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Revolutionizing Railway Safety with Distributed Acoustic Sensing (DAS)

Underground fiber optic

Stretching thousands of miles beneath your feet, a web of fiber optic cables listens to vibrations. Activities above ground, such as walking or driving, create characteristic vibrations that slightly disturb the way light travels through these cables. With the right equipment, scientists can interpret these disturbances to identify their sources and timings, to increase safety.

What is DAS?

This technique, known as distributed acoustic sensing (DAS), is extremely sensitive. Researchers have used it to monitor events like mass cicada emergences, volcanic eruptions, and earthquakes. Unlike traditional seismometers that are stationary, fiber optic cables provide a detailed picture of Earth’s movements across vast areas.

How is DAS Used to Increase Safety?

Scientists are now applying DAS to railroads. When a train travels along a track, it generates vibrations that can be monitored. Sudden changes in these vibrations could indicate problems such as cracks or rockslides. More gradual changes might reveal developing faults in track alignment. Since fiber optic cables already run alongside many railways for signaling and telecommunications, the infrastructure is largely in place, reducing costs.

An interrogator device fires laser pulses down the cables and analyzes the light that bounces back. For instance, if a rock hits the track 20 miles away, it creates a vibration that disturbs the fiber optics. By measuring the travel time of the light signal, scientists can pinpoint the disturbance within 10 meters.

DAS systems build vibration profiles for healthy railways. Anomalies in the data can indicate issues needing attention, similar to how an EKG detects heart problems. These systems can monitor tracks over long distances, potentially reducing the need for human inspectors and improving safety.

DAS generates vast amounts of data, requiring machine learning to process it. Sensonic, a DAS technology developer, has trained AI models to recognize events like rockfalls, sending alerts to operators. Although still in its early stages, DAS is showing promise for enhancing railway safety and monitoring various above-ground disturbances.

Read more about this technology here.

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