  This study introduces a low-complexity behavioural model to describe the
dynamic response of railway turnouts due to the ballast and railpad components.
The behavioural model should serve as the basis for the future development of a
supervisory system for the continuous monitoring of turnouts. A fourth order
linear model is proposed based on spectral analysis of measured rail vertical
accelerations gathered during a receptance test and it is then identified at
several sections of the turnout applying the Eigensystem Realization Algorithm.
The predictviness and robustness of the behavioural models have been assessed
on a large data set of train passages differing for train type, speed and
loading condition. Last, the need for a novel modeling method is argued in
relation to high-fidelity mechanistic models widely used in the railway
engineering community.
