Rail engineers face considerable pressure to maintain high levels of asset resilience in the face of a warmer, wetter climate placing unexpected pressures on ageing and over-stretched infrastructure. While the desire to upgrade or replace assets may be strong, the capacity to do so cannot possibly meet the demand, so alternative ways must be found to keep trains running safely and cost-effectively. Access to reliable, continuous data from automated condition monitoring systems can play a vital role in this battle.
Engineers at remote condition monitoring developer Senceive have been busy adapting their well-established wireless monitoring solutions to address two of the most critical challenges affecting the stability of railway earthworks slopes:
The early detection of landslips and other shallow failures such as washouts and drainage failures
Monitoring to detect rockfall events
Landslip detection
There is a clear relationship between the increasing frequency of extreme rainfall events and the number of slope failures affecting railway earthworks. Network Rail geotechnical engineers have relied on wireless remote monitoring solutions to provide early warning of landslips since 2019 and have now deployed more than 40,000 Senceive tilt sensors covering around 50km of the UK network. Utilising the company’s intelligent InfraGuard™ monitoring software, the technology has come a long way in that time.
One example of this continuous improvement is the transformative improvement made to the system’s cameras, which are triggered automatically by ground movement to provide high resolution images day and night – without needing a flash or illumination source. Using cameras capable of detecting a football-sized object at a distance of 50 metres in any light conditions, this supports quick decision making and can dramatically reduce the risk of disruption and derailments.
Another example is the slicker integration with geotechnical monitoring instruments, such as piezometers and inclinometers, meaning that the automated wireless system can now monitor both shallow and deep ground movement.
Rockfall monitoring
While wireless remote monitoring technology has been widely adopted to detect large mass failure of soil slopes, the established methodology was inappropriate for rock slopes, which are often characterised by movement of individual boulders or localised debris. Because these smaller objects can fall between tilt sensor locations – yet still pose a significant threat to rail and other infrastructure – a bespoke solution was required.
As the world’s biggest user of wireless slope monitoring, Network Rail expressed interest in adapting the existing wireless technology. In early 2024 it commissioned trials on rocky slopes at a test site in Switzerland, which supported the development of an innovative multi-mode wireless detection system.
In summary, this solution is built around monitoring the effects of rockfall debris hitting catchfences, and it can be triggered in any of three ways to provide a robust, reliable solution with a high detection rate and a low incidence of false alarms. In all three modes the unique intelligence built into the sensors can trigger the InfraGuard software to escalate an alert to users, accelerate reporting of neighbouring sensors, and transmit photos of the site.
- Mode 1: rock hits fence causing rotation of fence posts – detected by tilt sensors mounted on the posts.
- Mode 2: rock hits fence, but the force is absorbed by the wire and the posts do not move – the movement is detected by draw wire sensors
- Mode 3: rock bounces down the slope, hitting fence and bouncing over it – the sudden acceleration is detected by the impact sensors in the Senceive NanoMacro™ tilt nodes mounted on posts, regardless of their pre-set sampling frequency.
Innovation is crucial
Wireless innovation is crucial to improved climate resilience. With winter on the horizon in the northern hemisphere, the advantages of wireless solutions are significant. The ability to keep constant watch on vulnerable assets reduces the risk of trains hitting blockages on the line, and the automation of this process cuts the need for a lot of muddy, time-consuming, and costly site visits. The use of tilt sensors for track and earthworks monitoring does not rely on line-of-sight, so is unaffected by snow cover and short hours of daylight.
It is clear that wireless monitoring technology has come a long way in the last two decades, and that constant development and improvement of new applications is helping engineers to address the challenges posed by changing weather conditions.
Image credit: Senceive