Sensor Sleeper - the intelligent sleeper

The modern railway superstructure is characterized by using high-quality components in order to cope with ever-increasing load tonnages and increasing train frequencies. The top priority for every railway operator is to ensure the availability of the railway track.
In recent years, the so-called Under Sleeper Pad has proven as a tried and tested means of improving the characteristics of the railway track. The Under Sleeper Pad focusses precisely the critical interface between the bottom of the sleeper and the top layer of ballast. Due to the very high ballast contact pressures caused by high dynamic forces, there is particularly high wear behavior here. In this case, wear behavior means the destruction of the railway ballast as the weakest link in the load distribution area of the railway superstructure. This becomes visible through so-called white spots (powdered ballast), hollow sleepers and the resulting poor quality of the track geometry.

Since it is not possible today to look directly into this sensitive interface, the mechanisms of origin of this disadvantageous effect often remain purely theoretical.
Getzner has set itself the goal of developing digital technology that makes it possible to measure and monitor this critical interface directly and from any location, and to detect critical changes in time.
The measurement technology can be used for R&D or measurement purposes as well as for monitoring purposes.

The challenge

Until now, when researching the effectiveness of e. g. Under Sleeper Pads, indirect measuring methods such as vertical displacement measurements, vibration measurements and the observation of the longitudinal track alignment by measurement cars over a long period of time were the only options.
Many unknown factors at the interface between ballast and sleeper like ballast contact pressures, contact areas, load distribution are simulated, but have so far been difficult or impossible to be measured.
Innovations (e. g. padded sleepers) can only be verified via other factors, e. g. lengthy observation of track deterioration rates over a long period of time.

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The Getzner solution

Getzner developed the so-called "sensor sleeper", which makes it possible to measure surface contact pressures directly between the sleeper and the ballast without interfering with the characteristics of the track. It is a special pressure sensor, which is installed on the bottom of the sleeper. The pressure that individual ballast stones put on the sleeper can be detected over a long period of time. This not only makes it possible to characterise the Under Sleeper Pad with unprecedented accuracy, but also to analyse the load distribution characteristics of the various components of the track at train passing. The results can be used, for example, when aligning the Under Sleeper Pads, sleepers, turnouts and transition zones. The characteristic gained that the sleeper can be lifted, aligned and damped like any other sleeper makes it possible to get the required data quality. Of course, the new, digital innovation not only works in combination with Under Sleeper Pads, but also without them.

The new technology measures relevant data in an interface that has not been able to be measured by anyone in the world to date.
This is a patented technology - AT 522346 B1!

Advantages for customers

Use for measurement purposes:

With this innovation quantifying the stress and contact area of the ballast sleeper interface and thus analysing the load distribution characteristics is possible.
With this innovation quantifying the performance of different Under Sleeper Pad types (contact areas, pressure distribution, load distribution, ...) is possible.
With this innovation a 3D map of the stress and contact areas between sleeper and ballast (support conditions) is possible.
With this innovation measure changing in the ballast contact areas, the ballast contact pressures and the ballast contact points over time is possible.
With this innovation, essential track maintenance processes, such as the "tamping" of the ballast superstructure, can be measured, monitored and the processes optimized in the medium term, depending on the situation.

Use as a monitoring system:

The monitoring system shows how the ballast behaves at the interface on the bottom of the sleeper (pressure, contact area / force, position of the ballast point) over time (change).
The monitoring system provides the right information to carry out maintenance and repairs precisely and at the right time (predictive maintenance).
The digital solution allows the user to remotely monitor their assets worldwide without being on site (security, effort, time, ...)
The innovation provides a complete overview of the asset's quality status based on historical and real-time data.
The monitoring system provides a complete overview of the status of the asset and the required maintenance work.
The innovation makes it possible to monitor the rail infrastructure and provides insight into critical design parameters.
The digital innovation monitors the route quality at hot spots (turnouts, transitions, narrow curves, ...) and can predict their constitution over time.
The monitoring system can detect the formation of hollow sleepers or the destruction of ballast at an early stage