The objective of this research is to estimate optimized maintenance and in-spection intervals for as-welded (AW) and HFMI-treated bridge details (including non-load-carrying transverse welds and load-carrying transverse welds) with the life-cycle environmental impact and life-cycle cost as objective functions and the probability of failure/reliability as the constraint function. Specifically, when the reliability of the bridge falls below a certain threshold, maintenance and inspec-tion should occur, resetting the reliability to a given value after maintenance is performed. The inspection activity involves digital scanning of the weld toe for cracks and defects, while the maintenance activity is HFMI treatment. Perform-ing HFMI repairs cracks and resets the reliability and FAT resistance of the weld detail to a certain value, after which the weld detail becomes stronger and less prone to fatigue failure. The goal is to implement reliability- and sustainability-considered preventive maintenance procedures, as essential maintenance is ex-pensive and time-consuming; ideally eliminating essential maintenance could generate substantial cost savings.