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Instrumentation and Surveillance | Industrial News

Chris Preston has experienced diverse geospatial careers in the rail industry and has seen the rise and fall of many important technologies. A former professional head of Network Rail’s terrain services and a recent former chairman of a civil engineer, he looks back on changes in the way surveys and surveillance are done, noting the impact of one of the predominant technologies. – Wireless remote condition monitoring.

Nano tilt node.

In the 1960s and 1970s, surveillance was a labor-intensive issue and required regular site visits by staff. This usually provided relative measurements rather than absolute measurements, often simple tape offset measurements from theodolite, or angles and distances to tunnel and retaining wall points based on traditional optical leveling. Bore hole monitoring was often limited to simply lowering the probe to see if the tube was sheared. Accuracy and reproducibility issues were common and there was little chance of early warning of momentary events such as landslides or retaining wall failures. The results were derived from manual calculations and were slow to respond to stakeholders.

In the 80’s and 90’s, surveillance was still labor-intensive, but the advent of absolute surveillance has made it possible for all measurements in an area to be based on a single coordinate framework. Computer analysis of the study network improved accuracy and efficiency, but some relative measurements continued to be used. In the 90’s, GPS replaced traditional surveying triangulation and distance networks, greatly improving efficiency. Angles and distances to individual ground markers were used, and digital levels by barcoded level staff increased measurement speed.

Paris Metro track monitoring sensor.

Although this improved accuracy, it had reproducibility issues and was unlikely to detect significant early signs of sudden failure. The proliferation of computers has enabled manual data entry into spreadsheets and has begun to improve stakeholder response times.

More data, less wiring

Since the turn of the century, surveillance has really benefited from the use of modern technology. The total station is automated and additions to the toolbox include laser scanners, GNSS, accurate levels, extensometers, inclinometers, inclinometers, stories, digital calipers and automatic cameras. Meteorological stations provide environmental monitoring and can automatically measure noise and vibration.

Survey total stations can now lock on to individual survey prisms (automatic target recognition) in a defined observation sequence, providing a camera view of where they are being observed. This is useful if the prism is damaged or blocked.

However, most of these systems require power supplies, large cabling, and site visits to collect data from the sensors. This is problematic in terms of driving to keep the boots away from the ballast.

So it’s no surprise that the rail sector has adopted wireless remote monitoring technology to guide the way in detecting early signs of asset failure and tracking gradual changes in geometry. These autonomous systems often consist of long-life sensors powered by solar panels and wireless communication platforms. They provide stakeholders with data in near real time. Although this technology is robust and has high reproducibility of measurements, it is often used in conjunction with more orthodox research equipment and manual inspection for verification.

Extensive implementation

Many of the UK’s hottest infrastructure projects rely on data from wireless remote monitoring and will continue to do so. Examples include a capacity improvement project on the East Coast Main Line in Wellington and the construction of the A14 viaduct on the same line. In both cases, the wireless track sensor notified the project team of changes in movement and shape associated with ongoing construction work above and below the railroad.

HS2 has outsourced a large-scale deployment of wireless remote condition monitoring to existing assets, primarily within the scope of ongoing or planned construction activities. One example is the railroad tracks and structures on Curzon Street in Birmingham.

At the southern end of the route, hundreds of track sensor nodes are located on the line outside Euston Station, collecting baseline data on the shape of the track. They are set to remain throughout the construction phase. Equivalent development is outsourced to Old Oak Common Lane.

Monitoring system

Wireless surveillance has certainly not replaced optical surveying, and the two approaches are often used together. An example was the nearby Dublin Luas Light Rail system under construction. The combination of a total station called “Multi Stations”, a digital level, a wireless tilt sensor, and the Lecia GeoMoS monitoring software enables unobtrusive motion monitoring. These devices continuously scanned the dual tramway and hosted live data directly on a secure web page for relevant stakeholders to see. The captured scan consists of thousands of measurement points with x, y, and z coordinates.

The baseline is set with three initial scans. All subsequent scans were compared to this. The system provided an automatic alert to notify the specified stakeholders when the value exceeds the specified threshold. Accurate leveling on physical roads captured at the digital level was carried out weekly to provide warranty.

Automation and artificial intelligence

Over time, surveillance systems have become smarter and more automated, bringing many of the benefits associated with the Internet of Things. In contrast to the toolkits of previous decades, they are more than just damming equipment, they make measurements and send them to stakeholders. By triggering a wider sensor network, you can respond to events such as ground movement at one sensor location. Wake up and send reports frequently (less than a minute) and send images of your site in all light conditions.

In most rail environments, these results result in automatic alerts being sent to stakeholders. The most sophisticated and robust system sends alerts directly to route control, triggering the decision-making process to slow down trains or close lines in the event of a critical event such as a landslide. can do. In most cases, human intervention, such as a site visit, is still the first response. Verification and sense checking are wise precautions to prevent false positives.

Case Study

The value of wireless monitoring was demonstrated in 2019 in a well-documented case in Burnhurst, Southeast London. The Senceive FlatMesh wireless monitoring system, which consists of a tilt sensor and a cellular camera, detected early signs of landslides and allowed the train to slow down during the two-day course. When the slopes finally collapsed and about 300 tonnes of soil and vegetation deposited on the railroad tracks just hours before the morning rush hour, the system sent alerts and images in near real time, and the signal was immediately set to red. It was. This did not prevent confusion, but it significantly reduced the risk of potentially dangerous derailments.

A nano inclinometer that monitors tunnel deformation.
A nano inclinometer that monitors tunnel deformation.

Following this compelling demonstration of how intelligent surveillance technology can dramatically reduce the danger and disruption caused by slope failures, Network Rail has adopted the technology on a wider scale on many routes. Kent and Sussex are equipped with approximately 6,000 tilt sensor nodes, 222 cameras and 111 wireless communication gateways to relay data from the site to the cellular network.

One of the attractions of wireless surveillance solutions, such as the Senceive FlatMesh solution, is the speed and simplicity of installation. In the event of a structural or geoengineering failure, the system can be installed in hours, giving engineers important insights into ongoing movements.

Install the cellular camera and tilt node on the cut slope.

The value of this type of emergency surveillance was demonstrated in January when heavy rains washed away the material supporting the tracks on the West Coast Main Line near Rugby. The data from the emergency surveillance kit helped the engineer keep the train running until the next week while the repair was taking place, thus reducing the impact of the accident.

What’s next?

Wireless remote monitoring is often most effective when you want to integrate with other systems and data platforms to provide a wider range of information and increase the reliability of your results. Taking slopes as an example, data acquisition systems can combine wireless tilt sensors and cameras with ground or satellite synthetic aperture radar. Data management and an automated decision-making process allow you to integrate your data with highly localized weather forecasts.

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