RESET: Research into the stability of railway embankments
How can we ensure that the Dutch railway network remains safe and reliable as demands on it continue to grow—with more, longer, heavier and faster trains? And how can we gain a better understanding of the current condition of railway embankments in order to prevent incidents?
Within the RESET research programme (Reliable Embankments for Safe Expansion in Rail Traffic), Deltares is addressing these questions on behalf of ProRail, in collaboration with TU Delft. The focus is on improving our understanding of the subsoil beneath railway embankments and how it responds to loading from train traffic.
Why research into railway embankments is needed
The Netherlands has soft ground conditions that vary significantly from region to region. How much additional or more intensive rail traffic can our railway embankments withstand? Eighty per cent of these embankments were constructed before 1920, using the knowledge, standards and practices of that time. How they were built and which materials were used is often unknown. In addition, longer periods of drought and extreme rainfall cause greater fluctuations in groundwater levels, affecting the strength of railway embankments.
By investigating the strength of these embankments, RESET supports ProRail in making informed decisions about allowing additional train traffic and any reinforcements that may be required.
Within RESET, we investigate the actual strength of railway embankments. We are developing new methods for assessing track stability, enabling ProRail to make more realistic judgements about what levels of train loading can be safely accommodated.
Timo Schweckendiek, researcher in geotechnical reliability and risk
GeoCentrifuge experiments reveal failure mechanisms
A key component of RESET is a series of experiments conducted in the Deltares GeoCentrifuge, a unique facility that enables realistic upscaling of geotechnical processes.
In this centrifuge, scale models of railway embankments are subjected to accelerations of up to 50 g. This allows models at a scale of 1:50 to behave like full-scale embankments. In this way, we can study how embankments fail without having to damage real structures—providing crucial information that cannot be obtained in the field. In the various tests, we vary one parameter at a time, such as the composition of the subsoil or the geometry of the embankment.
The results are used to refine the geotechnical models applied in track stability assessments.
Field measurements
In addition to the GeoCentrifuge experiments, a field test was carried out on an operational railway line. During this test, we specifically examined how the subsoil and groundwater respond to train loading. Both conventional and innovative measurement techniques were used, including a pressure mat beneath the ballast bed.
A key question was the difference in the build-up of (groundwater) pressures between a stationary train and trains travelling at different speeds. This is important because, until now, stability assessments have not distinguished between stationary and moving trains. This was the first time such a test had been conducted in the Netherlands.
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Field test on a railway embankment.
Knowledge for design, management and policy
By combining GeoCentrifuge experiments with numerical simulations, field measurements, and the expertise of Deltares, ProRail and engineering consultancies, new assessment methods and guidelines for railway embankment stability are being developed. The results support ProRail in day-to-day practice, for example in:
- deciding whether heavier or longer trains, or higher train frequencies (i.e. more trains per hour), can be safely accommodated
- determining whether embankments require reinforcement
We also draw on knowledge gained from risk assessments of dykes, quay walls and sheet pile structures. The assessment of existing structures is a relatively new discipline and highly relevant in order to maximise the potential of our ageing infrastructure.
We build on knowledge developed in the risk assessment of flood defences and structures such as quay walls and sheet piling. Assessing existing infrastructure is a relatively new field, but extremely important for making the most of our ageing assets.
Timo Schweckendiek, researcher in geotechnical reliability and risk
Collaboration for a safe and efficient railway network
Within RESET, Deltares, TU Delft and ProRail combine their expertise, supported by the practical experience of four engineering consultancies (Arcadis, Haskoning, Sweco and Witteveen & Bos). The five-year programme (2022–2027) delivers new insights and practical tools for a safe and efficient railway network.
The knowledge gained contributes to achieving the ambitions of ProRail and the Ministry of Infrastructure and Water Management: enabling more train traffic while maintaining safety—now and in a changing climate.
