# An Intelligent Parking Management System for Urban Areas
## 4 Tests  
To test the proposed system under real conditions, it was installed in a parking area located on the Tafira Campus of the University of Las Palmas de Gran Canaria. This parking area has a capacity for 10 vehicles and has a single lane that is used both to enter and exit; the setup is shown in Figure 11. The tests were conducted to verify the behaviour of the following aspects of the system: communications system; establishing the configuration parameters of the system for correct detection of the passage of a vehicle (distance between the two speed bumps fitted with a sensor and the time each sensor indicating the presence of a vehicle must be active); and incorrect detection of the passage of a vehicle due to a false positive.  
To check the communications system was functioning correctly, an automatic periodic verification process was developed to check the status of each sensor node. Specifically, the sensor nodes were programmed, once they had been activated from the data processing centre, to send the status of their batteries every hour over a period of seven days. It was found that these were correctly identified by their IPv6 address and that the frames were sent correctly without errors and correctly routed through the gateway node to the central data processing system. One hundred sixty-eight packages of 168 were received, with an error rate of 0%. The weather conditions during the test were: clear sky, cloudy sky, and light rain.  
Bearing in mind the way that the method of detecting passing vehicles was designed, two values need to be correctly configured for the process to run reliably:  
* The distance separating the sensors placed in each speed bump. This is a fixed value that we have called L.
* The time that each sensor of the pair controlled by a node sensor needs to be active, thus indicating the presence of a moving object. This is a value that can be varied by reprogramming the sensor nodes. We have called these values T1 (value of sensor 1 timer) and T2 (value of sensor 2 timer); T1 = T2.  
The distance separating the two sensors, each installed in a speed bump, is a fixed value and, for a correct setting, the lengths of the different types of vehicles on the market must be taken into account. For this, we conducted a study of vehicle lengths (see Table 3), concluding that the most appropriate distance is 2.6 m, corresponding to the shortest wheelbase, but longer than the wheelbase of other moving objects, such as a bicycle or a motorcycle.  
Figure 11: Deployment of prototype sensor system to monitor access to the parking area. The sensors are installed in the speed bumps.  
The time that each sensor must be active indicating the presence of a moving object, T1 for sensor 1 and T2 for sensor 2, depends on the speed of the vehicle in the parking area access lane; the maximum speed allowed in parking areas is 20 km/h. Table 3 shows these values for different types of vehicles travelling at 20 km/h.  
False positive situations are impossible to avoid, due to moving objects other than vehicles entering the parking zone, or an intentional improper use of the deployed system. However, these kinds of errors did not appear during the test period, although false negative values were detected. These were caused by vehicles, generally short vehicles, not passing over both sensors situated on the ground, but avoiding one of them when entering or leaving the parking zone. These tests were performed using conventional passenger cars, not other types of vehicles, like trucks or buses, due to parking size restrictions.