In the United States, railroads represent a significant mode of transportation for moving freight. Thus, proper maintenance of the railway lines through repair and renewal is important for railroad operation and safety.
Track maintenance activities can be categorized into two groups: preventive maintenance and corrective maintenance. Preventive maintenance is pre-planned and carried out to avoid future defects, whereas corrective maintenance repairs existing defects in the infrastructure. Track repair is usually performed by a local track master in the network, and it is typically conducted on demand. Although corrective maintenance occurs on a relatively small scale as compared to preventive maintenance, it is important to repair severe track defects because they may lead to catastrophic train derailments.