Vertical Track Modulus Trending

Systems and methods for determining a trend in Vertical track modulus are disclosed in accordance with embodiments of the present invention. Vertical deflection data is collected along a particular section of railroad track. A first set of Vertical track modulus is determined, based in part, on the collected vertical deflection data. At a second time, vertical deflection data is again collected along the particular section of railroad track to be used in determining a second set of vertical track modulus. At least the first and second sets of Vertical track modulus are analyzed to determine a math ematical algorithm that facilitates developing a trend in the vertical track modulus of the railroad track

String GUT Scenarios with Stabilised Moduli

Taking into account the recently proposed poly-instanton corrections to the superpotential and combining the race-track with a KKLT respectively LARGE Volume Scenario in an intricate manner, we show that we gain exponential control over the parameters in an effective superpotential. This allows us to dynamically stabilise moduli such that a conventional MSSM scenario with the string scale lowered to the GUT scale is realised. Depending on the cycles wrapped by the MSSM branes, two different scenarios for the hierarchy of soft masses arise. The first one is a supergravity mediated model with M_3/2=1TeV while the second one features mixed anomaly-supergravity mediation with M_3/2=10^10GeV and split supersymmetry. We also comment on dynamically lowering the scales such that the tree-level cosmological constant is of the order \Lambda=(10^-3eV)^4.Comment: 22 pages, 13 figures; v2: refs. and explanation adde

‘Turnaround’ of Indian Railways: Increasing the Axle Loading

Axle loading had contributed significantly to the ‘turnaround’ of the Indian Railways (IR) in the two years 2004-06. As the Minister of Railways (MR) stated, “A one ton extra loading per wagon implied additional revenue of Rs 500 crore per annum for IR.” The axle loading initiative was a significant step by IR, though sustainability was a concern. This paper focuses on the key driving events, process issues, impact and implications, and sustainability of the initiative of taking the load per wagon from its carrying capacity (CC) to CC+8. Axle loading for a wagon had traditionally been 20.32 tons, except for the mainline versions of steam locomotives. In the early 1980s, the then Chairman of the Railway Board took initiative of increasing axle loading on an experimental basis which after his tenure, could not be sustained on the grounds of safety. In the late 90s, there were initiatives of regularizing the two ton slack normally permitted for excess loading for certain commodities which were usually on a short haul. The railway minister, during inspections in 2004, noticed significant overloading of many wagons in the iron ore and coal routes. This set him thinking on the axle loading initiative. When one of the Zonal Railways (ZR) proposed an increase of up to ten tons per four axled wagon, various directorates in the Railway Board (RB) gave their views, many of which opposed the initiative. The minister, through the RB, directed a variety of processes to bring about inter-departmental alignment, and the initiative was taken forward in a step by step manner over the two years over a large part of IR. The safety and research institutions of IR also had to be taken along. The initiative is still treated as an ‘experiment,’ with many issues that need resolution and strategizing.

The development of a simplified track modulus calculation procedure

With the constantly increasing demand for heavy freight transportation, railways have become an extremely important element in the economic wellbeing of any country, and particularly in a developing country like South Africa. It is thus the duty of track engineers to maintain a continued understanding of the rail track infrastructure. Track designs should be as cost-effective as possible and should be sensitive to the costs associated with the planning, development and maintenance of the track structure. Extensive and continuous research is therefore required to determine the influencing parameters and to maximise the track performance and the lifetime of the track structure. Deformation of the track structure is a good measure of the structural capability of a track structure or of the expected track performance. This deformation is vastly dependent on the support of the track structure. The ballast support and the foundation of the track structure are therefore key components. Poor support will lead to large deformations, which in turn will accelerate track deterioration. This will increase the maintenance need and therefore the total cost of operating the asset within an acceptable functional condition.http://www.civils.org.za/am201

A 3D numerical analysis of the railway to compare the performance of the granular and asphalt trackbeds.

In the last two decades, trains have been developed either to carry heavy weight of cargo or for high-speed rail transport. Nonetheless, track structure, have not been improved adequate to support the extra loads or dynamic vibrations of high-speed trains. As a result, the performance of track will be affected from heavy freight or high-speed trains. In the long term it results in trackbed damage by increasing the subgrade and ballast displacement. Besides, it negatively affects the performance of the locomotives. Therefore, alternative subballast, should be introduced to reduce the stress and deformation of the track under dynamic or heavy loads. Asphalt underlayment trackbed is an alternative solution, which has been applied in many countries. The thickness of the asphalt layer varies from 10 cm to 20 cm, depends on the regulation of each country. In this study Finite Element (FE) Program, ABAQUS, is used to simulate a three-dimensional railway track to predict the trackbed performance. The model is validated through an analytical model and experimental. The validated model then used to determine the effect of different parameters on the stress and displacement increments on the subgrade under a static load. In the next step, the comparison of the granular and asphalt trackbeds displacement has been studied. The numerical model is used to predict the stress-strain and displacement variations on the subgrade while the thickness of the asphalt layer is varied. Results show increasing the asphalt layer from 15 cm to 18 cm significantly reduces the stress and displacement of the subgrade and results in uniform displacement. Furthermore, results show placing the asphalt layer below the subballast is more efficient than above it. And using the theory of Winkley to determine the track modulus, which is one of the important indicator to determine the track performance

Study of railway track stiffness modification by polyurethane reinforcement of the ballast

This paper presents the measured results of full-scale testing of railway track under laboratory conditions to examine the effect on the track stiffness when the ballast is reinforced using a urethane cross-linked polymer (polyurethane). The tests are performed in the GRAFT I (Geopavement and Railways Accelerated Fatigue Testing) facility and show that the track stiffness can be significantly enhanced by application of the polymer. The track stiffness is measured at various stages during cyclic loading and compared to the formation stiffness, which is determined prior to testing using plate load tests. The results indicate that the track stiffness increased by approximately 40–50% based on the measured results and from the previously published GRAFT I settlement model. The track stiffness was monitored during loading for a maximum of 500,000 load cycles. The paper concludes by presenting and commenting on, the application of the technique to a real site where the Falling Weight Deflectometer was used before and after polymer treatment to determine the dynamic sleeper support stiffness. The very challenging site conditions are highlighted, in particular the water logged nature of the site, and comment made on the effect of the water on polymer installation. The results of the FWD measurements indicate that a good increase in overall track stiffness was measured. These results are consistent with the laboratory tests which are performed on a different soil and use a different measurement technique and hence confirm that regardless of the soil and measurement system track stiffness increases are observed using this technique

Inverse Dynamics Problems

The inverse dynamics problem was developed in order to provide researchers with the state of the art in inverse problems for dynamic and vibrational systems. Contrasted with a forward problem, which solves for the system output in a straightforward manner, an inverse problem searches for the system input through a procedure contaminated with errors and uncertainties. An inverse problem, with a focus on structural dynamics, determines the changes made to the system and estimates the inputs, including forces and moments, to the system, utilizing measurements of structural vibration responses only. With its complex mathematical structure and need for more reliable input estimations, the inverse problem is still a fundamental subject of research among mathematicians and engineering scientists. This book contains 11 articles that touch upon various aspects of inverse dynamic problems

Long-term behaviour of railway transitions under dynamic loading application to soft soil sites

Dissertação para obtenção do Grau de Doutor em Engenharia CivilTransition zones in railway tracks are built to mitigate damage and wear to tracks and trains, and discomfort to passengers, caused by structural and foundation discontinuities, such as those introduced by bridge approaches or culverts. However, additional strains are still generated that cause changes of track geometry, that lead to more frequent maintenance operations and sometimes speed restrictions, that raise costs, and need to be minimized. This thesis addresses those questions and describes research undertaken to model the dynamic response of the railway tracks, taking into account the behaviour of ballast at the aforementioned railway transition zones, where the long-term settlements are amplified by dynamical loading on the ballast due to the discontinuities. Novel numerical models for the simulation of the dynamic response of the system soilballast-track-vehicle and accounting for those phenomena are presented. The models are validated by field measurements performed at a passage over a culvert, located in a soft soil site. The models include the unloaded level of the track, the possibility of voids under the sleepers, and the non-linear constitutive behaviour of the ballast, as well as representation, albeit simplified, of the vehicles. The forces transmitted to the ballast at transition areas vary considerably, both in time and space: loading of ballast reaches higher values than in regular tracks, and the additional vibrations cause larger differences between loads transmitted to consecutive sleepers. This causes higher densification of ballast at transition zones. Transition zones solely composed of approach slabs are not effective in soft soil sites. The soil and ballast at approach regions settle more than the segment on top of the much stiffer structure, leading to the appearance of hanging sleepers. The subsequent combined effect of lower load on part of the ballast and motion of the approach slabs results on increased settlement of the ballast and sub-ballast, increasing the voids under the sleepers, and causing more severe actions on the track. Possible improvement measures were modeled and tested computationally at the later stages of the thesis. The numerical simulations showed that the use of soft railpads on the stiff side of the transition is beneficial, provided the problem is mostly caused by stiffness variation of the track support. Slab track solution was also tested and showed advantages over the ballasted track by showing much smaller differential rail displacements,for identical change of the track support stiffness.Fundação para a Ciência e Tecnologia - Ph.D grant (SFRH/BD/25297/2005), through the project “Interacção solo-via férrea para comboios de alta velocidade” (POCI/ECM/61114/2004), and through the project SMARTRACK (PTDC/EME-PME/101419/2008

Performance of ballasted track under impact loading and applications of recycled rubber inclusion

© 2018 Chinese Academy of Sciences. All rights reserved. In this paper a review of the sources of impact loads and their effect on the performance of ballasted track is presented. The typical characteristics and implications of impact loading on track deterioration, particularly ballast degradation, are discussed. None of the procedures so far developed to design rail track incorporate the impact that dynamic loading has on the breakage of ballast and therefore it can be said to be incomplete. An intensive study on the impact of induced ballast breakage is needed in order to understand this phenomenon and then use the knowledge gained to further advance the design methodology. A stiff track structure can create severe dynamic loading under operating conditions which causes large scale component failure and increases maintenance requirements. Installing resilient mats such as rubber pads (ballast mat, soffit pad) in rail tracks can attenuate the dynamic force and improve overall performance. The efficacy of ballast mats to reduce structural noise and ground vibration has been studied extensively, but a few recent studies has reported how ballast mats and soffit pads reduce ballast degradation, thus obviating the necessity of a comprehensive study in this direction

LOAD AND PRESSURE DISTRIBUTION AS A FUNCTION OF DYNAMIC CONTACT STRESS AT THE RAILROAD CROSSTIE-BALLAST INTERFACE

Excessive crosstie wear and abrasion and ballast wear and fouling are two of the fundamental problems contributing to inadequate railroad track performance. This adversely affects the attainment and long-term maintenance of desired track geometric requirements. The magnitudes and distribution of the stresses at the crosstie-ballast (CT-B) interface must be known to determine the stress distribution on the ballast. However, the stresses at the top of the ballast often vary significantly. This study examines a new approach to predicting dynamic contact pressures at the interface of crosstie and ballast using the ‘square wave theory.’ A data set of in-track CT-B interfacial pressures, taken from a freight mainline at Mascot, TN limited to speeds up to 64 km/h, in 2018, was analyzed to develop relationships in the form of equations to predict dynamic contact pressures as a function of specific information, including train speed, weight, number of axles, and wheel spacing. Several equations were developed to predict CT-B interfacial pressures as a function of these variables. Additionally, the developed square wave theory and obtained data are analyzed and compared to traditional recommended design practices. Longitudinal stress distribution over the crossties and the stress distribution along the crossties are presented. Based on the analyzed CT-B interfacial pressures, the ballast stress distribution is discussed, and recommendations are made