Smart Railway Traffic Monitoring Using Fiber Bragg Grating Strain Gauges

Abstract

There is today ample evidence that fiber Bragg gratings (FBGs) distributed along a railway track can provide robust axle counting and bring numerous assets compared to competing technologies in this practical environment. This work brings two relevant originalities with respect to the state-of-the-art solutions. First, a study of the strain distribution in the rail cross-section is performed to determine the sensitivity according to the charge and the position on the rail. Secondly, the technology is deployed along the rail track as a smart object where the sensor head is composed of four FBG wavelength-division-multiplexed in a single telecommunication-grade optical fiber and interrogated by a miniaturized read-out device. Two FBGs ensure the detection of the train direction and another two bring the required redundancy to reach a safety integrity level (SIL) 4. The read-out unit has been specifically developed for the application and contains a vertical-cavity surface-emitting laser (VCSEL) and a photodiode driven by a high-speed microprocessor unit that processes the data and communicates the useful information, i.e., the number of axles. On-field tests confirm that the proposed approach makes the installation process easier while it democratizes the technology.

Macrobending loss in fiber optic wrapped on rubber-spring wire structure under static load-pressure

“…Fiber optic sensors are widely used in various fields, such as health [8], engineering [9][10][11], civil works [12], and chemistry [13]. In civil and engineering fields, fiber optic sensors are widely used for load sensing and structural health monitoring [14][15][16]. Fiber optic sensors have advantages such as being unaffected by changes in ambient temperature, high responsivity to fast loads, and resistance to electromagnetic wave interference [4].…”

A New Form of Train Detection as a Solution to Improve Level Crossing Closing Time

“…The classic ways to detect a train are a track circuit or an axle counter [ 19 ]. Detection measures can be upgraded with the use of Fiber Bragg Gratings [ 20 ]. In the paper, we suggest using radars to detect trains; the conclusions of studies in [ 21 ] indicate that the radar solution produces better results than vibration or voice-based sensors.…”

Designing of Fiber Bragg Gratings for Long-Distance Optical Fiber Sensing Networks

“…When the Bragg condition is fulfilled, the reflected light forms a backward reflected peak with a central wavelength known as λ B . Such a grating structure, developed by the Bragg relation, acts as a mirror that reflects the wavelength λ B and transmits the rest of the optical signal further inside the optical fiber [5,8,9].…”