Tilt sensors are by no means a new invention. Nevertheless, there is no tradition of using such sensors in the rail industry.
A tilt sensor is able to measure very small changes in the slope of an object. Modern sensors can thus record changes of less than 0.1 mm / m. In addition, some sensors are available in wireless versions, making the installation of the sensors quick and easy and frequent measurements readily available. Sensors mounted on, for example, the sleepers of a railway track can provide very precise information about the track condition.
Wireless tilt sensors mounted on sleepers in Track 2 at Nyborg station
For monitoring track condition, specialized inspection vehicles are traditionally being used to periodically measure a set of parameters that express the track quality. These provide a basis for action in relation to the maintenance of the track. In the case of unstable ground conditions, however, far more frequent measurements may be required to guard against the effects of any sudden change. Therefore, additional measurement methods, manual and automatic, are used. Some of these require special optical equipment.
A direct comparison of information obtained from tilt sensors and traditional methods is not always possible. This is partly due to the different characteristics being measured. This should not, however, prevent the spread of tilt sensors as a useful alternative to existing methods. Instead, one should focus on the type of information that can be obtained and how to make the most out of it.
Increased need for security due to higher train speed and rising rainfall
An obvious application of tilt sensors is to provide live measurements directly to a monitoring and alert system that can be installed either temporarily or permanently in zones that are considered to be particularly exposed to impacts, for example when doing track work, in construction fields or on locations influenced by climate change or poor soil conditions.
” For infrastructure owners such as Banedanmark, higher security and productivity improvements can be achieved without having to be present 24/7. Also, savings by a factor of 2 relative to the investment are to be expected!”
Head of Department, Railway Sund & Bælt, Kristian Madsen
Railmonitor, a new player in the railway industry, has developed such a system that continuously monitors the track condition, and will warn if changes are noted that differ from the natural variations on the site. The ability to sense even the slightest deviations makes it possible in many cases to detect critical changes earlier than with other methods.
A monitoring and alert system provide a snapshot of the track condition as well as the ability to analyze historical data.
A warning from the system may, if necessary, cause additional information to be collected using traditional equipment in order to determine whether the quality of the track still complies with given specifications. However, some safety parameters of major significance, such as cant and twist, can be calculated immediately by the system without the need for additional measurements.
Other relevant applications for tilt sensors include monitoring of other infrastructure alongside the track, e.g. electric masts, tunnel and retaining walls, pillars, and embankments. The same system can thus monitor a wide range of installations on and surrounding the track.
To summarize, monitoring railway track condition using tilt sensors constitutes a really good supplement, and in some cases alternative, to traditional measurement techniques. The sensors can eliminate or reduce the need for traditional monitoring procedures causing several benefits:
- Always up to date information regarding the state of the track
- Increased security for passengers and staff
- Reduced data acquisition costs
Furthermore, the possibilities to monitor infrastructure in a much wider sense are greatly expanded.
