WITT ESAH-M G3 – Condition assessment of a points centre for DB Systemtechnik
How WITT Solutions determined the track alignment for DB Systemtechnik between 2017 and 2022 using a mobile measuring device that is unique on the market.
When passing over points with rigid heart pieces, the transition of the wheels from the wing rail to the heart piece generates an impact load, the magnitude of which is directly related to the wear condition of the track. Between 2017 and 2022, WITT Solutions made this load measurable for DB Systemtechnik in several operations using the ESAH-M G3: a compact, battery-powered measuring device which, using magnetically coupled sensors, can be installed on the track in under a minute and delivers analysable results on the switch position after just the first pass – at that time, the only device on the market capable of performing this type of measurement.
Tasks
- For DB Systemtechnik, to determine the condition of the switch point – specifically, the state of the switch point area – objectively and reproducibly, rather than relying solely on visual inspection
- To provide a device that does not require a permanent installation and can be fitted at different switch locations in the shortest possible time
- In addition to pure impact loads, record other relevant condition parameters: overrun speed, contact with the wheel guide/track flange (wheel guidance) and, optionally, the settlement of adjacent sleepers
- Make results available for analysis on site immediately and archive them for trend monitoring over the course of several years of operation
Project description
Between 2017 and 2022, WITT Solutions deployed the ESAH-M G3 on several occasions for DB Systemtechnik to determine the position of points. The device measures the acceleration of the point centre via two triaxial sensors (ACC1 on the point centre, ACC2 on the wing rail), which are attached using neodymium magnets without the need for drilling or fixed mounting. Two inductive sensors (Bero1, Bero2) also measure the speed of each passing axle; using the transit time between the two sensors and the maximum acceleration, the device calculates the spatial position of each contact point relative to the reference point N on the switch heart. Optionally, settlement at up to three sleepers can be measured using additional sensors.
The device displays the result of each pass directly on the screen as a bar chart (‘contact profile’): the cumulative contact points of all axles during a single pass, plotted spatially in relation to the centre-piece reference point N. This makes it possible to determine whether the load is distributed evenly or whether there is localised overloading of the rail material. In addition, the device detects, for each axle, whether there is normal overrun or whether the wheel flange is making contact with the centre piece (positive) or the wing rail (negative) – an indicator of the quality of wheel guidance within the track channel.
All measurements (up to 500) are stored internally and can be exported to a PC in a structured format via an Ethernet interface. The battery-powered device (IP67, –20 to +55 °C, operating time >10 hours) is ready for use with its sensors in under a minute – a decisive advantage for repeated use at different points across the entire project period.
Results/Benefits
- Market exclusivity: During its period of use from 2002 to 2022, the ESAH-M G3 was the only device available on the market capable of performing this type of switch position measurement in the heart of the track
- Immediate results rather than a wait: results shown on the display straight after the crossing, without the need for a separate measurement campaign or laboratory analysis
- Objective condition assessment: impact load, speed and wheel alignment as measurable, comparable parameters rather than purely visual assessment
- Quick installation without any intervention in the system: magnetic coupling instead of a fixed installation – can be used on different points without the need for modification, and reused multiple times over a five-year period
- Early detection of localised excessive stress on the rail material via the contact profile – the basis for targeted rather than blanket maintenance
