Drainage Properties of Fine-Contaminated Ballast

In 2017, the Federal Railroad Administration (FRA) and Transportation Technology Center, Inc. (TTCI) completed the initial phase of testing on a “Rainy Section” in the High Tonnage Loop at the Facility for Accelerated Service Testing (FAST) in Pueblo, CO, to measure drainage, settlement, and dynamic behavior of a fine-contaminated ballast section. This test section allows TTCI to control the wetting and drainage of the section, and simulate various rain events. The first iteration of the testing involved the use of sand-sized and non-plastic, silt-sized fines from granite ballast degradation to represent fine-contaminated ballast that would occur progressively during dynamic ballast degradation and not from surface or subgrade infiltration. This test section at FAST has 37.2 percent fine content (i.e., grain size below No. 4 sieve, 4.76 mm), with the fines filling a significant percentage of the available voids between ballast particles. Multiple tests were conducted to measure the drainage rate in the Rainy Section after wetting, and the following observations were made: (1) For the degraded ballast and unimpeded drainage, the section took approximately 20 hours to drain to pre-wetting conditions. This drainage time depends on the amount of fine-material, type of fine-material, and the drainage routes of the ballast section. Smaller grain sizes (e.g., clays) will generally result in longer drainage time, whereas larger grain sizes (e.g., sands) will generally result in shorter drainage time; and (2) Mud pumping occurred after 0.5 million gross tons (MGT) when the drainage was blocked and a 6-inch water table developed, resulting in the accumulation of fines in a mud slurry near the surface. This report is the first of an ongoing study investigating the drainage, settlement, and dynamic behavior of different types of fine-contaminated ballast when exposed to moisture and the benefits of various remediation strategies. The project was conducted by TTCI as part of a cooperative research initiative between FRA and the Association of American Railroads (AAR).

Language

  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; Photos; References;
  • Pagination: 4p
  • Serial:
    • Research Results
    • Issue Number: RR 19-01
    • Publisher: Federal Railroad Administration
  • Publication flags:

    Open Access (libre)

Subject/Index Terms

Filing Info

  • Accession Number: 01696580
  • Record Type: Publication
  • Files: TRIS, ATRI, USDOT
  • Created Date: Feb 7 2019 1:04PM