Operation Of Railway Vehicles Research Articles

Analysis of Non-Road Mobile Machinery Homologation Standards in Relation to Actual Exhaust Emissions

This article presents issues related to the current approval procedures in the group of off-road vehicles. Our research aimed to demonstrate significant differences between actual railway vehicle operation and stationary homologation tests regarding exhaust emissions. The research cycle consisted of analyzing emissions of toxic compounds from exhaust systems under real operating conditions, supplemented by a temporal share analysis based on the denormalized NRTC test upon which the tested object was homologated. Based on the conducted analyses, a significant difference was found between the actual operation of the tested railway vehicle and the stationary homologation test. By interpreting emission intensities within the parameter ranges of the propulsion unit’s operation, key areas with a significant impact on the vehicle’s overall emissions were identified. Based on the obtained results, a critical opinion is expressed regarding current homologation standards for the off-road vehicle group and the necessity for further empirical research in the area of actual operation of the tested vehicle group.

The Impact of Wheel Flat on Traction Drive System of Electric Locomotives

Wheel flat can seriously affect the wheel–rail contact performance and cause impact vibrations, which significantly threaten the safe operation of railway vehicles. It is crucial to accurately assess the effects of wheel flats on the wheel–rail contact performance and the vibration impact on the traction drive system. However, studies related to wheel flats have focused on the mechanical part and have yet to fully consider the electrical and mechanical parts of the entire traction drive system. Therefore, this paper first builds an electromechanical coupling model based on the electric traction drive system and the locomotive-track coupling dynamics model. Then, based on this model, the impact of the wheel flat on the electrical and mechanical parts of the traction drive system under different flat lengths, different flat depths, and different vehicle speeds was analyzed. The results indicate that with the increasing depth of the flat spot, the wheel–rail dynamic response, motor rotor speed, and motor torque exhibit more significant fluctuations. Additionally, as the locomotive speed increases, the impact of the flat on the wheel–rail contact performance intensifies. Wheel flats can excite the 1st bending mode of the wheelset, resulting in vibration shocks at 90 Hz.

The Safety, Operation, and Energy Efficiency of Rail Vehicles—A Case Study for Poland

The objective of the article was to describe the importance of a good technically and economically planned process for purchasing a rail vehicle. Compliance with this process with safety standards and energy efficiency is crucial regarding effectiveness in the long-life cycle cost of a rail vehicle. Methods that were used focused on audit and document analysis. In the result based on a specific audit of a railway company, some non-compliances were found, and it was methodically proven that they are significant risk factors in terms of performing such processes in the future. Major conclusions regarded the importance of fulfilling legal requirements of SMS for purchase purposes, involvement of a safety engineer post in this process, and usage of technical feedback regarding previous operation of railway vehicles and operational findings from the past. The transport policy of the EU and other developed countries sets ambitious goals for reducing energy consumption in transportation activities, which is linked to the aim of reducing environmental burdens.

Autonomous configuration establishment method of wireless network on condition monitoring for coupling and decoupling of railway vehicles

AbstractIn recent years, with the development of IoT, research and development of wireless sensor networks for monitoring has been advanced to monitor the condition of various devices in railway vehicles and notify train crews. In the operation of railway vehicles, the composition may be changed at stations by coupling and decoupling, and it is necessary to set up inter‐vehicle wireless network considering them. Therefore, to transmit sensor data in railway vehicles, we propose an autonomous configuration establishment method of wireless network for railway vehicles considering coupling and decoupling.

A Study on Wheel Member Condition Recognition Using Machine Learning (Support Vector Machine).

The wheels of railway vehicles are of paramount importance in relation to railroad operations and safety. Currently, the management of railway vehicle wheels is restricted to post-event inspections of the wheels whenever physical phenomena, such as abnormal vibrations and noise, occur during the operation of railway vehicles. To address this issue, this paper proposes a method for predicting abnormalities in railway wheels in advance and enhancing the learning and prediction performance of machine learning algorithms. Data were collected during the operation of Line 4 of the Busan Metro in South Korea by directly attaching sensors to the railway vehicles. Through the analysis of key factors in the collected data, factors that can be used for tire condition classification were derived. Additionally, through data distribution analysis and correlation analysis, factors for classifying tire conditions were identified. As a result, it was determined that the z-axis of acceleration has a significant impact, and machine learning techniques such as SVM (Linear Kernel, RBF Kernel) and Random Forest were utilized based on acceleration data to classify tire conditions into in-service and defective states. The SVM (Linear Kernel) yielded the highest recognition rate at 98.70%.

Applicability Verification of Restoration by Welding to Extend the Lifetime of Railway Wheel

Railway wheels, when subjected to wear beyond their designated usage standards due to the operation of railway vehicles, are traditionally managed through a turing maintenance method. This process involves turing the entire worn portion to secure the requisite cross-sectional shape. This approach often leads to disposal after just 2 to 3 turing maintenance cycles. Excessive turing, extending beyond the worn parts, can cause the wheels to fail to meet railway operating specifications. Discarded railway wheels, which contain a high carbon content essential for driving performance, are not repurposed but are instead entirely stockpiled. This research introduces a novel welding restoration technology for railway wheels, targeting the flange portion, a principal area of wear. Utilizing submerged arc welding techniques, this method enables the localized repair of worn parts, minimizing the turing thickness and thus extending the useful life fo railway wheel. To evaluate the on-site applicability and dependability of this welding restoration method, real rail vehicle driving tests were conducted using both conventionally turned and welding-restored railway wheels. Analysis of the wheel profiles substantiated that the welding restoration method delivers mechanical performance comparable to that achieved by traditional turning maintenance.

Defect Detection of Metro Wheel Set Tread Based on Image Recognition

In the operation of railway vehicles, the quality of bogies directly affects the operation quality and driving safety. Wheel set is one of the most important components in bogie, so the maintenance of wheel set is very important. For a long time, the detection of train wheel sets in China is still in the stage of manual measurement with backward technology and low efficiency. A new automatic detection method of wheel flange tread based on fuzzy neural network image processing technology is proposed in this paper. This method can accurately detect the defects of wheel flange tread. It collects the original image of the tested wheel set through the digital camera, inputs it into the computer, through certain calculation and processing, and compares it with the model established based on fuzzy neural network, so as to detect the defects of wheel flange and tread. First, the research status of wheel tread defect detection is summarized. Second, the basic principles of digital image technology are studied, the image processing models are confirmed, and the image processing method based on fuzzy neural network is established. Finally, eight wheel set treads are selected to carry out defect detection, and the analysis results show that the proposed method can obtain the better inspection precision.

Technological solutions for the efficient protection of workers in the track area

Abstract: Work on and in the vicinity of active railway tracks or other tracks is particularly hazardous work. They involve high risks for workers who may be hit or run over by moving rail vehicles or track machinery. Workers may also be electrocuted by the overhead catenary or overhead electrical network, which for non-traction purposes is supplied with 3000 volts DC. To ensure an adequate level of safety during this type of work, active tracks should be cordoned off and marked in accordance with railway regulations. Guidelines for securing the site of works carried out on closed track during the operation of railway vehicles on live track at a speed of V ≥ 100 km/h are defined in Railway Instruction Id-18. All types of construction work on live railway lines and overhead contact lines may only be carried out on the basis of the Instruction for Safe Work Performing (IBWR), which is an annex to the Safety and Health Plan (Safety and Health Plan). It is important to remember that the site protection systems used should be certified and approved for use on railway lines. Rail transport is a particularly demanding area in terms of safety. The key to increasing its level is to continue existing and take new measures to promote the idea of safety. Automatic Warning Systems are still an innovative solution in Poland, which has been successfully proven in Europe for several years and is a safer option for the railway signalman. The system is responsible for the safe warning of railway traffic in the area of the repaired and adjacent track. Risks arising due to human fallibility or caused by human error are eliminated to a minimum. Keywords: Technological solutions; Trackway; Railway line

Flow rate measurement in Intermittent jetting of Ceramic particle jetting device for Railway vehicles

Wheel slide or wheel slip that occurs during railway vehicle operation is one of the most important problems because it causes damage to the wheels and rails. A solution to this problem is the use of a ceramic particle jetting device that jets ceramics at high speed from a nozzle between the wheels and rails using the air of the vehicle. This device has been used by domestic and foreign railway companies, but there are no detailed regulations on the jetting method used, and each railway operator has its own standards and uses its own jetting time and method. As a result, the jetting is performed in a variety of settings, such as the single-shot jetting for a relatively long period of time or the intermittent jetting with repeated jetting in a short period of time, and there are currently no clear guidelines or established methods. The author has been developing a technique for measuring the mass flow rate of ceramic particles jetted in the ceramic particle jetting device. However, the measurements have so far been performed only under test conditions assuming the single-shot jetting. In this study, the author focused on the intermittent jetting of the ceramic particle jetting device and compared it with the single-shot jetting and verified changes in jetting flow rate and air consumption under different jetting time conditions.

Adhesion Characteristic Slope Estimation for Wheel Slip Control Purpose Based on UKF

Slip controllers are crucial for railway vehicle operation when a high tractive effort is required. The slip controllers have been developed for decades, and their developments continue. The developed slip controllers are based on many more or less effective principles. One of the perspective slip controllers determines a phase shift between an injected excitation signal to the required torque of the electric drive and the signal representation in a measured wheel angular velocity. The slip controllers that are based on the principle can effectively work with any adhesion conditions. However, the slip controller principle has some drawbacks like high filtration requirements, possible failure due to mechanical shock in the wheel-rail contact and long response time. The paper proposes a novel phase shift detection method for the slip controller based on an unscented Kalman filter that can cope with the known disadvantages of the original slip controller. When the proper output of the UKF is used, the slip controller becomes faster, more reliable and can work when the original slip controller fails. The proposed slip controller was verified on the measured data in an open-loop calculation and the mathematical model in the closed-loop simulation.

Application and improvement of a direct method optimization approach for battery electric railway vehicle operation

While the largely electrified rail network allows for direct utilization of renewable energy sources, there is still a considerable share of diesel-powered trains operating on non- and partly electrified tracks. To replace these, the more sustainable alternatives such as battery electric railway vehicles need to present a viable option with sufficient range. This paper aims to adapt and improve an existing optimization algorithm, previously used with diesel-powered trains, for the operation of battery electric railway vehicles. In this new approach, battery control is optimized alongside train control, utilizing a direct method solver to find the minimum energy trajectory. Furthermore, a detailed train model is implemented that is designed for operation on partly electrified tracks. To yield a highly accurate, yet also sufficiently fast algorithm, a numerical analysis is conducted and the parameters of the algorithm are determined accordingly. Finally, the application of the adapted algorithm on a use case in Germany shows that both velocity profile and control adapt in a way that minimizes utilization of the battery. The results indicate that the proposed algorithm presents a reliable and robust method to obtain minimum energy controls for battery electric railway vehicles with any electrification pattern.

Virtual Coupling of Railway Vehicles: Gap Reference for Merge and Separation, Robust Control, and Position Measurement

Virtual coupling, which refers to the operation of railway vehicles that enables the merge and separation of vehicles on the move by controlling the gap between the vehicles without any mechanical coupling, is one of the technologies for increasing the transport capacity and enhancing operational efficiency. This paper proposes a robust gap controller based on sliding mode control with a nonlinear train model with uncertainties. Additionally, a gap reference generation scheme is developed that ensures that the merge and separation of two trains is completed before a given location and respects constraints on acceleration and jerk. The position and velocity measurement errors arising from imperfect knowledge of wheel diameters are also considered, and a new error correction scheme is proposed to reduce the perturbation in the gap control performance. The proposed schemes are validated through simulations.

Wheelset bearing fault detection using morphological signal and image analysis

The detection of wheelset bearing faults is of extreme importance for railway vehicle operation safety. Wheelset bearing faults induce impulses in vibration signals, which are hard to detect because of signal modulation and environmental noise. To suppress noise and identify these impulses effectively, we propose a method that leverages morphological signal and image processing techniques. The proposed method mainly includes two aspects: a novel double cross-correlation operation for noise reduction and an improved image processing algorithm for highlighting the fault features. The performance of the proposed method was tested using real vibration signals collected from a wheelset bearing test rig and compared with other advanced methods reported in the literature. By analysing two wheelset bearing faults, namely, an outer race fault and a pin roller fault, the proposed method is demonstrated to be more effective in the detection of wheelset bearing faults.

Running Safety and Behavior Tests for a Scaled-Down Railway Vehicle Crossing a Floating Bridge

This paper proposes a test method to evaluate the operability of railway vehicles crossing floating bridges. To inspect the dynamic response of the floating bridge to the railway vehicle, the test setup was separated into wave tank and shake table tests. A scaled-down model representing a unit length of the floating bridge span was manufactured for the wave tank test. Several harmonic waves were artificially created and the displacement at the center above the top surface was measured using an optical position sensor. The response of the floating structure was analyzed to extract the relative amplitude versus the input wave for sway, heave, and roll. The harmonic motions using these responses were simultaneously used as input signals for a six-degree-of-freedom shake table. The scaled-down bogie model ran back and forth repeatedly on the railway placed on the shake table. The acceleration measured from the railway vehicle was analyzed to evaluate the running safety and behavior. All tests were performed without allowing derailment and showed sufficient margin to satisfy the running safety and behavior standards. The proposed test method was successfully conducted and showed a remarkable potential to evaluate the operation of railway vehicles on floating bridges under various wave conditions.

귀선전류 고조파에 의한 자동열차정지장치 (ATS) 영향 분석

The use of ATS(Automatic Train Stop) has been restricted recently with the introduction of a onboard ETCS(European Train Control System) Level 1 ATP(Automatic Train Protection). However, ATS are still installed and operated on most of Korea’s existing lines. Data may not be transmitted from ground equipment of ATS due to the effect of the return current harmonics. In such a case, the onboard ATS on the vehicle may cause emergency braking or malfunction and cause problems such as delays in train operation or accidents. For these reasons, the Railroad Safety Act obligates the government to verify the performance of a facility after the new installation of the ATS device.<BR>In this paper, the measurement and analysis method of whether these return current harmonics can affect the ground equipment of ATS is presented. In addition, the test results of electric railway vehicle operation are presented.

Changes in maintenance of railway vehicles as the sources of threats in the railway system

Proper operation of railway vehicles is the basis for the functioning of a safe railway system. At the same time, it is not possible to talk about the safe use of a vehicle without adequately carried out maintenance processes. Due to legislative changes in August 2017, the maintenance system of railway vehicles has changed significantly. In most cases, it is the entities responsible for maintenance that are fully liable for the shape of the maintenance documentation, not the national security authority (in Poland the President of the Rail Transport Office) as has been the case so far. That is a big challenge for everyone involved in maintaining railway vehicles. The article presents the system of maintenance of railway vehicles as critical for the railway system safety, with the division into those registered in the National Railway Register and the unregistered ones. National and EU requirements for maintenance systems as well as the conditions for the implementation of “changes” in these systems have been presented, based, among others, on the results of the risk assessment of the threats they generate.

Reliability as an Element of Process in Managing a Fleet of Railway Vehicles

Abstract Safe and economical devices, which are constantly growing in demand, lead to improvement of operational strategies applied in railway enterprises. Economic analysis and safety, and hence reliability and readiness, are the most important parameters in the operation of railway vehicles. The article presents a strategy for maintaining railway vehicles based on reliability indicators. The strategy was verified based on empirical research in a transport company.

Stress/Strain analysis in the bogie in linear motion

The railway wheel, together with the axle, represents one of the very important parts that support the safe operation of railway vehicles. Wheels support the entire weight of cars. Therefore, the reliability is demanded in terms of accuracy. Accordingly, the most important and fundamental characteristic in designing wheels is strength. The investigation of dangerous area in bogie is one of important area of study in railway manufactured. This essential information is required in structural integrity, failure and fatigue calculation to determine lifetime for scheduling the maintenance and regrinding necessity. The aim of this work is to determine the stress/strain in a bogie to common working in operating conditions using the 3D finite element method (FEM). The FEM results carried out using 3D elements allows the stress/strain distribution with good accuracy. Knowing the maximum stress/strain value in a bogie, prevents an unsafe construction from the design stage, and consequently increases safety in rail traffic.

Active Monitoring of Fatigue Crack in the Weld Zone of Bogie Frames Using Ultrasonic Guided Waves.

The bogie frame is an important structure of railway vehicles, transmitting the traction, braking force, lateral force, and vertical force during the traction operation. With the development of high speeds and heavy loads, the appearance of fatigue cracks in the bogie frames is increasing, which reduces the driving life of railway vehicles and even causes serious traffic accidents. Real-time monitoring on the integrity of the bogie is an inevitable requirement for ensuring the safe operation of railway vehicles. In this paper, ultrasonic guided wave-based active structural health monitoring (SHM) was developed to identify the fatigue crack of the bogie frame. Experiments were conducted on a welded T-shape specimen with a thickness of 12 mm. A total of 10 piezoelectric lead zirconate titanate (PZT) disks were mounted around the weld zone of the specimen, five of which were used as actuators, and the other five were used as sensors. Five-peak modulation narrow-band sine waves were input into the actuators to excite the specimen. From the sensor signals, the advanced damage index (DI) was calculated to identify the propagation of the crack. The experimental results demonstrate that crack damage as small as 2 mm in the weld zone of the bogie frame can be successfully detected. Some practical issues for implementing the SHM in real applications, such as crack quantification and environmental compensation, were also discussed.

Distributions and fitting of stress amplitude spectra for railway vehicle structures

Stress spectra are essential for estimating the structural fatigue and the fatigue life of railway vehicle structures. However, the data grouping and distribution fitting approaches employed by previous empirical data processing methods are excessively coarse and contain distinctive defects. To address these shortcomings, general theoretical distributions are herein corrected according to the requirements presented by lower stress amplitude data bounds, and converted into a Weibull distribution, truncated lognormal distribution, and truncated normal distribution for comparison. In addition, an innovative distribution consisting of a combined Weibull distribution and truncated lognormal distribution is proposed. The results of fitting to measured stress spectra suggest that the combined distribution has remarkable advantages. Stress spectrum extrapolation and fatigue damage calculation verify that the stress spectrum derived from the combined distribution provides the closest match of all distributions considered to that obtained from the measured spectrum, and therefore best represents the stress distribution at critical points during the practical operation of railway vehicles.