Technology Digests / Shoulder Ballast Cleaning in Mud Spot Location

TD22-017

August 1, 2022
Authors
  • Stephen Wilk
  • Richard Chaparro
  • Dingqing Li
  • Dante DeVencenty
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Key Findings

  • Spot shoulder ballast cleaning (SBC) was effective at reducing surface mud pumping and promoting drainage in a severely degraded ballast location. This ballast maintenance method can be useful at extending the time before undercutting or track renewal becomes necessary.
  • SBC can partially address, but not eliminate, the susceptibility to high settlement rates.
  • The effectiveness of SBC will likely vary from location to location and will be dependent on multiple factors, including geographic climate, fine gradation (FI levels and fine type), and tonnage.
  • The longevity of SBC benefits could not be fully assessed, but free-draining shoulders remained after 60 MGT (one year) and 19.65 inches of rainfall.
  • Fine migration did occur, primarily from surface runoff. As reference, internal fine migration would not be expected from a FI=40 material.

Shoulder Ballast Cleaning in Mud Spot Location

MxV Rail (formerly TTCI) performed spot shoulder ballast cleaning (SBC) on a severely fine-filled ballast location to evaluate how improved shoulder drainage affects track performance. Results showed SBC was effective in areas of highly degraded upper ballast layers, but the method’s overall utility will likely vary by location. This Technology Digest (TD) summarizes SBC performance over one year of testing in the “Rainy Section”1 of the Facility for Accelerated Service Testing (FAST®) in Pueblo, CO, focusing specifically on surface mud pumping, settlement, drainage, and fine migration (i.e., whether SBC “cleans out” the center ballast section). The manner in which different geographical climates may affect the results is also discussed. A companion TD2 currently in press will provide more detail about fine migration and how the fine type in the ballast affects drainage paths. This work was jointly funded by the Association of American Railroads (AAR) Strategic Research Program (SRI) and…