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The paper deals with the sleeper substructure design for a speed of 200 kph according to the Czech SŽ S4 standard. The paper includes the design of sub-ballast and capping layers. The second part of the paper is focused on transition area design. The conclusion brings recommendations of alterations which would be appropriate to incorporate into the standard. [ABSTRACT FROM AUTHOR]

This paper compares methods of designing the track bed structure that are used in the processes of design and review design of subgrade tracks located in Slovakia and Lithuania. Self-comparison is made on a particular type of track bed with the aim to highlight the differences between individual countries methodologies that affect not only the dimension of the sub-ballast layer, but also economic demands and reliability of the design of railways structure. [ABSTRACT FROM AUTHOR]

Track-side inertial measurements on common crossings are the object of the present study. The paper deals with the problem of measurement's interpretation for the estimation of the crossing structural health. The problem is manifested by the weak relation of measured acceleration components and impact lateral distribution to the lifecycle of common crossing rolling surface. The popular signal processing and machine learning methods are explored to solve the problem. The Hilbert-Huang Transform (HHT) method is used to extract the time-frequency features of acceleration components. The method is based on Ensemble Empirical Mode Decomposition (EEMD) that is advantageous to the conventional spectral analysis methods with higher frequency resolution and managing nonstationary nonlinear signals. Linear regression and Gaussian Process Regression are used to fuse the extracted features in one structural health (SH) indicator and study its relation to the crossing lifetime. The results have shown the significant relation of the derived with GPR indicator to the lifetime. [ABSTRACT FROM AUTHOR]

Each year, there can be three to six millions of service train axles running over an open plain track. In fact, these trains could impose a variety of dynamic loading conditions depending on the wheel and rail maintenance levels. Inevitably, the risk of high-intensity dynamic loading conditions by wheel-rail interactions due to wheel or rail irregularity cannot be disregarded. Imperfection of rail tracks could lead directly to the exceedance of permissible stress of a track component and later amplify rapid track deterioration rates causing cracking in sleepers and failure of track substructure. Practical railway track irregularities can be typically classified into short wave length (high frequency) and long wave length (low frequency) defects, of which previous researchers had studied each in isolation. This paper is the first to study the influence on railway track inspection and maintenance priorities caused by the coupling of wave lengths between dipped rail joint and differential track settlements. To study the dynamic coupling effects, P1 and P2 forces are evaluated at the track irregularity together with rail/sleeper contact force, ballast pressure and bending moments of sleepers using dynamic multi-body simulation approach. It is found that some patterns of coupling irregularity could cause a significant reduction in dynamic impact factors whilst some are associated with an increase in the wheel/rail impact force. The insight has then been integrated to establish track performance indicators that are paramount for prioritising track inspection and maintenance. [ABSTRACT FROM AUTHOR]

The number of railway lines both operational and under construction is growing rapidly, leading to an increase in the number of buildings adversely affected by ground-borne vibration (e.g. shaking and indoor noise). Post-construction mitigation measures are expensive, thus driving the need for early stage prediction, during project planning/development phases. To achieve this, scoping models (i.e. desktop studies) are used to assess long stretches of track quickly, in absence of detailed design information. This paper presents a new, highly customisable scoping model, which can analyse the effect of detailed changes to train, track and soil on ground vibration levels. The methodology considers soil stiffness and the combination of both the dynamic and static forces generated due to train passage. It has low computational cost and can predict free-field vibration levels in accordance with the most common international standards. The model uses the direct stiffness method to compute the soil Green's function, and a novel two-and-a-half dimensional (2.5D) finite element strategy for train-track interaction. The soil Green's function is modulated using a neural network (NN) procedure to remove the need for the time consuming computation of track-soil coupling. This modulation factor combined with the new train-track approach results in a large reduction in computational time. The proposed model is validated by comparing track receptance, free-field mobility and soil vibration with both field experiments and a more comprehensive 2.5D combined finite element-boundary element (FEM-BEM) model. A sensitivity analysis is undertaken and it is shown that track type, soil properties and train speed have a dominant effect on ground vibration levels. Finally, the possibility of using average shear wave velocity introduced for seismic site response analysis to predict vibration levels is investigated and shown to be reasonable for certain smooth stratigraphy's. [ABSTRACT FROM AUTHOR]

One of the technical possibilities to solve a gauge crossing is to install a dual gauge. This solution has several advantages and disadvantages discussed in this paper. Lack of experience of maintenance and lack of standards for the design of dual track are among the most important disadvantages. The wheel and rail interface on track curves is more difficult than in straight sections. Therefore, the subject of the present article is a geometrical parameter of dual gauge track, i.e., the rail superelevation, which has an impact on the wheel-rail interaction at curves and influences the value of uncompensated acceleration, occurring when a train passes a curve, and, consequently, the intensity of rail wear. The objective of the present article is to analyse the features of dual gauge track and the superelevation calculation methodology considered, to present the approach to rational calculation of superelevation for dual gauge track of Šeštokai-Mockava (Lithuania-Poland) using several calculation versions as well as to make recommendations for the calculation of superelevation. [ABSTRACT FROM AUTHOR]

This paper aims about the historical and technical evolution of scientific thought in railway vehicle behaviour, while running on straight track and cornering. The point of view of many railway scientists and mechanical approaches are presented and joined to the operational reality, referring from the beginning of railway use, through the idealization in modelling, to be able study the problem of wheel-rail interface. [ABSTRACT FROM AUTHOR]

An innovative stochastic dynamic model of a 3D train-track-bridge coupled system (TTBS) with refined wheel/rail interaction is established for a high-speed railway based on the random theory of probability density evolution method (PDEM). The multi-coupling effect of excitations can be simultaneously input into the new model, e.g. random track irregularity, random vehicle loads, stochastic system parameters, et al. Moreover, a new approach, named “Number theoretic method of multi-target probability functions” (NTM- mp ), is developed to obtain the discrete point sets of multidimensional random parameters in hypercube space, aims to solve the point design of system uncertainty. The stochastic harmonic function (SHF) is applied to generate representative random track irregularity samples. The results of TTBS got by PDEM are verified with several typical case studies for its efficiency and reliability, which are the deterministic results in the representative publication, the Monte Carlo method (MCM) results, and the field testing results on the high-speed railway. At last, a typical case study of TTBS on a high-speed railway is presented for numerical analysis. Discussions and significant conclusions on the random dynamic responses are presented. [ABSTRACT FROM AUTHOR]

Recently, track mileage with concrete crossties has been increasing throughout the world. In North America, for example, approximately 30 million crossties are currently in service on Class I freight railroads. It is essential to understand the concrete crosstie bearing capacity and flexure behavior for both design and safety purposes. The American Railway Engineering and Maintenance-of-Way Association (AREMA) Recommended Practices and Australian Standard’s (AS) current flexural design methodologies consider rail seat loads to be vertically transferred to the neutral axis. However, the International Union of Railways (UIC) assumes rail seat loads are distributed at a 45 degree angle to the neutral axis. This load distribution behavior is commonly seen in the design of concrete corbels and spread footings, but is not well documented in the design of concrete crossties, and different assumptions (i.e. in AREMA and UIC design methods) will result in different designs. Better understanding the load distribution in concrete crossties will help to improve the design of concrete crossties and optimize their performance. This study presents preliminary results from an on-going research project at the University of Illinois at Urbana-Champaign (UIUC) focused on concrete crosstie mechanical behavior. A parametric study using three-dimensional (3D) finite element modeling (FEM) was performed to investigate stress distribution below the rail seat and quantify the corresponding distribution angles in prestressed concrete crosstie under static wheel loading. Laboratory experiments were also performed and successfully validated the results obtained from the numerical simulations. The results from both numerical simulation and laboratory experiments indicate the stress distribution angle under rail seat is not constant which disagrees with the assumptions in UIC 713R. Moreover, the stress distribution angle under rail seat is found to be sensitive to crosstie support conditions, and its value follows a direct relationship with rail seat load magnitude. The findings from this study can help to optimize prestressed concrete crosstie bearing capacity design. [ABSTRACT FROM AUTHOR]

The recent development and use of new rail track models due to the evolution of the railway, especially with high speed and freight, has meant the introduction of slab track models with an associated variety of transition zones (between ballast and slab track) across railway networks worldwide. However, there are no studies about how the position of the supports could influence the track performance in general and track transitions in particular, how much bigger or smaller the gap must be between slab track and ballasted track. This study tries to find the optimal distance between the supports while maintaining good track performance which is assessed in terms of sleeper vertical displacements and stresses on ballast. Reducing these movements and stresses will increase track life and means less maintenance work. The aim of this paper is to study these effects and try to provide an optimal and low cost solution for existing and future track designs. [ABSTRACT FROM AUTHOR]

This paper investigates, for the first time, the behaviour and design of railway double track open timber floor plate girder deck steel bridges under combined buckling modes including web distortional buckling. A 3-D finite element model has been developed for the railway bridges, which accounted for the bridge geometries, initial geometric imperfections, material nonlinearities of the bridge components, bridge boundary conditions, interactions among bridge components and bridge bracing systems. Most of the aforementioned parameters are not incorporated in current design codes of railway bridges, which are credited to this study. The simply supported bridges investigated had a span of 30m, a width of 7.2m and a depth of 3.12m. The bridge components comprising main plate girders, stringers, cross girders, connections, bracing members, stiffeners, bearings, and field splices were designed following the design rules specified in the European Code for steel bridges. The live load acting on the bridge was Load Model 71, which represents the static effect of vertical loading due to normal rail traffic as specified in the European Code. The finite element model of the double track bridge was developed depending on additional finite element models, developed by the author, for small and full-scale plate girder steel bridge tests previously reported in the literature. Ultimate loads, load-mid-span deflection relationships, failure modes, stress contours of the double track bridge as well as of the small and full-scale tests were predicted from the finite element analysis and compared well against test results. Parametric studies were performed on the railway bridges highlighting the effects on the structural behaviour and ultimate loads carried by the bridges owing to the change in the bridge geometries, slenderness and steel strength. The paper presents a complete piece of work regarding the finite element analysis and design of railway steel bridges, which can be used for further parametric studies, finite element analyses and investigations of the bridges under different loading and boundary conditions. The parametric study has shown that the presence of web distortional buckling causes a considerable decrease in the ultimate load of the steel bridges. It is also shown that the use of high strength steel offers a considerable increase in the ultimate loads of less slender steel bridges. The study has also shown that the design rules, loading and recommendations specified in the European Code provide accurate and conservative estimations for the design of railway steel bridges, except for the bridges failing mainly by web distortional buckling [ABSTRACT FROM AUTHOR]

Railway operations are inherently complex and source of several problems. In particular, track geometry defects are one of the leading causes of train accidents in the United States. This paper presents a solution approach which entails the construction of an ensemble classifier to forecast the degradation of track geometry. Our classifier is constructed by solving the problem from three different perspectives: deterioration, regression and classification. We considered a different model from each perspective and our results show that using an ensemble method improves the predictive performance. [ABSTRACT FROM AUTHOR]

We explore a data-driven approach for monitoring rail infrastructure from the dynamic response of a train in revenue-service. Presently, track inspection is performed either visually or with dedicated track geometry cars. In this study, we examine a more economical approach where track inspection is performed by analyzing vibration data collected from an operational passenger train. The high frequency with which passenger trains travel each section of track means that faults can be detected sooner than with dedicated inspection vehicles, and the large number of passes over each section of track makes a data-driven approach statistically feasible. We have deployed a test-system on a light-rail vehicle and have been collecting data for the past two years. The collected data underscores two of the main challenges that arise in train-based track monitoring: the speed of the train at a given location varies from pass to pass and the position of the train is not known precisely. In this study, we explore which feature representations of the data best characterize the state of the tracks despite these sources of uncertainty (i.e., in the spatial domain or frequency domain), and we examine how consistently change detection approaches can identify track changes from the data. We show the accuracy of these different representations, or features, and different change detection approaches on two types of track changes, track replacement and tamping (a maintenance procedure to improve track geometry), and two types of data, simulated data and operational data from our test-system. The sensing, signal processing, and data analysis we propose in the study could facilitate safer trains and more cost-efficient maintenance in the future. Moreover, the proposed approach is quite general and could be extended to other parts of the infrastructure, including bridges. [ABSTRACT FROM AUTHOR]

Due to the modularity of the traditional track and the discreteness of the ballast bed, the application of the repeated and random train load would inevitably result in the accumulation of residual deformation and the track damage. A new steel pre-installed modular railroad track assembly was designed to provide better stability and reduce deformation. It includes a plurality of spaced-apart cross-ties, two side ties, intermediate ties and a pair of rails road track rails. In order to figure out the mechanical performance of this new steel pre-installed modular railroad track assembly, the 3-D finite element model of the steel modular railroad track including with the track, ballast bed, sub-ballast and the sub-grade was built. In this model, the load distribution and the vertical deformation of ties with different cross sections were discussed, and the stresses of the steel modular railroad track and the ballast bed were analyzed. The results indicate that, compared with the traditional track, the single wheel load will transfer to more ties of the new steel modular railroad track and the integrality of the new steel modular railroad track is much better. The maximum deflection of the steel modular railroad track located at the point of load application (under the wheel load). It is much smaller than that of the traditional track. As a result, it can be concluded that the new steel modular railroad track is more likely to induce less deflection under the series wheel load and have better rail regularity. [ABSTRACT FROM AUTHOR]

Crossties are critical components of the railroad track to facilitate load distribution to track substructure. Recent instrumentation at Kingston, Rhode Island indicated that a crosstie could have translations as well as rotations under train load repetitions. However, previous laboratory experiments on crossties did not fully take the crosstie rotations into consideration. In this paper, actual movements of railroad crossties under moving train loads were first characterized by numerical modeling and field investigation, and then the effect of tie rotations on track ballast performance was evaluated by discrete element modeling (DEM). A vehicle dynamics model coupled with a three-dimensional finite element track model were utilized to simulate the crosstie movements. To obtain the crosstie movements under train passage, field measurements were conducted on an Amtrak high-speed passenger line and a freight railroad short line. The measuring units were mounted on top of crossties to record the accelerations in vertical, lateral, and longitudinal directions and the Euler angles in roll, pitch and yaw. The translations of crossties were obtained by the double integration of accelerations and the rotations were represented in terms of the Euler angles. Both modeling results and field measurements indicate that crossties have not only translations but also rotations under moving trains. In addition, angular velocity and angular acceleration measured in the field tests indicate that the rotations could cause extra moments up to 5000 N-m on top of the ballast layer. The extra moments may not cause significant track failure, but may accelerate the deterioration of track components. Further, a DEM program was used to evaluate the effect of the crosstie rotations on track ballast. The results of DEM show that the crosstie rotations would increase the acceleration of individual ballast particles and contact forces between ballast particles. [ABSTRACT FROM AUTHOR]

The contact loss beneath track slab caused by deteriorated cement emulsified asphalt mortar (CA mortar) has been one of the main diseases occurring in the CRTS- (China Railway Track System-) I Slab Track of high-speed railway in China. Based on the slab track design theory and the vehicle-track coupling vibration theory, a vehicle-track vertical coupling dynamic FEM model was established to analyze the influence of the contact loss length on the dynamic characteristics of vehicle and track subsystems at different train speeds. A prototype dynamic characteristic experimental test of CRTS-I Slab Track with CA mortar contact loss was conducted to verify the FEM model results. The train load was generated by the customized ZSS50 excitation car. The results showed that when the operation speed is less than 300 km/h, the contact loss with length smaller than 2.0 m barely affects the running smoothness ride safety of vehicle. The contact loss length effect on the dynamic characteristics of track subsystem is pronounced, especially on the track slab. Once the contact loss beneath the track slab occurs, the vibration displacement and the acceleration of the track slab increase rapidly, while it has little influence on the displacement and acceleration of the concrete roadbed. [ABSTRACT FROM AUTHOR]

Rail discontinuities are one of the main sources of wheel impact causing high levels of noise, vibration and stresses in railway track. Even though various multi-body train-track interaction models have been developed in the past decade, accurate modeling and analysis of the track dynamic behavior in the vicinity of rail discontinuities is rare in the literature. In this paper, formulation of a new explicit multi-body dynamic (MBD) model incorporating detailed wagon, wheel-rail subsystems and track containing a rail discontinuity (rail joint) is reported. The predictions of the localized track responses are validated using the data from two gapped rail joints in the field test. The validated model accurately determines the impact forces and dynamic responses. The simulation results provide valuable insight on the behavior of track in vicinity of a rail discontinuity, the sensitivity of the design parameters to the impact forces and the track dynamic responses currently unavailable in the literature. [ABSTRACT FROM AUTHOR]

Sealed-space-filling self-compacting concrete (SSFSCC) is used in China Rail Track System (CRTS) III ballastless slab track of high-speed rail, which has been originally developed in China recently. In this track system, SSFSCC needs to be grouted into a flat, narrow, and sealed space (90 mm × 2500 mm × 5600 mm) which is enclosed by above prefabricated slab and bottom base plate. Good bonding between SSFSCC filling layer and above prefabricated slab has to be secured since these two layers are required to work as a composite plate. SSFSCC presents some special characteristics in comparison with normal SCC. This paper elaborated the property requirements of SSFSCC and the structural characteristics of SSFSCC layer of CRTS III ballastless slab track of high-speed rail. The compositions and mix proportioning of SSFSCC as well as construction technology were briefly introduced. The challenges of the application of this special SCC were also addressed. [ABSTRACT FROM AUTHOR]

Resonance and cancelation phenomena of a viaduct caused by moving loadings are relevant to the design of the railway viaduct and speed regulation of high-speed trains. In this contribution, resonance and cancelation phenomena occurring in a periodic viaduct under a series of equidistant moving loadings (SEML) are investigated. In order to simulate the dynamic response of the periodic viaduct to a SEML, the dynamic response of the periodic viaduct to a single moving loading (SML) is addressed first. By superposing the responses of the viaduct to all SMLs constituting the SEML, the representation for the dynamic response of the periodic viaduct to the SEML is determined. With the representation, the resonance and cancelation conditions for the viaduct subjected to the SEML are obtained. For the high-speed SEML, when the time interval between two neighboring moving loadings is equal to the integer or half-integer multiples of the period of one of the dominant resonance peaks of the corresponding SML response of the viaduct, resonance or cancelation will occur. Numerical results presented in this paper show the predicted resonance and cancelation phenomena, confirming the proposed resonance and cancelation conditions. [ABSTRACT FROM AUTHOR]

Ground-borne vibrations and noise, originated at the train/tram wheel–rail interface and transmitted through the rails to the ground, may cause significant disturbance to people passing by or residing alongside the railways. This paper presents a case study on the evaluation of the effectiveness for mitigating ground-borne vibration and noise by floating slab track system (FST). The underpass located at a major road junction in front of Konya Metropolitan Municipality building serves to thousands of people every day. The Konya Light Rail makes a curb right on top of the underpass, which generates considerable amount of noise and vibration to the environment. In this study, the noise and vibration acceleration measurements were taken before and after the FST system installment in order to evaluate the effectiveness of the isolation work. The collected acceleration data were analyzed and the resulting vibration velocity levels were compared. It was found that the vibrations and the ground-borne noise due to the passage of the trams were reduced considerably. The FST system was found to be quite successful in absorbing the vibrations. A noise level reduction up to 26 dBA was measured after replacing the old rail system with FST. [ABSTRACT FROM AUTHOR]

A composite railroad track is a rigid track system that is developed using quick-hardening infilling materials, and has the advantages of a reduced maintenance cost compared to a conventional ballasted track. Quick-hardening infilling materials were developed in this study, which does not require the processes of cleaning the aggregates crushed due to the repeated load imposed by rolling stock, and thus the materials can strengthen existing ballasted tracks with an enhanced level of efficiency and speed. Theoretical reviews of pore size, permeability, pore channel length and tortuosity depending on the size of the aggregate in ballasted tracks were conducted first to predict the influence of filling parameters of infilling materials for composite railroad tracks. Based on the theoretical filling performance analysis of ballasted tracks, a thermosetting polymer was developed, which is a 3D cross linking agent that performs redox radical polymerization reaction at room temperature. The polymer was used as a primary filling material to fill the lower ballast layer, which could not be filled by conventional cement-based filling materials. A double-layered composite was formed by filling the upper ballast layer with the ceramic-based secondary filling material using the reaction between dead-burned magnesia and acid ammonium phosphate. The performance of infilling materials was validated through strength measurement and microscopic analysis. [ABSTRACT FROM AUTHOR]

Sleepers are the primary structural components that provide the necessary gauge width and the structural stability to the ballasted railway track. High performance prestressed concrete sleepers of high-speed railways have strict design and production requirements to provide a safe, serviceable and a reliable railway superstructure. The production dimensions of a contemporary prestressed high performance concrete sleeper are within low tolerance values on the scale of a millimeter that is uncommon for ordinary structural concrete elements. Railways are within climatic conditions that could become effective in the dimensional stability of their sleepers. Within regions of low humidity levels, in addition to the elastic shortening of the prestressed sleepers, the effects of concrete creep and shrinkage could lead to total contraction values in excess of the allowed tolerances for the shoulder width of the sleepers. Therefore the dimensional design of a high performance prestressed concrete sleeper must include the effects of time dependent dimensional changes. This paper presents the possibility of falling out of dimensional tolerance for prestressed high performance sleepers and ways to mitigate those possibilities for railways in arid climatic conditions or within climatic zones undergoing a climate change. [ABSTRACT FROM AUTHOR]

A new theory is presented for predicting squat morphology on high and low rails of curves, based on tangential contact stress directivity for running bogies and local loading history. Notably, squats on high and low rails are predicted as distinct, with generally no branching on the latter. Field data confirm predictions, and illustrate three other aspects of squat growth: repetitive and transient tangential contact stress redistribution at the leading RCF-crack may explain branching; white etching material is found unrelated to crack initiation on head-hardened rails, and high-frequency dynamic wheel–rail interaction is shown incapable of explaining basic features of squat growth. [ABSTRACT FROM AUTHOR]

In this paper, the feasibility of the Frequency Response Function (FRF)-based statistical method to identify the characteristic frequencies of railway track defects is studied. The method compares a damaged track state to a healthy state based on non-destructive field hammer test measurements. First, a study is carried out to investigate the repeatability of hammer tests in railway tracks. By changing the excitation and measurement locations it is shown that the variability introduced by the test process is negligible. Second, following the concepts of control charts employed in process monitoring, a method to define an approximate healthy state is introduced by using hammer test measurements at locations without visual damage. Then, the feasibility study includes an investigation into squats (i.e. a major type of rail surface defect) of varying severity. The identified frequency ranges related to squats agree with those found in an extensively validated vehicle-borne detection system. Therefore, the FRF-based statistical method in combination with the non-destructive hammer test measurements has the potential to be employed to identify the characteristic frequencies of damaged conditions in railway tracks in the frequency range of 300–3000 Hz. [ABSTRACT FROM AUTHOR]

Rail vehicle-track modeling and simulations, in past many years is developed a long way from its origins as a research tool. This paper presents an overview of the current features and applications for components of rail vehicle-track dynamic modeling and few challenges which these applications find while doing the simulations. This paper discusses appropriate modeling choices for different applications and analyse the best practice for the optimum performance of suspension components, wheel-rail contact conditions and modeling inputs such as track geometry. [ABSTRACT FROM AUTHOR]

The main goal of this paper is to model track geometry deterioration using a comprehensive field investigation gathered over a period of 2 years on approximately 180 km of railway line. Artificial neural networks (ANNs) were adapted for this research. The railway line was divided into analytical segments (ASs). For each AS, the following data were collected: track structure, traffic characteristics, track layout, environmental factors, track geometry, and maintenance and renewal data. ANN models were developed for the main track geometry parameters and produced significant relationships between the variables. In addition, sensitivity analyses were performed to compute the importance of each predictor in determining the neural network. The obtained results proved that ANN may be an alternative method for predicting track geometry deterioration. [ABSTRACT FROM AUTHOR]

The evaluation of railway line capacity is an important problem, which effects majority of problems in rail transportation planning. The railway capacity is dependent on infrastructure, traffic, and operating parameters. A key factor affecting railway line capacity is the impact of different train types. As the combination of different train types increases, more interference is generated. In this paper, for evaluation of train type interactions on railway line capacity, an integer-programming model for both line and line section is presented. The problem is formulated as a multicommodity network design model on a space-discrete time network. The railway capacity is calculated using data typically available to planners. The inputs of the model are the characteristic of each train type and railway line attributes. The model determines railway capacity based on train type mixes. In addition, this model considers impact of train types on capacity and waiting time. In order to show the features of the model, a case study is implemented in Iran Railways. The capacity tends to increase non-linearly with small incremental changes in parameters. The mixture of train types reduces the railway line capacity. The proposed model can help railway managers for long-term planning. [ABSTRACT FROM PUBLISHER]

Am bereits 1851 dem Verkehr übergebenen Göltzschtalviadukt ergab sich im Rahmen der von der Deutschen Bahn geplanten Elektrifizierung des Streckenabschnitts Reichenbach-Hof die Aufgabe, den Brückenkopf in kürzester Zeit für die neuen Nutzungsanforderungen auszubauen. Über vergrößerte Auskragungen eines neuen Gleistragwerks sollte ein moderner Fahrweg hergestellt werden, welcher den vorgesehenen Geschwindigkeiten von bis zu 160 km/h gerecht wird. Gleichzeitig mussten die Voraussetzungen für die Anordnung von Oberleitungsmasten geschaffen werden. Neben einer Vielzahl von bautechnischen und baubetrieblichen Randbedingungen standen bei der Planung und Bauausführung die Aspekte der Denkmalpflege im Mittelpunkt. Hier ergaben sich im Spannungsfeld zwischen den Nutzungsanforderungen an einen modernen Fahrweg und dem Bestreben, bestehende Besonderheiten zu erhalten, interessante Kompromisslösungen. The renewal of the track supporting structure at the Göltzschtalviadukt - A 160 year old arch bridge with a new track for the electric railway Due to the planned electrification of the railway-track from Reichenbach to Hof by the Deutsche Bahn an enlargement of the bridge-head of the Göltzschtalviadukt had to be realised in a very short time. By using of a cantelivered structure the conditions for a modern track for speeds up to 160 km/h should been created. At the same time the space for the fastenings of the catenary masts had to be erected. In addition to a variety of construction and management constraints were the aspects of historic preservation at the center of planning and construction. From the conflict between the requirements of a modern infrastructure and the desire to preserve existing peculiarities resulted interesting compromise solutions [ABSTRACT FROM AUTHOR]

This article examines the contested and unprecedented process by which the Baltimore & Ohio Railroad laid tracks through Baltimore’s city streets in the 1830s. Laying tracks in busy thoroughfares raised profound questions about the meaning of urban space and the economic function of the city. Track opponents held that city streets should remain open to free-flowing traffic and condemned railcars for monopolizing public space. Track advocates countered that urban prosperity was rooted in the rapid, efficient movement of goods. This was not a battle of traditionalists versus progressives but a clash between competing visions of urban modernity. Examining these competing urbanisms gives us a window into the spatial dynamics of capitalism and the ways in which industrialization reconfigured local space. [ABSTRACT FROM PUBLISHER]

Railway bridges currently encounter the challenges of increasing the load capacity while the environmental sustainability should be achieved. However, it has been realised that the environmental assessment of railway bridges has not been integrated into the decision-making process, the standard guideline and criterion is still missing in this field. Therefore, the implementation of life cycle assessment (LCA) method is introduced into railway bridges. This article provides a systematic bridge LCA model as a guideline to quantify the environmental burdens for the railway bridge structures. A comparison case study between two alternative designs of Banafjäl Bridge is further carried out through the whole life cycle, with the consideration of several key maintenance and end-of-life scenarios. Six impact categories are investigated by using the LCA CML 2001 method and the known life cycle inventory database. Results show that the fixed-slab bridge option has a better environmental performance than the ballasted design due to the ease of maintenances. The initial material manufacture stage is responsible for the largest environmental burden, while the impacts from the construction machinery and material transportations are ignorable. Sensitivity analysis illustrates the maintenance scenario planning and steel recycling have the significant influence on the final results other than the traffic disturbances. [ABSTRACT FROM AUTHOR]

A rail vehicle-track interaction dynamics model has been applied to determine the track vertical dynamic forces due to rail shortwavelength dip defects such as squat, dip joints and welds, etc., which are required in both rail vehicle acceptance procedure and track maintenance. The model is validated using the field measurement data of rail squat defects and accelerations on a vehicle axlebox. The simulated track dynamic forces - the P forces due to rail dipped joints have been compared with those calculated by using a well-known formula. The results are compared and the formula's limitations have been discussed. The dependence of the track vertical dynamic forces on the rail dip defect size and vehicle speed has also been investigated. [ABSTRACT FROM AUTHOR]

Abstract: Pavement and railtrack design is of huge importance to society and yet the theoretical basis for most current design methods is still very simplistic and crude (Brown, 1996; Yu, 2006). This paper is part of a concerted effort at the Nottingham Centre for Geomechanics to develop improved theoretical foundations for pavement and railtrack design. It is mainly concerned with the development of rigorous lower-bound solutions for shakedown of cohesive-frictional materials under three-dimensional moving traffic loads. Compared with previous studies, two important aspects are taken into account. First, this paper considers a more general case of elliptical contact area between traffic and material surface, as most previous lower-bound studies considered the traffic load is applied through an infinite long roller. Secondly, by introducing a critical self-equilibrated residual stress field, this shakedown problem is reduced to a formulation in terms of a load parameter only. By using a simple optimisation procedure, the maximum load parameter leads to a lower-bound shakedown limit to this problem. Results for the special case of circular contact area are also presented in analytical form, which can then be readily applied for practical design. [Copyright &y& Elsevier]

The railway industry has been slow to adopt limit states principles in the structural design of concrete sleepers for its tracks, despite the global take up of this form of design for almost every other type of structural element. Concrete sleeper design is still based on limiting stresses but is widely perceived by track engineers to lead to untapped reserves of strength in the sleepers. Limit design is a more rational philosophy, especially where it is based on the ultimate dynamic capacity of the concrete sleepers. The paper describes the development of equations and factors for a limit design methodology for concrete sleepers in flexure using a probabilistic evaluation of sleeper loading. The new method will also permit a cogent, defensible means of establishing the true capacity of the billions of concrete sleepers that are currently in-track around the world, leading to better utilisation of track infrastructure. The paper demonstrates how significant cost savings may be achieved by track owners. [ABSTRACT FROM AUTHOR]

Railways around the world are experiencing growth in traffic demand and the need to expand their network and line capacity. To accommodate the substantial demand, the conventional railway operator in Taiwan, the Taiwan Railways Administration (TRA), is interested in understanding the potential benefit of adopting various advanced signaling systems, such as hybrid or moving-block systems. In this study, the authors developed a set of analytical capacity models for conventional rail operations with advanced signaling systems, which were implemented in the busiest corridor in the TRA system. The empirical results show that advanced signaling systems generally have positive capacity effects. However, the benefit may not be substantial due to constraints from the station track layouts. Therefore, possible capacity improvement alternatives, such as improving track layouts and upgrading signaling systems, should be considered together to determine the optimal capacity improvement plan. The use of these proposed capacity models can help railway agencies with similar operational environments in their capacity management and resource planning projects. [ABSTRACT FROM AUTHOR]

The welding of rail joints on sharp curves is not practicable due to the lack of sufficient lateral resistance of the railway track. Consequently, maintenance costs increase rapidly for many old railway tracks. Moreover, deterioration of the track components, plastic deformation and critical cracks in the rail head, failures in sleepers and fasteners, ballast bed damage and lateral movement of railway track occur in the rail joints. As the resistance of a sleeper to lateral displacement in a ballast bed mainly consists of the frictional forces between the ballast particles and the sleeper bottom, the present study investigated the changes in resistance of railway tracks to lateral displacement using the single sleeper push test on the frictional concrete sleeper (B70-F). The results were then compared with those for the standard sleeper, B70. An experiment was conducted on a track with and without frictional sleepers and its result showed that the lateral resistance of the railway track increased by 64% by using frictional sleepers. In addition, a field investigation was conducted on an actual track with and without B70-F sleepers in order to extend the results and the conclusion was that the resistance of the railway track to lateral displacement increased by approximately 68% when using B70-F sleepers. [ABSTRACT FROM AUTHOR]

The criteria currently employed for the design of railway infrastructure on ballasted track are based on the elements of the superstructure, traffic, and bearing capacity of the subgrade. In high-speed railway, the elements of the superstructure are relatively well defined because they are based on existing experience. The category of traffic is a variable that has an influence from the point of view of the number of axles, weight per axle, and speed; i.e., it is determined a priori, depending on the operating characteristics of the line in question. The third and last point refers to the quality of the subgrade that is based on the values of the California bearing ratio test. The quality of the subgrade has a considerable influence on the behavior of the track that manifests itself in the value the deformation and settlement takes, which is caused to the rail on the passage of traffic. This is attributable to the relationship between the vertical track stiffness and the quality of the subgrade. In turn, this deformation determines the value of the dynamic overloads that are transmitted to the track and consequently its deterioration. Therefore, it would be convenient to introduce a new indicator that is related to the quality of the subgrade: the vertical track stiffness value. This paper deals with the variation in the value of the vertical track stiffness parameter as a function of different types of substructure, presenting graphs and formulations that can be used in the infrastructure design of the rail track. Mathematical expressions to obtain the vertical track stiffness as a function of the height of embankment and the modulus of elasticity of the embankment and the natural ground are obtained from the graphs and a methodology for designing the type of ground used in each layer of the infrastructure is proposed. This methodology is applied to several examples to point out that the application of these tools are of special importance in the case of high-speed lines, where it is necessary to adjust the value of the vertical track stiffness owing to the large effect it has on the value of dynamic overloads generated by unsprung masses. [ABSTRACT FROM AUTHOR]

This study focused on the effects of track substructure material nonlinearity on sleeper design pressure for conventional heavy haul railway ballasted railway tracks. The material nonlinearity was applied by using Mohr-Coulomb criteria implemented in finite-element method analysis. By varying the railway track axle load, a sensitivity analysis was carried out considering the different clayey subgrade cohesions, elasticity modulus, and ballast internal friction angles. The comparison of analysis results for the elastic and elastoplastic conditions showed significant differences in the pressure distribution pattern and pressure values. By comparing the sleeper's average pressure values obtained from the nonlinear analysis with the American Railway Engineering and Maintenance Association and Standards Australia standard sleeper design pressure values, two multipliers were suggested. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a model for simulating vehicle–track interaction at high frequencies for investigations of rail roughness growth. The dynamic interaction model developed employs a substructuring technique and the whole system consists of a number of substructures that can be modelled independently. The systems are coupled through the forces at the wheel–rail contact and the railpad. A coupled, rotating flexible wheelset, a flexible track model and a non-Hertzian/non-steady contact model have been implemented and results are presented here for a free wheelset on a symmetrical track system with initial random and sinusoidal roughness. Both rigid and flexible wheelsets are considered. [Copyright &y& Elsevier]

In the design of railway track layouts, there are only a small number of geometric configurations that are used in practice, and a number of constraints as to how those configurations can be fitted together to create a whole layout. In order to solve these problems, we construct a Haskell combinator library. The library has been used for the design of real-world track layouts. [ABSTRACT FROM AUTHOR]

Understanding track geometry deterioration decisively influences the planning and optimisation of track maintenance and renewal works and consequently the substantial related costs (savings) each year of every railway. To understand this deterioration it must be accurately modelled, paving the way towards its forecasting into the future. The main aim of the present study was to model railway track geometry deterioration using multivariate statistical analysis of the variables involved and to predict the future behaviour of the track geometry deterioration. For this purpose, a track section of about 180 km in length was selected as the base for the model and divided into analytical segments of as uniform characteristics as possible using a special segmentation algorithm. The lengths of the individual analytical segments were not identical, but were also kept as close to uniform as possible. For each analytical segment, the following general information was collected: track structure, traffic characteristics, track layout, environmental factors, track geometry measurements records and maintenance and renewal history data. Consequently, multivariate statistical analysis was performed on the main track geometry parameters: twist, level, alignment, gauge and cant. The coefficients of the independent variables involved in track geometry were found for each parameter in order to predict future behaviour for the purposes of efficient maintenance and renewal management [ABSTRACT FROM AUTHOR]

Abstract: A railway wheelset is subject to normal wear due to large part to friction contact between the wheelset and the rail. Because the wear of wheelset will bring the hidden security troubles to the operation of the railway, it is very important to measure the wheelset''s geometrical parameters, especially the flange thickness. The optoelectronic method is proposed and can dynamically measure the flange thickness on line. Fast Fourier transform and wavelet analysis methods are used to denoise the sensor''s signals. It is found that the wavelet transform produces a much better way of denoising of the signals compared with the fast Fourier transform. Comparisons of the flange thickness measurement with the wheelset creeping and the optoelectronic system are presented. The root-mean-square errors of the flange thickness with the manual measurement with the wheelset creeping and the optoelectronic method measurement with the wavelet analysis are 0.22 and 0.18, respectively. The changing range of manual measurement is much larger than that of the optoelectronic method because of the difference between every operator''s measuring standard. Measurement results of the optoelectronic method show that the system has better repeatability and reliability compared to the manual measurement. [Copyright &y& Elsevier]

Abstract: In this paper, the dynamic performance of a certain kind of existing bridge under the action of high-speed railway traffic is addressed. Short-to-medium-span simply supported structures are susceptible to experiencing harmful transverse vibrations under resonant conditions, leading to excessive levels of vertical acceleration, the subsequent premature deconsolidation and degradation of the ballast layer, passenger discomfort and high maintenance costs of the corresponding lines. This dynamic problem, which can require the reduction of the design velocity or the temporary interruption of the railway service to undertake corrective actions, has been reported in Europe, China and Japan during the last decades (European Rail Research Institute (2000) , Duan (1995) , Ishibashi (2004) ). In particular, single-track simply supported short bridges appear to be quite critical structures in this regard. In what follows, the authors present an evaluation of the dynamic performance of three real bridges on the Spanish railway network, located in double-track branches but composed of structurally independent decks. The objective of the investigation is to compare their performance with that of hypothetical modified double-track versions of the original decks. An orthotropic plate finite element model, whose properties are updated from experimental tests performed on the bridges in the past, is used to predict the structural dynamic responses in the time domain. Finally, the predominant effect of the increase in the mass of the bridges over the increase in the eccentricity of the tracks, the reduction in the natural frequency experienced by the torsion mode, and the relevance of three-dimensional modal contributions is proven, leading to remarkable reductions of the maximum acceleration levels in the multiple-track modified structures. [Copyright &y& Elsevier]

The aim of this research is to improve the accuracy of conventional railway design methods by addressing the main track substructure parameters omitted in the current track design approach. Nonlinear and discrete properties of the track support system were studied and their influence on the calculation of railway design parameters was measured by conducting a field investigation and using finite element analysis. It was demonstrated that wheel loads and accumulative track loading are the key factors influencing nonlinear behavior of the track support system. Mathematical expressions were developed for the impact of the nonlinearity of the track support system based on the track analysis results, and correction factors were established for rail bending moments and rail deflections calculated by current methods. It was shown that the incorporation of these factors improves the accuracy and reliability of the conventional track design method. Cette recherche vise à améliorer la précision des méthodes traditionnelles de conception des voies ferrées en traitant des principaux paramètres de fondations de voies ferrées absents dans l’approche actuelle de conception des voies ferrées. Les propriétés non linéaires et discontinues du système de soutien des voies ferrées ont été étudiées lors d’une enquête sur le terrain et par analyse par éléments finis; l’influence des propriétés sur le calcul des paramètres de conception des voies ferrées a également été mesurée. Il a été démontré que les charges par roue et les charges cumulatives des rails sont les principaux facteurs influençant le comportement non linéaire du système de soutien des voies ferrées. Des expressions mathématiques ont été développées pour déterminer l’impact de la non-linéarité du système de soutien des rails sur les résultats de l’analyse des voies ferrées; des facteurs de correction ont également été établis pour les moments de flexion des rails et les déviations des rails calculés en utilisant les méthodes actuelles. Il a été démontré que l’incorporation de ces facteurs améliore la précision et la fiabilité de la méthode de conception conventionnelle des voies verrées. [ABSTRACT FROM AUTHOR]

A recently developed Flexible Track System Model integrated with a multibody dynamics software tool was used to simulate the dynamic interaction between a vehicle and two innovative slab track designs, comparing their performance with respect to conventional ballasted track. The design concepts are presented and the modelling assumptions are given. Simulations are then carried out to quantify, for example, the impact of ballasted track degraded state using the case of a hanging sleeper. In comparison, the benefit of the two innovative track designs is highlighted as they prevent this type of localised defect from occurring. The alternative track designs were also shown to be capable of carrying a vehicle safely and with less impact on the system over a localised weakened formation support, by simulating a washout event. [ABSTRACT FROM AUTHOR]

Abstract: Railway organizations are facing continuous increase in train frequency, running speed and axle load with ever limited financial resources. This is why methods broadening knowledge of external loads and internal rail stresses are of higher importance to address rail design or maintenance process. The following paper explains how the development and application of such methods has been conducted by a european partnership (called NOVUM) between railway organizations (SNCF, DB AG, RATP) and rail producer (CORUS) sharing their specific own competences, experience and material resources. Research institutes and universities (BAM, GKSS, INRETS, INSA, LMS) have been in charge of building sound numerical simulations or experimental tests and tools. Theoretical aspects of the method are described in independent paper “A global approach for modelling fatigue and fracture of rails”. A first task group of the program is dedicated to the determination of external forces coming from wheel/rail and from rail/support interactions. The second and third task groups are about material properties and internal stresses inside rail section. Laboratory and track validations are undertaken in the fourth task group. Two characteristic cases are then chosen to check the developed models. [Copyright &y& Elsevier]

Metronet's extensive programme of ballasted track replacements on London Underground lines causes a large number of high-consequence, low-probability structural risks. (The name 'Metronet' has recently ceased being used.) The acceptable level of risk is discussed. Many of the risks involve small temporary adverse changes, and it is shown that these are not acceptable simply because they are small. Economical mitigations of risk, involving reasoning or modest modification of the conditions during the track replacement, are described for situations where calculation alone cannot demonstrate an acceptable level of risk. [ABSTRACT FROM AUTHOR]