Technology Digests / Track Settlement and Ballast Tamping

TD23-002

July 11, 2023
Authors
  • Stephen Wilk
  • Dante DeVencenty
  • Ekrem Koç
  • Dingqing Li
Share

Key Findings

  • In general, tamp lift heights of 1 to 1.5 inches are necessary for crib ballast to be pushed underneath the tie. If this additional ballast is not pushed underneath the tie, the track will return to its pre-tamping elevation.
  • Optimized tamping parameters to achieve smoother track are known (multiple insertions and longer squeezes), but the important performance metrics (productivity vs. longevity) are still not well defined and require future studies.
  • Ballast condition metrics, such as Ballast Fouling Index (BFI), appear to relate with settlement in certain situations (e.g., isolated mud spots) and not in others (ballast recompaction).

Track Settlement and Ballast Tamping

MxV Rail incorporated measurements taken in 2021 and 2022 at the Transportation Technology Center (TTC), Pueblo, CO, into a high-level review of track settlement mechanisms versus ballast tamping practices. The goals of this review were to 1) summarize the current state of practice in a single document and 2) identify gaps in knowledge. Review findings are more applicable to spot tamping, but they can also direct future testing that will address production tamping questions such as recommended surfacing cycles or optimized tamping parameters. This work was supported by the Association of American Railroads (AAR) under its Strategic Research Initiatives (SRI) program.   Track settlement is a key factor in track geometry deviations, including surface profile, cross level, and warp. An understanding of track settlement mechanisms and different tamping procedures can provide longer-lasting, smooth track that will extend surfacing cycles and reduce repeat tamping at problematic locations.  SUBSTRUCTURE SETTLEMENT MECHANISMS  Settlement within…