Railway Practice Research Articles

Explicit finite element simulations of dynamic low adhesion behavior between wheel and rail in the presence of high-frequency vibrations

PurposeDynamic low adhesion (DLA) has become an urgent problem for the high-speed wheel-rail system because of continuous decrease of adhesion redundancy in the past decades. This article aims to provide a simulation method to reveal the mechanism of DLA under high-frequency vibrations.Design/methodology/approachA transient wheel-rail rolling contact model is developed for a typical Chinese high-speed railway system using the explicit finite element (FE) method. Instantaneous adhesion exploitation levels are studied in the time domain, for which driving cases over corrugated rails are taken as an example. A speed up to 500 km/h is considered together with different traction coefficients and corrugation dimensions. DLA is expected when the instantaneous adhesion exploitation level reaches 1.0, that is adhesion saturates and full sliding contact occurs.FindingsThe instantaneous adhesion exploitation level can be very high in the presence of corrugation, even at low traction coefficients. DLA is found to occur as great vertical unloading takes place and causes a significant increase of creepage. An approach is further developed to determine the critical depth of corrugation over which DLA occurs.Originality/valueThis study employs the transient wheel-rail rolling contact model to predict the instantaneous adhesion exploitation level under high-frequency vibrations. The presented results reveal a mechanism of DLA being beneficial to guidelines for future railway practice.

Railway Noise Reduction at the Source only. Is this possible or mandatory?

Climate change urges CO2 reduction also in traffic. Electrified Railways are a powerfull CO2 free and energy and space efficient traffic mode already today. Modal shift is demanded but environmental noise of railway hinder rail traffic growth significantly. Noise tunnels are not only expensive but also reduce energy efficency and increase interior noise. Noise barriers are very costly and optical obstacles. TSI-Noise values have many criticisms. They do not cover the most bothering situations, curve running and severe other critical operation conditions are missing. The noise limit values are very high. Many standard measures in all other technical fields, construction machines or road vehicles do not exist in the railway context. Even worse is the situation of the track noise. There are nearly no measures except the demand for smooth surfaces. But the noise radiation of rails and sleepers is not constant but can be reduced significantly. Even good railway practice in other countries does not push the noise reduction without legislatve demands. Exemple are quiet high speed pantographs and tamping machines in Japan. With general measures and low noise barriers and skirts on each track side the immision limt even at densly operated lines of LDEN 55 dBA is possible.

Is the cubic parabola really the best railway transition curve?

Abstract In the current study, the authors tested two railway transition curves in terms of their usefulness for railway practice. The first curve was a cubic parabola – the curve most popular in railway engineering. The second curve was a polynomial of ninth degree, and this curve was chosen due to the fact that this curve satisfies advanced geometrical demands. In this study, the model of a two-axle vehicle was applied. The study relied on the passage of the vehicle model through the route consisted of straight track, railway transition, and circular arc. Three different circular arc radii were used. The value – 0.6 m/s2 – of maximum lateral acceleration in the circular arc was applied. Three different vehicle velocities were also used. In this study, the authors simulated vehicle dynamics for different curves and ten lengths of the curves. As the main criterion, lateral acceleration of the vehicle body was applied. The results for these two mentioned curves were compared.

Influence of compaction on the deformation resistance of the sub-ballast layer

In railway practice, the results of static load tests are used most frequently to check the quality of compaction. However, the static load tests are preferably carried out to demonstrate the achievement of the required deformation resistance on the sub-ballast layers. The paper deals with the analysis of measured values of deformation resistance of the sub-ballast layer on the modernised track Považská Teplá - Žilina, depending on the compaction (achieved degree of soil compaction) and the possibility of mutual correlation of these qualitative parameters. In the analysis, the values of deformation resistance and compaction quality (degree of soil compaction) were used as part of the quality diagnostics of the performed work on the part of the modernised section of the line Považská Teplá - Žilina.

Eco-friendly High-Strength Concrete Engineered by Micro Crumb Rubber from Recycled Tires and Plastics for Railway Components

Abstract Crumb rubber concrete (CRC) is one of the new construction materials, which has been developed as a by-product from wasted rubber tires and plastics. Most previous research focuses on applications of low-strength CRC that cannot linearly predict the high-strength counterpart. This paper thus presents a study into engineering characteristics of higher-strength CRC and its benefits to the environment, as well as investigates the ability of micro crumb rubbers to enhance CRC’s mechanical properties. The results revealed that replacing fine aggregate with micro rubber particles caused a reduction in mechanical properties of concrete. However, because of the micro size of rubber content and silica fume (SFC), the compressive strength of CRC achieved over 55 MPa, which will significantly benefit the advanced construction of compliant structural systems. The tensile strength of CRC was higher than plain concrete by approximately 8.74 % (splitting tensile strength) and 17.46 % (flexural strength), but it was still lower than that of SFC concrete. Moreover, CRCs also provided the ability to resist cracking of the concrete. It is found that a suitable amount of rubber particles should not be more than 10 % of the weight for novel and sustainable high-strength CRC in railway applications. The outcome of this study will help improve the database for materials in civil constructions. The adoption of sustainable high-strength CRC in railway practices will significantly minimize wastes from used rubber tires and plastics, thus paving a robust pathway for environmental impact to societies.

Legislative activities of the Kyiv Law society in the field of railway transport

The research of the scientific heritage of the Kyiv Law Society, which worked at the Kyiv University of St. Vladimir in the second half of the XIX and early XX centuries, is of current relevance within the framework of civil society development in Ukraine. The variety of its scientific directions speaks of the tireless desire of the members of the Society to improve the national legislation, to solve a number of legal problems and to promote the development of legal science in the Ukrainian lands. This article investigates the problems in the field of railway transport to have been actively discussed at the meetings of the Kyiv Law Society. The main steps in the creation of a unified railway legislation in the Russian Empire in the second half of the XX century, which was mandatory for all railways in the country, are outlined. The role of the Commission for the Study of Railways in Russia of E. T. Baranov, which was created to study the state of railways in the country, has been considered. It is shown that the Commission consisted of leading scientists and public figures of the country – A. F. Koni, S. Yu. Vitte, А.А. Vendrykh, М.М. Annienkov and others. It has been stated that the main purpose of the Commission's activity was to collect the necessary materials from foreign and domestic railway and judicial practice, which could be studied as much as possible with the participation of representatives of science, trade, military affairs and industry, with the purpose of creating the General Statute of Railways of the Russian Empire, which became the first codified source of law precisely in the railway business. It has been shown how the KLS took part in this process. The speeches of individual scientists such as O. F. Kistiakivskyi, D. I. Pikhno, M. Ye. Krainskyi, A. H. Dolzhanskyi, O. F. Kvachevskyi who spoke on the problems of railway jurisprudence, put forward their proposals, discussed the possibilities of appropriate changes in the development of the railway industry and held discussions at the meetings of the Society have been analyzed. In addition, the history on the creation of the General Statute of Railways, its content and significance for the railway business in the Russian Empire, which became the first step in the formation of a unified legal field on the entire network of national railways, have been revealed.

Reliability-based life cycle costing analysis for embedded rails in level crossings

Reliability-based life cycle costing analysis (LCCA) supports optimized decisions on capital and operational expenditures for engineering asset management. In addition, it allows investigation of the impact of maintenance decisions on designing the service life of assets. The application of reliability-based LCCA in railway practice is challenging, as there is limited research with regard to integrating maintenance strategies, reliability and costs especially for embedded rail systems. Therefore, in this research, an LCCA model for these embedded rail system assets has been developed, which shows the optimum between the actual reliability profile, financial parameters and maintenance policies for specific variable conditions. This model incorporates both the uncertainties associated with degradation and maintenance strategies which have been integrated into a discounted age replacement model. This model facilitates a better understanding about the interaction among life cycle cost, rail degradation and maintenance strategies for a set of variable conditions. The output supports decision making on rail replacement and/or maintenance engineering. The model is demonstrated in a case study and validated with available (real) failure data from Dutch railroad service contractors. The potential of the applicability to ballasted tracks is also demonstrated.

Analysis of static forces generated in-track on a railway sleeper resting on an elastic foundation due to structural imperfections using the PONTOS system

In the paper a considered railway sleeper was analysed as an Euler-Bernoulli beam and a Timoshenko beam of finite length resting on a oneand two-parameter foundation. The foundation parameters were determined based on a modified and analogue Vlasov soil model and field investigations. The main concept for the executed investigations was to induce an intentional imperfection in an actual railway track, propose a way of appropriate measurement (e.g. the PONTOS system by GOM mbh), and utilize author’s field investigations results to calibrate necessary parameters for theoretical calculations. An experimental formula describing the value of the force transferred from the rail to the railway sleeper on the grounds of the survey site caused by a locomotive was given. Furthermore, the deflection of the chosen railway sleeper due to the generated imperfection was analysed. Finally the objective of the present analysis was to resolve the calculations into the beam element such that the results can be utilised in computational railway practice. In the presented paper also the computational examples, diagrams and tables reflecting influence of analyzed parameters on obtained a CWR track’s displacements are enclosed.

Determination of the optimal curvature of the turnout diverging track for HSR using dynamic analysis

The paper presents an analytical method of identifying the curvature of the turnout diverging track consisting of sections of varying curvature. Such turnout is mainly applied on High Speed Railway. Both linear and nonlinear (polynomial) curvatures of the turnout diverging track are considered in the paper. Obtained solutions enable to assume curvature values at the beginning and end point of the geometrical layout of the turnout.The paper focus on a fundamental and unexplained so far issue connected with selection of the most favourable curvature section from the operational requirements point of view. In order to determine the optimal curvature a dynamic analysis has been carried out on the several representative cases. It has been indicated that, used in railway practice, clothoid sections with nonzero curvatures at the beginning and end points of the turnout should be verified. It has been proved that the turnout with nonlinear curvature reaching zero values at the extreme points of the geometrical layout is the most favourable.

Reply to Giannakos, K. Comment on: Toughness of Railroad Concrete Crossties with Holes and Web Openings. Infrastructures 2017, 2, 3

This paper responds to the discussion [1] by Dr. K. Giannakos over our technical note [2].[...]

Dynamic Analysis of the Turnout Diverging Track for HSR with Variable Curvature Sections

The paper presents an analytical method of identifying the curvature of the turnout diverging track consisting of sections of varying curvature. Both linear and nonlinear (polynomial) curvatures of the turnout diverging track are identified and evaluated in the paper. The presented method is a universal one; it enables to assume curvature values at the beginning and end point of the geometrical layout of the turnout. The results of dynamics analysis show that widely used in railway practice, clothoid sections with nonzero curvatures at the beginning and end points of the turnout lead to increased dynamic interactions in the track-vehicle system. The turnout with nonlinear curvature reaching zero values at the extreme points of the geometrical layout is indicated in the paper as the most favourable, taking into account dynamic interactions occurring in the track-vehicle system.

Analysis on line capacity usage for China high speed railway with optimization approach

The purpose for the analysis of capacity usage is to utilize the rail infrastructure in a more efficient and practical way. The practical and theoretical challenge of the rail capacity is its dynamics and uncertainty, which are common in China and elsewhere. Based on the capacity balance, a train service-demand intention set (TSDIS) at High-Speed Rail (HSR) line (t@l-TSDIS) is defined, which takes the number of trains, the average speed, the heterogeneity and the stability as the core elements for the capacity usage. For dynamics and uncertainty, we update the norm for capacity measure as the time needed to fulfill the task list t@l-TSDIS. Then we develop the objectives and constraints for the Mathematical Program for Line Capacity (MPLC), which aims at minimization of heterogeneity and running time as well as maximization of reliability. For solving MPLC, the Pareto Archived Evolutionary Strategy (PAES) and fuzzy logic penalty function are introduced. Furthermore we propose a rolling optimization tactic oriented by the practical problem, which combines the improved Pareto Archived Evolutionary Strategy (iPAES) with an interactive technique. In a case study, we apply the proposed ideas and methodology to Beijing-Shanghai HSR (BS-HSR) line much closer to the railway practice. By using the computer language C# to compile the Console program, Pareto optimized results for MPLC are achieved, including the standard and practical values for the heterogeneity indices, reliability indices and running time indices. We also discuss the sensitivity of the heterogeneity index. This research demonstrates that it is useful to analyze the line capacity usage for China HSR with the proposed optimization approach.

Development of a Comprehensive Programme to Prevent and Reduce the Negative Impact of Railway Fatalities, Injuries and Close Calls on Railway Employees.

This article presents a strategy to prevent trauma, support and care for railway personnel who experience critical incidents (CI) on the job, usually fatalities by accident or suicide. We reviewed all publications on CI management, support and care practices in the railway industry, as well as practices in place in Canada (unpublished protocols). Semi structured interviews were conducted with 40 train engineers and conductors involved in CIs and the content was coded and analysed quantitatively. Employees' satisfaction with the help received after the incident varies according to the behaviour of the local manager, company officers and police, the level of compliance with existing company protocols to help them, the presence of unmet expectations for support and care, their perceived competency of clinicians they consulted and the level of trust toward their employers. On the basis of the interview results, the review of existing railway practices and discussions with railway stakeholders, a model protocol was developed for a comprehensive workplace prevention, support and care protocol to reduce the negative impact of railway critical incidents on employees. This protocol includes preventive actions before traumatic events occur, immediate responses at the site of incident, interventions within the first few days after the incident and longer term support and interventions provided by the company and by outsourced experts.

The Privatisation of the UK Railway Industry: An Experiment in Railway Structure

AbstractThe British rail network was privatised in the mid‐ to late 1990s. However, the sector was heavily regulated and not permitted to evolve according to market processes. Indeed, the government imposed a complex and fragmented structure on the industry which ran counter to traditional railway practices. As a consequence, economies of scale and scope were lost, while transaction costs were increased. There was a negative impact on costs and safety. Given the disappointing outcomes, there is a strong case for reforming the sector by facilitating the development of a privately owned and vertically integrated rail system.

Study on the Real-Time Security Evaluation for the Train Service Status Using Safety Region Estimation

For the important issues of security service of rail vehicles, the online quantitative security assessment method of the service status of rail vehicles and the key equipments is urgently needed, so the method based on safety region was proposed in the paper. At first, the formal description and definition of the safety region were given for railway engineering practice. And for the research objects which their models were known, the safety region estimation method of system stability analysis based on Lyapunov exponent was proposed; and for the research objects which their models were unknown, the data-driven safety region estimation method was presented. The safety region boundary equations of different objects can be obtained by these two different approaches. At last, by real-time analysis of the location relationship and generalized distance between the equipment service status point and safety region boundary, the online safety assessment model of key equipments can be established. This method can provide a theoretical basis for online safety evaluation of trains operation; furthermore, it can provide support for real-time monitoring, early warning and systematic maintenance of rail vehicles based on the idea of active security.a

실물 재하시험을 통한 성토사면에 근접한 철도 전철주기초의 저항모멘트 평가

철도선로에 설치되는 전철주기초의 모멘트에 대한 거동을 파악하기 위한 실물 재하시험을 수행하였다. 현행 시공방법에 따라 현장타설방식으로 설치된 직경 75cm, 깊이 2.5m의 원형 전철주기초 2본에 대하여 실제 조건과 동일한 모멘트 위주의 하중을 가하여 기초의 파괴모멘트를 확인하였다. 성토사면이 기초의 저항모멘트에 미치는 영향을 평가하기 위하여 사면방향과 사면반대방향으로 각각 모멘트를 가하였다. 국내 설계기준에 따라 성토지형에 설치된 전철주 기초는 파괴 이전까지는 변위가 거의 발생하지 않다가 급격한 전도로 파괴되는 취성거동을 보이는 것을 규명하였다. 성토사면의 영향으로 기초의 파괴모멘트가 30% 정도 감소하는 것으로 평가되었으며, 이를 토대로 전철주기초 설계에서 사면의 영향을 고려하기 위한 지형계수(K)로 0.7을 제안하였다. 또한 실물 재하시험 결과로 나타난 파괴모멘트를 국내외 설계방법의 저항모멘트 산정 결과와 비교함으로써 그 적합성을 평가하였다. The moment responses of electric pole foundations for a railway were investigated using real-scale load tests. Large overturning moments were applied to two circular rigid piles with a 0.75 m diameter and a 2.5 m embedded depth; the circular rigid piles were installed in an actual railway embankment fill. Two different loading directions-toward the fill slope and toward the track -were applied to evaluate the influence of the fill slope on the moment capacities of the foundations. It was found that the failure of the foundations that were constructed according to Korean railway practices exhibited a sudden overturning pattern without any significant pre-failure displacement. The moment capacity toward the fill slope was less than the moment capacity toward the track by 30%. From the test results, the geometry factor (K), which accounted for the reduction of the moment capacity, due to the fill slope, was 0.7. Moment capacities determined from the load tests were compared with those predicted from three existing design methods, and their applicability was discussed.

Commuter Rail

Federal regulators and passenger railways are both concerned about passengers with mobility impairments that limit their ability to use stairways. Federal policy and railway practice strongly encourage development of services that allow for level boarding and alighting from commuter rail trains. In addition to benefiting individuals who have trouble using stairs, level boarding can lead to significant improvements in service delivery for the rest of the public by reducing unproductive station dwell times, improving safety, and creating opportunities to improve crew efficiency. One obstacle to level boarding has been concerns presented by the freight railroads that operate over (and often own) trackage shared with the commuter trains. The freight operators wish to maintain a full horizontal clearance envelope allowing unrestricted operations. These concerns often limit the close door–platform interface necessary for level boarding. This paper summarizes current Federal Transit Administration policy on level boarding, discusses the benefits of level boarding, reviews the tension between freight clearance concerns and level boarding, and reviews the state of the practice in serving passengers with mobility impairments. On the basis of an industry review, it highlights three innovations that have been implemented or considered to expand the scope of level boarding among North American commuter railroads. Finally, it provides recommendations for further research.

Chemical Research in the Pre-Grouping Railway Industry and its Impact on Railway Engineering and Practice

All the large railway companies in existence prior to their amalgamation in 1923 into four groups had well-established chemistry laboratories with a staff of qualified chemists. The principal task of these laboratories was to perform quality control analyses on purchased materials. However, commencing in the 1890s, some of these laboratories were engaged in research projects. The principal areas of investigation were those of metals, lubrication and water treatment, but the railway chemists also conducted research on a considerable number of other topics. This paper considers the context in which chemical research was conducted in the railway laboratories, describes some of the work that was performed, and discusses its significance for the railway industry.

A new ripraped-rock slope for high temperature permafrost regions

Abstract Considering the strong wind condition in the Qinghai–Tibet plateau, the cooling effects of three traditional embankments were simulated taking into account the forced convection of air in porous media. The results showed that the traditional ripraped-rock slope cannot exploit the advantages of the thermal diode effect of the ripraped-rock slope to the full, and is not satisfactory in protecting the permafrost. Then a sunshade-blocking-wind ripraped-rock slope was suggested to gain better cooling effects and to overcome some specific problems that might occur in the Qinghai–Tibet Railway practice. The numerical simulations on the effect of the new measure proved that it would cool the underlying permafrost effectively and satisfactorily maintain the thermal stability of the Qinghai–Tibet Railway, and it would not encounter the problems that might happen to the traditional embankment, such as blocking of ripraped-rock by blown sands and snow, and the temperature difference between the south and north slopes.

On non-linear methods of bogie stability assessment using computer simulations

Stability assessment of rail vehicles is probably the most widespread form of dynamic analysis in railway vehicle engineering. The computer simulations using fully non-linear three-dimensional vehicle models constructed in a modern multi-body simulation tool allow detailed non-linear stability analysis for the specified conditions. However, high sensitivity to the wheel/ rail contact conditions and different definitions of stability in mechanics and in railway practise can lead to significant differences between prediction and the measurement. Different methods of non-linear stability analysis, which may be used in industrial applications, are introduced and compared on selected examples of contact geometry wheel set/track with high equivalent conicity. The comparisons show that the linearization of the contact geometry wheel set/track can enable a better assessment of the non-linear stability analyses. A decreasing equivalent conicity function in the range of amplitudes below ∼ 3 mm leads to supercritical Hopf bifurcation with small limit cycles and consequently to largest differences between the methods compared. When excluding the contact geometries leading to supercritical Hopf bifurcation, the results achieved are closer each other, but still with differences in the range of up to 10 per cent. This uncertainty in the stability prediction caused by the method applied must be taken into consideration, in addition to other uncertainties related to vehicle parameters, modelling, etc.