Assessing the deflection behaviour of mechanical and insulated rail joints through finite element analysis

Rail joints constitute a weak component in the railway system. In this paper three- dimensional (3D) finite element analyses (FEA) 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 4-bolted joints are investigated under a dynamically enhanced static load including a glued insulated rail joint (IRJ), a dry encapsulated IRJ, a dry non-glued IRJ and a mechanical RJ. The analysis focused on the accurate simulation of the contact types between the interfaces of rail joint components, namely among the rail, fishplate faces, bolts, insulating materials and on the effect of the elastic supporting structure of the joint on the overall joint deflection. The effect of bolt pretension is included in the model. The vertical displacement of IRJs is measured experimentally both by dial gauges and Video technique both in laboratory and in field. 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 RJ under a given support condition. The vertical displacement of the rail joint were presented and assessed against specified endurance tests’ limits 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 RJ types is included. The results indicate this FE model to be practical to be routinely applied to industry, as it was used in UK Rail industry study to allow designers to optimise life expectancy of IRJs

The application of track deflection measurements made by the video gauge

This paper presents direct track deflection data measured by the Video Gauge (VG), (a Digital Image Correlation method) that is used to remotely determine track stiffness characteristics. Two cases are discussed. Firstly, the deflection performance of two novel ballastless trackforms are coupled with an analytical model to assess their stiffness properties for known train loads. Secondly, 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. It shows these novel methods to be consistent with other approaches of track stiffness evaluation. It concludes on how this methodology can be utilised in the railway industry for assessing trackbed performance of critical zones without the need for track possessions

Assessment of highway filter drain fouling and performance considerations

The road carriageway and pavement sub-surface of many UK highways are drained by Highway Filter Drains (HFD). These are gravel filled trenches fitted with a porous carrier pipe at the base that convey surface and sub-surface water to an outfall. HFD are typically characterized as free draining upon construction however, over time the voids of the granular medium become filled due to the intrusion of fines washed from the adjacent earthworks or pavement surface. The lack of understanding of the deterioration mechanisms and the absence of a structured fouling characterization limit the assessment of operational and residual HFD life to qualitative or subjective estimation of in-service performance. This extends to maintenance procedures that are predominately reactive. This paper reviews the current state of knowledge of HFD performance and drainage media condition assessment. It then presents a method of fouling characterization based on assessment of samples from in service drains. Three fouling scales are thus suggested; the percentage drain fouling, the foulant-aggregate ratio and the free voids ratio. In-service HFD are found to be functioning at an acceptable standard with a limited number of localized failures attributed to highly fouled layers at the surface of the trench. It is proposed that a rational evaluation of a HFD section should employ means other than just visual indicators. The fouling assessment is linked to laboratory permeability tests conducted with different levels of filter material fouling. It is found that the extent, spreading and type of fouling are important to determine how the filter aggregate performs

Framework for carbon emission evaluation of road maintenance

In the United Kingdom, carbon emissions associated with business activities have shifted from matters of policy to sources of legal responsibilities under the Climate Change Act of 2008. A flexible and easy-to-use technique is needed so that businesses can assess their carbon emissions in response to regulations on the environmental impact of construction activities. The aim of this study was to develop a methodology that could offer businesses a carbon life-cycle assessment tool to identify emissions hot spots across the value chain and inform a carbon-reduction hierarchy. The approach employed was based on methodology described in the publicly available specification (PAS2050) protocol. The objective was to identify locations where the largest production of emissions occurred and provide for the biggest potential reduction within routine highway maintenance processes. The methodology framework allows businesses to make informed decisions in carbon terms through the identification and prioritization of areas of potential reduction of emissions

Potential for external reinforcement of insulated rail joints

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

Applicability of video gauge for the assessment of track displacement

Numerous techniques have been used for the measurement of the track displacements and consequently the assessment of track stiffness. Some of the most commonly employed are linear variable displacement transducers (LVDTs), geophones and older video monitoring techniques based on Particle Image Velocimetry (PIV). In this paper, the application of the Video Gauge, a relatively new technique, is investigated. This technique can be seen as a quick and reliable way to capture data of high quality and resolution, which can be directly employed for the evaluation of track displacement and hence stiffness.The Video Gauge is used at three different track sites measuring different ballasted track components under various train speeds and types

Evidence for a directed southward autumn migration of nocturnal noctuid moths in central Europe

Insect migrations are spectacular natural events and resemble a remarkable relocation of biomass between two locations in space. Unlike the well-known migrations of daytime flying butterflies, such as the painted lady (Vanessa cardui) or the monarch butterfly (Danaus plexippus), much less widely known are the migrations of nocturnal moths. These migrations - typically involving billions of moths from different taxa - have recently attracted considerable scientific attention. Nocturnal moth migrations have traditionally been investigated by light trapping and by observations in the wild, but in recent times a considerable improvement in our understanding of this phenomenon has come from studying insect orientation behaviour, using vertical-looking radar. In order to establish a new model organism to study compass mechanisms in migratory moths, we tethered each of two species of central European Noctuid moths in a flight simulator to study their flight bearings: the red underwing (Catocala nupta) and the large yellow underwing (Noctua pronuba). Both species had significantly oriented flight bearings under an unobscured view of the clear night sky and in the Earth's natural magnetic field. Red underwings oriented south-southeast, while large yellow underwings oriented southwest, both suggesting a southerly autumn migration towards the Mediterranean. Interestingly, large yellow underwings became disoriented on humid (foggy) nights while red underwings remained oriented. We found no evidence in either species for a time-independent sky compass mechanism as previously suggested for the large yellow underwing

Shape Transition of Nanostructures created on Si(100) surfaces after MeV Implantation

We have studied the modification in the Surface morphology of the Si(100) surfaces after 1.5 MeV Sb implantation. Scanning Probe Microscopy has been utilized to investigate the ion implanted surfaces. We observe the formation of nano-sized defect features on the Si surfaces for various fluences. These nanostructures are elliptical in shape and inflate in sizefor higher fluences. Furthermore, these nanostructures undergo a shape transition from an elliptical shape to a circular-like at a high fluence. We will also discuss the modification in surface roughness as a function of Sb fluence.Comment: 9 pages, 4 figure

A rapid review of children and young people's views of poverty and welfare in the context of Universal Credit

Children and young people's (CYP) life chances depend heavily on family resources. This paper reports a rapid review of qualitative/mixed method studies about Universal Credit undertaken with CYP in the UK; subsequently expanded to include additional descriptors of economic disadvantage. Sixteen studies were reviewed; narrative synthesis was used to explore themes. Most recruited CYP with experience of economic disadvantage; none explicitly reported perspectives of CYP experiencing disability or rurality. Findings show growing up in poverty has significant, negative impacts on health and well‐being, causing feelings of exclusion, shame and unfairness; raising important questions about the adequacy of welfare support in the UK

The influence of vibration transducer mounting on the practical measurement of railway vibration

When assessing ground-borne vibration related to railways, careful consideration needs to be given to the mounting and coupling of the transducers. This paper presents the results of research investigating some of these fundamental issues. Different couplant materials and four of the most commonly used transducer-to-ground coupling techniques (spikes, buried, slabs, and the transducer directly plastered to the ground), were compared and analysed within the frequency range 5 Hz to 500 Hz. The data demonstrate that transducer vertical alignment has limited influence at small angles. “Blu-tack” showed to be an adequate couplant. Above 50 Hz coupling systems can influence the reading by up to 20 dB. Using the train as a source of vibration yields a high degree of non-linearity on the coupling systems performance