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X. Liu
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1
This paper presents a matrix coupled model for the vehicle–track interaction analysis with the crossing panel taken into account. In this model, the wheel–rail contact is assumed to be elastic and solved by the mathematical matrix formulations. Specifically, the determination of the two-point contact during the transition of the wheel load in the crossing panel is demonstrated. To improve the efficiency while ensuring the accuracy in the simulation, a time step size varying solution is applied in the model. The performance of the crossing is validated using field measurement results and simulation results from other numerical methods. The comparable results proved that the model is capable to catch the main features of the wheel–rail interaction in the crossing panel. Moreover, the effect of track irregularities on the vehicle–track interaction is analysed. The simulation results indicate that track irregularities mainly affect wheel–rail interaction in the regular track. In the crossing panel, the variation of the rail geometry plays a dominant role in the wheel–crossing interaction rather than the track irregularity. This study contributes to the perfection of the current model for the vehicle–track interaction analysis and will help to provide more comprehensive guidance for the design, construction and maintenance of the railway track.
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This paper presents a matrix coupled model for the vehicle–track interaction analysis with the crossing panel taken into account. In this model, the wheel–rail contact is assumed to be elastic and solved by the mathematical matrix formulations. Specifically, the determination of the two-point contact during the transition of the wheel load in the crossing panel is demonstrated. To improve the efficiency while ensuring the accuracy in the simulation, a time step size varying solution is applied in the model. The performance of the crossing is validated using field measurement results and simulation results from other numerical methods. The comparable results proved that the model is capable to catch the main features of the wheel–rail interaction in the crossing panel. Moreover, the effect of track irregularities on the vehicle–track interaction is analysed. The simulation results indicate that track irregularities mainly affect wheel–rail interaction in the regular track. In the crossing panel, the variation of the rail geometry plays a dominant role in the wheel–crossing interaction rather than the track irregularity. This study contributes to the perfection of the current model for the vehicle–track interaction analysis and will help to provide more comprehensive guidance for the design, construction and maintenance of the railway track.
Development of Condition Monitoring System for Railway Crossings
Condition Assessment and Degradation Detection for Guided Maintenance
Railway crossings are essential components of the railway track system that allow trains to switch from one track to another. Due to the complex wheel-rail interaction in the crossing panel, crossings are vulnerable elements of railway infrastructure and usually have short service lives. The crossing damage not only results in substantial maintenance efforts but also leads to traffic disruptions and can even affect traffic safety. In the Netherlands, the annual maintenance cost on railway crossings is more than 50 million euros. Due to the lack of monitoring systems, the real-time information on crossing condition is limited. As a result, the present maintenance actions on railway crossings are mainly reactive that take place only after the occurrence of visible damage. Usually, such actions (repairs) are carried out too late and result in unplanned disruptions that negatively affect track availability. In the Netherlands, around 100 crossings are urgently replaced every year, accompanied by traffic interruptions. Also, there is a considerable number of crossings with the service life of only 2-3 years. The maintenance methods used by the contractors on such crossings are somewhat limited and usually ended up with ballast tamping. In this case, the root causes of the fast crossing degradation are usually not resolved, and the crossings are still operated in degraded conditions after the maintenance. In order to improve the efficiency of the current maintenance of railway crossings aiming for better crossing performance, the goal of this study is to develop a monitoring system for railway crossings using which the crossing condition can be assessed, and the sources of the degradation can be detected. Using such a system timely and proper maintenance on railway crossings can be provided. The main steps in achieving this goal were as follows: Based on the measured dynamic responses of railway crossings due to passing trains, several condition indicators were proposed; To provide the fundamental basis for the proposed indicators a numerical model for the analysis of vehicle-crossing interaction was developed; The effectiveness of the proposed indicators was demonstrated using the data from long-term monitoring of 1:9 and 1:15 crossings. The railway crossing conditions can be reflected in the changes in the dynamic responses due to passing trains. In this study, the responses were obtained from the crossing instrumentation and wayside monitoring system. The responses reflect the wheel-rail interaction, which consists of the wheel impact accelerations, impact locations and the rail displacements due to the impacts, etc. Based on the correlation analysis of the responses, the indicators related to the wheel impact, fatigue area and ballast support were proposed. The indicators form a basis for the structural health monitoring (SHM) system for the railway crossings. To verify the effectiveness of the proposed indicators, and to explain the experimental findings, a numerical vehicle-crossing model is developed using the multi-body system (MBS) method. The model is validated using the measurement results and further verified using the finite element (FE) model. The proposed indicators and the MBS model were applied to the condition stage identification and damage source detection of the crossings. The main outcomes are presented below. In the condition monitoring of normally degraded crossings, the proposed indicators were capable to catch the main degradation stages of the railway crossing ranging from newly installed to damaged and repaired ones. With the assistance of these indicators, the maintenance actions can be timely applied before the occurrence of severe damage. The proposed indicators can also be used for assessing the effectiveness of the performed maintenance (repair welding and grinding, ballast tamping, etc.). It was demonstrated that ballast tamping has no positive effect on the performance of the monitored 1:9 crossing. The proposed indicators can also help to detect the root causes of the crossing damage. In some cases, the degradation is caused by adjacent structures, and therefore the maintenance should be performed not on the crossing itself but of the track nearby. In this study, the fast degradation of the monitored 1:9 crossing was found to be caused by the lateral track deformation in front of the crossing. The numerical results confirmed the phenomenon that the train hunting motion activated by the track deviation. It was the source of the extremely high impacts recorded by the monitoring system that ultimately resulted in the fast crossing degradation. By knowing the damage sources, proper maintenance can be performed rather than the currently used ineffective ballast tamping. Additionally, it was found that crossing degradation can also result from external disturbances. It was proven that highly increased rail temperature due to the long duration of sunshine would amplify the existed geometry deviation in turnout. Considering the high sensitivity of wheel-rail interaction in the crossing, higher standards for crossing maintenance and construction are required for better crossing performance. This study contributes to the development of the condition monitoring system for railway crossings. The application of the condition indicators is a big step forward for the current maintenance philosophies from damage repair to predictive maintenance, and from “failure reactive” to “failure proactive”. The outcomes in this study will contribute to the better performance of railway crossings.
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Railway crossings are essential components of the railway track system that allow trains to switch from one track to another. Due to the complex wheel-rail interaction in the crossing panel, crossings are vulnerable elements of railway infrastructure and usually have short service lives. The crossing damage not only results in substantial maintenance efforts but also leads to traffic disruptions and can even affect traffic safety. In the Netherlands, the annual maintenance cost on railway crossings is more than 50 million euros. Due to the lack of monitoring systems, the real-time information on crossing condition is limited. As a result, the present maintenance actions on railway crossings are mainly reactive that take place only after the occurrence of visible damage. Usually, such actions (repairs) are carried out too late and result in unplanned disruptions that negatively affect track availability. In the Netherlands, around 100 crossings are urgently replaced every year, accompanied by traffic interruptions. Also, there is a considerable number of crossings with the service life of only 2-3 years. The maintenance methods used by the contractors on such crossings are somewhat limited and usually ended up with ballast tamping. In this case, the root causes of the fast crossing degradation are usually not resolved, and the crossings are still operated in degraded conditions after the maintenance. In order to improve the efficiency of the current maintenance of railway crossings aiming for better crossing performance, the goal of this study is to develop a monitoring system for railway crossings using which the crossing condition can be assessed, and the sources of the degradation can be detected. Using such a system timely and proper maintenance on railway crossings can be provided. The main steps in achieving this goal were as follows: Based on the measured dynamic responses of railway crossings due to passing trains, several condition indicators were proposed; To provide the fundamental basis for the proposed indicators a numerical model for the analysis of vehicle-crossing interaction was developed; The effectiveness of the proposed indicators was demonstrated using the data from long-term monitoring of 1:9 and 1:15 crossings. The railway crossing conditions can be reflected in the changes in the dynamic responses due to passing trains. In this study, the responses were obtained from the crossing instrumentation and wayside monitoring system. The responses reflect the wheel-rail interaction, which consists of the wheel impact accelerations, impact locations and the rail displacements due to the impacts, etc. Based on the correlation analysis of the responses, the indicators related to the wheel impact, fatigue area and ballast support were proposed. The indicators form a basis for the structural health monitoring (SHM) system for the railway crossings. To verify the effectiveness of the proposed indicators, and to explain the experimental findings, a numerical vehicle-crossing model is developed using the multi-body system (MBS) method. The model is validated using the measurement results and further verified using the finite element (FE) model. The proposed indicators and the MBS model were applied to the condition stage identification and damage source detection of the crossings. The main outcomes are presented below. In the condition monitoring of normally degraded crossings, the proposed indicators were capable to catch the main degradation stages of the railway crossing ranging from newly installed to damaged and repaired ones. With the assistance of these indicators, the maintenance actions can be timely applied before the occurrence of severe damage. The proposed indicators can also be used for assessing the effectiveness of the performed maintenance (repair welding and grinding, ballast tamping, etc.). It was demonstrated that ballast tamping has no positive effect on the performance of the monitored 1:9 crossing. The proposed indicators can also help to detect the root causes of the crossing damage. In some cases, the degradation is caused by adjacent structures, and therefore the maintenance should be performed not on the crossing itself but of the track nearby. In this study, the fast degradation of the monitored 1:9 crossing was found to be caused by the lateral track deformation in front of the crossing. The numerical results confirmed the phenomenon that the train hunting motion activated by the track deviation. It was the source of the extremely high impacts recorded by the monitoring system that ultimately resulted in the fast crossing degradation. By knowing the damage sources, proper maintenance can be performed rather than the currently used ineffective ballast tamping. Additionally, it was found that crossing degradation can also result from external disturbances. It was proven that highly increased rail temperature due to the long duration of sunshine would amplify the existed geometry deviation in turnout. Considering the high sensitivity of wheel-rail interaction in the crossing, higher standards for crossing maintenance and construction are required for better crossing performance. This study contributes to the development of the condition monitoring system for railway crossings. The application of the condition indicators is a big step forward for the current maintenance philosophies from damage repair to predictive maintenance, and from “failure reactive” to “failure proactive”. The outcomes in this study will contribute to the better performance of railway crossings.
The paper presents an integrated (experimental and numerical) tool for analysis of crossing performance in railway turnouts.
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The paper presents an integrated (experimental and numerical) tool for analysis of crossing performance in railway turnouts.
This paper presents the development of a multi-body system (MBS) vehicle-crossing model and its application in the structural health monitoring (SHM) of railway crossings. The vehicle and track configurations in the model were adjusted to best match the real-life situation. By using the measurement results obtained from an instrumented crossing and the simulation results from a finite element (FE) model, the MBS model was validated and verified. The results showed that the main outputs of the MBS model correlated reasonably well with those from both the measurements and the FE model. The MBS and FE models formed the basis of an integrated analysis tool, which can be applied to thoroughly study the performance of railway crossings. As part of the SHM system for railway crossings developed at Delft University of Technology, the MBS model was applied to identify the condition stage of a monitored railway crossing. The numerical results confirmed the highly degraded crossing condition. By using the measured degradation as the input in the MBS model, the primary damage sources were further verified. Through identifying the crossing condition stage and verifying the damage source, necessary and timely maintenance can be planned. These actions will help to avoid crossing failure and unexpected traffic interruptions, which will ultimately lead to sustainable railway infrastructure.
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This paper presents the development of a multi-body system (MBS) vehicle-crossing model and its application in the structural health monitoring (SHM) of railway crossings. The vehicle and track configurations in the model were adjusted to best match the real-life situation. By using the measurement results obtained from an instrumented crossing and the simulation results from a finite element (FE) model, the MBS model was validated and verified. The results showed that the main outputs of the MBS model correlated reasonably well with those from both the measurements and the FE model. The MBS and FE models formed the basis of an integrated analysis tool, which can be applied to thoroughly study the performance of railway crossings. As part of the SHM system for railway crossings developed at Delft University of Technology, the MBS model was applied to identify the condition stage of a monitored railway crossing. The numerical results confirmed the highly degraded crossing condition. By using the measured degradation as the input in the MBS model, the primary damage sources were further verified. Through identifying the crossing condition stage and verifying the damage source, necessary and timely maintenance can be planned. These actions will help to avoid crossing failure and unexpected traffic interruptions, which will ultimately lead to sustainable railway infrastructure.
This paper presents the investigation of the root causes of the fast degradation of a railway crossing. The dynamic performance of the crossing was assessed using the sensor-based crossing instrumentation, and the measurement results were verified using the multi-body system (MBS) vehicle-crossing model. Together with the field inspections, the measurement and simulation results indicate that the fast crossing degradation was caused by the high wheel-rail impact forces related to the hunting motion of the passing trains. Additionally, it was shown that the train hunting was activated by the track geometry misalignment in front of the crossing. The obtained results have not only explained the extreme values in the measured responses, but also shown that crossing degradation is not always caused by the problems in the crossing itself, but can also be caused by problems in the adjacent track structures. The findings of this study were implemented in the condition monitoring system for railway crossings, using which timely and correctly aimed maintenance actions can be performed.
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This paper presents the investigation of the root causes of the fast degradation of a railway crossing. The dynamic performance of the crossing was assessed using the sensor-based crossing instrumentation, and the measurement results were verified using the multi-body system (MBS) vehicle-crossing model. Together with the field inspections, the measurement and simulation results indicate that the fast crossing degradation was caused by the high wheel-rail impact forces related to the hunting motion of the passing trains. Additionally, it was shown that the train hunting was activated by the track geometry misalignment in front of the crossing. The obtained results have not only explained the extreme values in the measured responses, but also shown that crossing degradation is not always caused by the problems in the crossing itself, but can also be caused by problems in the adjacent track structures. The findings of this study were implemented in the condition monitoring system for railway crossings, using which timely and correctly aimed maintenance actions can be performed.
In the structural health monitoring for railway crossings, identifying the condition stages of the crossing elements is an important step for the crossing condition assessment. This paper presents the condition stages identification procedure using the multi-body system method. This study is carried out on the 1:9 crossings that are most commonly used in the Dutch railway and suffering a lot from damages. By introducing different types of damage into the vehicle-crossing model and compare the dynamic responses with the measurement results, the condition stages of the monitored crossing can be identified. The simulation results show that the development of vertical irregularity and clip damage are clearly reflected on the change of wheel-rail contact force and the rail vertical acceleration. The findings of this study can be further applied in the structural health monitoring (SHM) system for railway crossings developed by TU Delft.
...
In the structural health monitoring for railway crossings, identifying the condition stages of the crossing elements is an important step for the crossing condition assessment. This paper presents the condition stages identification procedure using the multi-body system method. This study is carried out on the 1:9 crossings that are most commonly used in the Dutch railway and suffering a lot from damages. By introducing different types of damage into the vehicle-crossing model and compare the dynamic responses with the measurement results, the condition stages of the monitored crossing can be identified. The simulation results show that the development of vertical irregularity and clip damage are clearly reflected on the change of wheel-rail contact force and the rail vertical acceleration. The findings of this study can be further applied in the structural health monitoring (SHM) system for railway crossings developed by TU Delft.
This paper presents a correlation analysis of the structural dynamic responses and weather conditions of a railway crossing. Prior to that, the condition monitoring of the crossing as well as the indicators for crossing condition assessment are briefly introduced. In the correlation analysis, strong correlations are found between acceleration responses with irregular contact ratios and the fatigue area. The correlation results between the dynamic responses and weather variables indicate the influence of weather on the performance of the crossing, which is verified using a numerical vehicle-crossing model developed using the multi-body system (MBS) method. The combined correlation and simulation results also indicate degraded track conditions of the monitored crossing. In the condition monitoring of railway crossings, the findings of this study can be applied to data measurement simplification and regression, as well as to assessing the conditions of railway crossings.
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This paper presents a correlation analysis of the structural dynamic responses and weather conditions of a railway crossing. Prior to that, the condition monitoring of the crossing as well as the indicators for crossing condition assessment are briefly introduced. In the correlation analysis, strong correlations are found between acceleration responses with irregular contact ratios and the fatigue area. The correlation results between the dynamic responses and weather variables indicate the influence of weather on the performance of the crossing, which is verified using a numerical vehicle-crossing model developed using the multi-body system (MBS) method. The combined correlation and simulation results also indicate degraded track conditions of the monitored crossing. In the condition monitoring of railway crossings, the findings of this study can be applied to data measurement simplification and regression, as well as to assessing the conditions of railway crossings.
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.
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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.
The paper presents an integrated approach for analysis and improvement of performance of railway crossings. The approach consists of a detailed finite element (FE) model of a wheel rolling over a crossing (validated against the measured crossing accelerations) and experimental tools installed on the crossings in situ. The studied crossings are the cast manganese steel 1:9 crossings. This type of crossings suffers from severe plastic deformations and cracks. The presented approach has been applied to improve the performance of these crossings and to assess the effectiveness of the maintenance actions.
The obtained numerical and experimental results have helped to explain the poor performance of the crossings. Moreover, a number of the design improvements have not only been proposed, but also effectiveness of these improvements have been confirmed by the numerical simulations and/or measurement results.
The results are presented and discussed. More details are in the extended version of this paper.
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The paper presents an integrated approach for analysis and improvement of performance of railway crossings. The approach consists of a detailed finite element (FE) model of a wheel rolling over a crossing (validated against the measured crossing accelerations) and experimental tools installed on the crossings in situ. The studied crossings are the cast manganese steel 1:9 crossings. This type of crossings suffers from severe plastic deformations and cracks. The presented approach has been applied to improve the performance of these crossings and to assess the effectiveness of the maintenance actions.
The obtained numerical and experimental results have helped to explain the poor performance of the crossings. Moreover, a number of the design improvements have not only been proposed, but also effectiveness of these improvements have been confirmed by the numerical simulations and/or measurement results.
The results are presented and discussed. More details are in the extended version of this paper.
Transition zones in railway tracks are the locations with considerable changes in the vertical support structures. Due to the differential stiffness and settlement in the open track and the engineering structure resulting in the dynamic amplification of the wheel forces, track settlement is usually observed in the approaching zones. The settlement in transition zones is detrimental to the track components and passenger comfort. This paper presents the results of the experimental analysis performed in three transition zones which were in various conditions. The dynamic displacements of rails due to passing trains were measured at multiple points (dynamic profile) in the approaching zones. The device employed is a contactless mobile device for measuring displacements, which is based on the digital image correlation technique. Because the operational parameters of the digital image correlation-based devices are important for measurement accuracy, prior to the in situ measurements, this device was tested in a laboratory to study the influence of the operational parameters, including the elevation/heading angles, the focal length of the cameras, and the measuring distance. After determining the optimal operational parameters for the railway field, multiple-point measurements were performed in the transition zones. The length of the approaching zone was studied first. Also, the dynamic profiles of the embankment–bridge and bridge–embankment transitions were analysed. Finally, by comparing the multiple-point displacements in the approaching zones in different conditions, it was found that the dynamic profile of the rail displacements has a good correlation with the track condition in the transition zone. The results are presented and discussed.
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Transition zones in railway tracks are the locations with considerable changes in the vertical support structures. Due to the differential stiffness and settlement in the open track and the engineering structure resulting in the dynamic amplification of the wheel forces, track settlement is usually observed in the approaching zones. The settlement in transition zones is detrimental to the track components and passenger comfort. This paper presents the results of the experimental analysis performed in three transition zones which were in various conditions. The dynamic displacements of rails due to passing trains were measured at multiple points (dynamic profile) in the approaching zones. The device employed is a contactless mobile device for measuring displacements, which is based on the digital image correlation technique. Because the operational parameters of the digital image correlation-based devices are important for measurement accuracy, prior to the in situ measurements, this device was tested in a laboratory to study the influence of the operational parameters, including the elevation/heading angles, the focal length of the cameras, and the measuring distance. After determining the optimal operational parameters for the railway field, multiple-point measurements were performed in the transition zones. The length of the approaching zone was studied first. Also, the dynamic profiles of the embankment–bridge and bridge–embankment transitions were analysed. Finally, by comparing the multiple-point displacements in the approaching zones in different conditions, it was found that the dynamic profile of the rail displacements has a good correlation with the track condition in the transition zone. The results are presented and discussed.