Resistivity and Hydraulic Conductivity of Fouled Railroad Ballast: Fid-Bau Portal

Resistivity and Hydraulic Conductivity of Fouled Railroad Ballast

Rahman, A. J. / Parsons, Robert L. / Han, Jie

Ballasted tracks are the most common tracks used in the railroad industry and are designed to provide a stable, safe, and efficient rail foundation. The main functions of ballast are to support the superstructure by distributing the loads from the moving train and to provide lateral resistance to tie movement and drainage. However, ballast fouling is a major issue in the railroad industry and can be caused by repeated loadings that lead to crushing of the ballast in contact with ties and migration of subgrade particles into the ballast. There is a need for methods to easily and inexpensively identify areas with fouled ballast. The objective of this study is to evaluate the potential for estimating fouling level in a ballast layer using soil resistivity and permeability tests. A test box was fabricated to perform the constant head permeability and soil resistivity tests. Hydraulic conductivity and soil resistivity were determined for fouled ballast at different fouling ratios. The tests showed a relationship exists between the percentage of fouling and ballast resistivity because the resistance of the ballast layer decreases as the percentage fouling increases due to water presence. The permeability also decreases as the percentage of fouling increases due to the presence of fine particles between the ballast particles.