## 3 Risk Assessment Model for Track Maintenance Operations
### Construction of the Risk Assessment Index System  
In this study, the risk factors associated with railway track maintenance operations were systematically identified based on the \"Detailed implementation rules for construction management on operational railway lines of Lanzhou Bureau Group Co., Ltd.\" (Lan Tie Construction (2024) No. 70, hereinafter referred to as \"Document No. 70\"), the \"Classification and code for the hazardous and harmful factors in process\" (GB/T 13861-2022) [24], the \"Implementation opinions on safety risk management in the railway maintenance system\" [25], as well as relevant national standards and expert experience. The influencing factors were categorized into four dimensions: human, equipment, environment, and management. These were further structured into a two-level index system: the first-level index, denoted as \(B=\{B_{1},B_{2},B_{3},B_{4}\}\), corresponds to the four main categories. Each first-level index is further divided into \(n_{i}\) second-level indices, denoted as \(B_{ij}\) (\(i=1,2,3,4\), \(j=1,2,\cdots,n_{i}\)), collectively forming the complete second-level index system \(B=\{B_{1},\ B_{2},\cdots,B_{in_{i}}\}\). The development of this index system was informed by previous studies [3; 4; 5; 6; 7; 24]. The final risk assessment index system for railway track maintenance operations is shown in Figure 2.  
(1) Human Factors \(B_{1}\)  
Personnel involved in track maintenance operations occupy critical roles, including operating staff, and protective personnel [3]. The degree to which the operating personnel adhere to standardized procedures directly influences the quality of the maintenance work performed [5]. Failure to meet the required construction standards can lead to severe consequences, such as train derailments, when trains pass through the affected sections. Protective personnel are responsible for monitoring train movements and issuing early warnings. Their response speed and warning accuracy are vital to ensuring that operators can evacuate the work site in time to avoid collisions. Similarly, transport drivers, who are responsible for moving personnel and equipment, play a key role in operational safety [26; 27]. Moreover, new employees or outsourced personnel often lack sufficient practical experience and a thorough understanding of standard railway maintenance procedures. Their inadequate training and poor execution of key tasks, such as equipment handling and process compliance, can lead to substandard maintenance work and significantly increase the risk of accidents. (2) Equipment Factors \(B_{2}\)  
According to the \"Technical Management Regulations for Railway\" [28], tools and protective equipment must undergo regular inspection and maintenance to ensure proper functioning. The use of unqualified or defective equipment is strictly prohibited. For example, damage to the insulating layer of tools may lead to the \"red light band\" phenomenon, which poses a significant safety risk. Additionally, if communication equipment malfunctions, it becomes difficult to ensure the accurate transmission and timely execution of operational instructions, increasing the likelihood of information errors or omissions. Such failures can result in serious safety hazards during maintenance operations [5]. (3) Environmental Factors \(B_{3}\)  
The operational environment plays a crucial role in influencing safety risks during railway track maintenance [3]. In areas with poor communication infrastructure, the transmission of protective instructions and dispatching information is often delayed or disrupted, directly endangering the safety of train operations [29]. Limited visibility conditions such as darkness, severe weather (e.g., fog, heavy rain, snow, and sandstorms), and insufficient lighting reduce operators' line of sight and environmental awareness, weaken protective personnel's ability to detect oncoming trains in a timely manner, increase the likelihood of operational errors, and significantly escalate collision risks.