Train speed calculation using ground vibrations

This paper presents a high precision train speed calculation technique based on ground vibration information. This versatile method can calculate speeds for trams, intercity locomotives and high speed trains on any track/embankment arrangement. Additionally, it has high accuracy for sensors located up to 100 m from the track, thus allowing semi-remote, non-invasive monitoring of train velocities. The calculation method combines three separate speed calculation techniques to provide estimates for arbitrary train speeds, even for sensors placed at large track offsets. The first estimation technique involves the use of cepstral analysis to isolate key harmonics for use with speed calculation. The second method is similar; however, the combination of a running rms and a previously developed “dominant frequency method” are used. The third method uses an analytical vibration frequency prediction model in combination with regression analysis to calculate train speed. All three methods are combined into one calculation procedure, resulting in high accuracy estimates. To show the robustness and ability of the new method to calculate a wide range of train speeds, it is used to predict tram, intercity and high speed rail train passage velocities generated from a previously validated vibration prediction numerical model. More importantly, it is used to predict train speeds during field trials performed on operational railway lines in Belgium and in UK. The new method is shown to offer high performance for several train types and track setups (including abutment and tunnel cases).