Fiber Optics Could Detect Earthquakes, Improve Railway Safety With Distributed Acoustic Sensing

Fiber optics have a lot to offer. According to a new report, it could help improve rail safety.

Fiber Optics For Rail Safety

Researchers are testing the possibility of implementing distributed acoustic sensing (DAS) on a nearby railroad. Over time, analysts can measure the vibrations produced by trains running down a particular length of track.

If the vibrations abruptly alter, it may be a warning of a rail issue, such as a crack or a shattered tie. Alternatively, DAS might also "hear" a rockslide crashing over a train on a mountain pass, alerting railroad operators to an issue their eyes had not yet caught. Gradient changes in the signal could indicate the emergence of alignment problems in the track.

Coincidentally, fiber optic cables are already installed along a number of railroads to link all of the telecommunications and signaling apparatus.

"You're utilizing the already available facilities and infrastructure for that, which can reduce the cost," says engineer Hossein Taheri, studying DAS for railroads at Georgia Southern University. "There could be some railroads where they don't have the fiber, and you need to lay down. But yes, most of them usually already have it."

An interrogator, which shoots laser pulses down the cables and examines the minuscule amounts of light that bounce back, must tap into that fiber. Assume, then, that a rock falls on the track twenty miles from the interrogation. As a result, the fiber optics next to the track are disturbed and experience a characteristic ground vibration manifested in the light signal. The exact time it took for the signal to return to the interrogator may be determined by scientists using the speed of light, which allows them to choose the disturbance's distance to within 10 meters, or roughly 30 feet.

You would have already built a vibration profile for a typical, healthy railway for a particular stretch of track by analyzing the DAS signals for a considerable time. You may have a problem if the DAS data suddenly reveals abnormalities. This is similar to an EKG detecting anomalies in a human heartbeat.

What Is Distributed Acoustic Sensing?

Distributed Acoustic Sensing (DAS), also known as Vibrational Sensing Systems, detects vibrations and uses optical fibers to store acoustic energy. Utilizing the asset's existing fiber optic networks, a distributed acoustic sensor collects real-time data and assists operators in making the best decisions. Classification algorithms are employed in identifying and localizing occurrences like leaks, cable malfunctions, entry attempts, or other unusual noises.

This technology makes it possible to measure continuously and in real-time along a fiber optic cable's length. Distributed sensing uses optical fiber instead of traditional sensors, which depend on discrete sensors taking measurements at pre-established locations.

The element that senses is the optical fiber. These devices make detecting auditory signals in challenging conditions and across great distances possible.

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