Satellite monitoring of railway infrastructure

This paper presents the use of dedicated satellite radar observations to aid in railway monitoring. These radar measurements are able to detect changes in the geometry of the tracks, with up to a millimeter precision, with a bi-weekly measurement update, and a high spatial resolution by using interferometric synthetic aperture radar (InSAR) techniques. When deformation of the infrastructure is mainly limited to the vertical and the horizontal transversal direction, it is possible to derive the deformation vector in three dimensions. Therefore we developed algorithms to tune this technology to the case of railways, in order to allow for routine and near-real-time monitoring. Special emphasis is on the spatio-temporal changes in geometry. Our methods are demonstrated on a segment of the Betuweroute, a freight railway between the Rotterdam harbor in the Netherlands towards Germany, eastwards, by using 248 satellite images from the TerraSAR-X satellite acquired between 2009 and 2013, with a bi-weekly interval.