*2.2. Criteria Selection*

According to Atkinson [25], human factors have a clear causal link with machine productivity rates. He also concludes that the production performance of machinery is largely reliant on the operator's skill and competence. Construction equipment operators are frequently called upon to handle difficult and demanding situations, which impacts their performance. The examined literature indicates the main criteria affecting an operator's performance, as depicted in Table 4.


#### **Table 4.** Criteria Sourcing.

#### 2.2.1. Operator's Competence

According to Holt and Edwards [26], the operator's competence is the operator's ability to effectively and efficiently apply the machine to the work task. It depends on the knowledge/experience [26] and the preparation/training that an operator has [27]. Motives can also be an additional factor in an employee's productivity levels; this factor is usually linked to earnings and insurance type [28]. Finally, stress and fatigue have been recognized by Haggag and Elnahas [32] as common conditions for operators, drastically affecting their competence.

#### 2.2.2. Relationships and Interactions

The risk related to the labor system may be generated by human resource errors, an inadequate job description, dangerous equipment, improper social relationships between employees, and/or physical/environmental factors [28]. Focusing mostly on the manufacturing technologies, they realized that occupational stress is being enhanced by the new constraints which employees are now obliged to cope with and has also generated the need for organizations to redesign the work environment in order to counteract both the traditional and the emergent risks. According to Beleiu et al. [33], the relationships and interactions between employees, and between employees and their employers, are critical performance factors. In addition, the way a disagreement is resolved affects their performance, but it also depends on how fast it is resolved. They also stressed the importance of on-site communication as a determinant factor in the project's success, so that its efficiency can be supportive to construction equipment operators.
