Review of Critical Factors Influencing Longitudinal Track Resistance

Abstract

Longitudinal track resistance is one of the most critical parameters required to accurately analyze longitudinal load propagation and refine rail neutral temperature (i.e., stress-free temperature) maintenance practices. However, longitudinal track resistance has not been consistently defined and has been quantified using multiple methods that should not be conflated. This paper documents common definitions of longitudinal track resistance and the two methods regularly used for its quantification: track panel pull test (TPPT) and single rail break (SRB). Further, this paper documents the differences in mechanics between these methods, summarizes and discusses the critical factors influencing the longitudinal track resistance values found in the literature, and adds novel TPPT longitudinal track resistance values for timber sleeper track to address the current scarcity of data found in the literature. In summary, TPPT values provide insight into the mechanics of load propagation and pre-buckle analysis while the SRB values aid in the maintenance and restoration of rail neutral temperature after a rail break or destress. Additionally, the TPPT longitudinal track resistance values reported in the literature were independent of panel length, were influenced most by the presence of a vertical load, and were reduced by 25% when the ballast was disturbed. Finally, novel TPPT results indicated the longitudinal resistance of timber sleeper track was 19% lower than concrete sleeper track and that unfastened sleepers still transferred longitudinal load when the cribs were full and ballast was compacted.