Passenger estimation system using Wi-Fi probe request

Public transportation is a popular means of travel for many urban residents. However, users may not know the location and number of people on a vehicle, which results in uncertainty and wasted time while waiting. To help users manage their time more efficiently, a passenger estimation system that can provide the location and occupancy of each vehicle would be useful. The location can be determined accurately by using GPS data, while it is noted that most passengers on a vehicle typically use smartphones, which are equipped with wireless systems that can be monitored to estimate the number of users in that area. Smartphones with Wi-Fi enabled always send out probe requests that contain unique MAC addresses. By monitoring these probe requests, the number of passengers on the vehicle can be estimated. The time period and signal strength from each probe request, along with the location of the vehicle, is used to categorize a group of smartphone users as passengers or non-passengers. The device is implemented and evaluated on the shuttle bus system of Thammasat University, Thailand.