# Automatic Generation of Guidance for Indoor Navigation at Metro Stations
## 4 Results
### Route 4--The First Direction After Exiting the Train  
A typical use case of navigation in a metro station is exiting the train on the platform and finding a way out on the ground level. Empirical tests have shown that the critical moment of the process is the first decision of users. They leave a train and, to perform the first manoeuvre correctly, must orient themselves in a space that is new to them. The problem is even more complicated since the users' location on the platform is not known. A user can enter the train at the beginning, middle, or end and then move to a different part of the train during the journey. This causes the user to start navigating from an unknown position on the platform. The problem becomes even more complex if we consider the different configurations of stairs to exit the platform. If the stairs are located at the end of the platform, as in Figure 15, no matter where the passenger gets off the train, they are supposed to turn right. If, however, the stairs are located on the platform between the platform ends, as in Figure 16, then the user should turn right or left depending on where they get off the train. In addition, if the user gets off at the end of the train, the indication to go left towards the stairs is ambiguous because they pass other stairs beforehand. The adopted solution to the problem was based on moving away from specifying the direction in which the passenger should turn after exiting the train. Instead, the direction contains an absolute indication of the position of the stairs on the platform relative to the train. The tests showed that it was sufficient to describe the position of the stairs with one of five terms: 'the start of the platform', 'the second carriage', 'the middle of the platform', 'the penultimate carriage', and 'the end of the platform'. Thus, the full guideline is as follows: 'proceed to the stairs at the second carriage' or 'proceed to the stairs at the end of the platform'. It is worth noting that, where possible, it is useful to refer to the platform, not the train, as it may have left in the meantime. During the tests, users intuitively understood  
Figure 14: Examples of floor connections: subsequent stairs of a different type; the maps present _Interior Spaces_ (grey), _Indoor Installations_ (purple), _Path Edges_ (green and red for parts of the route), and _Path Nodes_ (circles); decision points are marked in red. Figure 13: Examples of floor connections: (**a**) staircase with separated escalators, (**b**) staircase with subsequent escalators; the maps present _Interior Spaces_ (grey), _Indoor Installations_ (purple), _Path Edges_ (green and red for parts of the route), and _Path Nodes_ (circles); decision points are marked in red. that the start and end of the platform referred to the direction of the train. The tests also showed that users were able to identify the position of the second and penultimate carriage at the station without much effort, whereas references to other carriages required counting and discouraged users from trying to understand the message. Hence, the authors decided to use a reference to one of the five staircase positions. As the first navigation direction is independent of the user's starting position, the route is not drawn from the train exit but from the stairs. In Figures 11 and 12, the start of the route is marked with a red dot. The second problem related to the start of the route on the platform is the choice of the appropriate stairs. If there are several stairs on the platform leading to different parts of the station, then the situation is simplified, as it is optimal to choose particular stairs in order to exit the station at the right point on the ground level. However, there are stations where the choice of stairs on the platform is irrelevant, and passengers in this situation choose the stairs closest to them and would expect the algorithm to work the same.