Kilometer-Long Optical Fiber Sensor for Real-Time Railroad Infrastructure Monitoring to Ensure Safe Train Operation


This study is aimed to develop a real-time safety monitoring of kilometer-long joint rails using a distributed fiber optic sensor. The sensor measures the distribution of Brillouin frequency shift along its length with pulse pre-pump Brillouin optical time domain analysis (PPP-BOTDA). The measurement distance and spatial resolution can be up to 25 km and 2 cm, respectively. The fiber optic sensor was first characterized and calibrated for distributed strain and temperature measurement, and then instrumented on a smallscale joint rail-like specimen in laboratory. The specimen was loaded at room temperature, and its strain distribution along the sensor was measured using a Neubrescope with high accuracy and spatial resolution. Given a gage length, the joint open change was determined and visibly identified from the measured strain distribution. Finally, an implementation plan of distributed sensors on a railway is introduced, including sensor deployment, sensor repair when broken, and cost analysis. The gage length at a crack is an important parameter in sensor deployment and investigated using finite element analysis. The results indicate that the distributed sensor can be used successfully to monitor the strain and temperature distributions in joint rails.

Meeting Name

ASME/ASCE/IEEE Joint Rail Conference (2015: Mar. 23-26, San Jose, CA)


Civil, Architectural and Environmental Engineering

Keywords and Phrases

Distributed Fiber Optic Sensor; Joint Rail; Operation Safety Monitoring; PPP-BOTDA; Anchorages (Foundations); Fiber Optic Sensors; Finite Element Method; Frequency Domain Analysis; Gages; Image Resolution; Optical Fibers; Optical Pumping; Railroad Transportation; Temperature Measurement; Brillouin Frequency Shifts; Brillouin Optical Time Domain Analysis; Distributed Fiber Optic Sensor; Railroad Infrastructure; Strain Distributions; Time Domain Analysis

International Standard Book Number (ISBN)


Document Type

Article - Conference proceedings

Document Version


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© 2015 American Society of Mechanical Engineers (ASME), All rights reserved.

Publication Date

01 Mar 2015