# Literature Review of Digital Twins Applications in Construction Workforce Safety
## 2 Overview of Construction Workforce Safety
### Safety Awareness in Construction  
Similar to behaviour safety, safety awareness is heavily dependent on workers' safety experience. During the construction process, various kinds of interference occur, and the nature of the interference is intrinsically stochastic ([PERSON], 2015). Unsafe conditions are inevitable in construction activities, but the risks can be controlled within an acceptable range using appropriate means. Issues related to safety awareness refer to the situation where workers have relevant knowledge and understand the existence of unsafe conditions, but do not take appropriate measures and persist in construction activities. Safety awareness is difficult to measure directly, but it can be reflected in workers' behaviour. For example,the situations where a worker works around damaged guardrails, and a worker refuses to equip themselves with personal protective equipment (PPE) when working at heights indicate the workers lack safety awareness. Workers know these behaviours are wrong, but the unsafe behaviours often occur out of a lack of concern for their safety. The reasons for insufficient safety awareness are complex, including personal factors, social influences, environmental conditions, and so on [38]. The most immediate factor is the workers' failure to assess the risks properly. For some low-probability risks, because the accident has not yet happened, people will gradually pay less attention to it. This kind of fluke mentality can have serious consequences when an accident does occur.  
The cultivation of safety awareness largely depends on long-term training and practice. In practical projects, workers' safety awareness cannot be permanently improved in a short time. To counter the insufficient vigilance and underestimation of risks, safety signs have been designed and set to provide a warning at the construction site for a temporary increase in safety awareness [39]. The Australian code [34] recommends providing clear instructions at the construction workplace, such as \"no entry\", \"PPE required\" and other signs showing hazards. The relationship of the location of signs and the surrounding environment was found to significantly affect the information provision scope of signs [40]. [PERSON] et al. [39] developed an objective measurement paradigm to evaluate the cognitive load of different design features and evaluated the perceptual effects of workers in different attention situations. Based on these findings, visual cues need to consider multiple factors, including location, shape, and colour, to enhance the impact of safety warnings.  
Safety signs raise people's safety awareness to a certain extent by providing repeated prompts to people entering dangerous areas, but their limitation is obvious. Static signs are easily obscured by dynamic construction objects. Workers do not have to respond to a safety sign, so a sign will be ignored over time. Portable safety warning approaches, such as ringing or vibration, increase the situational awareness of workers as to when there is a hazardous situation [4]. This kind of real-time reminder can make people pay attention to the environment and reassess the risk in a short period of time, avoiding accidents. However, studies about warning mechanisms aimed at the construction industry remain rare. Large amounts of research are needed to help workers switch their attention from their work to hazards when a sudden danger arises.