Stretching beneath our feet, a vast network of fiber optic cables is listening to the world around us. This network of cables is known as distributed acoustic sensing (DAS), and it can detect vibrations caused by various activities, including walking over buried fiber optics or driving a car above them. Scientists can analyze these disturbances to determine their source and timing. DAS is being used for monitoring cicada emergences, detecting volcanic eruptions and earthquakes, and now, for monitoring railroad tracks. By analyzing the vibrations created by passing trains, DAS can identify potential problems with the tracks, such as cracks or rockslides. DAS technology relies on fiber optic cables that are already present in many railways, making it a cost-effective solution. To tap into the cables, an interrogator device fires laser pulses down the cables and analyzes the light that bounces back. By measuring the time it takes for the signal to travel back, the distance to the disturbance can be pinpointed. This enables the creation of a vibration profile for a normal railway, which can be compared to current data to detect any changes. DAS technology has the potential to reduce the need for manual inspections of railway tracks and improve safety. However, it also generates massive amounts of data, which
https://www.wired.com/story/fiber-optics-bring-you-internet-now-theyre-also-listening-to-trains/