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.

There are, on average, 12.5 Federal Railroad Administration reportable derailments per year on U.S. mainlines and sidings caused by “defective or missing spikes or rail fasteners.” Because fastener failures are most commonly caused by a combination of vertical, lateral, and longitudinal loads, it is important to quantify all loads placed on the fasteners to reduce the number of failed fasteners and increase rail safety. Multiple researchers have developed analytical models that leverage longitudinal track resistance and stiffness to quantify the fastener demands. Therefore, to support the refinement of these analytical models that leverage longitudinal track resistance and stiffness, track panel pull tests (TPPTs) were executed in the laboratory to expand on the values within the available literature. These TPPTs quantified the effect of sleeper type (i.e., timber versus concrete), given that 88% of previous studies have focused on concrete. Further, these novel tests quantified the effect of the fastening system, crib ballast height, shoulder width, and ballast condition on the panel’s longitudinal resistance and stiffness. From these experiments and the resulting analysis of data, multiple conclusions were drawn. For example, concrete sleeper panels exhibit 20% higher resistance than timber sleeper panels, disturbing ballast reduced the longitudinal resistance by 13% and stiffness by approximately 80%, and the crib, shoulder, and bottom ballast provide approximately 65%, 5%, and 30% of the total longitudinal resistance, respectively.

Management of continuous welded rail (CWR) stress is critical to maintaining railroad safety. To successfully manage the stress-state of the rail, knowing the rail neutral temperature (RNT) is critical. RNT is defined as the temperature at which the net longitudinal force in the rail is zero. If the RNT is set too low/high then the rail would buckle/pull apart and create unsafe operation conditions. To reduce unsafe operating conditions, researchers have previously developed guidelines for managing RNT maintenance activities. However, there remains an opportunity to improve these guidelines given there have been 24 derailments caused by buckled track between 2009 and 2018. Therefore, a research program has been established to improve current guidelines. It is difficult to manage the stress of CWR because the RNT is difficult to quantify, and has been shown to change over time, tonnage, or as a result of maintenance (tamping, etc.). Further, rail breaks may lead to local changes in RNT, leading to the need for RNT readjustment. Current guidelines estimate prevalent RNT before a rail break/cut based on rail gap size. Therefore, as a part of a broader research program, this paper reviews an analytical method presented by Kerr that quantifies rail break gap length and identifies the roles of longitudinal track resistance and stiffness. Results indicate that plastic track displacements driven by longitudinal track resistance dominate, and the longitudinal track stiffness has limited influence. This paper also identifies limitations of this analytical approach and documents recommendations for improved models.