## 2 Literature Review
[PERSON] [21] details the different typologies, configurations, and construction systems used in Russia. [PERSON] [22] specifies the most common station typologies in China. One of the important constraints in station design is the limited room for making structural modifications to subway stations, especially underground ones, which reduces their potential for expansion and optimization, among other factors. This leads to highly inefficient stations when expanded or converted into transfer stations due to construction limitations. This is because structural modifications in the construction of the station can affect the tunnel, adjacent buildings, or pre-existing stations. [PERSON] et al. [23] studied how to control deformations in buildings close to subway stations. Another design constraint in stations is related to the operational design of the line and the subway service exploitation strategy, which directly affects the system's capacity and impacts the station design. [PERSON] [24] studied how the operational design of maneuvers affects the behavior of the station. With respect to capacity, one of the classic areas of study in transportation is the relationship between flow, speed, and density. [PERSON] et al. [25] studied the relationship between speed and density of passenger flow on the platforms and stairs of Line 1 of the Beijing Subway. In their study, they developed a linear regression model that allows for the determination of capacity and service level. [PERSON] et al. [26] designed a passenger traffic assignment model with capacity constraints, which enables the evaluation of the interaction between capacity and comfort both inside the train and on the platforms. The Capacity and Service Quality Manual [27], in Chapter 10, specifies the capacities within a station, namely the access points, horizontal circulation, vertical circulation, platforms, and waiting areas, as well as the interaction between the various elements of a station. To measure the level of comfort in stations, the level of service (LOS) is used. The LOS is a quality measure employed to determine comfort levels under different conditions of flow, speed, and density in metro stations. Initially, the level of service only considered physical flow variables such as density and speed. However, in the area of pedestrian flows and subway services, new objective and subjective variables related to the infrastructure, the crowd, and the user in particular have been incorporated. These include factors such as lighting, climate control, perceived insecurity, and the perception of time, among others. The level of service, service quality, or passenger comfort has become an extremely important variable today, as congestion is frequent in cities and users demand higher quality in transportation services. [PERSON] et al. [28] studied how the degradation of subway service affects users and proposed strategies to minimize passenger dissatisfaction. [PERSON] and [PERSON] [29] conducted an analysis of the level of service and space requirements in stations in South Africa. For the purpose of this research, the study will focus solely on the components of the platform. Pedestrian flow behavior has various models derived from vehicular flows and hydraulic models of fluids and gases [30]. The similarity between the behavior of pedestrian crowds and that of gases or fluids was materialized and simulated by [PERSON] et al. [31] and [PERSON] et al. [32]. The conceptual foundations of the pedestrian level of service (LOS) were developed by [PERSON] [33], and various studies on speed and free-flow walking have been researched and compiled by [PERSON] and [PERSON] [34]. The behavior of pedestrian crowds in counterflow with self-organization has been described by [PERSON] [35]. In the specific context of pedestrian flow behavior in subway stations, pedestrian behavior and self-organization in subway corridors using social force models and cellular automata have been studied by [PERSON] [36].