Two experimental tools to measure the railway crossing dynamic responses are presented. One system is ESAH-M equipped with a 3-D accelerometer and a speed detection sensor that featured for crossing instrumentation and characterised by fast installation/uninstallation, automatic data recording and processing. The other system is a Digital Image Correlation (DIC) based Video Gauge System (VGS) that record the dynamic displacements of the rail/sleepers. A number of measurements have been performed aiming to explore the feasibility of these experimental tools, establish the relation between the measured dynamic responses and condition of the monitored crossings and estimate the effectiveness of crossing maintenances. The measurements based on crossing instrumentation show that the crossing degradation process can be described using the dynamic responses. The wayside monitoring in different problematic track sections have shown the capability of detecting and quantifying ballast conditions. Both systems will be further applied in long-term monitoring of railway crossings.

Transition zones in railway tracks are locations with considerable changes in the vertical stiffness of the rail support. Typically they are located near engineering structures, such as bridges, culverts, tunnels and level crossings. In such locations, the differential settlement always exists and continually grows without proper maintenance. Due to the effect of the differential settlement and bending stiffness of the rails, hanging sleepers may exist, which are invisible under ordinary circumstances, but generate high displacements and impact during train passages. Therefore, a method to detect the differential settlement (Or hanging sleepers) of track transition zones is presented, which is combined with numerical simulations and field measurements.The numerical model of the track transition zone developed here uses contact elements for modelling the connection between the sleepers and the ballast, bilinear springs for fastening system and Hertzian spring for wheel-rail interaction. The model is capable for simulating the dynamic behaviour of the transition zones with differential settlement or hanging sleepers. Using the model, the dynamic responses such as the vertical displacement of rail, the dynamic wheel load, the axial stress in rail and the vertical stress of ballast has been be obtained and analysed. The field measurements were performed as well. Using Video Gauge System (VGS) the vertical displacements of rail in the vicinity of a track transition zone were measured. The differential settlement of the measured transition zone was analysed by comparing the measurement and numerical results. Finally, based on the obtained findings and the simulation results some track design improvements and suggestions for maintenance actions are given.

This paper presented the performance study of two frogs in a double crossover in the railway network in the Netherlands. These frogs are located on the same track line. Each train passes through Frog 1 in the facing direction and Frog 2 in the trailing direction. Both frogs are monitored with ESAH-M crossing dynamic behaviour measurement tool and remote displacement measurement system Video Gauge.Results indicate that Frog 1 experiences high wheel/rail contact force (acceleration) and wear in Frog 2 develops fast. Frog 2 suffers from lack support of ballast, while the potential damage in Frog 1 is mainly related to the rail part.

The procedure for analyzing turnout crossing performance is developed in this paper. The experimental and numerical analysis are both conducted to evaluate the dynamic behavior of the crossing and to further improve the crossing performance. Geometry and acceleration measurements are performed on common single turnouts in the Dutch railway network for analyzing the measured crossing performance and providing the input for numerical modeling. Meanwhile, a three-dimensional finite element model of a whole wheelset rolling over the crossing has been developed. The wing rail and crossing nose geometry as well as the wheel geometry have been used in the model. The numerical responses of the model comprise the dynamic contact forces between the wheelset and the crossing, displacements of the wheelset and crossing as well as the local contact stress and strain distributions, by which the crossing performance is evaluated and the fatigue life of the crossing is predicted. By this approach further improvement of the crossing nose and wing rail geometry can be realized.

In this paper a numerical procedure for analysis of rolling contact fatigue crack initiation and fatigue life prediction for the railway turnout crossing is presented. To analyse wheel–rail interaction, a three-dimensional explicit finite element (FE) model of a wheelset passing a turnout crossing is developed to obtain the dynamic responses such as the contact forces, displacements and accelerations as well as the stresses and strain in the crossing nose. The material model accounting for elastic–plastic isotropic and kinematic hardening effects in rails is adopted. The fatigue life of the rails is defined as the time to rolling contact fatigue crack initiation. In predicting the fatigue life Jiang and Sehitoglu model is used, which is based on the critical plane approach. Using the FE simulation results the ten critical locations on the crossing nose susceptible to crack initiation are determined first. Then, using the fatigue model the critical planes in these locations are obtained and the number of cycles to fatigue crack initiation is calculated for each location, based on which the most decisive location and the crossing life is determined. The results of the numerical simulations are presented and discussed.

A three-dimensional (3-D) explicit dynamic finite element (FE) model is developed to simulate the impact of the wheel on the crossing nose. The model consists of a wheel set moving over the turnout crossing. Realistic wheel, wing rail and crossing geometries have been used in the model. Using this model the dynamic responses of the system such as the contact forces between the wheel and the crossing, crossing nose displacements and accelerations, stresses in rail material as well as in sleepers and ballast can be obtained. Detailed analysis of the wheel set and crossing interaction using the local contact stress state in the rail is possible as well, which provides a good basis for prediction of the long-term behaviour of the crossing (fatigue analysis). In order to tune and validate the FE model field measurements conducted on several turnouts in the railway network in the Netherlands are used here. The parametric study including variations of the crossing nose geometries performed here demonstrates the capabilities of the developed model. The results of the validation and parametric study are presented and discussed.

The procedure for analysing rolling contact fatigue crack initiation and fatigue life prediction of the railway turnout crossing is developed. A three-dimensional finite element (FE) model is used to obtain stress and strain results, considering the dynamic effects of wheel-crossing rolling contact. Material model accounting for elastic- plastic isotropic and kinematic hardening effects is adopted. The results from FE analysis are combined with J-S fatigue model that is based on critical plane approach, and fatigue crack initiation life is predicted according to different positions on the crossing. The most critical position on the crossing is found and number of cycles to crack initiation is predicted.

Transition zones in railway tracks are locations with considerable changes in the vertical stiffness of the rail support. Typically they are located near engineering structures, such as bridges, culverts and tunnels. In such locations, the vertical stiffness of the track support varies, resulting in amplification of the dynamic forces acting on the track, which ultimately leads to deterioration of the vertical track geometry. Also,,differential settlement of the track sub-structure on both sides of the transition contributes to the deterioration of the vertical geometry. The deterioration process accelerates with increase of the operational velocities of the passing trains. Finally, all these result in increase of the maintenance efforts on correction of the track geometry in the transition zones.To analyze the dynamic behavior of transition zones due to the differential settlement, a finite element dynamic model (using explicit integration) of a track transition zone is developed. The model is also accounting for the effect of hanging sleepers. The model is verified against the measurement results performed using the Video Gauge System (VGS). With the developed model, the differential settlement of ballast and soil has been introduced and the effects of this settlement on performance of the track are analyzed. The resulting wheel forces and the dynamic responses of the track components are obtained and analyzed. Special attention has been paid on the stresses of ballast, which is one of the most vulnerable track components in the transition zones. Finally, conclusions on the effect of the various internal and external factors on the degradation process of the track in transition zones are drawn. With the developed model, the differential settlement of ballast and soil is induced and hence, the effects of the differential settlements can be analysed. The contact forces of wheel- rail interaction and the dynamic response of track components are obtained and analysed. Special attention has been paid on the stresses of ballast which are one of the most vulnerable components in the track transition zones. Finally, conclusions on the effect of the various internal and external factors on the degradation process of the track in transition zones are drawn.

The continuous increasing demand of public transportation capacity requires the railway network operating in tight schedule. The high transporting volumes not only aggravate the degradation of railway infrastructure but also shorten the time for maintenance. Well-arranged infrastructure maintenance contributes to the budget reduction and reliability improvement. With the purpose of key parameters investigation in the turnout crossing degradation process, a series of subsequent measurements using instrumented crossing system (ESAH-M) on a 1:15 railway turnout at various stages were performed. The results indicate that wheel/rail impact area narrowed with deepened rail wear. This narrowing is a signal of rail damage. Frequency band pass filtered results describe the condition development of different structures in the turnout crossing section in the test period. Series of more systematic crossing measurements are in progress in a test section in the Netherlands. The ultimate purpose of this study is to form the crossing degradation function to be implemented in the structural health monitoring system (SHMS) for railway turnouts developed at the TU Delft.

Proper rail geometry in the crossing part is essential for reducing damage on the nose rail. To improve the dynamic behaviour of turnout crossings, a numerical optimisation approach to minimise rolling contact fatigue (RCF) damage and wear in the crossing panel by varying the nose rail shape is presented in the paper. The rail geometry is parameterised by defining several control cross-sections along the crossing. The dynamic vehicle–turnout interaction as a function of crossing geometry is analysed using the VI-Rail package. In formulation of the optimisation problem a combined weighted objective function is used consisting of the normal contact pressure and the energy dissipation along the crossing responsible for RCF and wear, respectively. The multi-objective optimisation problem is solved by adapting the multipoint approximation method and a number of compromised solutions have been found for various sets of weight coefficients. Dynamic behaviour of the crossing has been significantly improved after optimisations. Comparing with the reference design, the heights of the nose rail are notably increased in the beginning of the crossing; the nominal thicknesses of the nose rail are also changed. All the optimum designs work well under different track conditions.

The dynamic behaviour of turnout crossings is analysed using field measurements. The dynamic responses of a turnout due to passing trains are measured using a mobile device. The main elements of the device are the 3D acceleration sensor (to be installed at the crossing nose), the velocity sensor and the sleeper displacement sensor. The measured dynamic responses of the turnout primarily comprise of the accelerations of the crossing nose and the displacements of a sleeper recorded for the three dimensions. Geometry of the crossing nose of the turnouts has been measured using a laser-based device Calipri. Based on velocity of the passing trains (which is measured as well) the locations of the maximum accelerations of the crossing nose due to each wheel are derived. These locations indicate the most probable area for initiation of the fatigue defects on the crossing nose. Using the above-mentioned device a number of turnouts were measured. The dynamic responses were collected and analysed. From the measured results it was observed that the type of rolling stock and geometry of the crossing nose have strong influence on the location of the impact contact on the crossing nose and finally on its damage. Based on these results it can be concluded that by proper adjustment of the crossing nose geometry its condition can be controlled and damage to the crossing nose can be reduced.

This paper focuses on simulating the impact of a railway wheel on the crossing nose, when the train is passing through a turnout using a three-dimensional dynamic finite element model. The model provides the dynamic contact forces between the wheel and the crossing, as well as the wheel and crossing nose displacements; detailed investigations such as stress distribution in the rail are also possible. The realistic wing rail and crossing geometry has been used in the model to analyse the local contact situation. Several field measurements were conducted in the railway network in the Netherlands and were used to develop and validate the finite element model in this paper. The effects of various axle loads, train speeds are investigated. The model presented can be used to study the short-term behaviour of the crossing and provide a good basis for prediction of the long-term behaviour of the crossing.

Proper rail geometry in the crossing part is essential for reducing damages on the nose rail. A numerical optimisation approach to minimise impact damage and wear in the crossing panel by varying the nose rail shapeis presented in the paper.Theoptimisation formulatedas a weighted multi-objective problemis solved by adapting the Multipoint Approximation Method (MAM).Dynamic vehicle-turnout interaction as a function of crossing geometry is investigated using multi-body simulation method. The optimisation problem has been solved for different sets of weightcoefficients. Afterwards the robustness of the optimumdesigns has been analysed under different vehicle-track system conditions.