The Santiago of Chile subway system is nowadays one of the most used means of transportation in the city, therefore many passengers with reduced mobility prefer it. However, in the subway lines, we can find different vertical gaps that are generated between the train and the platform. These vertical gaps makes it difficult for passengers with reduced mobility to get on and off the train, by generating a change in their gait, affecting their stability. This stability can be represented by different variables such as the rejection and damping force, the travel ranges of each step component, and the area generated by these travel ranges. The objective of this paper is to study, experimentally, the effect of vertical gaps on the gait and stability of passengers with reduced mobility in the train-platform space of subway stations. For this purpose, the construction of full-scale experiments representing the train-platform transition was carried out at the Human Dynamics Laboratory of the Universidad de los Andes. To obtain the data, a Bertec force plate and Bertec Acquire 4 software were used, which allows, to obtain the force in the z-axis and the pressure centers in the x-axis and y-axis. The results show that the higher the vertical gap, the higher the instability in passengers with reduced mobility. In addition, it was also observed how passengers with reduced mobility change their gait strategy when having to face vertical gaps greater than 11 cm, since they changed the angle of inclination with which people position their foot when descending, to be able to do the process with greater stability. It is hoped that future experiments will expand the scope of this type of study, by implementing more instrumentation and a larger number of participants.