## 2 Existing Studies on the Platform-Train Interface  
Similarly to other public transport systems worldwide, according to the legal framework in Chile based on the Accessibility Law (2012), metro stations need to comply with the following:  
* Implement signage that considers different deficiencies that cause disabilities;
* Provide seats and reserved spaces for the use of people with disabilities and reduced mobility in at least one of the cars;
* Include seats for passengers with reduced mobility (10% of the seats), seat signage, preferential seats, and door signage (sound and visual);
* Provide stop request buttons (with a color that contrasts with the surface, with an acoustic and light signal). These standards are focused on the interior of the vehicles and therefore no clarity is provided on the design that the platforms or other circulation spaces around should have. In the case of cities such as London (2013) some manuals address the standards and dimensions for an adequate design of the platform-train interface, specifying variables such as door width, platform length, platform width, and exit routes. However, in the case of Santiago, the Metro company has its standards which are not publicly available. The Santiago Metro in its newest lines (3 and 6), has had an accessibility design, in which loading machines with the Braille system were included and special entrance doors for people with reduced mobility were placed. Inside the train, more seats were added, and preferential spaces were established to give more space for passengers with reduced mobility. This only applies to these new lines, leaving aside the old lines, which makes this a reason for complaints and confusion by the affected users. In 2015, a study was carried out on the London Underground to see how the behavior of users varied concerning different designs of the yellow line at the edge of the platform [16]. This study was conducted due to an accident at the platform-train interface, where a woman's coat got caught in the train doors, dragging her along the platform, and causing injuries to her leg and arms. The study was carried out in four stations, and each one had a different type of demarcation. It should be noted that in all stations the same material was used for the yellow line, in addition to the fact that in all of them, the distance between the train and the platform was increased, to have greater security. The study carried out had two main criteria to see if these changes were successful: that no negative effect was seen in delay times, and that acceptance by passengers was maintained or increased. The results of the study showed that delay times were not negatively affected by the variation of the yellow line, which is positive. Likewise, there was no information on any impact on the operations of the stations, which means that the changes did not affect the reliability or congestion of the network. Finally, based on field observations it was shown that fewer people were respecting the yellow line. However, it is worth noting that although compliance was reduced, passengers were generally further away from the edge of the platform than before the test. In addition, the yellow line was least respected when not all the people could get on the train, leaving passengers on the platform. Passengers moved forward to board the train but did not go back behind the yellow line if they could not board. In the case of Chile, a study carried out by Amestoy [17] defines the standards for universal accessibility and also provides a diagnosis of the Santiago Metro network. This study was carried out in collaboration with SENADIS (National Disability Service), as well as the Metro de Santiago company. SENADIS created the Accessibility Diagnosis Report, better known as the IDA file, which aims to quantify the efforts necessary to generate accessibility conditions that guarantee the right to access and use these facilities by people with disabilities.