Automated Monitoring of Critical Infrastructure

Your insights into IoT remote monitoring.

Rail monitoring with LoRa star IoT technology: your queries answered

Rail infrastructure is of key importance to modern society—and any failures can be costly in terms of lives and investment. That’s why it is important to ensure the safety of tracks and other structures through detailed, regular monitoring. However, carrying out automated topographical surveys can be time-consuming due to the site maintenance it requires, let alone if they are manual surveys. For this reason, the rail industry is increasingly turning to LoRa star wireless networks to collect data from remote sensors.

To delve into this important topic, Worldsensing joined forces with infrastructure monitoring leader Sixense to offer a free webinar on ‘Rail monitoring through LoRa star IoT and topographical surveying technologies’ in July 2021. The webinar featured James Saunders, Business Development Manager at Sixense, and three experts from Worldsensing: Rail Project Manager Ignasi Garcia-Milà Vidal, Application Engineer Angela Lluch Gracia, and UK Sales Manager Matt Azzopardi.

This blog covers their answers to the questions that came up during the event.

Questions

What is your experience with vandalism and theft?

Bi- or triaxial: which is more effective in rail monitoring?

What industry sectors could benefit more from remote monitoring, especially now with a pandemic?

How would you compare star and mesh radio frequency (RF) network topologies?

What’s the accuracy of different types of track monitoring?

Do you have any examples of laser distance meter applications?

Can tiltmeters can be oriented horizontally only?

What causes a tiltmeter to send data to the gateway?

Do you provide software for calculating cant and twist?

Do you have an intelligent system to filter false alarms introduced by temperature changes in the rail?

Do you need to check the coordinate changes of installed track tiltmeters to get absolute displacements?

What is your experience with vandalism and theft?

James Saunders: We’ve been pretty fortunate. For a lot of the products we do, you can often install the instruments in a way that you really need to try to vandalize them or take them from the project. They’re not super interesting [to vandals]. Tiltmeter have lesser value and may sometimes be easier to steal. But AMTSs [Automated Motorized Total Stations], despite being obviously higher-value instruments, are usually placed on a pole or structure. The prisms themselves aren’t that expensive.

Luckily, the only things that have sometimes disappeared so far on projects are the solar panels that we put up with our AMTSs.

Bi- or triaxial: which is more effective in rail monitoring?

Angela Lluch: Both could serve the purpose because we are talking about sub-horizontal structures. We are interested in monitoring along two axes, so biaxial or triaxial could work perfectly. Triaxial has the advantage of being able to be installed in any position. They could be used for other applications, like for example monitoring vertical or sub-vertical structures or tunnel sections, where they need to be installed in different orientations other than horizontal.

What industry sectors could benefit more from remote monitoring, especially now with a pandemic?

Ignasi Garcia-Mila: There are several sectors that could benefit from remote monitoring. I really believe that it improves operational capacity in several industry sectors. But linear infrastructures such as railways or motorways, which have several elements that need to be monitored for structural health, are the ones that are much more interesting for remote monitoring.

James Saunders: I think, especially now, we realize shouldn’t take site visits for granted. With an automated system, we can cut down on those. We’re also seeing a lot of dam owners and mining sites looking towards automated solutions.

How would you compare star and mesh radio frequency (RF) network topologies?

Angela Lluch: The main difference between a star and a mesh topology is the way the data travels. In a star topology, it’s quite straightforward. The data goes from the nodes to the gateway. In a mesh topology, the data cannot reach such long distances so it needs intermediate devices, so-called repeaters, so the data can keep on hopping from device to device until it reaches its final destination, which is the gateway.

If one of these devices fails, all the other devices will also be affected. In a railway project, because devices are mostly installed following a line, there is a higher risk of suffering a critical path interruption. In any case, both of them could be useful for railway monitoring if we’re not talking about large areas to cover. Otherwise, we might best consider star topologies.

What’s the accuracy of different types of track monitoring?

Matt Azzopardi: In terms of tiltmeters, the question really depends on what sort of range you’re looking at. The accuracy, with plus or minus 2º range, is 0.0025º and at 86º–as we have a tiltmeter capable of plus or minus 90º–it is around 0.06º.

James Saunders: For an AMTS, it depends on how you set it up, as long as you’re not exceeding the range of the total station—about say 120 meters. You’re getting millimeter accuracy: plus or minus 1 mm. If you extend that range it is still going to work but you will lose accuracy.

Do you have any examples of laser distance meter applications?

Angela Lluch: Yes, they are used in tunnels to get the convergence distance. They can also be installed in shafts or any kind of excavation for monitoring movement, to get to know if the shaft is expanding or shrinking. They can also be installed for monitoring slopes, for example, if we have spotted areas where we expect rock falls. In that case, we could place the tiltmeter and just target that rock or mass and see whether that distance changes over time.

There are many, many other applications where we could use laser nodes for monitoring.

Can tiltmeters be oriented horizontally only?

Angela Lluch: It depends on the measuring range. Our tiltmeter goes from zero to plus or minus 90º, so it can take any orientation. However, if you’re using tiltmeters from another manufacturer, you need to check the range of measurements they can provide.

What causes a tiltmeter to send data to the gateway?

Angela Lluch: Any measurement recorded on the tiltmeter is sent via radio to a network; it is not linked to any threshold. The frequency will depend on the sampling rate chosen for every device and on the number of sensors connected to the network. The sensor remains inactive and only wakes up for measuring and sending data.

Do you provide software for calculating cant and twist?

Angela Lluch: Through the Connectivity Management Tool it is possible to set up to calculate the cant.

Do you have an intelligent system to filter false alarms introduced by temperature changes in the rail?

Ignasi Garcia-Mila: Our new devices provide data set average, which can be used to filter noisy data.

Do you need to check the coordinate changes of installed track tiltmeters to get absolute displacements?

Angela Lluch: Yes, as explained during the webinar, tiltmeters only can provide relative movent that have to be offset against the zero or initial readings. As a result, you get differential movement over time. If you are interested in having absolute movement or coordinates you will need to carry out a topographic survey.

Rail

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