Workload is subjective and is affected by the person and his state, such as:
- physical and mental skills;
- experience;
- current health and fitness levels; and
- emotional state.
However, the circumstances under which the task is performed also have a strong affect on workload. Examples are:
- the degree of accuracy required;
- the time available to accomplish the task;
- requirement to carry out this task concurrently with another;
- existing environmental factors, like extremes of temperature, noise, etc.
As the workload of the engineer may vary, he may experience periods of overload and underload. This is a particular feature of some areas of the industry such as line maintenance.