Rail Sleeper Research Articles

Concrete sleeper crack detection based on image saliency

Abstract Concrete sleepers are crucial infrastructure in railway construction and operation. Sleeper cracks may cause structural damage or functional failure of sleepers, thereby endangering railway operation safety. A third-order residual crack saliency detection network (R3Net CSD) model was constructed based on ConvNeXt for detecting concrete sleeper cracks in track inspection images, which is used to accurately extract the saliency features of rail sleeper crack images. The model first uses ConNeXt to form the backbone network and Block module to form the first residual, followed by a spatial pyramid (DCSP) module based on the anti residual structure and dilated convolution group to form the second residual, and finally uses the saliency residual (Att-R) module to form the third residual. At the same time, combined with a multi-level joint loss function supervision strategy for supervised learning, the model fully utilizes the low-level edge information and high-level semantic information of cracks. Using the images collected by the hand pushed rail inspection vehicle, a dataset of rail sleeper cracks was manually constructed and the model was experimentally validated. The experimental results show that this model achieved the best results in multiple indicators, such as an average absolute error MAE of 0.0082, an average accuracy AP of 0.9764, and an AUC value of 0.995. By combining the calculation method of crack geometric parameters, quantitative indicators of crack length and width were obtained, with a detection accuracy of 0.001mm. The research provides a new solution for the detection of cracks in concrete sleepers and the measurement of geometric parameters.

Comparative analysis of methods for predicting train-induced vibrations

Railway systems cause more severe vibration pollution than road systems, and the vibration pollution caused by railway systems has been increasing annually over the past two decades. Despite this, there is limited investigation into the accuracy of train-induced vibration prediction methods. Therefore, the present study investigated the accuracy of the detailed and general procedures proposed by the US Federal Transit Administration (FTA) for predicting train-induced vibrations. The accuracy of these methods was determined by evaluating their predictions against in-situ measurements of ground vibration levels induced by passing trains. The field experiments conducted in this study involved the measurement of train-induced vibration levels, the estimation of line-source transfer mobility (LSTM) by dropping a weight on rail sleepers, the evaluation of force density levels, and the determination of ground LSTM by dropping a weight on the ground. In addition, graphs were plotted to determine the relationships of train-induced vertical vibration levels with train speed, distance from the track centreline, and train length. The study compared measured and predicted vibration levels to assess the accuracy of the FTA’s detailed and general prediction methods. Results indicate that detailed assessments tend to overestimate vibration levels, while an optimized general vibration assessment curve offers a more precise estimate. Additionally, on the basis of the measurement data, the study explored the impact of train length on ground vibration and demonstrated that track ballast can absorb vibration energy along the wave propagation path. A frequency propagation contour plot was also created to analyse vibration energy across different frequencies. These findings enhance the reliability of train-induced vibration prediction methods and provide insights for improving vibration mitigation strategies in urban railway systems.

Dynamic response of polymeric railway sleepers under harsh loading and environmental conditions

ABSTRACT Several composite sleeper technologies have been developed, possibly allowing the railway sector to replace wood and concrete sleepers. Although high-magnitude impact loads can occur on the railway track and sleepers due to wheel/rail abnormalities or train derailment, the behaviour of these sleepers under impact loading has not yet been well understood. In this paper, a high-energy drop hammer facility was utilized to investigate the impact behaviour of a polymeric composite rail sleeper made of high-density polyethylene (HDPE) and unidirectional glass fibre reinforced plastic (GFRP). Quasi-static tests and high strain rate tests were conducted on the materials at room and low/high temperatures to gain more insight into the effects of the temperature and strain rate on the mechanical properties of the HDPE and GFRP made of virgin resin. The results suggest that both materials exhibit strong viscoelastic plasticity, temperature softening, and strain rate-hardening effects. High strain rate and low temperature made the GFRP material extremely brittle and prone to develop cracks. Due to the temperature and strain rate dependency of the thermoplastic materials of the sleepers, in addition to impact tests at room temperature (~23°C), impact tests were also performed at low temperatures (~ minus 30°C) on the sleepers. The findings suggest that low-temperature impact assessment should be considered for all polymeric sleepers (to be installed in regions having extremely low temperatures) since these low temperatures affect the ductility of polymers, decreasing the ultimate impact load-bearing capacity of composite sleepers.

Analysis of mesoscopic mechanical dynamic characteristics of ballast bed with under sleeper pads

The meso-dynamical behaviour of a high-speed rail ballast bed with under sleeper pads (USPs) was studied. The geometrically irregular refined discrete element model of the ballast particles was constructed using 3D scanning techniques, and the 3D dynamic model of the rail–sleeper–ballast bed was constructed using the coupled discrete element method–multi-flexible-body dynamics (DEM–MFBD) approach. We analyse the meso-mechanical dynamics of the ballast bed with USPs under dynamic load on a train and verify the correctness of the model in laboratory tests. It is shown that the deformation of the USPs increases the contact area between the sleeper and the ballast particles, and subsequently the number of contacts between them. As the depth of the granular ballast bed increases, the contact area becomes larger, and the contact force between the ballast particles gradually decreases. Under the action of the elastic USPs, the contact forces between ballast particles are reduced and the overall vibration level of the ballast bed can be reduced. The settlement of the granular ballast bed occurs mainly at the shallow position of the sleeper bottom, and the installation of the elastic USPs can be effective in reducing the stress on the ballast particles and the settlement of the ballast bed.

Effect of Critical Factors Influencing Longitudinal Track Resistance Leveraging Field Experimentation

As extreme temperatures increase, there is an increased need to ensure that continuous welded rail (CWR) stresses are more accurately set and better maintained. Therefore, to improve the management of CWR rail stresses and to increase safety through the reduction of buckled track derailments this paper documents the results from a field experimentation program of controlled single rail breaks (SRBs). SRBs were conducted at multiple field site locations to quantify the longitudinal resistance on both timber and concrete sleeper track. Accurate longitudinal resistance values are critical, because if the wrong value is selected, the rail neutral temperature could easily be set to a low value, increasing the probability of a track buckle or rail pull-apart, further compounding the impact of extreme temperatures. The results presented quantify the effect of sleeper and fastener type as well as ballast consolidation, and compare them with relevant results from the literature. From this, it was found that well-maintained concrete sleeper track exhibited a longitudinal resistance greater than the currently recommended value. Further, well-maintained timber sleeper track with anchors on every other sleeper exhibited a longitudinal resistance 44% lower than concrete sleeper track and 30% lower than timber track with anchors installed on every sleeper. Additionally, disturbing the ballast reduced the longitudinal resistance by 15%. Finally, the results indicated that slip was primarily occurring at the rail–sleeper interface for unanchored timber sleepers and at the sleeper–ballast interface for anchored timber sleepers and concrete sleepers.

Track‐Bridge Interaction: Influence of Transition Zone on the Stability of Continuous Welded Rail

AbstractRealization of high‐speed rail track demands continuous welded rail (CWR) to be laid on bridges without providing special expansion joints. In India, the existing rail bridges must be evaluated for their suitability for upgradation to CWR. CWR Inherently develops axial stress on account of the surrounding temperature changes. CWR in track‐bridge transition zone is subjected to additional stress and displacements as a result of track‐bridge interaction (TBI). Longitudinal thermal loading is a major source of rail stress and substructure forces due to TBI. Also, TBI results in accumulation of large compressive stress in transition zone. Further, the tamping effect in the transition zone by passing vehicles due to sudden change in vertical stiffness weakens the transition zone ballast. CWR is a slender steel element prone to buckling under large compressive stress. A numerical model is developed for track bridge interaction phenomenon in SAP2000 considering the aspect of CWR track buckling. In this study, the developed model is utilized to perform nonlinear buckling analysis to assess the influence of change in ballast stiffness on CWR stability in transition zone. Also, the influence of missing ballast contact raising from ballast subsidence locally in the transition zone was investigated. A single span simply supported steel bridge is considered. Longitudinal thermal loading is considered in this study. CWR supported on the ballasted track is considered. Material Nonlinearity associated with ballast is considered. Maintenance of CWR track is found to play a key role in track stability as the loose ballast or missing of ballast underneath the rail sleeper is to introduce discontinuity in CWR track support and reduces the critical buckling temperatures of the track considerably. Overall, this study contributes to the understanding of track‐bridge interaction and the stability of CWR in the transition zone.

Sensor system for determining the risk of track distortion in the continuous welded rail

The article considers the peculiarities of load formation in the continuous welded railroad tracks depending on temperature factors, geometric parameters and local curvature. The approach is proposed to determine the risk of distortion of the railway track depending on a combination of force and geometric factors on the ability of the ballast to keep the rail sleepers from moving laterally in relation to the direction of the track.

Bayesian System Identification of Rail–Sleeper–Ballast System in Time and Modal Domains: Comparative Study

Bayesian System Identification of Rail–Sleeper–Ballast System in Time and Modal Domains: Comparative Study

The sleeper group influences on lateral resistance and stability of ballast bed

ABSTRACT The sleeper group, composed of a certain number of rail sleepers, influences the characterization of lateral resistance and the stability of continuous welded rail (CWR). According to full-scale model tests and discrete element model simulation tests of ballast bed, we established a new lateral stability analysis model of CWR considering the effect of sleeper group and resistance sharing characteristics, and compared it with the traditional model. The case analysis shows that the lateral stability analysis result of CWR is safer when considering the effect of sleeper group. When the curve radius is 300 m, the safety margin of the sleeper group model is about 20.8% larger than that of the traditional model. For CWR with potential large lateral displacement in special sections (such as small-radius and large temperature difference), it is advisable to consider the effect of sleeper group for the lateral stability analysis.

Utilization of Waste (Plastic) Material in Road Construction

Abstract: The disposal of plastic garbage is the most serious issue this type of garbage is not biodegradable. In the developing countries disposal of plastic garbage is also one of the challenging issues and in the developing countries like India such type of garbage disposal problem has been encountered. The most suitable method of utilization of these waste materials is to adopt them in road construction, which is both economical and durable. With the help of the presentation, we are attempting to introduce various ways in which plastic can be utilized, and because our project is primarily focused on plastic roads, we’ve also gone over the many processes to take while using plastic on roads. With this technology, a major problem of plastic waste disposal may be tackled at the same time. Using plastic in roadways boosts the strength and longevity of roads while also being cost-effective, pollution-free, and safe. Plastic technology encompasses a wide spectrum of applications. Since this can be used to make textiles, rail sleepers, and plastic can also be used as a construction material, if plastic roads become more common, the demand for transportation engineers who are familiar with this technology will expand. Increased demand for plastics will result in more plastic pickers being employed, therefore resolving the job issue. Keywords: Environmental Pollution, Waste Material, and Road Pavement

On the selection of the most plausible non-linear axial stress–strain model for railway ballast under different impulse magnitudes

The effective maintenance and health monitoring of ballasted railway tracks, which involves the determination of differential settlement, track support stress and stiffness, and the strain-hardening property of ballast, is essential. The vertical stress–strain behavior of the ballast layer is primarily responsible for the irrecoverable strains and settlements in tracks, leading to further track degradation. This article reports the development of a series of applicable yet simple uniaxial models and the selection of the most plausible one for capturing the behavior of vertical stresses and strains in ballasts utilizing a set of measured vibration data of the rail–sleeper–ballast system from a Bayesian perspective. From the literature, the dynamic behavior of ballast can be divided into linear and non-linear regions. Under small amplitude vibration, the stress–strain property is linear and elastic, while the behavior becomes non-linear and inelastic once the elasticity limit is exceeded. By integrating the linear phase to some well-known non-linear engineering material laws, a list of new ballast stress–strain model classes was developed. An enhanced Markov chain Monte Carlo–based Bayesian scheme was utilized to explicitly handle the uncertainties in the model updating process, while the Bayesian model class selection method was employed to select the most plausible ballast stress–strain model class under the prevailing system conditions. The proposed methodology was verified using three sets of measured acceleration data from impact hammer tests on an in situ sleeper with simulated ballast damage. The obtained results suggest that the linear-elastic model is sufficient for small amplitude vibrations, while the modified Voce model is the most plausible amongst the investigated model classes for high impact load. The results also demonstrate the importance of the non-linear ballast model in ballast damage identification and the potential applicability of the selected ballast model in field track monitoring.

Study on the Mechanical Characteristics of the Sleeper Slab Track on a Long-Span Steel Truss Bridge

This paper uses the long-span steel truss slab track as its research subject to analyze the new type of sleeper slab track structure with an experimental method. Firstly, a full-scale model was established in the laboratory to form a “rail–sleeper slab–self-compacting concrete cushion–steel beam” composite structure, and a fatigue test was performed on the track structure. The cyclic load was set up as a sine form with a range between 75 and 375 kN at a 5 Hz interval and 3 × 106 cycles. Based on the test, the performance of the track structure under cyclic train load was studied. Secondly, after every 106 loading cycles, the vertical static loading test and horizontal resistance test of the track structure were carried out to obtain the strain and displacement under different loading cycles. Finally, after 3 × 106 cycles of sine cyclic loading, the horizontal ultimate resistance test of the track structure was carried out to study its horizontal failure mode. The aims of this paper were to verify the applicability of the sleeper slab track, identify the mechanical properties, and determine the unfavorable position. The findings can provide an important reference for the practical use of the sleeper slab track structure.

RAILWAY STRUCTURES PERFORMANCE DUE TO FREIGHT INTERMODAL SERVICE AT BOJONEGORO – KALITIDU ROUTE


 
 
 
 Goods movement using container are quite efficiently assessed because it can carry a great amount of goods fit to container capacity. Freight transportations is a primary component of all supply-chain and logistics systems, but in contrary using a truck as its transportation means causing many problems such as air and noise pollutions, traffic congestions, road accidents and road damage. Depart from this facts, so government is looking for another means of freight transporter which more efficient with a bigger load capacity advantages. This options goes to train as a solutions of intermodal freight transportations lack. In order to supporting intermodal freight transportations, right now double track of railway is available for Jakarta – Surabaya route (Northern line route). By now, noted that freight transportation with double track railway frequency is potentially increase to 15 trip per days with capacity 500 TEU (Twenty feet Equivalent Units) per days and fuel consumptions (with truck) can be thrifted into 115 kl per days also reducing carbon monoxide emission amounts 350 tons per days. According with an official statements from Directorate General of Railways, Ministry of Transportations, explained that Jakarta – Bojonegoro route on double track railway is fully operated so this paper is conducted to determining feasibility of railway structure performance due to freight intermodal transportations at Bojonegoro – Kalitidu route. Railway structure performance feasibility is observed from loading distributions, rail strength, rail sleeper strength, and railway subgrade endurance to planned freight trains. As a result of this research obtained that tension force that occurred on rail is 830,10 kg/cm2 < permitted tension on rail (first class rail) 1325 kg/cm2. So, tension force that occurred on rail is safe. Moment force that occurred on rail bottom is 14521,25 kg.cm < permitted moment force (150.000 kg.cm) Moment force that occurred in the middle of rail sleeper is 58993,978 kg.cm < permitted moment force (93000 kg.cm). Tension force that occurred on above railway subgrade (σ2) is 4,17 kg/cm2 < qu (29,671 kg/cm2). It means that railway subgrade is capable to supporting load of freight transportation operations along Bojonegoro – Kalitidu route.
 
 
 

Time-domain Markov chain Monte Carlo–based Bayesian damage detection of ballasted tracks using nonlinear ballast stiffness model

This article reports the development of a methodology for detecting ballast damage under a sleeper based on measured sleeper vibration following the Bayesian statistical system identification framework. To ensure the methodology is applicable under large amplitude vibration of the sleeper (e.g. under trainload), the nonlinear stress–strain behavior of railway ballast is considered. This, on one hand, significantly reduces the problem of modeling error, but, on the other hand, increases the number of uncertain model parameters. The uncertainty associated with the identified model parameters of the rail–sleeper–ballast system may be very high. To overcome this difficulty, the Markov chain Monte Carlo–based Bayesian model updating is adopted in the proposed methodology for the approximation of the posterior probability density function of uncertain model parameters. Owing to the nonlinear behavior of the system, the model updating is performed in the time domain instead of the modal domain. The applicability of the proposed damage detection methodology was first verified numerically using simulated impact hammer test data in two damaged cases perturbed with Gaussian white noise. Second, impact hammer tests of in situ sleepers in the full-scale in-door ballasted track test panel were carried out to collect data for the experimental verification of the proposed methodology. Artificial ballast damage was simulated under the target concrete sleeper by replacing normal-sized ballast particles (∼60 mm) by small-sized ballast particles (∼15 mm). The proposed methodology successfully identified the location and severity of ballast damage under the sleeper. From the calculated posterior marginal probability density functions of model parameters, one can quantify the uncertainties associated with the damage detection results. The proposed methodology is an essential step in the development of a long-term railway track health monitoring system utilizing train-induced vibration.

Study of the stress state of the sleeper base and sleepers of rail track with accounting variable conditions of their resting

The live problem of the stress state of the sleeper base and rail sleepers is considered in the article with taking into account specific normal and specific shear stresses under variable conditions of the sleepers resting on the base. The methodology is aimed at the determination of the mutual influence of normal (compressive) and tangential (shear) specific stresses on formation of stability due to the displacement of individual parts of the base. Stability zones and shear zones of the sleeper base parts are also determined by the authors at different conditions of the sleeper resting on the base. Further, zones with insecure position of the base under the sleepers are found when they and their under-rail parts continuously rest on the base. It is stated that insecure position of the base is formed when specific shear stresses excess specific stresses of shear resistance, which consists of specific friction and specific cohesion between the parts in the base. It is also established that loss of stability of the ballast particles causes their displacement in the direction of the action of specific shear stresses. In these zones, density and rigidity of the sleeper base decreases leading to a gradual redistribution of reactive resistance of the base along the sleeper, and, depending on this redistribution, a change in the bending moments acting on the sleeper occurs. It is found that when the sleepers rest only by their under-rail parts, shear stresses and forces, as well as stresses and shear resistance forces under the middle part of the sleepers are distributed in such a way that shear forces exceed resistance forces up to the depth of 60 cm from the sleepers sole. This phenomenon leads to the displacement of ballast particles under the middle part of the sleeper, consolidation of the ballast and resting of the sleepers by their middle part with possible cracks formation. In the end sections of the sleepers, there is also a loss of ballast stability. Recommendations for improving stability indicators of the sleeper base and strength of the sleepers are given. The obtained results of the study can be used for the mine, industrial and railway transport.

Bridge transition monitoring: Interpretation of track defects using digital image correlation and distributed fiber optic strain sensing

Railway bridge transitions represent locations of vertical stiffness variations that are believed to amplify the dynamic wheel loads which contribute to the development of both differential track settlement and hanging sleeper issues that are difficult to resolve despite the current knowledge of bridge transition behaviour. This paper presents a field monitoring study of a railway bridge transition in which track defects – including both gaps between the rail and sleeper plates, i.e. “rail–sleeper gaps,” and rail flange scrape marks exposing bare steel – were observed during a visual inspection of the transition. Trains were monitored by measuring both track displacements using Digital Image Correlation and distributed rail strains using a Rayleigh-based fiber optic analyzer. Through analysis and interpretation of the collected monitoring data, it was found that measurements of rail–sleeper gaps could be used to obtain a first-order estimate of the shape of the differential track settlement profile. Additionally, it was found that measurements of scrape marks on the rail flange could be used to estimate the extent of longitudinal rail movement that could occur during train passage, and that the loads applied to the bridge structure were influenced by the nature of the rail–sleeper gaps at the monitoring site.

Study of Direct Finite Element Method of Analysing Soil–Structure Interaction in a Simply Supported Railway Bridge Subjected to Resonance

This paper presents the dynamic soil–bridge interaction under high-speed railway lines, under different soil stiffness conditions. Starting from the analysis of a simply supported Euler–Bernoulli beam model subjected to moving loads, a three-dimensional multi-body (soil–abutment–bridge–ballast–sleeper–rail) model formulated in the time domain to study the vibrations induced due to the passage of moving concentrated loads was analysed using the direct finite element method of soil–structure interaction analysis. The high-speed train was considered to be a set of concentrated loads, the rail was modelled as a Euler–Bernoulli beam (frame element), and the sleepers, ballast, bridge, abutments and soil were modelled using eight-node solid (brick) elements. Layered soil stratum’s effects on the dynamic response of the bridge deck and variation of stresses were studied. From this study, it was observed that the direct method of FE analysis can be an effective tool to solve the complex dynamic soil–structure interaction problems.

Mixed mode crack tip parameters for different wheel positions relative to a vertical crack at the rail foot

AbstractFinite element method is used to analyze a rail with a vertical bottom up crack at its foot, under the axle load and surface traction of a wheel. The possibility of crack formation at the foot of the rail in the neighborhood of a welding connection is discussed. A brief review on the importance of T‐stress in brittle fracture is presented. Seven cases with different locations of the crack relative to rail's sleeper contact region are considered. Numerous positions of the wheel are considered, and in each case, 3 crack parameters KI, KII, and T‐stress are calculated. Then, the biaxiality ratio and the mixity parameter for each loading and crack condition are calculated. It is shown that the location of crack and wheel can create mixed mode loading in the cracked rail and that the magnitude of crack tip parameters are strongly dependent on these geometric variables. In particular, the magnitudes of T‐stress and biaxiality ratio are significant in some cases. The effect of friction between the crack faces in the presence of compressive mode I loading on the mode II stress intensity factor is studied. Under mixed mode loading, due to the axle load and surface traction, the most critical condition is the formation of vertical cracks near the sleeper contact region.

Initiation and development of rail corrugation based on track vibration in metro systems

Rail corrugation, one of the most deleterious types of track wear, affects the railroad industries in many countries. Rail corrugation leads not only to vehicle and track vibration, lifespan reduction of infrastructure, and safety and passenger comfort issues but it also produces track noise. This paper, based on the track vibration theory, studies the initiation and development of rail corrugation in both the time and frequency domains. First, four track models for the frequency-domain analysis are developed to model the common short sleeper track, vibration absorbing fastener track, elastic short sleeper track and ladder sleeper track. The frequency response analysis is performed to calculate the characteristic frequencies of the track models. In order to analyse the relationship between the natural vibration of track structures and rail corrugation, the characteristic frequencies are compared with the measured passing frequencies of tracks due to rail corrugation. Second, the vehicle–track–tunnel three-dimensional dynamic models are developed for the four track structures to study the initiation of rail corrugation under the influence of track vibration using the time-domain analysis. Finally, the development of rail corrugation for the four track structures is investigated by means of the wear growth rate. Moreover, the influence of other factors, such as the curve radius, the rail–sleeper relative position, the driving velocity and the wheel–rail friction coefficient, is discussed.

ОБОСНОВАНИЕ ВЫБОРА РЕЛЬСОВОГО СКРЕПЛЕНИЯ ДЛЯ ТЯЖЕЛОВЕСНОГО ДВИЖЕНИЯ

Objective: To improve track maintenance, which includes the reduction of damageability and life endurance improvement of ferroconcrete rail sleepers in maintenance, elimination of factors of increased dynamic impact on sub rail support, rail fastening design for heavy haul operation, which provides for traffic safety and improvement of economic performance indicators under increased mechanical loading conditions, taking into account severe weather conditions (freeze and thaw). Methods: Service damage analysis, laboratory and benchmark tests of individual track elements and in the assembled condition. Results: Operation rate and axial load increase demands improved durability of the applied track structure components under complete passenger transportation safety control. In this case economic efficiency of the applied components is a significant factor. The research results and technical solutions, having a common purpose – to improve track maintenance under the conditions of heavy haul operation were presented in the study. The measures on elimination of factors of increased dynamic impact on sub rail support were suggested in the study: 1) application of more reliable in operation bonded-bolted joints and metal-polymer bars instead of composite ones; 2) the use of higher quality rail induction welding. The improved rail fastening design was developed for rapid curves and heavy haul operation, leading to significant increase of service life of both metal parts, due to heat strengthening of the latter, and the fastening as a whole. Practical importance: The results of the conducted research make it possible to minimize the cases of destruction of ferroconcrete sleepers and solve the issues of qualitative improvement of rail fastening components.