**Abstract**

There are many technologies associated with optical fiber sensing (OFS) and depending upon the type of application, a specific OFS technology plays a crucial role in the associated application as compared to the use of conventional sensing technologies with these applications. The same is true with the railway industry and the two most suitable OFS technologies in the railway sector are distributed acoustic sensing (DAS) and fiber Bragg grating (FBG). The two mentioned technologies in association with the railway industry are explained briefly in this chapter.

**Keywords:** distributed optical fiber sensing, distributed acoustic sensing, Brillouin optical-fiber time domain reflectometry, Brillouin optical-fiber time domain analysis, Raman-based distributed temperature sensing
