# Understanding Safety Performance of Prefabricated Construction Based on Complex Network Theory
## 5 Discussion  
### Comparison of Safety Risks  
Motivated by the observation that there is a restricted improvement of safety performance in prefabricated construction, this study applied complex network theory to unveil the underlying reason for the unsatisfactory condition and formulate corresponding strategies. Overall network topology analysis revealed the fact that PCSRN processes small-world and scale-free characteristics, which was also discovered in Subway construction safety risk network (SCSRN) [37] and Behavioral risk chain network of accidents (BR-CNA) [54] in building construction. The presence of these two phenomena indicates that although safety risks of prefabricated construction are diverse from general construction safety risks, the nature of effortless transmission and efficient diffusion in safety risks are constant. Precisely because of the complex interactions among safety risks, the prediction and uplift of safety performance in prefabricated construction become arduous work. In terms of key nodes identification, four criteria provide diverse ranking of nodes subject to their importance. In light of the hub of HITS and k-shell decomposition, safety risks at the design stage are more influential. While in the context of degree difference, the essentiality of critical management risks in the manufacturing and assembly phases is manifested. Considering the authority of HITS, the most significant material and equipment risks during manufacturing, transportation, and assembly are detected. Obviously, compared with the method of a single dimension indicator, the way adopted in this study covering different criteria results in a more comprehensive identification of critical safety risks. Management safety risks involving R21 (Poor organizational communication) and R22 (Inadequate safety education and training) play prominent roles in PCSRN on account of their strong capacity for triggering and transmitting other risks. Such a result is consistent with the finding in BRCA, where improper communication and coordination, as well as lack of safety education and training are regarded as two significant accident causes [54]. Poor organization communication, which is affected by a lack of interactive platforms for safety communication and lower involvement of different project stakeholders (e.g., architects, manufacturers, engineers, transports, and contractors) in cooperation, remains the foremost impediment to the safety practice within prefabricated construction. More often than not, the absence of organization communication leads to improper component size design, sketchy technical clarification, and construction process conflicts. Given that the implementation of prefabricated construction regularly necessitates bulky and heavy modular components fabricated in manufacturing plants, hoisting, moving, and installation of these oversized heavy loads would be constrained by space and technical restrictions. Nevertheless, the principal workforce for prefabricated construction is aging workers from rural areas who do not complete training for safety-related skills and knowledge [97]. It could be asserted that without proper safety education and training in safety management, workers would be exposed to numerous hazards unconsciously owing to incomprehensive understanding or misunderstanding of these restrictions. As for R20 (Unsecured equipment/tool/object), R16 (Quality defects of prefabricated components), and R18 (Insufficient connection strength of prefabricated component), they all pertain to the material and equipment factors of the prefabricated construction process. Compared with the traditional cast-in-place concrete construction method, struck-by injuries caused by falling objects abound in prefabricated building projects owing to the unfixed prefabricated components, materials, and tools used or produced during the construction. Moreover, conditions in which the modular component itself was defective occurred oftentimes.