Abstract: “The paper presents a system monitoring operational safety of structures used in civil engineering. The system is based on the fibre Bragg grating (FBG) sensors or sensors using the optical time domain reflectometry (OTDR) technology. The essence of the solution is to introduce FBG sensors into the structure to make them act as its “nervous system”. The system may be implemented in existing civil engineering structures made of steel, concrete, reinforced concrete, as well as in shells and new structures at the design stage. The paper presents an example of an actual system operating based on FBG sensors and analysing the safety of Poland's longest steel footbridge. The footbridge is 35 years old. Periodic inspections of the Technical Inspection Office allow the footbridge operation if the structure meets the requirements stipulated by relevant regulations, but the decision is not based on a continuous analysis of the footbridge safety. The applied monitoring system makes it possible to”

Keywords: safety of civil engineering structures, fibre