# Literature Review of Digital Twins Applications in Construction Workforce Safety
## 7 Discussion
### The Status Quo of Digital Twins (DT) to Improve Construction Workforce Safety  
The main problem in the construction environment safety category is that useful safety information in complex construction environments is mixed with useless information, which is difficult to distinguish for both construction managers and on-site workers. This also complicates the proper implementation of safety regulations for the construction environment. These problems are widespread in construction projects, and the following solutions are proposed based on the DT concept. 4D BIM and sensors can be used to digitise the construction site [43; 46; 49]. The 4D BIM simulates the construction activity, and the sensors synchronise real-time data during construction to monitor unexpected events. Therefore, a digital twin of the construction environment can be generated to virtually simulate the construction environment [53; 86]. Through natural language processing, the content of safety regulations can be mapped to the properties of objects in the construction site item by item [76; 77; 78]. By analysing the digital replica, a script automatically checks the BIM based on regulations to identify the construction environment safety problems. This process extracts hidden information from a large amount of data and plans and checks the safety regulations.  
The categories of behaviour safety and safety awareness are related to on-site workers. Only when workers have sufficient experience and knowledge and correctly estimate the risks in construction activities can they act safely [60]. Therefore, the solution to this problem should focus on both the long-term improvement in workers' quality and the timely prevention of unsafe behaviours in the short term. Firstly, construction knowledge based on articles, manuals, and experience should be summarised to generate a knowledge base [78; 79]. With the help of ontology, connections between knowledge and physical entities can be established to describe the behaviours of workers that could lead to accidents under certain circumstances. In terms of the behaviour of workers, the current research has two main branches: the location and the motion information of workers. In both cases, digital replicas are created to synchronise physical entities. The study of digital replicas not only avoids the interference of construction activities [4] but also reasonably removes redundant information [62], which confirms the important role of the DT concept in construction workforce safety. Together with the digital twin of the construction environment, the synchronisation with the worker achieves the fundamental DT concept in construction. By integrating and analysing the position, equipment, and behaviour of workers, the relationships among them are matched with the relationships described in the ontology knowledge base. Therefore, (1) the occurrence of risky behaviours can be documented to supplement knowledge gaps, (2) training programs can be customised based on unsafe behaviour to improve workforce quality, and (3) real-time warnings can be triggered to stop unsafe behaviour in time, thus directly avoiding accidents.