BALLAST QUALITY AND BREAKDOWN DURING TRANSPORT

摘要

Union Pacific Railroad has prioritized optimizing the life span of ballast material utilized across the system. A multi-faceted approach is presented which addresses (1) obtaining hard, durable ballast; (2) ensuring that the ballast delivered satisfies the specification; and (3) evaluating the resistance of ballast to breakdown during transportation. The initial focus included a quality management system to verify that properly graded and clean ballast is loaded into the railcars. Periodic testing and unannounced quarry visits are in place for each ballast source. Petrographic testing was completed for each source to identify potential problematic mineralogical issues. The second focus is ballast degradation during transport. The study included three railcars shipped to a central location where a gradation analysis on each railcar was completed in its entirety. Vari6us sampling methods were utilized at the ballast sources during loading of the railcar and are compared to the unloaded results. The variability of gradation results from different sampling methods was a significant outcome of the study. The test results indicate that the half inch particle size increased during transport. The outcomes of these series of studies are constant evaluation of ballast suppliers is warranted, obtaining representative samples of ballast for gradation quality control is difficult, and transportation results in a minor increase of the half-inch particle size.