Vessel Traffic Management (VTM) operation is complex and dynamic in nature thereby resulting in high degree of human fatigues. In general, human fatigues are the leading contributors to errors in decision making. The proposed work is designed to investigate and mitigate human fatigues in VTM focusing on operators’ workload and human factors, as well as the VTM workspace environment and system ergonomics. Recognizing causal factors is generally considered as the first step in understanding human fatigues in decision making. Thus, the first specific aim of this proposal is to determine the potential causal factors of human fatigues in VTM with a focus on operators’ workload and human factors. With the better knowledge of causal factors of human fatigues in VTM, appropriate interventions can be designed to improve the human-machine interface so as to minimize exposure to these causal factors and thus prevent the occurrence of human fatigues in VTM. The second specific aim is to develop and evaluate preventive interventions for minimizing human fatigues in VTM. Two separate projects will be conducted. In the first project, causal factors of potential human fatigues will be identified by a combination of field observations, unstructured interviews, and review of incidents. Preventive interventions for reducing human fatigues will then be proposed in the second project. These interventions will be evaluated by their effects on VTM operators’ mental workload and situation awareness in lab-based simulations of VTM operation.