The informal public transportation sector in Sub-Saharan Africa contributes significantly to public transport, and yet little is known about passenger mobility patterns. We propose a low cost system to measure occupancy in a minibus taxi, and to improve understanding of passenger mobility in the taxi industry. A low cost capacitive proximity sensor for seat occupancy detection based on the loading mode capacitive sensing technique is designed and integrated with cellular communications to provide real-time information. The capacitive sensor uses a single electrode to detect an occupant. We use modules for a dynamic wireless system integration where sensors can be added or removed without modifications. A mathematical model of the capacitive sensor is developed to determine the capacitance on the sensor’s electrode. The occupied capacitance is double the unoccupied capacitance. Our results show that the proposed capacitive sensor can distinguish clearly between an unoccupied and occupied seat for multiple seats.