Correlation Study Between In-Situ Auscultation and Satellite Interferometry for the Assessment of Nonlinear Ground Motion on Crossrail London

This paper aims to provide a cross-checked overview of two different and independent techniques used to assess the state of the stability of London works conducted by Crossrail Limited over the entire city. The two techniques compared are Radar Persistent Scatter Interferometry technique carried out by Altamira Information for Crossrail Ltd, and auscultation measurements, such as precise levelling networks, robotic theodolites, hydrostatic level cell networks or tilt-meters, carried out by Crossrail Ltd and their contractors.

Both types of measurements have diverse objectives. While auscultation measurements are almost continuous data which involve a real-time assessment of the impact of the works carried out in the scene and very close surroundings in several specific chosen points in order to avoid risk or mitigate its impact, InSAR is a non-real time technique which works with discrete data and can assess vast areas using images acquired on different dates separated by days/weeks or months, allowing an insight of local and large displacement bowls during the period analysed. Thus, it can be affirmed that both techniques are complementary and add value to each other.