Automation & IT / Water/Wastewater

Accurately Determine Console Operator Workload

Determining the correct console operator workload requires more than simply counting control loops.

By Ian Nimmo and John Moscatelli,User Centered Design Services LLC

In today’s competitive environment, all plants are interested in reducing costs to maximize profitability. One fixed-expense area most frequently targeted is hourly staffing level. If one duty station can be eliminated in a plant that operates 24 hours a day, head count can be reduced by at least four full-time employees. Taking into account salary, benefits, overtime and other related expenses, this typically represents a savings of $500,000 per year. However, one major incident caused by inadequate staffing can wipe out these savings for many years.

Management argues for fewer positions, whereas the workers, who are frequently unionized, always want more positions. A question that always comes up is, “What’s the right number of operators for our facility?” This question does not have an easy answer, as German chemical manufacturer Hoechst discovered a few years ago. After a series of accidents, the German government and labor unions insisted that Hoechst rehire recently laid-off employees.

Due to similar incidents in the industry, different local [1], state and federal organizations are getting more and more involved in setting criteria that must be addressed before staffing reductions can be implemented.

Until recently, the method most often employed to determine staffing reductions was management edict. Unfortunately, many managers, although well intentioned, don’t have the skills or experience to understand the full scope of the change because their previous education has been predominantly engineering and accounting, with little in the way of human factors and personnel development.

The task analysis method, or time-in-motion study, is still in use today, but has several shortcomings. As prescribed by this method, an observer follows a few operators and makes note of the amount of time they spend doing certain tasks. The most obvious problem with this method is that even the most dedicated operator will change his behavior while being watched. Likewise, any unusual conditions that occur during the sample period, such as a large amount of maintenance activities, will cause the job to look busier than it really is. Further, this method does not attempt to address any management-system issues. Although this is an improvement over the management edict, the method is still sorely lacking.

There are other methods that better account for the issues we will discuss. One such method that is factual, uses empirical data and has a qualitative risk assessment at its conclusion is outlined below.

Assess several factors
Some time ago, a guideline was developed and generally accepted that a console operator could handle about 200 control loops, with an upper limit of around 280 loops. Interestingly, it’s difficult to find the origin of this rule. A literature search yields no studies or published articles rationalizing the estimate. However, like a good urban legend, it’s widely believed and still used today to determine console loading at many facilities.

But what really impacts the console operator’s work load? Is it really as simple as just the number of loops?

Loop count is a measure of control span and it is certainly a factor in console operator workload. Loop count gives us an idea of how many things the operator needs to keep an eye on at any one time. But, does storage-tank-level control create the same workload as reactor-temperature control? Is a small wash-water flow adding as much to the workload as a furnace fuel-gas-flow controller? I think we can all agree that the answer to both questions is no. It’s not just the number of loops, but the type of equipment and the complexity of the process that contributes to the workload.

Anyone who has spent any time in a control room knows that a large portion of an operator’s work can be caused by upstream or downstream disturbances. A unit drawing feed from tankage and sending its products to storage is typically much easier to run than a highly integrated unit that takes hot feed from other processes and directly feeds another unit(s). These interactions can have a huge impact on job complexity and must be considered. Likewise, it requires more effort for a console operator to communicate with a large number of closely linked units than if the feed and products are isolated by tankage.

How about the physical situation of the operator? Can this impact the operator’s workload? An operator’s duties and his surroundings vary from working out of a local shelter and having both field and control responsibilities, to dedicated console operators based in a centralized control room. Might we reasonably expect the dedicated operator to handle more control work than an inside/outside operator?

What about the type of control hardware and the level of automation? A variety of control hardware is in use today, from pneumatic field controllers to distributed control systems (DCSs), and everything in between. To complicate the situation further, some plants have advanced dynamic control and online optimization, whereas others have poorly tuned loops with a large percentage not running in their optimal mode. It seems reasonable that the operator with the DCS and advanced control can handle more responsibility than the operator with poorly tuned loops who is forced to make frequent, manual adjustments.

Let’s look further at the DCS, since such systems are frequently used to justify staffing reductions. Although the DCS can be a huge improvement compared to the old panel boards, it can also introduce its own problems. Poorly laid-out graphics can make important information easy to miss in the clutter. Poor navigation schemes can cause operators to waste time during an emergency while they move between screens trying to find critical information. Poorly designed alarm systems can generate thousands of alarms in minutes during an upset so that operators miss crucial alarms (see CP, January, p. 28, for more information about alarm overload and how to deal with it).

These and other issues are created by poor DCS implementation, and have caused console operators to reject the DCS’s capabilities, ignore the human-computer interface, and attempt to run the unit using DCS controller faceplates arranged in small groups. They long for the old panel board days when the controllers were laid out in large groups and it was easy to monitor the whole picture. These issues must be considered when deciding on proper staffing levels.

Determine staffing levels
These metrics can be combined into a staffing assessment model and can allow companies to compare staffing levels between various parts of a single complex, the industry average and pace- setters (Figure 1). The model can also be used to anticipate staffing changes as units are added or shut down, or as units are altered mechanically or from a control perspective (Figure 2). The model also captures the impact of poor DCS implementation and its effect on operator workload. Many managers have wondered why they have two console operators for a relatively simple unit or group of units. The union and the operators insist that one person cannot do the job, and any attempt to do so would lead to an increase in incidents. The staffing assessment uses factors that affect workload, including equipment complexity, unit interactions and the integrity of the DCS implementation, and allows managers to get head count under control (Example 1).

Once established, a model that compares operator workload can be used to optimize the mix of an operator’s duties by providing a rational basis for workload redistribution or consolidation. The final step is to review the new responsibilities by completing a risk assessment, which is based on an analysis of the management systems and includes a review of scenarios based on different operating modes [2]. These areas are frequently overlooked when considering staffing changes, but they are critical to success. While assessing the quality of the plant’s management systems can be challenging, requiring internal and external resources, this must be done before staffing changes can be safely attempted (Example 2). Let’s look at some of the key management systems in a bit more detail.
Selection, training and development of operators. The quality of the operators has an impact on their ability to take on greater workloads. Who hasn’t experienced times when activities have been postponed because the wrong crew was on shift?

To assess the ability to reduce staffing, the facility must take an honest look at the quality of the workforce. A few examples follow:

  • How are new-hire operators selected? A rigorous screening process should select the best available, rather than throwing a few  API tests at the candidates.
  • How are the operators initially trained? A formal training process should concentrate on all pertinent aspects of the position. It is not sufficient to have six weeks of new-hire training followed by on-the-job training. Separate, formal training should exist for the console job.
  • How are console operators chosen? The move to a dedicated console-operator post should be treated as an upgrade in duties and pay. The selection should not be based solely on seniority, but on testing and competency models to ensure the best person is selected.

Procedures. A good set of operating procedures can be an invaluable tool, but only if the procedures are correct, up-to-date, easily accessible and actually used. Procedures should be available that cover all pertinent situations, such as normal operations, abnormal conditions and emergency situations. Further, they have to be written with the correct level of detail and in the correct format so they are useful to new operators, as well as experienced operators.

Each operator’s roles and responsibilities need to be clarified before implementing the procedure. In the past, workload was often divided differently by each shift based on experience and personal preferences, but was well understood by each individual team. Having console operators in a remote location often removes them from this planning phase.

Management of change (MOC). As a consequence of OSHA 1910, everyone has an MOC policy. But not all policies are created equal, nor are sufficient resources and discipline always devoted to ensure the policy is fully implemented. When done properly, the MOC policy is a powerful tool to communicate critical information to the operators. All MOC policies should definitely cover the following areas:

  • There must be a mechanism in place to keep all operators informed of changes in the plant in a timely fashion, especially personnel at remote work stations.
  • The MOC system should scrutinize changes to ensure they are well thought out and implemented.
  • The system should be fully utilized in the field and periodically audited to ensure compliance.
  • The system must be applied to control systems and organizational changes, as well as mechanical changes.

Teamwork, roles and responsibilities. The organization must be structured and implemented to fully support the operator during normal and abnormal situations. It must also be capable of continuing to support the operators when they take on additional responsibilities. It is important that everyone knows his or her role in the organization. Good, reliable communication systems must be in place. Key support personnel must be available when needed. All of these issues must be reviewed before staffing changes can commence [3].

Willingness to act. This area is vitally important to the success of the console operator. Is there an environment of support and empowerment in place so the operator feels free to act? Does the operator have to clear every move through a foreman to avoid being reprimanded? Management must routinely stress the importance of safety before production. Management must reward operators for taking the initiative to act in an emergency. If the plant culture is one that fosters hiding mistakes due to fear of reprisal and stresses production at all costs, the console operators will not be able to achieve the level of performance required to reach Best in Class staffing levels.

Alertness and fatigue. A console operator at a modern plant is expected to be awake, alert and ready to take decisive action at a moment’s notice. However, we frequently provide working conditions that actively work against this goal. Are light levels kept low? This is often done to combat glare on the DCS screens, which is caused by poorly designed lighting systems, or to reduce the eye strain caused by black DCS-screen backgrounds. Is the ventilation poor, causing extreme changes in temperature? Are the air vents filthy and is the air quality poor? Do schedules allow, or even require, operators to work excessive overtime and consecutive days so that they can’t get adequate rest? All these issues create, at best, an uncomfortable environment and, at worst, one that causes the operators to be drowsy and inattentive.

Don’t expect a simple answer
At the beginning of this article we arrived at that common plant management question: “What’s the right number of operators for our facility?” The simple answer to that question is that there is no simple answer, no effective short-cuts, and no guidelines that can be safely applied.

Reducing staffing levels should be viewed as a long-term, continual process. You can start by identifying areas that can be improved to facilitate staffing reductions. Then implement changes in those areas as resources become available and follow that up with feasible reductions. Almost all plants can achieve a reduction in staffing levels, but attempting to make a significant reduction in personnel without addressing other areas of concern might be difficult and possibly create a dangerous situation.

Ian Nimmo is president and founder of User Centered Design Services, Anthem, Ariz., a firm that specializes in abnormal-situation management, alarm management and other control issues. E-mail him at John Moscatelli is the managing partner of User Centered Design Services. E-mail him at

1. Contra Costa County Ordinance No. 98-48 and amendments from 2000-20 Industrial Safety Ordinance (1998).
2. Brabazon, P. and H. Conlin, “Assessing the safety of staffing arrangements for process operations in the chemical and allied industries,” contract research report for the Health and Safety Executive (2001).
3. Parker, S.K. and H.M. Williams, “Effective teamworking: Reducing the psychosocial risks,” HSE Books, Norwich, England (2001).



Example 1:
An independent refiner wanted to perform a staffing analysis in conjunction with the building of a new, central control room. The operators had inside/outside responsibilities and a small span of control. The refiner planned to create dedicated console operator positions and move these operators into the new control room.

The staffing analysis identified which units should be combined under the control of a single operator, as well as a reasonable target number of operators. Although this refiner had some management-system issues to address, we were able to safely recommend console operator staffing reductions of 30%, with another 12% that could reasonably be achieved after some improvements in the management systems. This was significantly higher than the refiner had anticipated.

Example 2:
Another independent refiner had dedicated console operators working out of a number of shelters located throughout the site. This company also planned to consolidate operations in a new state-of-the-art, centralized control building and wanted to perform a staffing analysis in conjunction with the project. The facility manager had preconceived ideas as to the correct staffing levels. He expected to reduce the number of console operator positions by 50% and thought the study would validate this figure.

The workload model, which includes the equipment, interaction and control system scores, indicated that the proposed consolidations were aggressive, but not beyond workload levels that were being handled successfully at other facilities. However, the management system review showed significant gaps in the areas of training, console operator selection, procedures, communication systems, teamwork and willingness to act.

As a result of the study, the refiner decided to focus efforts on making improvements to the management systems to ensure that the proper support system would be in place to support the new positions.

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