Technology Digests / Consideration of Factors for a Ballast Degradation Model

TD23-009

July 25, 2023
Authors
  • Stephen Wilk
  • Dingqing Li
  • Dante DeVencenty
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Key Findings

  • MxV Rail investigated factors that should be considered for a ballast degradation model, including maintenance activities, ballast fouling index, axle load and ballast quality. The eventual goal of such a model is to aid in ballast maintenance cycle planning.
  • Longevity of ballast cleaning and the loss of ballast cleaning effectiveness are necessary parameters for the model, and these two parameters have not been measured in previous studies.
  • Higher ballast degradation rates are anticipated for higher accumulated tonnages, higher axle loads, and lower ballast quality areas. Concrete ties, wetter climates, rougher geometry, tie movement, and poor drainage may also contribute.

Consideration of Factors for a Ballast Degradation Model

MxV Rail developed a mechanics-based ballast degradation model using available data from multiple past research studies. The project goal was to identify key ballast degradation parameters and incorporate these parameters into a single model that could aid in ballast maintenance planning. As there are many other considerations beyond ballast degradation, the model is not intended to be the only source for planning ballast maintenance cycles. Instead, this model could be used to identify high degradation regions and compare long-term economic tradeoffs from different ballast maintenance activities. In addition, the model development process has identified key knowledge gaps for the focus of future research. This research is supported by the Association of American Railroads (AAR) under its Strategic Research Initiatives (SRI) program.  When ballast breaks down (i.e., degrades) from repeated train loadings, it can result in increased track movement, inadequate drainage, and track geometry issues. Promoting drainage and improved track performance,…