The present work reports an investigation for systematic condition evaluation and subsequent strengthening of longitudinal girders of a Road Over Bridge (ROB) in India. ROBs are grade-separated structures carrying heavy traffic. As a result, they are suffering several distresses due to which their strengths are degraded along with the service life. In this work, several nondestructive (NDT) tests were carried out on all the distressed girders of the ROB to meticulously evaluate the structural health of the girders. Significant reduction in concrete quality, loss of material due to spalling, and corrosion of reinforcements with lower pH values were found from the test results. After the condition assessment, the investigation carried out repair and retrofitting measures, with the incorporation of contemporary materials, aimed at enhancing the resilience and durability of the ROB. Repair using micro-concreting, epoxy injection grouting, and sealing was carried out with application of anti-corrosive treatments for reinforcements to regain the strength of the girders. A post-repair NDT tests indicated that there is significant improvement of the quality and strength of the members. This study thus contributes valuable insights to the field of infrastructure maintenance management in enhancing the performance of transport infrastructure.