How does job design shape operator performance?

Performance-Shaping Factors Series

NEWSLETTER ARTICLE

Like all complex systems numerous variables affect operator performance, for good or for bad. This series explores what these performance-shaping factors are (Figure 1), what issues exist because of them, and how they can be optimized.

Lesson 2 – Job Design

The tasks required by the system need to be organized and allocated to someone or something. An early part of human factors was the determination of which tasks should be allocated to machines instead of people. We’ll discuss this in more detail when we talk about automation. Today’s focus is on the tasks that people need to perform for the system to function.

Life Before Dedicated Console Operators . . . 

You may think that process plant jobs don’t really seem to change, but I’ve seen dramatic changes in the course of my career. When I started, it was not uncommon for an operator to handle all the operational-related tasks for their unit, as in Figure 2. I remember going into control rooms, and no one would be there; everyone was out on the unit (an alarm would sound a horn in the unit). So, I’d grab a chair and wait. Eventually someone would come back in. Operators were assigned a unit(s) or a section of a large unit, responsible for physically monitoring and manually controlling process variables such as temperature, pressure, and flow rate. This was both inside and outside the control room.

Figure 2: Job Design Until 1980

The Way Things Are Now . . .

Implementation of distributed control enabled consolidation of the optimization, control, and monitoring into a single position, the console operator (Figure 3). Having distinct roles, the DCS console operator could focus more on monitoring and analyzing process data to optimize the process and troubleshoot issues, while the field operator—freed in great part from these duties—could perform the remaining hands-on tasks more efficiently and with a greater degree of control.

An initial issue was whether an operator should rotate through all the positions or, once an individual became a console operator, rotation ceased. These two paths have significant impact on the other performance-shaping factors, creating different training, selection, and interface requirements. Most companies have chosen to make the console operator a separate, dedicated position which only occasionally rotates to the field. There are still those where an operator rotates through all positions. This means the console operator has been away from the console for 3-4 weeks. I was at an olefin plant where swapping heaters is a common practice. The console operator—who had been with the company for three years—had never done a heater swap, due entirely to the vagaries of scheduling. Even more controversial is whether the console operators still need to “qualify” on the field jobs. Several companies have answered that with a big “no”.

Tech Will Shape the Future . . .

Distributed control resulted in re-designing jobs; will wireless technology do the same? The console operator did the monitoring of the process because they had all the instruments. However, if field operators can access instrument data anywhere, does the console need to do all the monitoring? Freed from monitoring, increased spans of control could be obtained using remote Integrated Operations Centers (IOC). Should the field operators still be aligned on a unit basis? A different design could have one operator handling mechanical integrity across multiple units, while another handles control system reliability, and another takes on lab/quality performance (Figure 4). This would enable specialized training to match the job requirements.

Even though all these functions may need to be performed at some point, they are not equally likely to occur at any point in a day or week. You wouldn’t expect to walk into a control room or process unit on a Saturday at midnight and see precisely the same activities as at 8 AM Tuesday. Operational tasks, obviously, are time-sensitive and can happen at any time since they’re initiated by the process. But the remaining field tasks? Take maintenance: LOTO, permits, and so on are largely a function of when maintenance personnel are present at the plant. Should Field Operator 3, in the figure above, be a day maintenance operator, leaving fewer shift (24/7) operators?

Fewer operators at night!? What if something goes wrong?! What if we were to lose power? That’s a topic for the next lesson.

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