Stock Rail Research Articles

Research on ultrasonic guided wave-based high-speed turnout switch rail base flaw detection

Turnout switch rail fracture detection is currently a serious issue in the field of railway transportation. Guided wave detection, a non-destructive testing method, is a good way of studying this issue and looking for a suitable solution. For this paper, a guided wave mode and an excitation position were selected based on the phase velocity dispersion curve and the wave structure. After this, a model was devised for the turnout switch area using the finite element (FE) method. This model considered the straight switch rail, curved stock rail, bolt hole, spacer block, and sub-rail foundation, and verifies the validity of the simulation model through the experiment. The propagation characteristics of guided waves in the switch rail were then simulated in different fracturing states by means of a 30-kHz excitation applied vertically to the rail base. The results showed that a single mode of the guided wave could be generated by this excitation method, showing that it could be used as an effective means for fracture detection. The growth rate of the root-mean-square (RMS) value of the time-domain acceleration signal could then be analysed to identify the state of fracture in the straight switch rail. This discrimination method is suitable for finding fractures parallel to the rail cross-section with a width of 5 mm or more at the bottom of the straight switch rail.

3D rolling contact finite element analysis of high-speed railway turnout considering ratchetting effect

The present work introduces a three-dimensional finite element model for the wheel-turnout-sleeper system, incorporating a cyclic constitutive model that accurately captures the nonlinear hardening behavior of rail steel under cyclic loadings. At the same time, a mixed implicit-explicit finite element method is employed to investigate the transient rolling contact behavior of wheel-turnout. Through dynamic analysis, the transient rolling contact status of the wheel-turnout, stress and strain responses of the turnout, and wheel-rail forces are investigated under varying crossing speeds and number of cycles. It is found that during the wheelset crossing, the contact stress remains relatively stable on the stock rail, and multi-point contact occurs at the wing rail and long point rail, and the contact stress on the surface of the long point rail is more significant. With an increase in crossing speed in the same cycle, there is a gradual rise in contact stress on the long point rail face. At the same crossing speed, with the increase in the number of cycles, the contact position between the wheelset and the long point rail gradually moves back, and the top width of the contact position gradually expands. Meanwhile, the fluctuation range of vertical displacement of the wheel center diminishes, and the wheel flange moves away from the long point rail. Additionally, a progressive accumulation of ratcheting strain is observed on the rail, and the ratcheting strain on the long point rail significantly exceeds that on the stock rail. The research results will help to provide a reference for the optimization and design of the critical cross-section profile of the long point rail and will have guiding significance for the maintenance and repair of turnouts.

Influence of different factors on the value of the rail wear rate

The article deals with the study of the influence of train operating modes on the uphill and downhill sections with radii less than 450 m, as well as the influence of railway superstructure design in curved sections on the wear rate of rolling stock wheel flanges and rails. The aim of the research is to reduce the wear that occurs between the wheel flanges of the rolling stock and the rails. Rail joints have been found to be the main shock source in the dynamic interaction between the railway and the rolling stock. There is unstable motion within the transition curves and at the joints of the curved rail on the curved track sections. This is accompanied by abrupt lateral rail wear in the joint area between the trailing and facing rails in the direction of train movement. It has been found that reducing the weight of the trains leads to a reduction in intensive lateral rail wear on curved track sections and can reach the following percentages: in curves with a radius of up to 300 m: up to 33% uphill, up to 55% downhill; in curves with a radius of 300 m to 450 m: up to 32.9% uphill, up to 26.3% downhill; in curves with a radius of 450 m: up to 3.2% uphill, up to 17.6% downhill. On the uphill and downhill sections, reducing the height and adjusting to the speed limit in percentage gives a positive result from 4.7% to 53.59%.

Dynamic vehicle–track interaction and structural loading in a crossing panel – calibration and assessment of a model with a 3D representation of the crossing rail

A three-dimensional (3D) finite element model of a railway crossing panel for use in multibody simulation (MBS) of dynamic vehicle–track interaction is presented. It is a two-layer track model with stock rails and sleepers represented by beam elements and a crossing rail represented by 3D solid elements. The track model uses linear bushings for the rail fastenings and bi-linear bushings for the ballast to allow for potentially voided sleepers. Based on the output from the MBS, the structural loading of the crossing in terms of strains, stresses and sleeper-ballast contact pressures is extracted in a post-processing step. The model is calibrated and validated to measurement data from a comprehensively instrumented switch & crossing (S&C) demonstrator installed in the Austrian railway network as a part of the European research programme Shift2Rail. The applied procedure for the calibration and critical assessment of the crossing model is described in detail. It is based on a model parameterisation with eight parameters relating to the rail fastening and foundation stiffnesses and to a distribution of the ballast voids. The calibration method uses Latin hypercube samples to explore the parameter space in a sensitivity analysis before a parameter optimisation is performed using a gradient-based method on a response surface built from a polyharmonic spline. In a comparative study it is shown that the 3D model and a more conventional beam model of the crossing rail show similar calibration results and good agreement with the measured data. The 3D model allows for the extraction of stress concentrations in the crossing rail but has an increased computational time of about 30% compared to the beam model.

Investigation of frictional rolling contact behavior in a switch panel considering traction load

The dynamic effects involved in wheel-rail interactions can be increased by the traction force potentially causing rapid degradation of turnout rails. A precise stress/strain analysis is essential for wheel-rail frictional rolling contact and the related degradation. Therefore, an explicit finite element method is established considering dynamic effects related to the contact. Furthermore, the frictional rolling contact solutions and related degradation with different traction coefficient in turnout are investigated. The results indicate that the effect of asymmetric excitation caused by traction force and geometric irregularities will lead to yaw motion of wheelset. The width of running band on the switch rail is increased as the top surface width of the switch rail increases. In addition, the contact patch on the switch rail will gradually shift forward compared to that on the stock rail, leading to excessive shear stress and increase of microslip. Meanwhile, the adhesion-slip distribution, uneven wear and severe plastic deformation during transition are recognized.

Evenness improvement method for high-speed turnout crossing areas

In this study, an evenness improvement method for new high-speed turnout crossing areas is proposed for the development of high-speed turnout and amplification of the wheel–rail dynamic impact in the crossing areas. A dynamic analysis model of the vehicle–turnout coupling system is established. In this model, the stock and switch rails as well as the wing and point rails are independent units. These independent units are connected using spring–damper units with variable parameters to accurately simulate the wheel-load transition process and the dynamic characteristics of the turnout. On this basis, an optimized scheme is developed for point rail–wing rail matching based on the center-of-mass oscillation compensation of wheelsets, and the rationality of the optimization method is verified via dynamic simulation evaluation at a high speed. Finally, the proposed method is validated through indoor actual-scale tests. The following are the results of this study. (1) As the vehicle passed over the crossing under the existing design scheme, the center-of-mass oscillation reached an oscillation length of 1.16–1.52 mm such that lifting the wing rail alone failed to eliminate the center-of-mass oscillation of the wheelsets. This is because the point and wing rails were incorrectly matched, leading to a backward shift in the wheel-load transition, thus causing a sharp drop of the wheelsets. Together with wing rail lifting, the longitudinal slope matching of the point rail effectively retained the wheel-load transition characteristics under the existing design scheme and eliminated the center-of-mass oscillation of the wheelsets. (2) As the train passed through the turnout crossing at a high speed, the optimized scheme substantially reduced the center-of-mass oscillation of the wheelsets, wheel–rail dynamic impact, and axle-box vibration while ensuring consistency of the wheel-load transition characteristics with the existing design scheme. (3) The maximum deflection change rate of the wing rail in the assembled crossing was only 1.67 mm/m, which could not meet the requirement of the theoretical longitudinal curve, and would cause the problem of turnout sleeper lifting, affecting the precision of laying turnouts on-site. Computer numerical control machining should be used to achieve the longitudinal curve requirement of the wing rail. The iron plate thickness should be increased gradually to 0.5 mm from the #82 sleeper to the #86 sleeper. Accordingly, the amount of machining of the wing rail should be increased from 0 mm to 2 mm. At the #92–#95 sleepers, this amount of machining should be decreased from 2 mm to 0.6 mm and then increased to 2 mm. This process would accurately realize the theoretical longitudinal slope curve.

Study on wear characteristics and authorized limits of switch rails of high-speed turnout

PurposeIt is quite universal for high-speed turnouts to be exposed to the wear of the stock rail of the switch rail during the service process. The wear will cause the change of railhead profile and the relative positions of the switch rail and the stock rail, which will directly affect the wheel–rail contact state and wheel load transition when a train passes the turnout and will further impose serious impacts on the safety and stability of train operation. The purpose of this paper is to provide suggestions for wear management of high-speed turnout.Design/methodology/approachThe actual wear characteristics of switch rails of high-speed turnouts in different guiding directions were studied based on the monitoring results on site; the authorized wear limits for the switch rails of high-speed turnout were studied through derailment risk analysis and switch rail strength analysis.FindingsThe results show that: the major factor for the service life of a curved switch rail is the lateral wear. The wear characteristics of the curved switch rail of a facing turnout are significantly different from those of a trailing turnout. To be specific, the lateral wear of the curved switch rail mainly occurs in the narrower section at its front end for a trailing turnout, but in the wider section at its rear end when for a facing turnout. The maximum lateral wear of a dismounted switch rail from a trailing turnout is found on the 15-mm wide section and is 3.9 mm, which does not reach the specified limit of 6 mm. For comparison, the lateral wear of a dismounted switch rail from a facing turnout is found from the 35-mm wide section to the full-width section and is greater than 7.5 mm, which exceeds the specified limit. Based on this, in addition to meeting the requirements of maintenance rules, the allowed wear of switch rails of high-speed turnout shall be so that the dangerous area with a tangent angle of wheel profile smaller than 43.6° will not contact the switch rail when the wheel is lifted by 2 mm. Accordingly, the lateral wear limit at the 5-mm wide section of the curved switch rail shall be reduced from 6 mm (as specified) to 3.5 mm.Originality/valueThe work in this paper is of reference significance to the research on the development law of rail wear in high-speed turnout area and the formulation of relevant standards.

Mechanical deformation properties of Continuous Welded Rail on kilometer-span suspension bridge for high-speed railway

The complex bridge-track interaction between kilometer-span bridges and continuous Welded Rail (CWR) brings great challenges to CWR designing. Taking a suspension bridge with laying CWR as a case, the mechanical properties of CWR on the bridge are analyzed to reveal the sensitive areas of the track, and the design method of CWR and track structures on the beam ends are proposed. The results show that the unidirectional Rail Expansion Joints(REJ) need to be installed on the beam end of the kilometer-span bridge to reduce rail longitudinal force. Due to the bridge characteristics, there is no CWR fixed area on the kilometer-span bridge, and rail longitudinal force on the main span caused by bending loads needs to be concerned. The deformation of track on the beam end is complex, which is the weak area on the kilometer bridge, the large relative displacement between the stock rail of REJ and the main beam can cause poor stability of ballast bed on beam end, small resistance fasteners need to be laid on the sides of stock rail on the main beam to increase the stability of ballast and fasteners on the beam end. To improve the driving safety and comfort of beam end, the Sleeper-Supporting Apparatus (SSA) should be specially designed to ensure the uniform transition of track on beam ends. Temperature and wind loads have a significant impact on track regularity on the kilometer span bridge, the dynamic response of trains and bridges under those loads needs to be attended to.

Multi-body dynamics analysis for the wear of front-rod bearing during the switching operation of railroad switches (Effect of adjustment condition)

Since the wear of front-rod bearings of railroad switches induce the switch failure, wear evaluation is indispensable. On the other hand, the various parts of railroad switches are adjusted so as to avoid derailment. For example, the attachment position of the adjustment nut of switch adjuster rod could enlarge the contact force between tongue rail and stock rail. The extension of front rod is also used to eliminate the gap between the toe of tongue rail and stock rail. In this paper, the bearing wear during the switching operation is estimated by multi-body dynamics simulation. The effects of the attachment position of adjustment nut and the extension of front rod are also evaluated. When the switch moves rightward, the driving force of electric point machine is transmitted to switch rod through switch adjuster rod. Then, the force is transmitted to right tongue rail through right switch rod bracket which connects switch rod and right tongue rail. Although the attachment position of adjustment nut controls the contact force between tongue rail and stock rail, that does not change the path of force transmission and the force acting on the bearing. Therefore, the attachment position does not affect the bearing wear. On the other hand, the extension of front rod changes the path of force transmission. The most of driving force of electric point machine is transmitted to the left switch rod bracket, front rod and right tongue rail in order. Therefore, the increase in the force acting on the bearing increases its wear. In the case of 6 mm extension of front rod, the estimated amount of wear is 3.44 μm, which is 3 times larger than the case of no extension.

Is the standard ride comfort index an actual estimation of railway passenger comfort?

Comfort on railway vehicles has been proven to depend on the number of passengers on the car, on their seating arrangement, as well as on the position in which it is assessed. The number of possible seating arrangement combinations is so large that comfort at a given location becomes a random variable even if passengers are considered deterministic vibration absorbers. In this paper we determine probability density functions (PDF) of comfort using a Monte Carlo scheme in which the number of passengers, their seating locations and their vibration characteristics (derived from passenger mass) are all random parameters with their own PDFs. Two types of distributions are obtained: the expected comfort of a single passenger and the compound comfort of all passengers on a given railway car. The carbody is represented by a beam model in which the first bending mode frequency has been allowed to vary so that the scope of results widens slightly. This variation is within the range of human sensitivity because this is the case in current lightweight construction, making carbody flexibility a key contributor to passenger comfort (or discomfort). Results confirm that comfort is indeed a stochastic variable with sizeable variance, and this prompts questions about the relation between the stochastic distribution and the tests prescribed in standard EN–12299. It will be shown that, surprisingly, comfort PDFs may be inferred with a high degree of accuracy (errors lower than 2%) from the tests in standard EN–12299. This is a most fortunate finding that radically transforms the interpretation of said standard, and allows rolling stock manufacturers and rail transport operators to have a much richer assessment of comfort on their vehicles from the same tests they now conduct, without having to perform Monte Carlo tests or simulations.

Random analysis of dynamic wheel–rail interactions in the switch panel of a turnout with geometric tolerances based on the probability density evolution method

During train operation, the geometric tolerance in a turnout can be very random, posing a challenge for traditional deterministic vehicle-turnout coupling studies and for daily maintenance. In light of the above situation, a coupled vehicle-switch panel model with random geometric tolerances is proposed. These tolerances result from the discrepancy in relative height difference of rail tops between the straight switch rail and the curved stock rail, and from the gap between the straight switch rail and the curved stock rail in the closure part. The model takes rail flexibility into consideration. The probability density evolution method (PDEM) is applied to capture the resultant probability density function (PDF) of dynamic wheel–rail interactions. The Monte Carlo method is employed for verification of results obtained from the PDEM. The results show that stronger randomness of the vertical wheel force is induced compared with that of the lateral wheel force. The probabilistic range of the vertical wheel force is found to be around 50 kN on the straight switch rail side. Given the largest maximum mean value of rail displacement, it is found that the part of the straight switch rail with a top width of 40 mm requires significant attention.

Sliding Window Dynamic Time-Series Warping-Based Ultrasonic Guided Wave Temperature Compensation and Defect Monitoring Method for Turnout Rail Foot.

Temperature changes are a major challenge in outdoor guided wave structural health monitoring of rails. Temperature variations greatly impact the waveform of guided wave signals, making it challenging to diagnose and characterize defects. Traditional temperature compensation methods, such as signal stretch and scale transform, are restricted to use in regular structures, such as plates and pipes. To solve the temperature compensation problem in long rails with serious mode conversion and complex structure echo, we propose a temperature compensation and defect monitoring method, namely, sliding window dynamic time-series warping (SWDTW), which overcomes the challenges of mass computation and overcompensation of dynamic time-series warping (DTW). The basic idea of SWDTW is to utilize sliding windows to accelerate the computation and identify defects from subsequence scales. Then, an index, window subsequence Teager energy (WSTE), is used to indicate the local abnormality of guided wave signals, and a sliding window net (SWnet) is devised to monitor the occurrence of defects automatically. Outdoor monitoring of turnout rails showed that the proposed method can effectively reduce the temperature noise and recognize an artificial defect with 1.16% and 0.36% cross-sectional change rates (CSCRs) on the switch and stock rails, respectively, at different temperatures; moreover, the defect signals processed by SWDTW showed better defect identification performance than those processed by scale transform and DTW.

Mechanism of Derailment at the Guardrail Position of Turnout and a Reasonable Guardrail Interval Limit

Recently, derailments have been occurring frequently at the guardrail position of double-slip turnouts. In order to provide a theoretical basis for effectively avoiding derailment at the guardrail position of turnouts, this study presented a derailment mechanism, discussed the rationality of the current guardrail interval limit and its calculation method, and proposed a method for calculating the guardrail interval limit based on the vehicle running attitude and wheelset angle of attack. Based on the established calculation model, this paper calculated the guardrail interval limit for the main types of single turnouts and double-slip turnouts in China, and studied the main factors influencing the interval limit and corresponding patterns. The following conclusions were drawn. (1) In actual maintenance, it suggested to set the guardrail interval limit at 1365 mm, which can meet the requirements of the most turnouts and avoid wear incurred by vehicle–track interactions at the opening section of guardrails and derailment. (2) For single turnouts, the required guardrail interval limit becomes smaller with the decrease of the frog number, radius of the lead curve, and the increase in gage width. Further, the interval limit decreases when the endpoints of the lead curve and gage widening become closer to the buffer segment at the toe end of the guardrail. Adopting straight-track design at the restoring segment of gage widening is more likely to cause a larger twisting angle of the bogie than a curved-track design, and larger twisting angle means requiring a smaller guardrail interval limit. (3) For double-slip turnouts, the required guardrail interval limit is reduced with the decrease in the frog number and increase in gage width. The broken rail comprising the switch rail and stock rail in front of the guardrail can also enable the bogie to approach or reach the inscribing state, resulting in a negative impact not smaller than that produced by a curved rail. The larger the attack angle at the tip of the switch rail and the closer the tip of the switch rail and the end of gage widening to the buffer segment of the guardrail, the smaller the guardrail interval limit.

Exporting the Luxembourg Rail Protocol to the Convention on International Interests in Mobile Equipment to Africa

Abstract This article recommends the Cape Town Convention on International Interests in Mobile Equipment and appeals to African countries to accede to the Luxembourg Protocol on Railway Rolling Stock (Rail Protocol). The discussion in this article focuses on the extent to which Article XXII of the Rail Protocol can be applied with respect to Africa. The article critically analyses the competence of the African Economic Community (AEC) and its sub-regional organizations to accede to the Cape Town Convention and Rail Protocol. The author provides a detailed argumentative analysis of the legal mandate of the AEC and the influence of African Union (AU) laws on the competence of the AEC’s sub-regional organizations to make declarations under the Cape Town Convention and Rail Protocol. The analysis confirms that competence to accede to the Convention and Rail Protocol resides with sovereign States in Africa and not with the AU, the AEC, the Organisation pour l’harmonisation en Afrique du Droit des Affaires, or any existing sub-regional organization in Africa.

A finite element modelling approach for the numerical analysis of switch rail contact loading and cyclic profile degradation

A dynamic 3D finite element model for the calculation of profile degradation in the switch panel is presented. The model includes the contact between wheel and rail, as well as the contact between switch rail and stock rail to allow an elastic relative movement between the two rails. Break-outs of the switch rail tip can be facilitated by this relative movement and the stresses and strains at this interface are calculated. The profile degradation of the switch rail due to contact loading between wheel flange and switch rail is numerically simulated considering the cyclic plastic deformation of the rail material. The sliding wear is evaluated separately and superimposed to the geometrical change caused by the plastic deformation.

A multi-objective optimisation method of rail combination profile in high-speed turnout switch panel

This paper presents a multi-objective optimisation method considering the switch and stock rail profiles in the switch panel. Based on the non-uniform rational B-spline (NURBS) theory, a parameterised model of the measured turnout profile is constructed to determine the variables. This study selects the vehicle dynamic performance and wheel-rail contact damage as the objective function to establish a multi-objective optimisation mathematical model that is solved using NSGA-II. Overall performances of the measured profile and the optimised profile are compared and evaluated for two aspects, dynamic performance and wheel-rail contact damage. The following are the conclusions: The maximum lateral vibration acceleration of the axle box is reduced from 2.64–2.09 m/s2, which has a 20.83% decrease. Concerning wheel-rail contact damage, the maximum wear index is reduced from 13.46–11.47 N, the reduction is 14.78%. At the same time, the cumulative surface rolling contact fatigue (RCF) is reduced from 8.29×10−5–7.38×10−5. This article can provide a profile repair method for worn turnouts, which can maximise the comprehensive performance of the turnout within a limited amount of grinding, and can reduce the wheel-rail contact damage of the turnout while taking into account driving stability.

A vision-based method for line-side switch rail condition monitoring and inspection

In railway systems, switch rails are one of the key components of switches & crossings (S&C). They are controlled by switch machines to guide trains from one track to another. Due to the discontinuity in geometry, switch rails are exposed to high-impact loads as train wheels pass through. The long-term impact loads can cause local plastic deformation. These faults, and general alignment changes, can lead to the development of a gap between the switch rail and the stock rail known as a toe gap, as well as non-optimal contact with the wheel flange, both of which can endanger the safe operation of passing trains. Currently, periodic visual inspection is the main method for detecting these defects. This is not efficient or reliable enough to support the ever-shortening maintenance windows available in modern railway systems. The development of computer vision technologies and constantly improving processors make it possible to monitor the health status of such safety-critical components in real time. This research proposes a line-side condition monitoring approach for the switch rail. With the use of dedicated identification algorithms, the status of the switch rail, including movement, position, toe gap and the edge of the toes, can be monitored remotely in real time. This approach has been tested in a high-speed train testing centre in China. The results show a capability to further improve the safe operation of S&C while simultaneously reducing the cost and increasing the safety of inspection.

The application of neural networks for the life-cycle analysis of road and rail rolling stock during the operational phase

The aim of this article is to assess the possibility of using neural networks to analyse the life cycle of rolling stock in the operational phase by selecting the number of rolling stock sets and rail using the example of public transport in the Szczecin agglomeration. The research was conducted in September 2019 and June 2020. It included the number of tram and bus rolling stock sets on individual public transport lines based on data from the Central Public Transport Management System in the Szczecin agglomeration. The research, which was based on comparative analyses of individual types of rolling stock and their technical and economic data, took into account the life-cycle assessment criteria associated with the operation of vehicles in relation to the number of rolling stock sets. The use of neural networks on the example of the city of Szczecin for the purpose of life-cycle analysis, can make a significant contribution to creating a decision model for the improvement of public transport in cities with various types of public transport vehicles.

Theoretical and Experimental Research on Switching Optimization of No. 9 Single Turnout with 60-kg/m Rails

Based on the necessity of optimizing the structure of No. 9 single turnouts of 60-kg/m rails, we addressed the issues associated with existing turnout switching design methods. Based on finite element analysis, we established a refined calculation model for turnout switching. The model can determine the plane alignment of a switch rail separated from the stock rail based on the actual force acting upon the switch rail. The obtained plane alignment is consistent with the actual situation and is thus reliable. Based on the established turnout switching model, the minimum flangeway width and dynamics between the strokes of the first and second traction points under different conditions were analyzed by numerical simulations. Accordingly, we propose an optimized scheme that takes 160 mm and 85 mm as the stroke value for the first and second traction points, respectively. The scheme helps to meet the requirements for minimum flangeway width while making the deformation of the switch rail more even and therefore minimizing the traction power. Based on the proposed design, trial production and laying of the new No. 9 single turnout with a 60-kg/m rail was conducted, and a switching test was performed. The switching forces at the first and second traction points of the new No. 9 turnout were approximately 1200 and 2000 N, respectively, which were higher than those of existing No. 9 turnouts with 60-kg/m steel rails. Besides, the minimum flangeway width satisfies the requirement for safe vehicle passage with a safety margin of 3–5 mm. The test results proved the effectiveness of the proposed turnout switching design method and parameter optimization scheme.

Considering the interaction of switch and stock rails in modelling vehicle-track interaction in a switch panel diverging route

Vehicle-track interaction in a switch panel diverging route is studied with a focus on the way its components may interact in the lateral direction. Taking one of the cases of S&C benchmark as the base model, several variants of the co-running track model are considered. In the first series of simulation, the effect of the lateral separation of the switch rail and stock rail is investigated, showing that only small differences are found in terms of wheel/rail forces between a track model where both rails are coupled, and one where they are free to move with respect to one another. Only transient effects are visible at the beginning and at the end of the two-point contact on both rails. While small, these differences can have some influence in terms of rolling contact fatigue and wear prediction. In the second series of simulation, co-running track models are developed including the baseplate and taking into account such effects as switch rail/stock rail contact at the undercut plane and dry friction. Significant changes are observed in the load distribution within the switch panel. Conclusions should be consolidated through experimental field measurement and using more realistic track models, e.g. discretely supported rail beam models.