Towards understanding and improving the safety of informal public transport in Sub-Saharan Africa : a real-time sensing and reporting system for minibus taxis

• Main Author: Zeeman, Adriaan Siebrits
• Other Authors: Booysen, M. J.
• Format: Others
• Language: en_ZA; en_ZA
• Published: Stellenbosch : Stellenbosch University 2013
• Subjects: Occupancy detection; Reckless driving > Testing; Public transportation > Sub-Saharan Africa; Dissertations > Electrical and electronic engineering; Minibuses > Sub-Saharan Africa; Road safety > Sub-Saharan Africa; Real-time control; Theses > Electrical and electronic engineering
• Online Access: http://hdl.handle.net/10019.1/85624

Thesis (MScEng)--Stellenbosch University, 2013. === ENGLISH ABSTRACT: Developed countries have led the way in the implementation of Intelligent Transport Systems (ITS), with the main objectives of improving road safety and efficiency. Current ITS solutions are heavily dependent on advanced and expensive technologies, and do not necessarily meet the unique requirements of public transportation in Sub-Saharan Africa (SSA). The informal minibus taxi sector dominates public transport in SSA in general, and in South Africa in particular, and is notoriously dangerous – leading to many fatalities annually. This work presents the design and testing of a sensing and reporting system for public transport in SSA. The system contributes to improving the safety and efficiency of minibus taxis in SSA. The system provides three core functions, namely, reckless driving detection, multiple occupancy detection, and wireless reporting to a visualised online platform. The reckless driving detection system implements a novel model that augments inertial vehicle acceleration data with GPS speed information. The model is based on standards used in road design, and takes into account the relationship between a vehicle’s tyres and the road surface. A lateral acceleration threshold, which is speed dependant, and a longitudinal acceleration threshold are suggested to detect reckless driving. Acceleration data is filtered to remove both high-frequency noise and zero-frequency offset, and compared to the thresholds to detect reckless driving events. The occupancy detection system detects multiple occupants in the minibus taxi using low-cost capacitive sensor electrodes, which utilise the electrical field properties of a human body for presence detection. A simplified mathematical model was created to calculate the expected capacitance on the occupancy sensor electrode, and was compared to the measured capacitance in the minibus taxi. The theoretical and empirical results demonstrate that the capacitance of an occupied seat is more than double that of an unoccupied seat. Occupants were clearly detected in various scenarios, such as different occupant sizes, water on seat, various seated positions on the sensor, etc. The wireless reporting inside the vehicle is implemented using a ZigBee network on an Arduino platform. The extra-vehicle wireless reporting uses the existing SSA cellular network, and the online data visualisation is implemented on Trinity Telecoms’ SMART platform. The complete sensing and reporting system is implemented as a prototype, and tested in South African and Ugandan minibus taxis. The results demonstrate that the system achieves the set goals, and could be used to make transport in SSA safer and more efficient. === AFRIKAANSE OPSOMMING: Ontwikkelde lande neem die voortou met die implementering van Intelligente Vervoer Stelsels (IVS) met die hoof doelwit om padveiligheid en vervoerstelsels se effektiwiteit te verbeter. Huidige stelsels wat ontwikkel is vir IVS is baie afhanklik van duur en gevorderde tegnologieë en bevredig dus nie die huidige vereistes binne die openbare vervoer stelsel van Sub-Sahara Afrika (SSA) nie. Die minibus taxi sektor domineer die openbare vervoer stelsel in SSA en meer spesifiek in Suid-Afrika, en daar is jaarliks duisende ongelukke waarvan baie tot sterftes lei. In hierdie werkstuk word daar ’n stelsel voorgestel wat minibus taxi’s in SSA kan monitor. Die doel van die stelsel is om die openbare vervoerstelsel se effektiwiteit en padveiligheid te verbeter. Die stelsel bestaan uit: roekelose bestuur opsporing, veelvoudigepassasier waarneming (monitor van aantal passasiers in voertuig) en network verslagdoening na ’n aanlyn platform. ’n Nuwe model is ontwikkel om roekelose bestuur op te spoor – deur die voertuig se versnelling en spoed te kombineer in berekenings. Die model se berekenings is ook gebasseer op die verwantskap tussen die voertuig se bande en die padoppervlak. Roekelose bestuur word bespeur deur ’n laterale en longitudinale drempel wat spoed afhanklik is. Versnellingsdata word gefilter om hoë-frekwensie geraas en nul-frekwensie afwykings te verwyder. Gefilterde data word dan met die gepaste drempel vergelyk om te bepaal of die bestuurder ’n roekelose beweging uitgevoer het. Die veelvoudige-passasier waarnemingstelsel is getoets in ’n minibus taxi en bestaan uit ’n lae-koste kapasitiewe sensor stelsel. Die stelsel meet ’n passasier se liggaamlike elektriese lading. ’n Wiskundige uitrukking van die kapasitiewe sensor stelsel is bepaal wat ’n teoretiese kapasitansie waarde gee. Dié waarde is met die gemete kapasitansie op die sensor elektrode vergelyk. Die resultate bevestig dat die ontwikkelde stelsels duidelik ’n sittende passasier kan identifiseer. Verskeie toetse is gedoen om te verseker dat die kapasitiewe stelsel gepas is vir die heterogene minibus taxi omgewing. Draadlose verslagdoening word binne die voertuig uitgevoer met behulp van ’n ZigBee netwerk wat geïmplementeer is op ’n Arduino platform. Die buite-voertuig verslagdoening stelsel gebruik bestaande sellulêre kommunikasie netwerke en die inligting word dan op Trinity Telecoms’ SMART platform visueel vertoon. Die volledige ontwikkelde stelsel is as ’n prototipe geïmplementeer en getoets in Suid-Afrikaanse en Ugandese minibus taxi’s. Die resultate toon aan dat die stelsel die doelwitte bereik en dat dit gebruik kan word om die vervoer stelsel in Suid Afrika veiliger en meer doeltreffend te maak.