## 2 Existing Studies on the Platform-Train Interface
The IDA file has a specific structure and design; however, it undergoes different variations for each project under evaluation. The variables defined by the IDA tab are the following:  
* Accessibility standards in stations: access, ramp, walkways, fixed stairs, escalator, elevator, platforms, intercom, movement corridor, mezzanine, obstacles, tactile guide pavement, ticket office, preferential ticket office, self-service machines, turnstiles, turnstiles for passenger with reduced mobility, platform, tactical band at the edge of the platform, seats on the platform, information screens, sound system, exit doors for passengers with reduced mobility, preferential car, and difference in height or distance between the train and platform;
* Accessibility standards in trains: train doors, preferential cars, preferential seats, preferential spaces, train hardrails, train handles, and train intercom. Other studies have been performed worldwide. For example, accessibility in the Istanbul metro stations was studied [18]. The author used a questionnaire to study two types of people. The first group was made up of five people with visual impairment, while the second group was made up of seven wheelchair-users. Both groups were required to enter the station and then answer some questions. In the case of the platform, the users identified that it is important to use the tactile band for alerting and moving guides. Without this element, users could not take the train or leave the platform. Similarly, in the Bangkok Metro system, a study was reported through a questionnaire to 600 users, of which 10% were older adults (>60 years old) and 4.5% had some type of mobility or reduced functionality [19]. The authors studied the facilities and connectivity for station users (for example, elevators). In addition, nine indicators were used: psychological (e.g., comfort), temporal (e.g., duration of the trip), affordability (e.g., monthly income), basic needs (e.g., if service responds to needs), connectivity (e.g., mixed use of spaces),attractive design (e.g., use of services), equity (e.g., access to opportunities), time and activity (e.g., location of activities), and urban environment (e.g., impact caused by the growth of expanded cities). Each user had to rank each accessibility question between 0 (little accessible) and 1 (very accessible). [PERSON] et al. [20] examined the technologies used to study the platform-train interface and used a virtual tracking tool to identify when passengers crossed the yellow safety line in metro stations. The use of automatic tracking tools could help to identify if passengers are respecting the yellow safety line. Recently, [PERSON] et al. [21] used an algorithm to detect passengers' locations on the platform through laboratory experiments, in which the yellow safety line was an important factor when identifying their behavior. Laboratory experiments have been performed in the last decade to study the behavior of passengers and their accessibility. One of the first experiments was performed by [PERSON] et al. [22], in which the vertical and horizontal gaps were studied using a carriage and its adjacent platform. The authors found that behavior and accessibility are affected by the platform height, door width, fare collection method, internal layout of the vehicle, and occupancy of the vehicle. [PERSON] et al. [23] reported that the door width is an important element to achieve accessibility at the platform-train interface. Similarly, [PERSON] et al. [24] and [PERSON] et al. [25] studied the relationship between the door width and the vertical/horizontal gaps through laboratory experiments. In relation to the level of access, [PERSON] et al. [26] reported that the use of an elevated platform could improve accessibility at the platform-train interface, however, ramps should have a moderate slope and must not be located in front of a train door. According to [PERSON] et al. [27] steps also affect behavior and accessibility at the platform train doors.