Application of MEMS Sensors for the Condition Monitoring of Urban Tramways Based on MODWPT

The condition monitoring of urban tramways constitutes an important task of municipal authorities for safeguarding the safety of public transport and efficient managing of the tram lines. Microelectromechanical systems (MEMS)-based sensors are low-cost and low-power devices easily integrated with elements of smart city infrastructure. The aim of the study is to determine the bounds of the application of MEMS sensors for monitoring the condition of tramway rail tracks. Monitoring the frequency spectrum of vibrations caused by rail track irregularities is proposed for deriving information on the rail conditions. The study employs a maximal overlap discrete wavelet packet transform (MODWPT) algorithm to extract the features from MEMS accelerometer datasets collected during tram trips. The Katowice (Poland) urban tramways are the objects of a case study. The results confirm that vibrations of tram bodies with high energy in characteristic frequency bands indicate faulty tramway tracks. The acceleration measurement ranges and the sampling rates of the MEMS sensors fulfill the requirements of the proposed monitoring approach.