This paper aims to investigate alternative ways of reducing the deterioration and failure of railway track insulated rail joints (IRJs). Joints deteriorate faster than rail initially due to the structural discontinuity present. This weakness results in both extra displacement as a consequence of applied load and the dynamic force that results as a consequence. Over time this situation worsens as the impacts and applied stresses both damage and soften the ballast and supporting subgrade under the joint. This study initially presents a static finite element model designed to simulate the mechanics of IRJs and a comparison between plain rail and a suspended insulated rail joint under various support stiffnesses. Product design options of reinforced IRJs are then chosen as input variables of the model. Results of the model are compared with field and laboratory data acquired via the Video Gauge, which is a new high-resolution optical measurement technique. Results show that the use of strap rails or more robust I-beam sections in the vicinity of the IRJ to stiffen the support structure can significantly reduce the displacement and the subsequent dip angle seen at an IRJ. This potentially presents a means of improving the IRJ behaviour. Their impact becomes more significant for soft support conditions. Although these results are indicative for new IRJ conditions, field measurements indicate that the magnitude of deflection of IRJs is a result of the structural discontinuity of the rail, the dynamic P2 force, the wheel condition, the degraded ballast and it significantly increases with time under repeated load. Thus, it is recommended that careful field implementation and testing will indicate the effect of an external enhancement on the timely degradation of insulated rail joints.

Rail joints constitute a weak component in the railway system. In this paper, three-dimensional finite element analyses are carried out to study the structural deflection performance of rail joints under a fatigue static test through vertical stiffness assessment. Four different types of four-bolted joints are investigated under a dynamically enhanced static load including a glued insulated rail joint, a dry encapsulated insulated rail joint, a dry non-glued insulated rail joint and a mechanical rail joint. The analysis focused on the accurate simulation of the contact types between the interfaces of rail joint components, namely the rail, fishplate faces, bolts and insulating materials. It also focused on the effect of the elastic supporting structure of the joint with regard to the overall joint deflection. The effect of bolt pre-tension is included in the model. The vertical displacement of insulated rail joints is measured experimentally by dial gauges and a video technique in both laboratory and field settings. The numerical modelling investigated the effect of different contact types on the interfaces of the rail joint components during the performance of fishplates, and of the rail in the vicinity of the rail joint under a given support condition. The vertical displacement of the rail joint was presented and assessed against specified limits of endurance tests and field-measured deflection values that validate the model. Stress distribution in the fishplates was presented that could allow the calculation, through a stress-life approach, the fatigue life of the fishplates and, consequently, of the joints due to repeated wheel passage. A comparison of the performance of the aforementioned rail joint types is included. The results indicate that this finite element model can be routinely used in industries, as it was used in the UK Rail industry study, to allow designers to optimize the life expectancy of insulated rail joints.

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This paper presents direct track deflection data measured using a video gauge (VG) (a digital image correlation (DIC) method) to determine track stiffness characteristics remotely. Two cases are discussed. First, the deflection performance of two novel ballastless trackforms are coupled with an analytical model to assess their stiffness properties for known train loads. Second, the performance of a bridge transition is evaluated under live train passages by the VG; the traffic loads are assumed based on train type to allow track stiffness interpretation from a number of train passes. A track deflection bowl is assessed to show the performance of the transition. The paper initially discusses the DIC technique and the importance and assessment of track stiffness. It then presents the VG deflection data, the global support stiffnesses and deflection bowls. These novel methods are shown to be consistent with other approaches of track stiffness evaluation. The paper concludes with a discussion of how this methodology can be utilised in the railway industry for assessing the trackbed performance of critical zones without the need for track possessions.