How an infrastructure operator uses the SMM-200 mobile device to measure the settlement of railway sleepers whilst trains are running, rather than relying on visual inspection.
Summary
It is almost impossible to reliably assess by eye whether a ballast bed has settled under traffic loads or whether a sleeper is hollow. An infrastructure operator has therefore opted for the mobile WITT SMM-200 for quality assurance following track construction or tamping work, as well as for targeted inspections of sections of track that appear to be problematic: a battery-powered settlement measuring device which is positioned directly on the sleepers to be tested using up to five sensors and triggers automatically when a train actually passes over – without interrupting operations and without the need for a permanent installation on the track.
Tasks
- To determine objectively and reproducibly the actual settlement or hollow spots in railway sleepers during a real-life train passage, rather than relying on visual inspection
- To use a mobile device that can be deployed flexibly at different measurement locations without the need for a fixed installation and without interrupting operations
- Record several thresholds or measurement points in a single run in order to obtain comparative values for evaluation
- Store the measurement results in a structured manner for further analysis and documentation
Project description
The operator deploys the WITT SMM-200 on a mobile basis on selected sections of track, for example to carry out acceptance checks following tamping work or to carry out targeted inspections of sections of track with increased maintenance requirements. To do this, up to five high-precision displacement sensors are positioned directly on the sleepers to be tested using a chisel and a quick-release tripod; a sensor automatically detects the passage of the train and triggers the measurement. Over a measurement period of 20 seconds per train passage, the device records the maximum settlement of each connected sleeper at a sampling rate of 1 kHz and displays the result directly on the screen.
As the device is battery-powered (operating time > 8 hours) and does not require a fixed installation, it can be set up at a new measurement location in a short space of time – an advantage when several sections of a route are to be inspected in a single day. All measurement values are stored internally and can be downloaded via USB; analysis and visualisation are carried out using the supplied NI DIAdem plug-in, allowing results from multiple measurement sessions to be compared.
Results/Benefits
- Objective quality assurance: Reliable measurement data rather than visual inspection – for example, for acceptance checks following compaction work or for before-and-after comparisons
- Measurement under live conditions: Data collection whilst a train is actually passing, without interrupting operations
- Flexible use: Mobile assembly without the need for a permanent installation, allowing for multiple measurement positions in a single day
- Comparable results: up to 5 thresholds per measurement, structured storage and analysis across multiple measurement dates
