# Fiber Monitoring System Applied to Railway Bridge Structures in a Near-Fault Region
## 5 Conclusions  
Traditionally, to determine the safety of bridges, manual inspections must be carried out. These inspections are mostly carried out by eye. This makes inspections prone to human error and not able to achieve real-time feedback. This research presents a new approach to monitoring bridge structures in real time. To monitor the bridge effectively, sensing fibers are attached to the bridge, and a DFOS system is used to collect the BFS of the fibers. The BFS is then calculated as the strain of the fiber by excluding the factor of temperature change. The strain data of the fiber can be processed into the strain data of the bridge structure by incorporating the bridge geometry into the calculation. Furthermore, data on bridge displacement and deformation can be acquired through data processing techniques. By analyzing the above data over time, engineers will be able to judge if a structure is deformed or on its way to failure. This will be the first time that the incremental movement of bridge structures can be observed over a long period of time in high resolution across the length of a bridge.  
Fiber optics systems applied to bridge monitoring provide more comprehensive and real-time data. Potential structural problems and deficiencies can be detected through the continuous monitoring of structural changes in a bridge. This enables malfunction detection and preventive maintenance to be performed beforehand. The safety and reliability of bridges have greatly improved, which will decrease accidents caused by structural problems. Bridge management personnel can better understand the condition of a bridge and take effective measurements to guarantee the safety of bridge transportation.  
Future designs for bridges could reference data from this fiber sensor system and enable the manufacture of more structurally stable bridges. Cost reductions could also be achieved by decreasing overengineering. This study will prove to be valuable for the technological advancement of future bridge maintenance and overall structural safety.  
Figure 14: Vertical angular displacement of a box girder.  
Figure 13: Horizontal angular displacement of a box girder.  
**Author Contributions:** W.-K.H.: analysis, validation, and main editing and reviewing; H.-C.S., T.-H.H. and Y.-L.L.: analysis and validation; N.-T.Y. and N.-H.C.: physics model analysis, software programming and computation, on-site measurement, and data curation. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research received no external funding.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Data are contained within the article.  
**Acknowledgments:** This test and study were conducted using a DFOS system and sensing fibers that were provided by OlitGlobal Technology (Kaohsiung, Taiwan) to measure the strain and temperature of the tested rail. We also thank the Taiwan High-Speed Rail Corporation for their assistance during the test period.  
**Conflicts of Interest:** Authors [PERSON] and [PERSON] were employed by the company OlitGlobal. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.