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Lacking a holistic framework for analyzing risk factors would result in the inaccurate assessment of safety performance and poor safety management. This research aims to establish a Bayesian-network (BN)-HFACS hybrid model to proactively predict safety performance in construction projects. First, a causation framework for analyzing the underlying factors influencing construction safety performance was established using the Human Factors Analysis and Classification System (HFACS). This causation framework incorporates 18 risk factors from organizational, environmental and human aspects that are categorized into five levels: L1: “unsafe acts of workers,” L2: “preconditions for unsafe acts,” L3: “unsafe supervision and monitoring,” L4: “adverse organizational influences,” and L5: “adverse environmental influences.” The relationships between these factors and project safety performance were then hypothesized in the BN-HFACS model, and validated by data collected with questionnaires. The proposed model was applied to a subway project with AgenaRisk software. This application demonstrated the model’s capabilities in systematically identifying risk factors, predicting the probabilities of safety states in project level and in the five specific cause levels, and diagnosing the most sensitive risk factor. This research contributes to safety assessment and management by modifying the original HFACS for the causation analysis of construction safety performance, and by establishing a BN model for quantifying the total influences of the risk factors at five distinct levels on project safety performance. The integration of HFACS and BNs may be instructive in other contexts where diverse safety risk factors are involved in a system and safety prediction of the system is necessary.

Active shooter incidents present an increasing threat to the American society. Many of these incidents occur in building environments, therefore, it is important to consider design and security elements in buildings to decrease the risk of active shooter incidents. This study aims to assess current security countermeasures and identify varying considerations associated with implementing these countermeasures. Fifteen participants, with expertise and experience in a diverse collection of operational and organizational backgrounds, including security, engineering, law enforcement, emergency management and policy making, participated in three focus group interviews. The participants identified a list of countermeasures that have been used for active shooter incidents. Important determinants for the effectiveness of countermeasures include their influence on occupants' behavior during active shooter incidents, and occupants' and administrators' awareness of how to use them effectively. The nature of incidents (e.g., internal vs. external threats), building type (e.g., office buildings vs. school buildings), and occupants (e.g., students of different ages) were also recognized to affect the selection of appropriate countermeasures. The nexus between emergency preparedness and normal operations, and the importance of tradeoffs such as the ones between cost, aesthetics, maintenance needs and the influence on occupants' daily activities were also discussed. To ensure the effectiveness of countermeasures and improve safety, the participants highlighted the importance of both training and practice, for occupants and administrators (e.g., first responder teams). The interview results suggested that further study of the relationship between security countermeasures and occupants' and administrators’ responses, as well as efficient training approaches are needed.

Human behavior is fundamental to human safety and the outcomes of building emergencies. It is correlated with social environments, building environments and emergency situations. This study presents a review about human-human interactions (i.e., interactions among people or groups of people and their influence on behavior during emergencies), human-building interactions (i.e., how buildings influence human behavior and how human behavior impacts the building performance during emergencies), human-emergency interactions (i.e., how emergency situations impact human behavior and people’s coping strategies with emergencies), and second-order interactions among humans, buildings, and emergencies. The review reveals that while various human-human interactions among building occupants have been investigated, some of them (e.g., grouping behavior, information sharing) are less understood, and the interactions between building occupants and staff members need further explorations. With regard to human-building interactions, prior studies have been limited to certain types of buildings and building attributes, while the aggregate impact of a combination of building attributes should be more studied. Moreover, building fires were the most frequently examined emergency type, while other types of emergencies, such as earthquakes and acts of extreme violence, received less attention. Additionally, second-order interactions among humans, buildings and emergencies have not been widely studied. This paper also puts forward recommendations for future research, including validating prior findings when transforming them into real-world applications, leveraging the strength of different data collection and interpretation methods, as well as collaborating more closely with researchers and practitioners in related areas.

This study examines the effects of architectural visual access on people's wayfinding behavior and evacuation performance during building emergencies using virtual reality. Fire evacuation experiments were conducted in an immersive virtual metro station, which was based on a real metro station in Beijing, China. A total of 226 participants, positioned among evenly or unevenly distributed crowd, were asked to evacuate the station that was designed with low or high visual access, manipulated through building design features (e.g., changing wall materials, removing columns in hallways). Crowd was presented in the virtual metro station by incorporating non-player characters assigned to different evacuation routes. To explore the possible influence of cultural background on participants' wayfinding behavior, experiments were conducted in London, Beijing, and Los Angeles. The results showed that improving architectural visual access could improve participants' virtual evacuation performance during emergencies; it could also influence participants' directional choices during evacuation, depending on the design strategy used and the spatial characteristics of the building. In addition, participants' tendency of following the crowd was reduced when there was an alternative route with high architectural visual access.