This project developed an in-line grating and scattering fiber optic sensing system for strain, temperature, and steel mass loss measurement in bridge applications. Long period fiber gratings (LPFG) sensors are responsive to thermal and mechanical deformation, and the refractive index change of their surrounding medium. Brillouin scattering sensors are responsive to temperature and strain along an optical fiber. A CO2 laser aided fiber grating system was assembled for LPFG fabrication. To enable mass loss measurement, a low pressure chemical vapor deposition (LPCVD) system was built to synthesize a graphene/silver nanowire composite film as flexible transparent electrode for the electroplating of a thin Fe-C layer on the curve surface of a LPFG sensor. Combined with two LPFG sensors in LP06 and LP07 modes for simultaneous strain and temperature measurement, three Fe-C coated LPFG sensors were multiplexed and deployed inside three coaxial steel tubes to measure critical mass losses through the penetration of tube walls and their corresponding corrosion rates in the life cycle of steel rebar. Thermal, loading and accelerated corrosion tests were conducted to validate the performance of the proposed sensors and demonstrate their feasibility for in-situ applications.