2.2.4. Task

Dumitrescu and Delsenicu [28] define the task as the complexity of activities which are undertaken by an individual as part of a working process, the timeframe for activity completion, the job requirements, etc. Thus, each task can affect the operator's performance levels. They acknowledged that natural and environmental issues appearing in the field directly affect the operator's performance. Machines operate in an abrasive environment, where the operators' security is one of the most crucial issues in the construction sector [27,32]. Designing a work environment to meet the needs of the employees and the job requirements is a fundamental factor for enhancing productivity. Moreover, lighting conditions and noise levels, exposure to dust and emissions, soil properties, and weather conditions, especially in earthmoving work and road construction projects, are the main environmental factors, with a significant impact on their productivity levels.

#### **3. Materials and Methods**

#### *3.1. Research Process*

This research adopts a seven-step approach for identifying and hierarchizing the criteria that have the most effect on the construction equipment operator's performance. The first step is to identify the relevant literature concerning the equipment operator's performance during a construction project. The review also focuses on investigating any criteria referred to by previous authors. The second step is to supplement those criteria with others mentioned by construction equipment experts and operators, through structured on-site interviews. Several oral interviews with construction management experts and construction equipment operators highlighted the importance of the criteria affecting the performance of the operators. In addition, construction sites were visited, and many interviews were gathered, leading to the consolidation of a final criteria list, as shown in Table 4. The third step is to classify those criteria into two main categories in order to distinguish between those which are based on personal experience and those which are verifiable facts. The formed opinion or viewpoint helps to distinguish the objective from the subjective criteria. Most commonly, subjective means something based on the personal perspective or preferences of an operator, meaning the subject who is observing, and this often implies that it comes with personal biases. In contrast, objective is the attempt to be unbiased, and this means that it is not influenced by an individual's personal viewpoint.

The fourth step of the process introduces the final development of the decision tree, as shown in Figure 5. This hierarchy model is vital when it comes to utilizing the AHP for weighting those influential criteria. It also constitutes the basis for forming a specialized questionnaire (fifth step), which is applicable for weighting the criteria through Saaty's scale [41] (as described in Section 3.2). The application of the AHP (sixth step) in the current research is reviewed in the following sections. The results coming from the AHP method formulate the final scoring of the criteria weighting, leading to the seventh and last step of the process. The overall process is visualized in Figure 5.

**Figure 5.** Methodology milestones.
