We have filed our ninth Indian Patent title “A system for measuring vertical strain using the packaged structure and the method thereof”. The invention discloses a metallic packed Fiber Bragg Grating (FBG) sensor structure for vertical strain sensing. An embodiment of the packaged structure comprises pair of fixtures, sensor element and bare Fiber Bragg Grating (FBG) sensor. The sensor element is welded on the pair of fixtures on both sides. Finally, the FBG sensor with fiber optic cable is pasted on the surface of the sensor element to accomplish a metallic packed Fiber Bragg Grating sensor structure. The invention discloses a real time-based method and system for vertical strain monitoring using packaged structure. The system includes packaged structure, Optoelectronic instrument, data processing unit (DPU) and the GUI (Graphical User Interface). The structure receives stress and leads to a change in the Bragg wavelength of the sensor. The Optoelectronic instrument captures and analyzes all Bragg wavelength variations with respect to time. The data processing unit converts the shift in Bragg wavelength to corresponding strain developed due to the stress and computes this vertical strain on the rail at rail-wheel contact. Further, GUI displays this information to remote users.