Safety management is regarded traditionally as an aggregate attribute for Human Resources (HR) in which the focus is placed on safety of construction crew by assuming same behaviour, capabilities and thus level of exposure to risk for all workers in the crew. In line with this, a team-based approach is generally adopted for task assignment to workers in construction operations. However, this approach tends to disregard the differences between skill level, experience, capabilities, learning rates and fatigue rates of different individual workers forming the team. In particular, due to differences in visual, auditory, cognitive and psychomotor capabilities of different workers and brain resource demands of different activities, the traditional approach may result in inconsistent workloads and uneven fatigue rates within a crew, affecting the workers’ and crew's safety negatively. This paper proposes a novel framework for task assignment to construction workers in which safety of individual workers and thus the crew is ensured through optimizing workload distributions within a crew. The framework computes visual, auditory, cognitive, and psychomotor requirements of the jobs assigned to a worker and minimizes the identified workload imbalances through collaborative execution of shared tasks. The application of the proposed framework is examined on a pipe spool fabrication operation of a refinery project in a simulation environment.