Objective Small numbered turnouts are widely used in urban rail transit. especially in metro depots. but their large switch angles pose a derailment risk when vehicles pass through them. It is necessary to investigate the reasons for vehicle derailment at the turnout frog positions in metro depot. https://www.roneverhart.com/Turbosound-TS-18SW700-8A-18-Low-Frequency-Loudspeaker-p31480/