The following three case studies are “traditional” in that the problems were musculoskeletal injuries in manual workers with the solutions within the realm of standard ergonomics interventions.
Cost Justification for Implementing Ergonomics Intervention 4-9
They illustrate three types of interventions, all of which were costed by the use of cost-benefit analysis.
The ergonomics interventions (cases) are:
. Section 4.4.1 — almost no-cost changes to the work methods where the management and men experimented to find the best solution
. Section 4.4.2 — an ergonomics intervention where an ergonomist altered working heights to over- come poor posture
. Section 4.4.3 — large capital investment where engineers designed new equipment for injury prevention
We intend that these case studies are illustrative of cost-benefit analysis rather than ergonomics solutions and are simplified examples of the ones given by Oxenburgh et al. (2004). For a more detailed analysis, please see this reference.
4.4.1 Warehouse Work — Truck Loading
The manager of a warehousing and transporting enterprise became concerned when a number of his warehouse staff and drivers began reporting of neck and shoulder pain. A risk assessment identified the source of the shoulder and neck pains as arising from loading bulky packages into the delivery trucks.
The packages were about 1.5 m wide by 0.4 m in diameter, weighing about 8 to 10 kg, soft and flexible and covered by a slippery plastic and, with no handles, the packages were awkward to handle. Although the weight of the individual packages was not high their soft, flexible character made the packages awkward to lift and, as the rows filled, it required pressure to push the last packages into position on each row.
The simple ergonomics solution was to provide a platform within the truck, which enabled the ware- house staff to work at a height that gave them better mechanical efficiency. This eliminated most of the loading above head height so that the top layers could be packed with minimal stress to the shoulders.
The warehouse staff have found the method more comfortable and they are not getting neck and shoulder pains any longer.
Although the new packing system has been successful interms of injury prevention, has it been success- ful in terms of cost-benefit analysis?
The new system increased the time required to load each truck from 35 to 45 min thus increasing the cost to load each truck by about 30%. However, using the original loading system each truck was packed to 89% volume capacity but, with the new system, the capacity was increased to 95%. This made such a difference that the drivers were able to load the entire day’s deliveries of product into one less truck.
Table 4.1 shows the cost-benefit analysis of the improved loading system. In this analysis only the direct wage costs and truck running costs are used. Despite the increased loading/employment costs, the improved loading of the trucks led to a net savings of about 45,000 “units” per year. The pay-back period was less than 1 week.
TABLE 4.1 Cost-Benefit Analysis for Loading and Delivering Bulk Packages
Initial Case Improved Loading Employment costs for the loading work (units/year)a 50,200 55,700
Truck costs (units/year) 501,400 451,300
Total yearly costs for loading and delivery 551,600 507,000
Intervention costs: management and warehouse staff time (units)b
— 625
Savings (units/year) — 44,600
Pay-back period — 1 week
aFor reasons of confidentiality, “units” are used for costing.
bA “one-off ” cost.
4-10 Fundamentals and Assessment Tools for Occupational Ergonomics
4.4.2 Manual Handling Made Easy: Barrel Handling
The work station was the wash line in a brewery where empty aluminium beer casks were received from public houses and washed ready for reuse. Preparatory to washing the plastic keystones, the top caps, were removed from the casks by levering out with a chisel and the shives, wooden bungs on the sides of the casks, were removed with a hammer and chisel.
The barrels travelled along a conveyor at floor level so that the operators had to bend their backs when manually removing the casks off the conveyor. The force and repetition needed to break and remove the wooden shives using the hammer and chisel led to musculoskeletal shoulder injuries. This work situation led to back and shoulder injuries and lost time for the two employees who worked in this section of the wash line. Other employees had to work overtime to cover this lost time.
Additionally, when the shives were removed, the wooden pieces fell to the floor forming both a trip- ping hazard and getting trapped in the conveyor belt causing damage to the belt. When the belt was damaged it had to be stopped. A mechanic repaired the damage and this took about 15 min for each stoppage; on an average, a belt stoppage occurred three times each day. When this happened the rest of the wash line, an additional nine men, were also idle.
The ergonomist measured the average elbow height of the men working there and, after allowing for the heights of the casks, determined the most suitable conveyor belt height. Of course, the height of the conveyor belt had to be low enough so that the keystone cap on top of the barrel could be removed and so bending could not be completely eliminated. Other means (improved hand tools) reduced the stress on the shoulders. Although the solutions were compromises (not ergonomically “ideal”), they have been effective in reducing, and in fact eliminating, absence due to bad backs and shoulders. Reduced injury resulted in reduced overtime (Table 4.2).
During the belt breakdowns not only were the two deshiving men idle but so were the nine men of the wash line. The cost-benefit analysis model (the Productivity Assessment Tool) used here, calculated the productive employment cost of the 11 men on the wash line and the mechanic to repair the conveyor belt at approximately £43.00 per breakdown of 15 min. By expansion to the full year, at a rate three of breakdowns per day and taking into account factory closures, the total cost of breakdowns is approximately
£32,000.
The ergonomics intervention resulted in improvements both in safety and productivity. Reductions in overtime and conveyor breakdowns paid for themselves in 3 months although the benefit continued beyond this period, which is an increase in profit.
In this case study, as well as the previous one, there were unexpected improvements in produc- tivity beyond the immediate reason for the ergonomics intervention. In the first case, the improved loading of the trucks and, in the second, the reduction in line breakdowns. These were not the reasons for the intervention and were not forecast in the original assumptions made by the management. We believe that this is a common occurrence as “good ergonomics is also good economics.”
TABLE 4.2 Reduction in Injury Absence, Overtime, and Conveyor Belt Breakdowns
Initial Case Improved Work Case Total cost of employment for the deshiving area,
including overtime (£/year)
56,400 50,400
Cost of breakdowns (wash line idle) (£/year) 32,000 650
Total cost (£/year) 88,400 51,050
Intervention costs (£)a — 8,830
Savings (£/year) — 37,350
Pay-back Period (months) — 3
aA “one-off ” cost.
Cost Justification for Implementing Ergonomics Intervention 4-11
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 $15,300 to the intervention costs.
After installation of the cable handling machine the injuries had been halved to three per year with a remarkable reduction in injury severity; only a total of 22 h was lost in each year or about 1 day lost per injured miner per year.
Table 4.3 illustrates the cost-benefit analysis of the introduction of the cable handling machine but it only includes the direct wages of the miners and the underground supervisors (deputies) and the direct costs of the cable handling unit and associated training.
For major machinery purchases in this industry a pay-back period of less than 4 yr can be considered to be financially satisfactory. In any cost-benefit analysis it is only necessary to include enough infor- mation to provide a reasonable estimate of the costs and benefits. Additional costs would include the administration staff, head office costs and so on but the extra effort required to include the other costs may not be necessary unless the project is of marginal benefit.
References
Ahonen, G., The nation-wide programme for health and safety in SMEs in Finland. Economic evaluation and incentives for the company management. Protection to Promotion. Occupational Health and Safety in Small-scale Enterprises. People and Work. Research Reports 25, Finnish Institute of Occupational Health, 1998, 151 – 156.
TABLE 4.3 Cost-Benefit Analysis for the Introduction of a Cable Handling Machine Including Direct Wages and Supervisory Costs
Manual Handling of the Cable
Design and Use of the Cable Handling Machine Miners’ wage cost to move the cable
($ 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
aA “one-off ” cost.
4-12 Fundamentals and Assessment Tools for Occupational Ergonomics
Applied Ergonomics, Special Issue: Cost Effectiveness. Vol. 34, number 5, September 2003.
Bohle, P. and Quinlan, M.,Managing Occupational Health and Safety, 2nd ed., MacMillan, Melbourne, Australia, 2000.
Connon, C., Reeb-Whitaker, C., and Curwick, C., Healthy Workplaces Technical Report 67-3-2003, 2003, Washington State Department of Labor and Industries, Olympia, WA.
Deming, W.E.,Out of the Crisis, 1982, Cambridge University Press, Cambridge, UK.
Kupi, E., Liukkonen, P., and Mattila, M., Staff use of time and company productivity,Nordisk Ergonomi, 4, 9 – 11, 1993.
Mossink, J. and Licher, F., Proceedings of the European Conference on Costs and Benefits of Occu- pational Safety and Health,Proceedings of the Conference, Amsterdam, NIA TNO, 1997.
Osborne, D.J., Branton, R., Leal, F., Shipley, P., and Stewart, T.,Person-Centred Ergonomics: A Brantonian View of Human Factors, Taylor & Francis, London, 1993.
Oxenburgh, M.S. and Guldberg, H.H., The economic and health effects on introducing a safe manual handling code of practice,Int. J. Ind. Ergon., 12, 241 – 253, 1993.
Oxenburgh, M., Marlow, P., and Oxenburgh, A.,Increasing Productivity and Profit through Health &
Safety: The Financial Returns from a Safe Working Environment, 2nd ed., Boca Raton, FL, CRC Press, 2004.
ProductAbility, 2004. Software for the Productivity Assessment Tool. See www.productAbility.co.uk or e-mail [email protected]
Spilling, S., Eitrheim, J., and Aara˚s, A., Cost-benefit analyses of work environment investment at STK’s plant at Kongsvinger, inThe Ergonomics of Working Postures, Corlett, Wilson, and Manencia, Eds., Taylor & Francis, London, 1986, pp. 380 – 397.
Cost Justification for Implementing Ergonomics Intervention 4-13
5
Humans in Work System Environment
Holger Luczak Sven Hinrichsen Susane
Mu¨tze-Niewo¨hner
RWTH Aachen University
5.1 Objectives and Structure of the Article . . . 5-2 5.2 Overview of Selected System Approaches . . . 5-2
General System Theory and Cybernetics† Socio-Technical System Approach † Evolution-Theoretical
Approach †Engineering-Scientific System
Approaches † Sociologically Formed System Approaches
5.3 Work System Approach as an
Analytical Framework . . . 5-10
Overview of Work System Approach† Elements of a Work System
5.4 Systematic Design of Work Systems . . . 5-18
Process of Work System Design †Corrective and Conceptive Work System Design † Sequential and Integrated Work System Design †Technocentric and Anthropocentric Work System Design
5.5 Approaches to Anticipatory Work
System Design . . . 5-24
Ordering Model † Inter-relations between Ordering Model and Work System Approach †Identification of Recovery Times in Heat Work as an Example
of Work System Design at Level S1 † Coordination of Movements as an Example of Work System
Design at Level S2† User-Centered Design of an
Autonomous Production Cell (APC) as an Example of Work System Design at Level S3 †Computer-Based Prospective Job Design and Evaluation with
Spaceþas an Example of Work System Design at Level S4 † Criteria-Based Identification of Areas for Group Work as an Example of Work System Design at Level
S5 † Aachener PPC-Model as an Example of Work System Design
at Level S6 †Cooperation between Companies as an Example of Work
System Design at Level S7
5.6 Conclusion . . . 5-47
5-1