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Atwood & Fennell Oct 2001 Cost Effective Human Factors Techniques for Process Safety 1

Cost-effective Human Factors Techniques for Process Safety

By

Dennis Attwood

Human Factors Consultant

ExxonMobil Biomedical Sciences, Inc.

Baytown, TX 

and

David Fennell

Senior Safety Advisor

Imperial Oil Resources Limited

Calgary, AL

ABSTRACT

This paper illustrates how the structured application of Human Factors can be costeffective. It proposes a model for the analysis and implementation of Human Factors in 

existing plants and presents a case study that describes the results of a series of human 

Factors analyses that were conducted in several process plants. The case study 

summarizes the recommendations made, itemizes the follow-up that resulted and 

estimates the costs of the analyses and follow- up and the subsequent savings based on 

the interventions. Recommendations provide prospective users of Human Factors 

services with a set of processes to assist them to conduct similar analyses.

1. INTRODUCTION

Human Factors is defined as the systematic process of designing for human use. It is a discipline 

that improves the interface between humans and the systems they operate to reduce the 

occurrence human errors and their consequences. Since its formal introduction as a scientific 

discipline in the early 1940's, Human Factors has had a far reaching effect on the usability of 

workplaces and equipment world wide. Not surprisingly, Human Factors design techniques have 

also been introduced into the design of the facilities and operating systems of process plants

It is estimated that within the process industry, Human Error accounts for 70-80% of all 

operating incidents resulting in billions of dollars of loss each year (Essex, 1992) and countless 

deaths and injuries. So, improving the human-system interface should increase profitability and 

reduce the number and severity of injuries resulting from operating incidents.

The safety and industrial literature contains many examples of the cost-benefits of human 

factors. Hendrick (1997) recounts case studies from the forestry, steel and the petroleum industry 

where human factors interventions were cost effective. Little (1998) and Springer (1992) 

provide several examples from the office environment where changes to the workspace had 

beneficial effects on office workers. Well known examples of catastrophic accidents that have 
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Atwood & Fennell Oct 2001 Cost Effective Human Factors Techniques for Process Safety 2

occurred in the process industry include Three Mile Island, Bhopal and Chernobyl. Less well 

known incidents such as the Piper Alpha explosion and the Ocean Ranger sinking are also 

examples of disasters that have extracted a large toll in loss of life and property. In each case, 

poor human Factors design of the man-machine interface either contributed to or was the rootcause of the disaster. Incident analyses suggest that each disaster could have been prevented by 

the proper human factors design of the interfaces. In some cases, the plants or rigs were built 

before the benefits of Human Factors were as well known as they are today. The question facing 

the process industry is whether the cost of conducting a Human Factors assessment and 

improvement program in each of these plants and rigs after they were put into service would 

have been cost-beneficial? 
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Figure 1 illustrates one version of the systematic process of designing for human use. The model 

begins with the integration of Human Factors into the Safety Management Systems of the 

company. This initiative underscores the importance that management places on the use of 

Human Factors in the design of facilities, equipment and work processes such as shift schedules 

and procedures and permitting systems. Once Human 

Factors is established in the management systems, it 

then becomes a legitimate (sponsored) part of the 

management process. Next, plant personnel are trained 

in Human Factors techniques. Training is attended by 

not only the plant workers and first line supervisors, 

but also by the plant management. The content and 

length of training is tailored to the requirements of the 

attendees. Design staff, for example, needs more 

information on the use of Human Factors in the design 

of equipment and facilities. Management requires an 

overview and familiarization and Operations Staff 

needs to know how to analyze existing units and affect 

change. A process is built into each of the training 

programs to identify tasks with critical HF issues for 

follow-up.

The plant's risk analysis systems can also be used to 

identify those tasks that pose the highest risk of error or 

musculoskeletal stress. An analysis of the selected 

tasks can then be conducted to identify the Human 

Factors issues. The issues are evaluated and analyzed 

using a battery of tools specifically designed for this 

purpose, interventions are identified and action plans 

are developed and implemented. Finally, the results of 

the interventions are measured to ensure that they were 

effective at resolving the issues. If an issue has not been satisfactorily resolved, follow-up is 

initiated and the process repeated. 

For new projects, the model for analysis and implementation consists of applying unique Human 

Factors tools at each stage of project -- planning, design and execution. 

2. CASE STUDY: Analysis of control systems at process plants

During the 1995-96 period, a series of Human Factors analyses was conducted of the process 

control spaces and systems in several Gas plants. The Human Factors surveys were undertaken 

for several reasons:

 To evaluate specific issues that were identified as a problem for the process control 

operators

 To evaluate the effects of consolidating process control rooms or systems

 To evaluate the effects of introducing new equipment

Train Personnel

Identify HF issues

Integrate HF into 

Management Systems

Prioritize HF issues

Evaluate/Analyze Issues

Develop Action Plans 

and Implement

Measure

Follow-up and improve

Fig. 1: The HF analysis and 

implementation Model
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 To proactively evaluate the process control spaces and equipment design for 

improved efficiency

The evaluation included all aspects of Human Factors interface design to determine what, if 

anything, could be done to improve the layout, the ergonomic design of the control consoles and 

panels and the design of the operator interface with the process control system. This case study 

describes the results of a series of Human Factors analyses, summarizes the recommendations 

made, itemizes the follow-up that resulted and estimates the costs of the analyses and follow- up 

and the subsequent savings based on the interventions.

2.1 Methodology

The methods used in the analysis of the sites included a wide range of human factors tools that 

sought to assess the ergonomics design of the process control space and furnishings, the noise, 

lighting and temperature environment that the operators worked in and the design of the interface 

of the process control system. This latter analysis was conducted using several tools as follows:

1. Alarm function analysis

2. Communications analysis

3. Training analysis

4. Critical task analysis

Each of the surveys were completed on-site within 2-3 days and the report was completed within 

2-4 days. The interventions that were completed as a result of the recommendations from the 

analyses were usually accomplished within days or weeks and generally consisted of minor 

facilities improvements or modifications to the design of existing process control screens or 

changes in work processes.

2.2 Results

The costs and benefits of Human Factors improvements are best determined by viewing the 

improvement as the elimination or minimizing of waste. Although some of the benefits are 

easily measured and tracked, most are ambiguous and more difficult to peg down. The following 

examples from three control room assessments have quantifiable benefits that will demonstrate 

the cost effectiveness of Human Factors improvements.

2.2.1 Ring Back feature on alarms:

The control system in one plant was fitted with a number of alarms and shut downs for high 

level, gas detection, low level, high and low pressures etc. Each alarm would provide an audible 

and visual signal when a set point and/or shut down level were reached. The plant could not be 

restarted until the alarms had cleared, however, many of the alarms required that the operator 

look at the alarm level or pull up a new screen on the control system to determine that the alarms 

had actually cleared. This would result in delays of approximately 15 minutes in the start up 

process and up to 30 minutes during very busy periods. The Human Factors consultant 

recommended installing a ring back feature when the alarms had cleared. This allows the 

operator to acknowledge the cleared alarm and begin his start up process without searching for 

alarms that may have already cleared. For the plant in question, shut down or diversion of 

product costs about $1.5 k per 15 minutes and there were about 50 such diversions or shutdowns 

per year for a total annual cost of $75k. The reprogramming to eliminate this longer than 

necessary down time was completed with 8 hours of instrument technicians time at 

approximately $0.4 k.
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2.2.2 Reduction of Emissions:

Emissions from another gas plant are strictly regulated and violations of the emissions standards 

can result in fines of $5 k per violation. Although no fines had been levied against the plant, 

approximately 26 exceedances of the standards per year did occur. Basic human factors control 

items, mostly programming of warning alarms, providing consistency of read outs, and providing 

alarms on inlet streams that caused sulphur plant upsets that lead to emissions, were applied 

based on the consultants recommendations. The human factors initiatives, along with other 

improvements resulted in the annual emissions being reduced to 8. This meant that a total of 18 

potential fines had been avoided. This case demonstrates that once again simple programming 

changes that took less than 2 person days ($0.8 k) to implement had a potential saving of $90 k 

in penalties.

2.2.3 Consolidation of Control rooms made possible:

The consolidation of the control rooms in two separate plants was made possible through the 

Human Factors recommendations of a 1995 review. This reduction from two to one control 

rooms had a direct saving of $400k through the elimination of one shift position. Although there 

were costs associated with a number of hardware changes required to control both plants from 

the one control room, the key issue in this strategy was to ensure that the one operator could 

work efficiently with both control systems and that there would be no confusion, no duplicate 

systems and no contradicting control systems. The human factors study identified numerous 

simple changes, mostly programming, that would make this possible. The solutions involved 

identifying and implementing common screen design, consistent protocols for alarms, run 

switches, ESD’s and consistent patterns and terminology for screen layout. This ensured that 

one operator could effectively monitor both plants. Programming time for these changes took 

approximately 45 days of instrument tech time (approx. $45 k) and it made it possible to achieve 

the $400k savings.

2.2.4 Nominations Screens:

The deliveries of natural gas to a Government-owned utility were based on daily contracts or 

"nominations" If the plant delivered on the nomination (up to 5% over) there was no penalty. If 

they under-delivered by any amount at all then the penalty was applied. The penalty would 

depend on the amount of the nomination, so an average value of $5K per under delivery was 

used on any one day.

The analysis showed that the operators did not have the information that they required to meet 

the NOMINATION. History had shown that there was a potential for an under-delivery, because 

of the human factors issues about 5 times per month, giving a total average of $25K per month. 

This would happen throughout the year with a higher potential in the winter months. So, the 

potential was to under-deliver 5 times a month for about 8 months a year for a total of about 8 x 

$25K = $200K.

The changes to the process control system as a result of the analysis virtually eliminated underdeliveries resulting in savings of $200K per year. The cost of the process control system 

modifications was 2-person weeks of programming ($4K).

2.2.5 Control system consolidation:
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The control system for a production field was moved into the control room of an associated 

production plant. The plant night shift operator could monitor the field control system for shut 

down wells and facilities and call out operators to correct problems. The plant control systems 

all had alarm screens that scrolled in from the top of the screen and new alarms showed as bold 

until acknowledged. The field system had alarms that scrolled in from the bottom with no 

distinction in print. Approximately 60 field alarms per year were missed by the plant operators 

resulting in a lost production of $1.6 k per alarm. Three days of programming ($1.2 k) was able 

to align the alarm screens and resulted in no missed alarms in the next year for a savings of 

$100k.

In summary, the above interventions resulted in an estimated savings of about $865K. To 

achieve this result, the sites involved invested about $30K for analysis from outside consultants 

and another $52K internally for follow-up work. The benefit to cost ratio is about 10.5.

2.3 Discussion

As a result of the above Case Study the following cost-effective strategies for implementing 

Human Factors analyses of control rooms and process control systems are proposed.

2.3.1 Leave the Operation with the skills to implement the solutions. 

The benefits of a human factors review can be multiplied when some basic skills, tools 

and techniques are left with the key people in an organization after the assessor or 

consultant has left. Every assessment should include a planned training session for those 

who will be implementing the solutions. This provides them with an understand of what 

is to be achieved, the most cost effective way of achieving it, and skills for identifying 

and correcting future problems independently. 

2.3.2 Programming changes can be cheaper than hardware:

Many of the changes recommended in the control room assessments required absolutely 

no new hardware or equipment. The improvements were achieved simply through 

programming changes to sequences, displays, enunciations, alarms and using the full 

strength of the control system for calculations, nominations and reminders. 

2.3.3 Evaluate the cost-effectiveness of recommended interventions during the survey:

In most cases, the resultant savings from an intervention can be estimated by the plant 

staff while the evaluation is proceeding. For example, most gas plant personnel can "ballpark" the hourly or daily cost of a plant shutdown and hence the potential savings if a 

shutdown is avoided. At the same time, most operations personnel can estimate the cost 

of installing sensors and equipment and applications technicians can estimate the time 

required to reprogram the process control system.

2.3.4 Negotiation can achieve the same purpose as hardware:

The intent of a Human Factors recommendation may be achieved cost effectively through 

means other than the purchase and installation of expensive monitoring equipment. The 

intent of a sensor and alarm on a pipeline is to provide early warning of an off spec 

product so a facility can prepare for its arrival and adjust their processes to minimize its 
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Atwood & Fennell Oct 2001 Cost Effective Human Factors Techniques for Process Safety 7

impact. The cost of this equipment may not be necessary if an agreement can be reached 

with the supplier that they will provide the advanced warning for the plant.

2.4 Recommendations

The results of this investigation demonstrate that retrospective Human Factors analyses of 

Process Control Rooms and Process Control Systems can provide interventions that save much 

more in productivity than they cost to develop or implement. However, in many cases the 

interventions have not been implemented and the benefits of the intervention have not been 

determined. With this in mind the following processes are recommended for on-site evaluation of 

cost effectiveness:

2.4.1 Establish operations and instrumentation contacts to be part of the evaluation team. 

This provides training for the instrument technician, an understanding of the issues by the 

instrument technician and operator and leaves them with the ability to provide quick 

effective implementation of the simpler programming recommendations.

2.4.2 Pre-establish costs of Business Interruptions and down time. 

This allows the assessors to instantly connect the value of recommendations to real 

dollars at the facility. For example if a particular recommendation will eliminate 20 

instances of diverting an off spec product and the value of those diversions has already 

been recorded through tracking of business interruptions, then the benefit of the 

recommendation can be instantly quantified.

2.4.3 Establish approximate costs of programming. 

Many of the recommendations on control room human factors improvements involve 

programming changes within the system. Knowing the costs of that programming time 

will allow the assessment team to attach a cost for implementing those recommendations. 

2.4.4 Estimate the rough cost for hardware that is usually associated with HF 

improvements. (i.e. costs of ergo chair, adding a monitor, installation of an additional 

end point sensor)

2.4.5 Allocate a small amount of money and time for low cost, quick hit benefits. 

(recommend an amount of money equal to the cost of the assessment plus 5 days of

instrument tech time for programming)

2.4.6 Allocate a small amount of money for comfort/annoyance issues. 

There is great value in addressing these type issues immediately after an assessment as it 

helps maintain the momentum of the implementation of the HF recommendations. 

3. DISCUSSION

The results of the Case Study, presented above, demonstrate that Human Factors interventions in 

existing plants can be extremely cost-effective. The results also point out that the value of the 

benefit-to-cost ratio depends, to a large degree, on five items:

1. The willingness of site management to undertake the Human Factors analysis and 

implementation process and provide funding and resources.
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2. The preparation of the site personnel.

3. The participation of site personnel in the process and their willingness to own (follow-up) 

the results

4. The quality of the analysis and the proposed interventions

5. How well the site is prepared to estimate the costs and benefits of the proposed 

interventions.

4. REFERENCES

Essex Corporation (1992) Containing error in the workplace. Internal publication.

Hendrick, H. (1997), Good ergonomics is good economics. Ergonomics in Design, April 1997

Little, R. (1998), Ergonomics an exercise in economics. Office Life, April, 11-13.

Springer, T.J. (1992), Does ergonomics make good business sense? Facilities Design and 

Management, July 1992.