# Efficient Railway Turnout Design: Leveraging TRIZ-Based Approaches
## 2 Literature Review
The study investigated the factors that influence the reliability and lifetimes of S&C components, with a particular focus on maintenance practices. By analysing the lifetime distributions of individual components, the research provides valuable insights into optimising maintenance strategies and improving the overall reliability of S&C units used in railway systems. A derailment mechanism that focuses on understanding the factors that contribute to derailments in railway systems is presented in a recent study [41]. The researchers evaluated the rationale for the rail clearance maximum and its method of calculation, which is critical to ensuring safe rail operations, and they suggested a new approach to calculating the maximum guardrail clearance based on the running attitude of the vehicle and the angle of attack of the wheelsets. This new approach considers the dynamic behaviour of the vehicle and the angles at which the wheels interact with the guardrails. In the context of wear, ref. [42] developed a comprehensive methodology for the simulation of wear, rolling contact fatigue and plastic deformation in switches and crossings (S&C) in a mixed traffic situation. This methodology aids researchers in understanding the wear patterns and fatigue behaviours of S&C components, especially when subjected to different types of traffic loads. Additionally, ref. [43] conducted a parametric study using vehicle-track simulations and multibody simulation software to explore the sensitivity of operational factors and their impact on switch panel wear loading. By varying operational parameters, this study provides insights into the factors influencing wear on switch panels and guides decision-making in terms of optimising switch maintenance and prolonging the life of S&C components. Lastly, ref. [44] addressed various issues concerning aspects such as maintenance, wear and tear, structural integrity, and the overall performance of the turnout. Addressing these issues is crucial to ensuring the safe and efficient operation of the railway system and enhancing the longevity of S&C units. In addition, a study of wheel-rail interaction and damage in S&C was carried out in [45]. The focus of the research was to evaluate the influence of stochastic variations in traffic variables on switch and crossing deterioration, helping us to understand the way in which varying traffic conditions affect the wear and degradation of S&C components. Furthermore, in [46], a study was presented on the improvement of the interaction between vehicles and turnouts. The study focused on optimising the crossing nose shape using a numerical optimisation approach, having the aim of minimising rolling contact fatigue damage and wear in the crossing panel by varying the nose rail shape. In [47], real-world experiments were conducted to analyse selected ground imperfections in terms of track susceptibility for both linear and non-linear systems. The focus of the research was to evaluate the effect of wheel pressure on the local ground irregularities within the railway switch, showing that these imperfections, along with the calculated additional deflections, can cause disturbances in the progressive movement of the rolling stock. Finally, ref. [48] presents a process for the production of innovative designs for next-generation switches and crossings to address the capacity constraints imposed on the rail network by current designs, using the Pugh Matrix method to minimise bias and subjectivity in the decision-making process. By incorporating sensitivity analysis, the research investigates potential biases and enhances the reliability of decision-making throughout the design process. In summary, the findings of this paper contribute to the advancement of the design and optimisation of the railway infrastructure to ensure safer, more efficient and more reliable railway operation in the future.