Ballast Degradation Under Heavy Axle Load Trains at the Western Mega Site

Transportation Technology Center, Inc. (TTCI) and the University of Illinois Urbana-Champaign (UIUC), in conjunction with Union Pacific Railroad (UP), investigated ballast performance under 36-ton heavy axle load (HAL) traffic near Ogallala, NE, at the western mega site from 2010-2015. Periodic sampling and laboratory tests were used to monitor ballast degradation and deformation behavior of four mainline-quality ballast materials. Testing was jointly funded by the Association of American Railroads (AAR), the Federal Railroad Administration (FRA), and UP to quantify the effects of ballast gradations and material types on ballast performance. In November 2010, new ballast materials from four sources, labeled Types 1 through 4, were installed in a 2-degree curve and tangent test zones, as well as subjected to 220-250 million gross tons (MGT) per year. Ballast Types 1-4 were screened after delivery and before installation to remove particles less than 3/8-inch screen size. The Type 5 material was identical to the Type 2 material, but it was installed as delivered without additional screening. Steel boxes separated the ballast types, and samples were collected at six different times over the testing period of 737 MGT. Sieve analyses were performed on the sampled ballast to determine changes in the gradation with tonnage. Permanent deformation trends of the ballast samples were evaluated using a large-scale repeated load triaxial test device. Finally, the ballast sample nonorganic carbon contents from car lading were measured using a carbon, hydrogen, and nitrogen chemical test. In these test zones, ballast degradation rates due to HAL traffic differed substantially among the four mainline-quality ballast types. In general, Types 1 and 2 had lower degradation rates due to material types. However, higher percentages of degradation and organic carbon content in the ballast generally corresponded to higher permanent deformation in laboratory testing, with increasing traffic volume. With additional screening of the Type 2 ballast over the Type 5 control ballast at source gradation, the Type 2 ballast stayed cleaner to the test termination. Finally, for the western mega site, it took 737 MGT to accumulate significant amounts of carbon-based fines in ballast samples. Testing also revealed that carbon based minerals migrated downwards over time and that the Type 3 deep samples contained the highest organic carbon content of 16 percent. The Type 3 also accumulated the highest laboratory permanent deformation at 10,000 cycles, at the final 732 MGT level.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; Photos; Tables;
  • Pagination: 4p
  • Serial:
    • Research Results
    • Issue Number: RR 18-09
    • Publisher: Federal Railroad Administration
  • Publication flags:

    Open Access (libre)

Subject/Index Terms

Filing Info

  • Accession Number: 01671843
  • Record Type: Publication
  • Files: TRIS, ATRI, USDOT
  • Created Date: Jun 7 2018 2:23PM