Terrestrial laser scanning for assessing the risk of slope instability along transport corridors

Transport networks play a crucial part in the global economy, with roads and railways being of particular importance at regional and national scales. However, roads and railways are founded on earthworks such as embankments, which can be susceptible to slope failure. Slope instability is a costly problem, which can lead to travel disruption, and injury or loss of life. Earthwork stability assessment is therefore a critical activity for management bodies. However, current approaches are largely limited to hazardous on-foot site inspections. Although high resolution geospatial datasets are becoming increasingly available, there is currently a mismatch between the availability of these datasets, and the ability to use this data in support of decision making. This paper presents one aspect of an integrated methodology for risk assessment in transport corridor environments. The potential of terrestrial laser scanning (TLS) for assessment of slope deformation and failure is examined through application to two test sites in the north of England. The first site is a full-scale test embankment, while the second is a modern highway embankment. Results have shown that for both sites, multi-Temporal TLS surveys facilitate the detection of minor changes, such as soil creep and surface runoff. However, vegetation was found to be a complicating factor, contributing to registration errors between individual scans. This was resolved through the use of a least squares surface matching algorithm, which ultimately facilitated detection of change at the centimetric level. These results confirm the potential of TLS for embankment stability assessment, while highlighting some of the practical limitations.