Extracting information from Wi-fi traffic on public transport
Free (open access)
Volume 5 (2021), Issue 1
15 - 27
András Bánhalmi, Vilmos Bilicki, István Megyeri, Zoltán Majó-Petri & János Csirik
The utilization and the quality of public transport are important for the customers, maintainers and service providers. Passive measurement techniques, when humans are not involved are the cheapest way for collecting large amounts of long-term data from multiple public transport lines. Useful data can be collected from various sources, such as from cameras, infrared sensors and Wi-Fi routers. We addressed the problems of estimating passenger counts in two different ways, and also to get travel statistics like the number of passengers getting on or off a vehicle at a bus stop; and even to compute an origin–destination matrix from Wi-Fi monitoring data. In this study, we focus on Wi-Fi data, which can be still useful for extracting relevant data after many years. here we describe Wi-fi data collection methods, and then prove the usefulness of applying simple artificial intelligence-based methods to extract information from the huge amount of Wi-Fi data. We will also show that ‘lower-level re-estimation’ can be useful for further optimization, which means that globally modelled data may have to be re-modelled on partially selected groups to get better results. Namely, after building linear models and estimating absolute and relative errors, we found that the relative error of the Wi-Fi-based estimation can be markedly reduced if data are processed and analysed in more detail. When a daily Wi-Fi analysis is split into between-stops parts, an additive linear correction can be computed and applied to these parts, and as a result, the relative error of estimates can be reduced.
axle load-based estimation, public transport, Wi-Fi frame monitoring