5.6 Controls, Human Performance, and Evaluation
Key Takeaways
- Ergonomic controls should follow the hierarchy of controls, with redesign and engineering changes favored when feasible.
- Human performance factors include fatigue, attention, pace, complexity, staffing, recovery, and error-likely task design.
- Administrative controls such as rotation and breaks can reduce exposure only when they create meaningful task variation or recovery.
- Evaluation should verify both implementation and exposure reduction after controls are installed.
Choosing Controls That Actually Change The Work
The hierarchy of controls applies to ergonomics. Elimination may remove an unnecessary manual handling step. Substitution may use a lighter component, different package, or less forceful process. Engineering controls may include lift assists, adjustable stations, conveyors, fixtures, tool suspension, improved handles, automation, or layout changes. Administrative controls and training can help, but they are usually weaker when used alone.
A control should be tied to the risk factor it is meant to reduce. If the problem is high reach, a lift assist may not solve it unless it also changes hand location. If the problem is repetition, job rotation helps only if the alternate task uses different body regions and gives recovery. If the problem is vibration, a generic glove policy may be weaker than selecting lower-vibration equipment and improving maintenance.
| Exposure problem | Stronger control logic |
|---|---|
| Heavy floor-level lift | Raise the pickup, reduce load weight, use mechanical assistance, or change storage. |
| Repetitive overhead reach | Lower the work, change parts presentation, or automate the overhead step. |
| High pinch force | Redesign the part, tool, or fixture to allow a power grip or reduced force. |
| Static standing | Add movement variety, seating options, foot support, and layout improvements. |
| Vibration | Reduce vibration at the source, maintain equipment, isolate the path, and manage time. |
Human performance is part of ergonomics because people work within limits. Fatigue, pace pressure, poor visibility, confusing controls, awkward access, staffing shortages, and long duration can increase error likelihood and physical strain. A task that is safe during a short demonstration may become risky during a peak production run or after several hours without recovery.
The exam may present a worker error after a difficult shift. A narrow answer blames attention. A stronger answer asks whether the task design made error likely: hard-to-see labels, identical controls, awkward reach, time pressure, excessive force, or poor feedback. Ergonomic thinking and human performance thinking both look for system conditions that shape behavior.
Administrative controls need careful design. Rotation should move workers among tasks with different physical demands, not among three jobs that all load the same shoulder. Breaks should be realistic for the production system. Staffing changes should not simply spread an excessive exposure across more people without planning a durable fix.
Evaluation closes the loop. The safety professional should confirm that the control was installed, employees were trained, supervisors support the change, maintenance owns upkeep, and the exposure actually decreased. Metrics can include symptom trends, discomfort surveys, observation scores, equipment use, near misses, first-aid patterns, quality data, and employee feedback.
For ASP exam strategy, prefer answers that define the risk, select a control matched to that risk, and verify effectiveness. Be cautious with answers that rely only on awareness, discipline, or personal toughness.
A job rotation plan moves employees between three stations that all require repeated overhead reaching. What is the main weakness?
Which post-control action best closes the ergonomics program loop?
A worker makes an assembly error after hours of high-paced work with poor visibility and awkward reach. What human performance response is strongest?