Development of a Positioning Technique for Traffic Data Collection Using Wireless Signal Scanners

The study purpose is to utilize communication technologies in automated transportation data collection. The goal is to find a solution for positioning beacons transmitting wireless signals suitable for traffic data collection. The technique developed in this paper for positioning is based on the strength of Bluetooth signals transmitted by beacons, creating radio maps, and applying an algorithm called k-nearest neighbors (k-NN). Four Bluetooth signal scanners and a beacon were used in the experiments in an intersection and its adjacent streets. Numerous stations and scanners arrangements were tested for enhanced accuracy. The results confirm the functionality of the technique in positioning based on wireless signals. The modifications in the set-ups and arrangements clearly indicate that increasing the distance between the stations on the radio maps, along with meeting the minimum positioning accuracy requirements and making the arrangement of stations and scanners asymmetric, can enhance the accuracy level of positioning by reducing the error probability of the algorithm and causing more distinction in the radio maps. It was observed that by increasing the distance between the stations in each lane, from 3 m to 5 m, and making the stations and scanners asymmetric in arrangement, the positioning percentage with an error of 5 m or less may be increased to 90% from 73.5%. Also, the accuracy of positioning tends to decrease as the distance between the beacon and the scanners increases. This paper studies both stationary and moving beacons. It was found that although positioning of stationary beacons can be done with a precision of up to 90% with an error of 5 m or less if the stations and scanners are properly arranged, the positioning of moving beacons is more challenging.