Vehicle Derailment Research Articles

Design and analysis of train anti-derailment device based on full-scale derailment tests

This paper proposes an anti-derailment device that can be installed on the bogie to minimize the loss incurred by derailment accidents. The device is designed to create a stable four-point contact between the bogie and the rail once the wheel climbs the rail and derails, thereby preventing derailment. Full-scale derailment tests have been carried out to demonstrate the efficacy of the anti-derailment device. During the bogie test, the anti-derailment device successfully reduced the lateral acceleration at the derailed wheel axle box by 18.1%, effectively preventing wheel derailment. Since vehicle derailment tests are destructive, simulation models were used to compare the safety improvement of the anti-derailment device under derailment conditions, which showed a reduction of lateral acceleration at the derailed wheel axle box by 35.9%. Compared with the normal vehicle, the critical operation speeds of the vehicle are amplified greatly by the anti-derailment device. The results demonstrate that the anti-derailment device is a practical solution that effectively mitigates train derailment accidents caused by wheel derailment.

Investigation on the mechanism and measures of derailment of empty freight train passing a turnout in the diverging route

The derailment of railway vehicles at a turnout is a worldwide concern. However, the derailment of empty freight trains in the switch section of a turnout in the diverging route is rarely concerned. Therefore, in order to analyse the derailment mechanism of empty freight trains in the turnout switch area and to propose appropriate preventive measures, field investigation and dynamic simulation of the derailment are carried out on the basis of an empty freight train derailment in the turnout switch area of the diverging route. Firstly, the background of the derailment is presented and the potential influencing factors of the derailment are analysed according to the field investigation. Secondly, a detailed train-turnout dynamic model is established, taking into account the variable cross-sections of the turnout switch rail and the effect of the longitudinal coupler force. Thirdly, based on the model, the derailment mechanism of the empty freight train is revealed through theoretical analysis and simulation calculation. Finally, the effect of the potential derailment influencing factors is analysed and preventive measures are proposed to reduce the derailment risk of the empty freight train at the turnout switch area in the diverging route. The results indicate that this derailment is caused by the combined effect of the inherent structural characteristics of the switch, the large longitudinal coupler force, and the high wheel rail friction coefficient. The possibility of derailment can be reduced by reducing the longitudinal coupler force and the wheel rail friction coefficient. In addition, the installation of a guard rail in front of the turnout can effectively prevent empty freight train derailment in the turnout area.

State-of-the-Art Wayside Condition Monitoring Systems for Railway Wheels: A Comprehensive Review

In recent decades, there has been a constant demand for faster, longer, and safer railway networks. This also brings challenges for condition monitoring systems in modern railway vehicles. More specifically, critical parts of railway vehicles like wheels degrade over time due to various operational and environmental reasons. Different dynamic effects such as skidding/sliding over the track and the presence of contamination between wheel-rail cause various wheel defects. Faulty wheels ultimately lead to the derailment of railway vehicles. To avoid worst situations like railway derailments, various research has been conducted for developing efficient condition monitoring systems for railway wheels. In addition, there have been some commercial condition monitoring products that can be deployed with railway vehicles. These systems incorporate various sensors such as strain gauges and vision sensors to collect data for diagnosis and prognosis. Various methods have been explored but yet there is a broad research gap in terms of developing advanced onboard condition monitoring systems. With the progress in technology, advanced systems with Machine Learning/Deep Learning methods can provide more efficient and robust condition monitoring of dynamic railway systems. Considering the need for advancement in condition monitoring systems for railway vehicles, a comprehensive review of existing condition monitoring systems for railway wheels is conducted in this paper. The review is aimed at understanding the feasibility and potential of new methods for modern railways. This paper provides a detailed overview of studies on the existing wayside systems and reports their advantages and disadvantages concerning its recently emerging counterpart on-board monitoring systems. Data acquisition systems and analysis methods are critically reviewed which could assist in developing more efficient and reliable condition monitoring systems for railway wheels. This article also reviews the current progress of wayside systems and their limitations. The article is targeted at the researchers and engineers working in this domain, who can pave the way for developing advanced and cost-effective condition monitoring systems for railway wheels using modern technologies.

A New Derailment Detection Method of Rail Vehicles

Aiming at the problem of train derailment detection, researchers at domestic and abroad mainly focus on the derailment coefficient and wheel load reduction rate, but the derailment coefficient and wheel load reduction rate can’t accurately reflect the status of rail vehicle derailment in time. In this paper, a new derailment detection method of rail vehicles is designed based on the lateral acceleration and roll angle as the key characteristic physical quantities of wheelset derailment. Firstly, the virtual simulation method is used to grasp the characteristics of the key physical quantities. Then, the appropriate scheme of derailment detection system is proposed to measure the key characteristic physical quantities and judge whether the rail vehicle is derailed. Finally, the simulation data is used to prove the effectiveness of the detection method, which can lay the foundation for the practical engineering application.

Fragility analysis for vehicle derailment on railway bridges under earthquakes

With the rapid development of high-speed railways around the globe, the safety of vehicles running on bridges during earthquakes has been paid more attention to. In the design of railway bridges, in addition to ensuring the safety of the bridge structure in earthquake, the vehicle safety should also be ensured. Previous studies have focused on the detailed analysis of vehicle derailment on bridges, proposing complex numerical algorithms for wheel–rail contact analysis as well as for parametric analysis, but they are inconvenient for designers. Intensity measure (IM) used in performance-based earthquake engineering is introduced in this study. A method to evaluate the vehicle safety on bridges under earthquakes is proposed with respect to the optimal IM. Then, the vehicle derailment case of the Kumamoto earthquake in Japan verifies the decoupling method of vehicle–bridge interaction model. In the assessment of vehicle derailments, eight IMs are systematically compared: the IMs of bridge deck motion are generally better than those of ground motion; the variation coefficient of spectral intensity of the bridge deck is the smallest at different frequencies. Finally, the derailment fragility cloud map is presented to evaluate the vehicle safety on bridges during earthquakes.

A Code-Type Method to Assess the Running Safety of Railway Vehicles on Bridges Shaken by Earthquakes Including Girder’s Torsional Motion

The safety of railway vehicles running on bridges needs to be evaluated in the seismic design of bridges. This study examined the spectral intensity calculated from the lateral vibration of the bridge deck during earthquakes, a Japanese code-based index to measure bridge vibration’s strength. In addition, the effect of the torsion of the bridge deck on vehicle derailment is investigated using a nonlinear vehicle–track–bridge model. The bridge deck torsion increases the derailment risk, especially for bridges with a low natural frequency. The reason lies in that the lateral and torsional deck motions are highly correlated for bridges with lower frequency. Based on this observation, a code-type formula was proposed to evaluate the vehicle running safety including both lateral and torsional motions of the bridge deck. The accuracy of the proposed formula was demonstrated by comparison with vehicle–track–bridge simulation excited by ground motion records. The new procedure overcomes the non-conservative assessment of derailment caused by ignoring bridge torsion.

Study on the derailment of the remote locomotive in a heavy-haul train with distributed power at the turnout frog area: field investigation and numerical simulation

The derailment of railway vehicles in the turnout area is a worldwide concerned issue. Previous studies mainly concentrate on the derailment at the switch area, and the risk at the frog area is seldom concerned. Based on a specific derailment case of the remote locomotive in a 20,000-tonne heavy-haul train, a study on the derailment of the locomotive at the turnout frog area is presented. The conditions of the derailed locomotive and turnout track are introduced, and the potential influence factors are screened according to the field investigation results. A detailed simulation model that considers the complex wheel-frog/guard rail contact relationship and the interaction between adjacent vehicles is established. Through numerical simulation, the derailment process of the locomotive at the turnout frog area is reproduced, and the derailment mechanism is revealed, followed by the influence analysis of the potential factors. The results indicate that the combined effect of the compressive coupler force and the coupler jack-knifing promotes the derailment remarkably. Moreover, the derailment at the turnout frog area is more likely to occur under low-speed conditions, and the possibility of derailment can be reduced by decreasing the compressive coupler force and the friction coefficients between the wheel and stock/frog/guard rail.

Estimation of fatigue life parameters of an Alumino Thermic weld on UIC60 rail joint using LEFM

At wheel track contact point, the high stress concentration, poor weld quality, and heterogeneity of weld material are the main factors that cause fatigue crack on any rail weld. Railway network agencies are concerned about the safety of the railway track when it comes to detecting and fixing weld faults to avoid vehicle derailment and loss of lives. This study analysed a numerical simulation of fatigue crack and its evolution under loaded service condition. A 3-D CAD wheel rail weld assembly model was built to study an AT welded joint under fatigue, and for stress concentration factor (SIF) calculation. The results are found by inserting a semi elliptical crack on the rail weld head surface with ANSYS, and then numerical simulation has been performed to get the different three modes of SIF at rail weld crack. The analysis findings data was recorded with critical fracture parameters of SIFs and its number of cycles to failure using LEFM technique and respective results have been plotted. With ANSYS the stress intensity on a crack will be resulted. By using numerical method, the critical crack size and number of cycle load with fatigue life of rail would be determined. The numbers of rail weld inspection per year has been determine by using the maximum number of cycle. The aim of this paper is to develop an effective inspection and maintenance frequency based on rolling contact surfaces crack propagation analyse. This will help to prevent the occurrence of rail failure by taking the required action at the right time, and extend the rail life expectancy, reduce the rail maintenance work and its cost.

Hypothesis for fault dynamic monitoring evolution in railway systems

This paper presents the technical analysis and results of an inquiry carried out by General Directorate for Railway and Maritime Investigations (DiGIFeMa) belonging to Infrastructure and Transportation Italian Minister. The target of this study tries drawing how the prognostic theory can be applied to railway maintenance in order to optimize procedures and operational features on railway safety. The case of study points on a HS railway vehicle derailment event, that has analysed in an Official Investigation Report drawn by Italian Transportation and Infrastructure Ministry. This document, drafted according to Legislative Decree n. 50/2019, represents the identification of technical faults, which have generated the accident, and leads to specific technical recommendations. Starting from these results, one of the most important Italian Railway Undertaking has carried out a verification of the existing vehicle safety monitoring devices, used during high-speed rail operation. Moreover, due to the prognostic’s theory, a wide research and series of experimental tests could be developed on old and new devices which verify the functional status of mechanical elements connected to the rotation of the railway wheelsets.

Influence of undercrossing tunnel excavation on the settlement of a metro station in Dalian

Numerous tunnel excavation projects have been undertaken in China to address the ever-increasing demand for tunnels, which is driven by the rapid development of urban cities. Tunnel excavations generally induce the settlement of existing tunnels and sometimes result in the derailment of metro vehicles. In this study, the Nanyan Fourth Circuit Transmission Reconstruction, located in Dalian City in China, was selected to investigate the local settlement of a metro station caused by an underlying tunnel excavation project. The theoretical solution of the stochastic medium theory was calculated for a horseshoe-shaped tunnel based on the Gauss–Legendre integral in a non-uniform convergence situation. Results were compared with data measured at the metro station. A three-dimensional model was developed to further explore the variations in stress and deformation, which were difficult to measure during the excavation. The results showed the existence of a settlement gradient of the metro station in the direction of the excavation after the underlying tunnel was excavated. The numerical results were in good agreement with the data measured onsite. The non-uniformity of the settlement in the direction of the excavation was investigated. The findings of this study can provide a reference for predicting and controlling the impact of undercrossing tunnel excavation on the deformation of metro stations.

Dynamic analysis of railway vehicle derailment mechanism in train-to-train collision accidents

Train collision-induced derailment may result in serious casualties. This study investigates the railway vehicle derailment behaviour and explores the derailment causes in train-to-train impacts. A train-track coupled dynamic model is developed and validated. The lateral ( Yde) and vertical ( Zde) relative displacements of the wheel/rail pair are used for the derailment evaluation. The results show that the wheelset jumping derailment and the saw-tooth buckling mode may occur during the high-speed collisions. Derailment is mainly caused by car body yawing rotation and wheelset lateral and vertical displacements. Yawing and pitching motions of car body influence wheelset displacement significantly. Vehicles with the higher velocity generate more severe derailment behaviour. Under circumstance of the same train impact energy, the higher vehicle mass and greater car numbers have the stabilizing influence for reducing the derailment risk. Increasing the force on the main energy-absorbing structure which is set in the front-end crushing zone of a vehicle to dissipate the train impact energy and the damping coefficient of the secondary yaw damper can decrease the derailment risk. The train safety operation areas and derailment boundaries indicate that the reliability of the Yde criterion is higher.

Full‐scale tests on bridge kerbs subjected to horizontal actions

AbstractThe construction of new kerbs or the replacement of existing ones is usually due to the need of installing safety or anti‐noise barriers. A suitable experimental survey has been studied and developed at the Laboratory of the University of Rome “Tor Vergata" aiming at verifying the vulnerability of the system kerb safety barrier in a bridge deck. The main scope is the analysis, through full‐scale experimental tests, of the system performances under horizontal actions simulating the vehicle derailment. Particular care has been devoted in reproducing actual geometries and materials. Furthermore, the actual elements usually installed in Italian infrastructures (roadways and highways), are adopted, in order to highlight the true damage typologies and failure modes. Both the cases of application of barriers on existing and new cast kerbs are analyzed, and two kerbs geometries, generally found in Italian bridges are cast and tested. The obtained results provide useful information on the safety check to be developed on this kind of structures.

Numerical investigation of dynamic derailment behavior of railway vehicle when passing through a turnout

Wheel flange climb derailment of vehicles in railway turnouts is a serious safety issue. In particular, derailment accidents in smaller turnouts, caused by poor track alignment before the turnout or structural degradation, are becoming more and more frequent. Most of the previous research on derailment has focused on main track areas, while the dynamic derailment mechanism for turnouts is still not clear. For this reason, a field derailment investigation of freight wagons in No.6 symmetrical turnouts is presented in this paper. Taking this into consideration, a half-car multi-body dynamics model and flexible turnout model, subject to wheel flange climb derailment, has been established. In addition, a field test for wheel-rail interaction was carried out to verify the dynamic model. This model is capable of revealing derailment evolution of the front and rear wheelset for a bogie under critical derailment conditions. The influence of several sensitive parameters of the derailment model on critical derailment behavior has been carried out. Results show that the simulation results of the wheel climb derailment are very consistent with the filed investigation, and the safety of the bogie depends on the status of both front and rear wheelset. This work is a world first in providing a solid understanding of dynamic derailment behavior and motion posture, giving guidance on the prevention of wheel flange derailment in turnout areas.

An investigation of rocking derailment of railway vehicles under the earthquake excitation

The rocking derailment mechanism of railway vehicles due to the earthquake-induced roll motion is investigated through a coupled vehicle/track dynamic model together with a simplified roll-plane vehicle model. The coupled vehicle/track dynamic model is formulated through a typical high-speed train model incorporating with a track model to study dynamic responses and rocking derailment procedure under earthquake excitations. The results indicate that the lateral earthquake excitation can impose significant effects on the running safety of vehicle, and further lead to the rocking derailment. A simplified roll plane vehicle model subjected to the lateral earthquake excitation is thus developed to derive the critical condition of rocking derailment, which further contribute to a criterion for earthquake- induced rocking derailment. Moreover, a conservative limit, in term of equivalent acceleration of lateral earthquake excitation, has been identified considering different earthquake excitations. This could serve as a threshold for assessment of operational safety of rail vehicle in the presence of earthquake condition.

Reducing wheel wear from the perspective of rail track layout optimization

Wheel wear (W-wear) is one of the most critical issues affecting vehicle-track performances and operating costs. Currently, the works on W-wear behavior and W-wear reduction are mainly based on four aspects: wheel-rail (WR) tribology, WR profile, vehicle structure design and active control of vehicle suspensions. Little attention has been paid to the effects of track layout parameters, such as superelevation, gauge, and cant. To supplement the existing research, this work aims to investigate the relationship between W-wear and track layout parameters and ultimately reduce W-wear through optimizing track layout parameters. The framework consists of a series of steps. Firstly, a multibody dynamics simulation (MBS) model of an Sgnss wagon with 55 degrees of freedom (DOFs) is built. Then, taking a 375-m-radius curve as a case, the influence of track layout parameter (superelevation, gauge, and cant) on W-wear and vehicle derailment safety is investigated based on Kriging surrogate model (KSM). Finally, based on optimized results obtained by KSM and particle swarm optimization (PSO), two optimal regions and three reasonable suggestions concerning the layout of a 375-m-radius curve are given from the perspective of reducing W-wear. This study is promising for the parameter setting of those dedicated lines, on which the train speed is usually fixed, such as metro, light rail, and tram.

Probabilistic assessment of vehicle derailment based on optimal ground motion intensity measure

Railway vehicles frequently have derailed during major earthquakes. Although a probabilistic approach based on fragility analysis was established in structural engineering, it has never been applied to railway vehicles. Thus, the aim of this study was to select optimal intensity measures (IMs) and develop fragility curves for the derailment of vehicles. Eight commonly seen IMs were examined to determine their suitability for use in analyzing the derailment of vehicles. The railway vehicle response was analyzed using a nonlinear vehicle-track simulation, and 22 far-field and 28 near-field ground motion records were used as input. Based on the results of the simulation, the correlations of these IMs with the responses of vehicles were evaluated in terms of commonly accepted criteria in the literature, such as efficiency, practicality and sufficiency. It was found that spectral IMs were superior to peak-type IMs. In addition, the acceleration spectral intensity (ASI) and the velocity spectral intensity (SI) were shown to be optimal IMs for the evaluation of derailments. Using the selected IM (ASI), derailment fragility curves were developed for three levels of vehicle performance, which facilitated the probabilistic assessment of vehicle derailment in a performance-based manner.

On the task of allocating investment to facilities preventing unauthorized movement of road vehicles across level crossings for various statistical criteria

Aim. Railway transportation is affected by a whole range of transportation incidents, both related to rolling stock, i. e. vehicle-to-vehicle collisions, derailments, broken cast parts of bogies, etc. , and infrastructure, i. e. broken rail, fires at railway stations and terminals, broken catenary, etc. Among the above incidents, collisions at level crossings are the most likely to cause a public response, as collisions between trains and road vehicles often cause multiple deaths that are reported in national media, which entails significant reputational damage for JSC RZD. Additionally, collisions often cause derailment of vehicles, which may cause deaths and major environmental disasters, if dangerous chemical products are transported. Beside the reputational damage, collisions at level crossings cause significant expenditure related to the repair of damaged infrastructure and rolling stock, as well as damage caused by trains idling due to maintenance machines operation at the location of incident. That brings up the issue of optimal allocation of investment to facilities preventing unauthorized movement of road vehicles across level crossings (hereinafter referred to as protection systems). This problem is of relevance, as replacing level crossings with tunnels and viaducts is not going fast and does not imply the eventual elimination of all level crossing. Hence is the requirement for rational allocation of funds to the installation of protection systems over the extensive railway network. Given the above, the aim of this paper is to develop decision-making guidelines for the reduction of the number of transportation incidents in terms of statistical criteria, i. e. quantile and probabilistic. Methods . The paper uses methods of deterministic equivalent, of equivalent transformations, of the probability theory, of optimization . Results. The problem of maximizing the probability of no incidents is reduced to integer linear programming. For the problem of minimizing the maximum number of incidents guaranteed at the given level of dependability, a suboptimal solution of the initial problem of quantile optimization is suggested that is obtained by solving the integer linear programming problem through the replacement of binomially distributed random values with Poisson values. Conclusions. The examined models not only allow developing an optimal strategy with guaranteed characteristics, but also demonstrate the sufficiency or insufficiency of the investment funds allocated to the improvement of level crossing safety. Decision-making must be ruled by the quantile criterion, as the probability of not a single incident occurring may seem to be high, yet the probability of one, two, three or more incidents occurring may be unacceptable. The quantile criterion does not have this disadvantage and allows evaluating the number of transportation incidents guaranteed at the specified level of dependability.

Two-parameter bifurcation analysis of limit cycles of a simplified railway wheelset model

The effect of the nonlinear terms on bifurcation behaviors of limit cycles of a simplified railway wheelset model is investigated. At first, the stable equilibrium state loses its stability via a Hopf bifurcation. The bifurcation curve is divided into a supercritical branch and a subcritical one by a generalized Hopf point, which plays a key role in determining the occurrence of flange contact and derailment of high-speed railway vehicles, and the occurrence of this critical situation is an important decision-making criteria for design parameters. Secondly, bifurcations of limit cycles are discussed by comparing the bifurcation behavior of cycles for two different nonlinear parameters. Unlike local Hopf bifurcation analysis based on a single bifurcation parameter in most papers, global bifurcation analysis of limit cycles based on two bifurcation parameters is investigated, simultaneously. It is shown that changing nonlinear parameter terms can affect bifurcation types of cycles and division of parameter domains. In particular, near the branch points of cycles, two symmetrical limit cycles are created by a pitchfork bifurcation and then two symmetrical cycles both undergo a period-doubling bifurcation to form two stable period-two cycles. Around the resonant points, period orbits can make several turns, whose number of turns corresponds to the ratio of resonance. Thirdly, near the Neimark–Sacker bifurcation of cycles, a stable torus is created by a supercritical Neimark–Sacker bifurcation, which shows that the orbit of the model exhibits modulated oscillations with two frequencies near the limit cycle. These results demonstrate that nonlinear parameter terms can produce very complex global bifurcation phenomena and make obvious effects on possible hunting motions even though a simple railway wheelset model is concerned.

철도차량 윤중편차 변화에 따른 주행안전성 특성 검토 연구

Trains running on the track at the prescribed speed are generally safe, but they are evaluated quantitatively by the safety of derailment of the train (lateral force/vertical force, wheel unload ratio). This quantitative evaluation can cause several problems. This is because the derailment safety standard that can express the risk of derailment as an index is not yet established in Korea as a standard or standard. Also, the relation between the change in the radius of curvature and the vehicle derailment is not clearly known. In this study, the influence of deviation on derailment safety is analyzed through numerical analysis to secure the running safety of trains. As a result, the variation rate of the decrease rate of the wheel load ratio is increased sensitively, but the estimated derailment coefficient is almost constant as the passing speed is faster in the wheel load ratio of the outer based on the variation of the curve passing speed. The effect of the change in the ratio of the stopping torque on the outboard wheel to the estimated derailment coefficient at a slightly larger radius of curvature based on the change of the curve radius is small, The value of the estimated derailment coefficient increases sensitively. In addition, the change wheel unload ratio due to the increase of the static wheel load ratio of the outer wheel was sensitively increased at a given radius of curvature. In this way, it can be confirmed that the static wheel load ratio, that is the wheel load deviation, adversely affects the safety of the running of the vehicle.

Development of method for experimental determination of wheel–rail contact forces and contact point position by using instrumented wheelset

This paper presents the development of a unique method for experimental determination of wheel–rail contact forces and contact point position by using the instrumented wheelset (IWS). Solutions of key problems in the development of IWS are proposed, such as the determination of optimal locations, layout, number and way of connecting strain gauges as well as the development of an inverse identification algorithm (IIA). The base for the solution of these problems is the wheel model and results of FEM calculations, while IIA is based on the method of blind source separation using independent component analysis. In the first phase, the developed method was tested on a wheel model and a high accuracy was obtained (deviations of parameters obtained with IIA and really applied parameters in the model are less than 2%). In the second phase, experimental tests on the real object or IWS were carried out. The signal-to-noise ratio was identified as the main influential parameter on the measurement accuracy. Тhе obtained results have shown that the developed method enables measurement of vertical and lateral wheel–rail contact forces Q and Y and their ratio Y/Q with estimated errors of less than 10%, while the estimated measurement error of contact point position is less than 15%. At flange contact and higher values of ratio Y/Q or Y force, the measurement errors are reduced, which is extremely important for the reliability and quality of experimental tests of safety against derailment of railway vehicles according to the standards UIC 518 and EN 14363. The obtained results have shown that the proposed method can be successfully applied in solving the problem of high accuracy measurement of wheel–rail contact forces and contact point position using IWS.