPENDIX A 

Table 1. Demographics of each Illinois and Kentucky hypothetical mine. 

# Empl Total Inj 

(over 3 yrs) 

Prev Inj 

(over 3 

yrs) 

Avg Loss Loss Cost Rate Payout/ Yearly Payout (excluding black lung) Injury 

Admin Fee Avg Yearly 

Salary 1 Year Payroll 

Illinois Hypothetical Mines 

Mine 1 67 28 3 $28,449 $799,417 $16.47 1.46 $51,000 $3,417,000

Mine 2 67 28 4 $28,449 $799,417 $16.47 1.46 $51,000 $3,417,000

Mine 3 67 28 6 $28,449 $799,417 $16.47 1.46 $51,000 $3,417,000

Mine 4 67 47 5 $28,449 $1,334,258 $16.47 1.46 $51,000 $3,417,000

Mine 5 67 47 7 $28,449 $1,334,258 $16.47 1.46 $51,000 $3,417,000

Mine 6 67 47 9 $28,449 $1,334,258 $16.47 1.46 $51,000 $3,417,000

Mine 7 67 66 7 $28,449 $1,869,099 $16.47 1.46 $51,000 $3,417,000

Mine 8 67 66 10 $28,449 $1,869,099 $16.47 1.46 $51,000 $3,417,000

Mine 9 67 66 13 $28,449 $1,869,099 $16.47 1.46 $51,000 $3,417,000

Mine 10 150 63 6 $28,449 $1,792,287 $16.47 1.46 $51,000 $7,650,000

Mine 11 150 63 10 $28,449 $1,792,287 $16.47 1.46 $51,000 $7,650,000

Mine 12 150 63 13 $28,449 $1,792,287 $16.47 1.46 $51,000 $7,650,000

Mine 13 150 105 11 $28,449 $2,987,145 $16.47 1.46 $51,000 $7,650,000 

Mine 14 150 105 16 $28,449 $2,987,145 $16.47 1.46 $51,000 $7,650,000 

Mine 15 150 105 21 $28,449 $2,987,145 $16.47 1.46 $51,000 $7,650,000 

Mine 16 150 147 15 $28,449 $4,182,003 $16.47 1.46 $51,000 $7,650,000 

Mine 17 150 147 22 $28,449 $4,182,003 $16.47 1.46 $51,000 $7,650,000 

Mine 18 150 147 29 $28,449 $4,182,003 $16.47 1.46 $51,000 $7,650,000 

Kentucky Hypothetical Mines 

Mine 1 67 36 4 $35,582 $1,288,068 $24.78 1.115 $47,000 $3,149,000

Mine 2 67 36 5 $35,582 $1,288,068 $24.78 1.115 $47,000 $3,149,000

Mine 3 67 36 7 $35,582 $1,288,068 $24.78 1.115 $47,000 $3,149,000

Mine 4 67 60 6 $35,582 $2,145,595 $24.78 1.115 $47,000 $3,149,000

Mine 5 67 60 9 $35,582 $2,145,595 $24.78 1.115 $47,000 $3,149,000

Mine 6 67 60 12 $35,582 $2,145,595 $24.78 1.115 $47,000 $3,149,000

Mine 7 67 84 8 $35,582 $3,003,121 $24.78 1.115 $47,000 $3,149,000

Mine 8 67 84 13 $35,582 $3,003,121 $24.78 1.115 $47,000 $3,149,000

Mine 9 67 84 17 $35,582 $3,003,121 $24.78 1.115 $47,000 $3,149,000

Mine 10 150 81 8 $35,582 $2,882,142 $24.78 1.115 $47,000 $7,050,000

Mine 11 150 81 12 $35,582 $2,882,142 $24.78 1.115 $47,000 $7,050,000

Mine 12 150 81 16 $35,582 $2,882,142 $24.78 1.115 $47,000 $7,050,000

Mine 13 150 135 14 $35,582 $4,803,570 $24.78 1.115 $47,000 $7,050,000 

Mine 14 150 135 20 $35,582 $4,803,570 $24.78 1.115 $47,000 $7,050,000 

Mine 15 150 135 27 $35,582 $4,803,570 $24.78 1.115 $47,000 $7,050,000 

Mine 16 150 189 19 $35,582 $6,724,998 $24.78 1.115 $47,000 $7,050,000 

Mine 17 150 189 28 $35,582 $6,724,998 $24.78 1.115 $47,000 $7,050,000 

Mine 18 150 189 38 $35,582 $6,724,998 $24.78 1.115 $47,000 $7,050,000 
 

APPENDIX A (cont’d) 

Table 2. Factors to calculate the MOD for Illinois and Kentucky (NS = no screen, S = screen). 

Exp 

Losses, 

$k 

Exp Prim 

Losses, $k 

Exp Ex 

Losses, 

$k 

Actual Prim 

Losses, $k 

Actual Ex Losses, 

$k Total A, $k Total B, $k MOD 

Illinois 

NS S NS S NS S NS S NS S 

Mine 1 $1,047 $157 $890 $141 $127 $659 $593 $1,071 $1,031 $1,180 $1,180 0.908 0.874 

Mine 2 $1,047 $157 $890 $141 $120 $659 $560 $1,071 $1,011 $1,180 $1,180 0.908 0.857 

Mine 3 $1,047 $157 $890 $141 $113 $659 $528 $1,071 $990 $1,180 $1,180 0.908 0.840 

Mine 4 $1,047 $157 $890 $235 $211 $1,100 $990 $1,341 $1,274 $1,180 $1,180 1.137 1.080 

Mine 5 $1,047 $157 $890 $235 $200 $1,100 $936 $1,341 $1,241 $1,180 $1,180 1.137 1.052 

Mine 6 $1,047 $157 $890 $235 $188 $1,100 $879 $1,341 $1,206 $1,180 $1,180 1.137 1.022 

Mine 7 $1,047 $157 $890 $329 $296 $1,541 $1,386 $1,612 $1,517 $1,180 $1,180 1.366 1.286 

Mine 8 $1,047 $157 $890 $329 $280 $1,541 $1,311 $1,612 $1,471 $1,180 $1,180 1.366 1.247 

Mine 9 $1,047 $157 $890 $329 $263 $1,541 $1,233 $1,612 $1,423 $1,180 $1,180 1.366 1.206 

Mine 10 $2,343 $351 $1,992 $315 $284 $1,477 $1,330 $2,285 $2,172 $2,604 $2,604 0.877 0.834 

Mine 11 $2,343 $351 $1,992 $315 $268 $1,477 $1,255 $2,295 $2,125 $2,615 $2,615 0.878 0.813 

Mine 12 $2,343 $351 $1,992 $315 $252 $1,477 $1,182 $2,295 $2,070 $2,615 $2,615 0.878 0.792 

Mine 13 $2,343 $351 $1,992 $525 $473 $2,462 $2,216 $3,047 $2,859 $2,615 $2,615 1.165 1.093 

Mine 14 $2,343 $351 $1,992 $525 $446 $2,462 $2,092 $3,047 $2,764 $2,615 $2,615 1.165 1.057 

Mine 15 $2,343 $351 $1,992 $525 $420 $2,462 $1,970 $3,047 $2,671 $2,615 $2,615 1.165 1.022 

Mine 16 $2,343 $351 $1,992 $735 $662 $3,447 $3,102 $3,799 $3,536 $2,615 $2,615 1.453 1.352 

Mine 17 $2,343 $351 $1,992 $735 $625 $3,447 $2,929 $3,799 $3,403 $2,615 $2,615 1.453 1.302 

Mine 18 $2,343 $351 $1,992 $735 $588 $3,447 $2,758 $3,799 $3,273 $2,615 $2,615 1.453 1.252 

Kentucky 

Mine 1 $1,219 $207 $1,011 $181 $163 $1,107 $997 $1,380 $1,300 $1,353 $1,353 1.020 0.961 

Mine 2 $1,219 $207 $1,011 $181 $154 $1,107 $942 $1,380 $1,260 $1,353 $1,353 1.020 0.932 

Mine 3 $1,219 $207 $1,011 $181 $145 $1,107 $887 $1,380 $1,221 $1,353 $1,353 1.020 0.902 

Mine 4 $1,219 $207 $1,011 $302 $272 $1,844 $1,661 $1,913 $1,780 $1,353 $1,353 1.414 1.316 

Mine 5 $1,219 $207 $1,011 $302 $257 $1,844 $1,569 $1,913 $1,714 $1,353 $1,353 1.414 1.267 

Mine 6 $1,219 $207 $1,011 $302 $241 $1,844 $1,474 $1,913 $1,645 $1,353 $1,353 1.414 1.217 

Mine 7 $1,219 $207 $1,011 $422 $380 $2,581 $2,324 $2,446 $2,261 $1,353 $1,353 1.809 1.671 

Mine 8 $1,219 $207 $1,011 $422 $359 $2,581 $2,193 $2,446 $2,165 $1,353 $1,353 1.809 1.601 

Mine 9 $1,219 $207 $1,011 $422 $338 $2,581 $2,064 $2,446 $2,072 $1,353 $1,353 1.809 1.532 

Mine 10 $2,728 $464 $2,265 $405 $365 $2,477 $2,229 $3,098 $2,891 $3,014 $3,014 1.028 0.959 

Mine 11 $2,728 $464 $2,265 $405 $344 $2,477 $2,104 $3,098 $2,787 $3,014 $3,014 1.028 0.925 

Mine 12 $2,728 $464 $2,265 $405 $324 $2,477 $1,982 $3,098 $2,685 $3,014 $3,014 1.028 0.891 

Mine 13 $2,728 $464 $2,265 $675 $608 $4,129 $3,716 $4,474 $4,130 $3,014 $3,014 1.484 1.370 

Mine 14 $2,728 $464 $2,265 $675 $574 $4,129 $3,508 $4,474 $3,957 $3,014 $3,014 1.484 1.313 

Mine 15 $2,728 $464 $2,265 $675 $540 $4,129 $3,303 $4,474 $3,786 $3,014 $3,014 1.484 1.256 

Mine 16 $2,728 $464 $2,265 $945 $851 $5,780 $5,202 $5,851 $5,369 $3,014 $3,014 1.941 1.781 

Mine 17 $2,728 $464 $2,265 $945 $803 $5,780 $4,911 $5,851 $5,127 $3,014 $3,014 1.941 1.701 

Mine 18 $2,728 $464 $2,265 $945 $756 $5,780 $4,624 $5,851 $4,887 $3,014 $3,014 1.941 1.621 

Table 3. Workers’ compensation costs and savings for Illinois and Kentucky (NS = no screen, S = screen). 


5 

Illinois Kentucky


WC Per $100 

Payroll 

WC Per $100 

Payroll with 

Admin Fee 

WC Premium, $k 

WC 

Savings, 

$k 

WC Per $100

Payroll

WC Per $100 

Payroll with WC Premium, $k 

Admin Fee 

WC

Savings,

$k 

NS S NS S NS S NS S NS S NS S 

Mine 1 $31.61 $31.05 $46.15 $45.33 $1,577 $1,549 $28 $31.52 $30.06 $35.15 $33.52 $1,107 $1,056 $51 

Mine 2 $31.61 $30.77 $46.15 $44.92 $1,577 $1,535 $42 $31.52 $29.33 $35.15 $32.71 $1,107 $1,030 $77 

Mine 3 $31.61 $30.49 $46.15 $44.51 $1,577 $1,521 $56 $31.52 $28.60 $35.15 $31.89 $1,107 $1,004 $102 

Mine 4 $35.39 $34.44 $51.66 $50.29 $1,765 $1,718 $47 $41.29 $38.86 $46.04 $43.33 $1,450 $1,364 $85 

Mine 5 $35.39 $33.98 $51.66 $49.61 $1,765 $1,695 $70 $41.29 $37.64 $46.04 $41.97 $1,450 $1,322 $128 

Mine 6 $35.39 $33.50 $51.66 $48.91 $1,765 $1,671 $94 $41.29 $36.39 $46.04 $40.57 $1,450 $1,278 $172 

Mine 7 $39.16 $37.83 $57.17 $55.24 $1,954 $1,887 $66 $51.06 $47.65 $56.93 $53.13 $1,793 $1,673 $120 

Mine 8 $39.16 $37.19 $57.17 $54.30 $1,954 $1,855 $98 $51.06 $45.91 $56.93 $51.19 $1,793 $1,612 $181 

Mine 9 $39.16 $36.53 $57.17 $53.33 $1,954 $1,822 $131 $51.06 $44.21 $56.93 $49.29 $1,793 $1,552 $241 

Mine 10 $31.11 $30.40 $45.42 $44.38 $3,475 $3,395 $80 $31.71 $30.01 $35.35 $33.46 $2,492 $2,359 $133 

Mine 11 $31.12 $30.05 $45.43 $43.87 $3,476 $3,356 $120 $31.71 $29.15 $35.35 $32.50 $2,492 $2,291 $201 

Mine 12 $31.12 $29.70 $45.43 $43.36 $3,476 $3,317 $159 $31.71 $28.31 $35.35 $31.57 $2,492 $2,226 $267 

Mine 13 $35.85 $34.67 $52.34 $50.62 $4,004 $3,872 $132 $43.02 $40.19 $47.97 $44.82 $3,382 $3,160 $222 

Mine 14 $35.85 $34.07 $52.34 $49.74 $4,004 $3,805 $199 $43.02 $38.77 $47.97 $43.23 $3,382 $3,048 $334 

Mine 15 $35.85 $33.49 $52.34 $48.89 $4,004 $3,740 $264 $43.02 $37.37 $47.97 $41.66 $3,382 $2,937 $445 

Mine 16 $40.59 $38.93 $59.26 $56.84 $4,533 $4,348 $185 $54.34 $50.38 $60.59 $56.17 $4,272 $3,960 $311 

Mine 17 $40.59 $38.10 $59.26 $55.62 $4,533 $4,255 $278 $54.34 $48.39 $60.59 $53.95 $4,272 $3,804 $468 

Mine 18 $40.59 $37.27 $59.26 $54.42 $4,533 $4,163 $370 $54.34 $46.42 $60.59 $51.76 $4,272 $3,649 $623 
6 

APPENDIX B 

1.8%

2.7%

3.6%

2.3%

3.4%

4.6%

2.7%

4.0%

5.3%

3.3%

5.0%

6.6%

3.4%

5.0%

6.7%

4.1%

6.1%

8.2%

0%

2%

4%

6%

8%

10%

12%

14%

% Savings in Workers' Compensation Premiums

5% 10% 15% 20% 25%

(Illinois)

4.6%

6.9%

9.3%

5.4%

8.1%

10.7%

5.9%

8.8%

11.9%

6.6%

9.9%

13.2%

6.7%

10.1%

13.4%

7.3%

11.0%

14.6%

0%

2%

4%

6%

8%

10%

12%

14%

5% 10% 15% 20% 25%

% Savings in Workers' Compensation Premiums

(Kentucky)

% Reduction in Injuries due to Implementing Roof Screen

30% (% of Number of Employees Injured, 67 employees) 30% (% of Number of Employees Injured, 150 employees)

50% (% of Number of Employees Injured, 67 employees) 50% (% of Number of Employees Injured, 150 employees)

70% (% of Number of Employees Injured, 67 employees) 70% (% of Number of Employees Injured, 150 employees)

Figure 1. Percent reduction in workers’ compensation costs for Illinois and Kentucky if injuries were reduced by 10%, 15%, or 20% due to implementing 

roof screening. Figure also shows expected savings when the number of MSHA reportable injuries is 30%, 50%, and 70% of the total number of 

employees. (Note: Number of injuries reported to NCCI during this time period were greater than the number of MSHA reportables by a factor of 1.4 and 

1.8 for IL and KY, respectively.)