## 5 Use Case  
This section describes a system's use case. The system is used to obtain points on the route of a vehicle at which it systematically stops. This information is useful to regulatory agencies because they can:* Verify that the stops used by transportation company vehicles are located at the positions that were agreed upon with transportation companies.
* Determine the frequency of use of each of the stops. This information is useful to adequately define the locations of the tops in the transportation network and determine how they are outfitted.
* Improve knowledge about the transportation network by incorporating new entities that affect the duration of vehicle routes. Specifically, these new entities are points on the routes that are not scheduled to be used for passenger pick-up or drop-off (stops and stations) but are where vehicles systematically stop or reduce their speed, therefore affecting the duration of the trips; these are also of interest when attempting to obtain information about the state of traffic on the roads that make up the transportation network.  
This case of application describes how the system is able to identify points at which the vehicle systematically stops. These points can be of two types:  
* Points of scheduled stops (PP, for its initials in Spanish). Points at which the vehicle must stop according to plan: stops and stations.
* Singular points (SP). These points are locations where the vehicle systematically stops due to the presence of traffic signals (traffic lights, pedestrian crosswalks, stop signs, _etc._) or changes in road topology (road narrowing, roundabouts, intersection with another road without having the right-of-way, _etc._).  
The method used is capable of identifying SP type points in a route while only making use of the data provided by the system. Using only GPS readings, the precision of these readings must be considered, which as was mentioned before, can have a maximum error of 100 m. Therefore, the technique described has a restriction; the distance between two consecutive systematic stop points must be greater than 100 m. The technique is based on executing the following steps:  
1. Select the vehicle positioning data sample.
2. Filter erroneous or irrelevant GPS readings.
3. Classification: 1. 1. Identify the set of scheduled stop locations in the route (PP). 2. Identify the set of locations at which the vehicle systematically stops without the stops being systematic stop locations (SP).  
A description of each of these steps follows, including the results obtained when applying this technique to an interurban route traveled by a vehicle selected from the fleet, called the laboratory vehicle. The route being studied has an approximate length of 23 km and duration of 40 min. The route passes through urban areas with high traffic density and non-urban areas with a more fluid traffic. The explanation will be complemented with aerial photographs of the sample route provided by the Google Earth service (Figure 2).  
As mentioned previously, the onboard system makes periodic measurements every second of the vehicle position and stores these measurements in the PT table described in the section about data management. To obtain the positioning reading sample, a significant period of time is established, and all the records obtained in that period are extracted from the PT table. A period of 3 months was established for the route being studied, resulting in a sample of 7,862,400 positioning readings.