Civil Engineering Reference
In-Depth Information
TABLE 4.3 Cost-Benefit Analysis for the Introduction of a Cable Handling Machine Including Direct
Wages and Supervisory Costs
Manual Handling
of the Cable
Design and Use of the Cable
Handling Machine
Miners' wage cost to move the cable
($ per year)
36,600
5,200
Direct supervisory costs for total hours on
cable handling ($ per year)
6,800
980
Net labor costs for total hours on cable
handling ($ per year)
43,400
6,180
Intervention costs ($)
a
65,300
Savings in labor costs ($ per year)
—
37,220
Pay-back period (months)
—
21
a
A “one-off ” cost.
4.4.3 Manual Handling in Coal Mines
In longwall excavation, as the coal seam is progressively removed the longwall mining machinery has to
be moved forward. Although heavy machinery and trucks are used to move the longwall equipment there
are still some tasks requiring manual labour and one of these tasks is moving and rehanging 11 kV cables.
The cables, which are heavily armoured, weigh nearly 12 kg
m. Due to the stiffness of the cable, the six
men on the task would be holding about 20 m length above the ground at shoulder or head height at any
one time (about 240 kg weight of cable) and it would take 3 to 4 h to put up a 300 m run. This task is
repeated weekly.
Clearly, this task is a back and shoulder stress problem and there had been about six injuries per year
accounting for 1200 h of lost time (an average of nearly 6 weeks lost per injured miner).
The colliery engineering and safety staff visited several coal mines in the area to see if there were any
better systems and came to the conclusion that the various methods they saw were not good enough and
decided that they would have to design a system themselves.
In collaboration with a mining equipment manufacturing company, a cable handling machine was
designed and constructed at a unit cost of $50,000. All the wages of the 80 underground miners who
were trained in the use of the machine as well as the direct wages of the colliery staff who assisted in
the design of the machine were included in the intervention costs. This added an extra $15,300 to the
intervention costs.
After installation of the cable handling machine the injuries had been halved to three per year with a
remarkable reduction in injury severity; only a total of 22 h was lost in each year or about 1 day lost per
injured miner per year.
Table 4.3 illustrates the cost-benefit analysis of the introduction of the cable handling machine but it
only includes the direct wages of the miners and the underground supervisors (deputies) and the direct
costs of the cable handling unit and associated training.
For major machinery purchases in this industry a pay-back period of less than 4 yr can be considered
to be financially satisfactory. In any cost-benefit analysis it is only necessary to include enough infor-
mation to provide a reasonable estimate of the costs and benefits. Additional costs would include the
administration staff, head office costs and so on but the extra effort required to include the other
costs may not be necessary unless the project is of marginal benefit.
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References
Ahonen, G., The nation-wide programme for health and safety in SMEs in Finland. Economic evaluation
and incentives for the company management. Protection to Promotion. Occupational Health and
Safety in Small-scale Enterprises. People and Work. Research Reports 25, Finnish Institute of
Occupational Health, 1998, 151-156.
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