Crowdsensing for indirect Footbridge Structural Health Monitoring using smartphones and bicycles

Existing SHM methods normally consist of direct instrumentation of infrastructures (e.g., bridges) with sensors for continuous or periodic health assessment. However, traditional SHM techniques can be time-consuming and expensive due to the requirements for on-site installations (especially cable deployment). Recently, indirect vibration-based SHM strategies have been proposed in the literature, which make use of the dynamic response of instrumented vehicles to carry out “drive-by” monitoring of road pavement and bridges. Such vehicles are generally cars or trucks on which sensors are installed. The use of bicycles for indirect SHM purposes has been much less explored. In this paper, the potentialities for innovative indirect vibration-based SHM using only commercial bicycles and smartphones are proposed. Smartphones are widespread, contain several types of sensors, and have on-board computing capabilities, embedded batteries, and internet access. Hence, in this study, a smartphone, fixed on bicycles, is used to collect different types of data (acceleration, angular velocity, position, orientation, magnetic field), which are fused using a Kalman filter algorithm, thus enabling the extraction of the main dynamic parameters of footbridges. The methodology is applied to two real footbridges in Northern Italy.