## 1 Introduction  
The Santiago Metro is an underground transportation system that connects 32 boroughs in Santiago, Chile, with a total of 7 operational lines and 136 stations distributed across its different lines and a total length of approximately 140 km, which in 2019 transported a maximum of 695 million passengers [1]. The Santiago Metro has been recognized as one of the most modern and efficient underground transportation systems in Latin America, standing out for its punctuality, safety, and comfort for passengers [2]. The continuous expansion of the network, with the implementation of new lines, has allowed for an expansion of services, offering access to a greater number of users. It is expected that even more lines will be inaugurated in the near future, indicating that demand for the Santiago Metro will continue to increase. Each day, more than 2.5 million trips are registered in the urban railway network of Santiago, generating high interaction and congestion levels, which affect the infrastructure performance of escalators inside the stations [3]. A study carried out by the Moovitapp App revealed that, on average, a passenger spends 84 min a day on the Santiago Metro and that 74% of passengers transfer to other modes of transport at least once a day [4]. The high interaction and congestion levels are generated especially at connection points between different spaces in urban railway stations: the train platform, the platform-stair area, mezzanines, complementary spaces (for example, commerce), and the city (street level). However, all these spaces have connections through stairs or escalators, which may cause bottlenecks and evacuation problems, affecting the capacity of the whole station [5]. Infrastructures such as escalators are intended to speed up the evacuation process of passengers, connecting different spaces within the station and to the city. However, these infrastructures may lose their efficiency when a high agglomeration of passengers is reached at the base of the escalator or when there is inappropriate passenger behavior, affecting the use of the infrastructure and generating crossings of pedestrian flows or accidents. In terms of safety, the risks of accidents due to crowding are becoming increasingly higher considering the constant increase in population that the city is experiencing. Therefore, the accident rate on escalators has been increasing, which has been a topic of interest for the Metro company to ensure the well-being of users [6]. To solve this, different measures have been applied in urban railway stations. In the case of the London Underground, signaling with audible and visual information is used to indicate that passengers must keep to the right when moving up through the escalator, generating the possibility for those who want to move faster to overpass those passengers from the left-hand side (see Figure 1a) [7]. In the case of the Santiago Metro, there have been some attempts to solve this type of problem. Some stations such as Plaza Egana (Line 4) have signs located on the ceiling of the station and markings on the stairs of the escalator to indicate where passengers should be located when evacuating the station (see Figure 1b). It is well known that the behavior of passengers in urban railway stations is affected by different factors such as the physical design, people around, information, and environment [8]. Taking this sentence into the context of the Santiago Metro, the situation is as follows: passengers are not used to standing on the right-hand side of the escalator, which affects those passengers moving at a higher speed or needing more space to evacuate the station. Therefore, the effect of these types of solutions on the capacity of the escalator is unknown, and it is not possible to understand their relationship with passenger behavior. For this study, the general objective was to study the effect of passenger behavior on the escalator infrastructure in urban railway stations, taking the Santiago Metro as a case study.