Determining the Stresses in Steel Railroad-Track Rails Due to Freight Movements Using Non-Contact Laser-Speckle

® The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the information presented herein. This document is disseminated under the sponsorship of the Department of Transportation University Transportation Centers Program, in the interest of information exchange. This research was aimed at developing a procedure to determine the existing stresses in steel rails used in railroad tracks. These stresses are caused by the combination of both thermal restraint and physical/mechanical loads. However, since the track sections are installed at various temperatures and then continuously welded together and secured to wood or concrete ties, the stresses existing in the track at any given time are currently unknown. In fact, not only the magnitude of stress is unknown, but also the basic knowledge about whether the rails are in tension or compression at a given time. Since the stresses due to thermal and physical loading are additive in the elastic range, the existing safety factors of the rail system when subjected to heavy freight movements are also unknown. The research focused on extending the existing technology of laser-speckle strain measurements for concrete surfaces to use on steel rails.