eRTM
rail thermometer
Wireless, battery-powered sensor network for real-time tracking of rail temperature, to help prevent track buckling
>> eRTM
Continuous monitoring
Rail temperature is one of the key parameters of a railway track, since it is directly linked to the internal stress in the rail. A rail restrained in its thermal expansion can buckle in summer, posing a derailment risk. The eRTM measures the actual rail temperature with thermistor sensors on the rail web, making stress distribution traceable along the whole section.
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01
Installation, no cabling
The sensors run on batteries and communicate wirelessly, so installation requires no cabling, no separate substructure and no breaking up of the track. The system forms a wireless mesh network: using repeaters, even long track sections can be covered.
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02
Track data monitoring
Measurement data arrives at the on-site gateway unit, which processes and logs it, then forwards it over a broadband connection to the central diagnostic server. From there, trend analysis, forecasts and alarms are available via a web interface.
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03
Self-diagnosis, alarms
The system continuously monitors its own condition, including the charge level of the batteries, and automatically signals when any element needs maintenance or replacement. The alarm thresholds can be customised by the operator.
>> Design
From sensor to dispatch centre
Measurement is done by thermistors on the rail web, which measure the rail's internal temperature rather than the ambient air. Each measuring module has its own embedded electronics, so the measurement stays noise-free and highly accurate.
The sensors run on batteries and communicate wirelessly on the 868 MHz ISM band. The repeaters form a mesh network: the distance may be up to 100 metres between a sensor and a repeater and up to 1000 metres between two repeaters, so even long track sections can be covered without cabling.
The measurement data arrives at the on-site gateway unit, which processes and logs it, then forwards it over a broadband connection to the central diagnostic server. Maintenance staff can reach the gateway unit on site via an Ethernet or a Wi-Fi connection.
The system continuously monitors the condition and availability of all of its elements, including battery charge levels. If the operation of any component is disrupted, or a battery is close to depletion, the system automatically sends an alarm to the operator, so that maintenance always remains plannable.
>> Features
eRTM system functions
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Thermistor measurement: records the rail's internal temperature, not the air
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Embedded electronics in every measuring module for noise-free, precise measurements
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Wireless connection between the on-site system elements, with cost-effective installation
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Battery-powered sensors, a gateway unit with mains power supply and an uninterruptible backup
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Encrypted data transmission via the mobile network or over a wired connection line
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Automatic self-diagnostics and continuous remote monitoring
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Warning and alarm threshold values freely adjustable by the operator at any time
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Trend analysis and forecasting in the central system
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Solution that can be integrated into the infrastructure manager's own IT system
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Installs on the existing track structure without traffic restrictions or opening the rail
>> Technical data
Measurement specs
- Measurement accuracy
- ±1 °C
- Temperature resolution
- ±0.5 °C
- Measuring range
- -40 °C / +125 °C
- Rail temperature range
- -40 °C / +75 °C
- Sensor time constant
- shorter than 1 second
- No. of measuring points
- up to 256
- Measurement frequency
- adjustable from 10 minutes to 12 hours
- Repeater-sensor distance
- max. 100 m
- Repeater-repeater distance
- max. 1000 m
- On-site communication
- 868 MHz (ISM band)
- Sensor battery life
- 3 years (at hourly measurement cycle)
- Operating temperature
- -40 °C / +85 °C
- Protection
- IP67
- Rail type (UIC)
- 48, 49, 54, 60
- Gateway unit power supply
- 230 (190-250) V, max. 50 VA
- Service life, MTBF
- min. 10 years, 10,000 hours
>> Benefits
4 reasons to choose eRTM
In summer heat, the internal stress building up in a rail restrained in its thermal expansion can lead to buckling and ultimately derailment. The eRTM detects the onset of buckling in time, forecasts it and sends an alarm, so the operator can take the necessary measures in time. By preventing derailments, the life of both the track and the vehicle fleet is extended.
In winter, measurement-controlled points heating delivers considerable energy savings: heating switches on only when and where the actual rail temperature justifies it. Installation itself is cost-effective, as it needs no cabling, separate substructure, traffic restrictions or breaking up the track.
Based on the real-time rail temperature and the forecast, the duration, location and extent of speed restrictions can be determined precisely, which improves punctuality. By forecasting rail faults linked to temperature changes, maintenance also becomes more plannable - stress-free periods can be designated for track works.
Measurement-controlled operation of points heating reduces energy use and with it the carbon dioxide emissions of rail operations.
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