# System Proposal for Mass Transit Service Quality Control Based on GPS Data
## 5 System Overview
### The SQCM
#### 5.2.1 The Improved Transport Network Model
The distance threshold used in this case is the maximum error that the system assumes for a GPS reading, the variable \(E\) which was fixed at 25 m in Section 3. * Case B: the vehicle stops at stop \(p\). This case occurs when there are passengers at the stop or passengers on the bus who want to alight at \(p\). In this case, the time of arrival at stop \(p\) is obtained by taking centroid \(C_{r,p}\)--obtained in the classification of GPS stationary vehicle data for route \(r\) as described in Section 5.2.1--as the stop position. The arrival time at stop \(p\) of a service line \(l\) on route \(r\) is the time at which the GPS position for the \(QAVL_{\tau,T,l}\) set was recorded, and which must meet the following conditions:
* It is stationary. * Of all the \(QAVL_{\tau,T,l}\) stationary data, it is the nearest to \(C_{r,p}\). #### 5.2.5 Step 4: Calculating the Metrics

Having obtaining the passing times for each of the stops on line service \(AT_{\tau,T,l}\), the values of the various metrics used to evaluate the punctuality or regularity of the service line are then obtained. To monitor punctuality, for line services scheduled by timetable, the basic parameter is \(AD\) (1). From this value the remaining metrics used to evaluate punctuality may be obtained. To monitor regularity, for services scheduled by frequency, the basic parameter is \(HR\) (3). From this value the remaining metrics used to evaluate regularity may be obtained. ## 6 Use Case: Results and Discussion

Currently the system described in this article is in operation at the public transport company, Global Salcai-Utinsa S.A. This company is based on the island of Gran Canaria (Canary Islands, Spain), has a fleet of 345 vehicles, and operates 127 different routes on a transport network that contains 2686 stops. In 2015, this company carried out an average of 2395 line services on all routes, covering 28,897,002 km and carrying 19,284,378 passengers in that year. The system has been integrated with the other components used by this company on its onboard systems and its communications systems. The quality control results obtained for one of its routes are described below. The route itself is 23 km long, starts in the city of Las Palmas and ends in the city of Arucas; it has 30 stops, and it begins in an urban area in the city of Las Palmas, until the sixth stop, after which it becomes an intercity route, until the last four stops, where it again becomes an urban route through the town of Arucas. The company uses the code 210 to identify the route; therefore in the formalisation developed for this article, \(r\) = 210. Figure 6 gives an aerial view of the route with the stops represented by bus icons. The results were obtained during period \(T\)--the whole of 2015--therefore in our formalisation it will be indicated as follows: \(T\) = 2015. Route 210 was scheduled by timetable during the analysed period. The AVL system recorded 51,499,404 position readings during all the line services completed for this route. The number of vehicles involved in these line services for the selected route was 166, being 16 the number of vehicles that carried out these services systematically. In the preliminary analysis of the route to detect systematic stopping points that are not stops on the route, 7 such points were identified. Figure 7 displays these points as numbered red icons. These points are the centroids of a set of stationary vehicle data. Figure 7,\(c\) are photographs of two of these points. Figure 7 corresponds to point number 5; this is a systematic stop point because the road on which the vehicle is travelling is a bus lane ending in a roundabout, and entry into the roundabout is controlled by a traffic light. Figure 7 is a photograph of point number 7; this is a point where the vehicle stops because it is on a slip road (right lane) that joins a dual carriageway (left lanes) and does not have right-of-way. Figure 6: Aerial view of the route used for the case study. The bus icons represent stops on the route.