The main objective of the research is to study the impact generated by the dimensions of the horizontal (distance between the train and the platform) and vertical (height between the train and the platform) gap on passengers who use different mobility aids. The aim is to find standard dimensions in the design of the platform train interface, allowing an accessible boarding and alighting process for users with disabilities or reduced mobility. The method is based on experiments performed in a controlled environment at the Human Dynamics Laboratory (LDH) in Universidad de los Andes (Chile), through a mock-up configured with representative characteristics of a train and its adjacent platform. Using cameras arranged on the ceiling, the boarding and alighting process was registered according to a new accessibility level. The results allow obtaining scenarios with a 'desirable gap', as well as scenarios with inaccessible gaps.