Train Speed Estimations from Ground Vibration Measurements Using a Simple Rail Deflection Model Mask

Abstract

The speed of passing trains is conventionally estimated using Doppler speed guns, or optical sensors. However in many cases, these techniques are not applicable when the measured trains are not visible (for example in tunnels) or close access to the track is not possible. An alternative method to estimate train speed from ground vibration measurements is presented in this paper. The method takes advantage of the relation between vibration levels and the cyclic repetition of the excitation forces created by the wheels. A train mask, expressed in the wavelength domain, is derived from a simple rail deflection model induced by the train wheels. The vibration spectrum at very low frequency and the train mask are qualitatively compared to match the various peaks. Vibration and train speed measurements have been undertaken near St Denys station, Southampton. Very good agreements have been observed between the direct train speed measurements and the proposed estimation method.