Remote geotechnical monitoring of rail track surroundings stability
Rail transport has been around for more than 200 years. But there is still plenty of room for improvement in terms of safety, efficiency and sustainability, according to experts speaking at a Worldsensing-sponsored Tech Talk Webinar in October 2021. Rail technical teams continue to seek ways to monitor and control embankment slippage, rock falls, physical infrastructure stability and tunnel convergence.
And the risks are increasing because of climate change, said Angela Lluch, Geologist and Civil Engineer at Worldsensing. “We have heard from meteorologists that climate change is leading to more frequent episodes of heavy rain,” she said. “That additional amount of water is increasing the risk of having shallow landslides in cut-ins and other natural slopes.”
At the same time, however, technology advances are giving geotechnical engineers new ways to deal with the challenges. Automated total stations remain one of the preferred monitoring tools, said Lluch. But where there is a need to cover large areas, rail operators may opt for a hybrid monitoring approach that includes a range of sensor types. For example, said Lluch, “An option to get to know the condition of slopes and even prevent slope failure would be to use tiltmeters.
“These tiltmeters can be mounted onto poles, buried into the soil or just rest on a base structure made of concrete, for example.”
Growing use of tiltmeters for rail track monitoring
The UK has seen “a big push” to have tracks monitored using tiltmeters, noted Tim Clegg, Commercial Manager at Geosense. “However, we are also seeing a much more rounded monitoring requirement, with total stations and tilts and other sensors all going into one central place.”
Inadequate drainage is a common reason for slope displacement. Often the best monitoring option is to use total stations but where there is no direct line of sight to a wireless gateway then tiltmeters are an effective alternative. Another tool for slope monitoring is a laser tiltmeter; the LaserTilt90, for example, a three-in-one laser distance meter, inclinometer and data logger that can monitor targets up to 150 meters away.
Wireless sensor technology is also being used to monitor the integrity of structures such as retaining walls, or emerging faults such as soil cracks. Where weather may be contributing to rock falls, it is possible to monitor risks using devices such as draw-wire extensometers, crack meters and thermistors.
A wide range of monitoring tools for rail
The tools available to the rail industry extend to subsoil monitoring devices such as in-place inclinometers. “Chains of digital sensors can be connected to one digital logger that can run on internal batteries with no need for an external power supply,” Lluch commented.
Beyond monitoring the integrity of specific structures, rail engineers can use sensors to monitor environmental parameters such as precipitation, temperature and wind speed and direction, all of which can contribute to operational risks. This information can be tracked simply and cost-effectively using data loggers.
“It’s interesting to see what a comprehensive range of sensors and technologies is out there and available to achieve a holistic view of what’s going on in a track environment,” said Matt Azzopardi, UK Sales Manager for Worldsensing, who moderated the webinar.
· To find out more, watch the webinar now.