Conventional Railway Research Articles

<b>Research and Development Concerning Superconducting Maglev and Research on Applying Its Technology to the Conventional Railway System</b>

RTRI is promoting the fundamental research and development concerning superconducting maglev. The topics of research are high-temperature superconducting magnet, maglev vehicles motion simulation, evaluation of the ground coil and the diagnostic technology of systems. Research on application of maglev technology to the conventional railway system is advanced in cooperation with other organizations. The main topics of this issue are a flywheel energy storage system using superconducting magnetic bearings and a magnetic refrigeration system for air-conditioners. This paper describes the existing circumstance of these researches and developments.

Use of Matrix-Based Tactile Surface Sensors to Assess Fine-Scale Ballast–Tie Interface Pressure Distribution in Railroad Track

The pressure distribution at the ballast–tie interface of conventional railroad track plays a key role in overall track support. Loads exceeding the strength of the ballast or tie can contribute to degradation of track quality. In this study, matrix-based tactile surface sensors (MBTSS) were used to study the load distribution at the ballast–tie interface. MBTSS allows for fine-scale pressure distributions to be measured unobtrusively and in a dynamic load environment. In this application, the loads imparted by individual ballast particles can be measured. Laboratory ballast box testing and in-track testing were conducted at the Transportation Technology Center. Ballast gradation at the interface was varied for both laboratory and in-track testing. Laboratory results indicated that under nominal heavy axle loads, average peak ballast–tie pressures ranged from 284 psi (1,960 kPa) on sand to 1,450 psi (10,000 kPa) on new ballast. In-track testing found that six of the 10 ties tested showed higher pressures adjacent to the rail and not directly underneath it. In both cases, the contact area was shown to increase under an increasing applied load, in part because of additional ballast particles being engaged as the tie deflects. The high peak pressures observed in the laboratory and the variability of pressure distribution along the tie observed in-track significantly varied from the ballast–tie pressure distribution recommended by the American Railway Engineering and Maintenance-of-Way Association's Manual for Railway Engineering. Ballast–tie interface characterization has implications for tie structural design, ballast degradation, and under-tie pad design.

Wear Behavior of Newly Developed Bainitic Wheel Steels

The present work concentrates on the analysis of wear behavior of bainitic steels made by austempering from a microalloyed steel MAS2, meant for making railway wheel, and comparison with that of a conventional railway wheel steel, wheel-R19. Austempering of the MAS2 steel samples has been performed at different times and temperatures to obtain different morphologies of bainite. Linearly reciprocating dry sliding wear tests of these samples have been carried out at laboratory scale using five different loads. The wear behavior of the bainitic steels has been compared with that of the ferritic-pearlitic steel, wheel-R19. Mechanical properties of the bainitic MAS2 steels are found to be more than that of the wheel-R19 steel. Considerable enhancement in wear resistance of the bainitic steels is attributed to high hardness and strength of the steels. The wear mechanism has been critically analyzed by examining wear track morphology. The wear data gathered have been graphically presented in the form of wear mechanism map to understand the material behavior under different sliding conditions and subsequent morphological variations.

고속 및 일반철도용 연동장치와 선로전환기간 효율적 인터페이스 방안 연구

고속 및 일반철도용 연동장치와 선로전환기간 효율적 인터페이스 방안 연구

Study of the active radial steering of a railway vehicle using the curvature measuring method

This study assesses the capability of an active steering bogie to run effectively on a curved track. It presents a curvature measuring method that can be implemented in a railway vehicle system to steer a railway vehicle. This method was used to conduct a field test. The angle of attack and lateral force were reduced in a railway vehicle model on a curved track and analyzed. An active steering system was implemented to improve certain states when a railway vehicle runs on this track, such as wear and derailment index. The railway vehicle was also equipped with an active steering bogie to limit lateral contact forces and wear rates between the wheel and the rail. Finally, this paper describes the modeling of this active steering system and of a system to control the performance of a vehicle as it curves. Simulation results with this bogie were better than those obtained with a conventional railway vehicle, including in terms of lateral forces and the wear number of the wheels. Therefore, the proposed model is more effective than conventional systems with respect to operation on a curved track.

Impact of European Railway Traffic Management System on Human Performance in Railway Operations European Findings

The safety of railway system operations depends on several internal and external factors. The former include rail traffic rules, infrastructure, rolling stock reliability, organizational safety culture, and human factors. The railway systems in Europe, North America, and Australasia have seen significant technological developments for improved capacity and efficiency. Europe, for instance, is implementing the European Railway Traffic Management System (ERTMS). However, transition to a more automated traffic management system requires, among other things, changes to infrastructure, rolling stock, operational procedures, or all three. Concerning operational procedures, the literature shows that train drivers, signalers, and controllers have the greatest effect on the safety of a railway network. Therefore, the reliability and safety integrity of the railway network are largely dependent on human factors, in particular, the performance of human operators. This performance in turn is affected by a number of factors broadly known as performance-shaping factors (PSFs), with deficiencies in communication accounting for more than 90% of incidents for the conventional railway system. Therefore, this study investigated the influence of ERTMS and in particular the Global System for Mobile Communications–Railway (GSM-R) on operators’ performance. The study analyzed 74 accident and incident reports of railway operations before and after GSM-R implementation from several European railway organizations. The results identified the communications-related factors that affected human performance in the conventional and upgraded railway system based on the existing railway-PSF taxonomy. Finally, the results showed the positive impact of GSM-R implementation on operators’ performance.

Physical Model for Studying the Migration of Fine Particles in the Railway Substructure

Abstract To study the interlayer creation and the mud-pumping phenomena in the conventional French railway substructure, a physical model was developed with a 160-mm-thick ballast layer overlaying a 220-mm-thick artificial silt layer (mixture of crushed sand and kaolin), both layers being compacted in a transparent cylinder of a 550-mm-inner diameter. One positive pore water pressure sensor, three tensiometers, and three time domain reflectometer (TDR) sensors were installed around the ballast/silt interface allowing the evolution of pore water pressure (negative or positive) and volumetric water content to be monitored, respectively. A digital camera was installed allowing direct monitoring of different movements (ballast, ballast/subsoil interface, etc.). The effects of loading (monotonic and cyclic loadings) and degree of saturation of subsoil (w = 16 %, Sr = 55 %, and near-saturation state) were investigated. It was found that the development of pore water pressure in the subsoil is the key factor causing the migration of fine particles, hence, resulting in the creation of interlayer, as well as mud pumping. In particular, the camera exposed the pumping up level of fine particles during the test, showing that the migration of fine particles was not only a result of the interpenetration of ballast particles and subsoil, but also of the pore water pressure that pushed the fine particle upward. The quality of the recorded data showed that the physical model developed worked well and the test protocol adopted for studying the mechanisms of intermixing of ballast and subsoil and mud pumping was appropriate.

휠-레일 방식 초고속열차용 초전도 선형동기전동기의 지상권선 방식별 특성 분석

Recently, an interest in a hybrid system combining only the merits of the conventional wheel-rail system and Maglev propulsion system is growing as an alternative to high-speed maglev train. This hybrid-type system is based on wheel-rail method, but it enables to overcome the speed limitation by adhesion because it is operated by a non-contact method using a linear motor as a propulsion system and reduce the overall construction costs by its compatibility with the conventional railway systems. Therefore, the design and characteristic analysis of a coreless-type superconducting Linear Synchronous Motor (LSM) for 600km/h very high speed railway system are conducted in this paper. The designed coreless-type superconducting LSMs are the distributed winding model, the concentrated 1 layer winding model and the concentrated 2 layer winding model, respectively. In addition, the characteristic comparison studies on each LSM are conducted.

Fault diagnosis in fixed‐block railway signaling systems: a discrete event systems approach

AbstractIn conventional railway systems (or fixed‐block railway signaling systems), railway lines are divided into subsections, called railway blocks, which start and end with a signal. In order to prevent collisions, only one train is allowed in each railway block at a time. Since the occupancy of the next block is indicated by the signals, train drivers have to pay attention to the signals during their journey. In spite of the conventional railway systems having several drawbacks such as the reduction in railway line capacity and the same safe braking distances for all kinds of trains, they have been in use since the mid‐1800s. In this paper, we study fault diagnosis in fixed‐block railway signaling systems from the discrete event systems point of view: first the signaling system equipment are modeled by using Petri nets, and next a diagnoser is designed to show the diagnosability of the system. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

철도교량형식의 경간에 따른 효율성 비교연구

일반철도 및 고속철도를 포함한 철도교량의 상부구조로 현재 우리나라에서 주로 사용되고 있는 교량형식은 크게 박스 거더교와 I형 거더교로 구분된다. 박스 거더교는 동적 거동에 대한 안전성이 우수하기 때문에 주로 고속철도 교량으로 많이 사용된다. I형 거더교는 일반철도 교량으로 주로 사용되며, 일반 PSC 거더교 형태와 철골철근콘크리트로 합성화된 구조인 프리플렉스 거더교의 형태로 크게 구분되고 또한 새로운 형식도 지속적으로 개발되고 있는 추세에 있다. 본 연구에서는 현행 철도교설계기준에 의거하여 각 형식별로 경간장에 따라 거더 설계를 실시하여 적절한 형고를 분석하여 경간장에 따른 구조적 및 경제적 효율성을 비교분석하였다. 비교분석을 수행한 결과, 구조적 효율성의 측면에서는 프리플렉스 거더교 형태의 교량이 경간장에 따른 형고가 가장 낮은 것으로 나타났으며, 경제적 효율성의 측면에서는 일반 PSC 거더교 형태의 교량이 가장 효과적인 것으로 평가되었다. The superstructure type of the railway bridge in our country, is mainly classified into the box girder and the I-type girder. The box girder is widely used in the high speed railway bridge because of the safety due to dynamic behavior. The I-type girder is used in the conventional railway bridge, and is also divided into the general type and the composite type, and the newly modified types have been developed. According to the current railway bridge design code, the girder design by the span length in various railway bridge types are performed in this study. The suitable girder height by the span length are analyzed, and the comparative analysis of the structural efficiency and the economical efficiency is carried out. From this study, the composite type girder is appeared the good result in respect of the structural efficiency. However, in the economical aspect, the general I-type girder is required less cost than the other types.

Field Evaluation and Durability Analysis of an Eco-Friendly Prestressed Concrete Sleeper

AbstractWhile there have been various research activities to develop the green vehicles which reduce the energy consumption such as high-speed train, tilting train, light rail transit, wireless tram, and so on, researches on the eco-friendly railway infrastructure have been very limited to deal with the important social issue of reducing CO2 emissions. In this background, eco-friendly prestressed concrete (PSC) sleeper, using ground granulated blast furnace slag and rapid-cooling electric arc furnace oxidizing slag, has been recently developed to reduce the usage of cement and natural fine aggregate as main ingredients of the concrete. It was already found that eco-friendly PSC sleeper satisfied its static and dynamic performances required by international standards. In this paper, the field performance of eco-friendly PSC sleeper was evaluated in the operating line of conventional railway and its durability against extreme environmental conditions was performed in the laboratory as well. Steel slags (gro...

Effect of fine particles on the hydraulic behavior of interlayer soil in railway substructure

The conventional railway substructure in France was built by emplacing ballast directly on subgrade. Over years of operation, the interpenetration of ballast and subgrade created a soil layer between them. Under different conditions, this naturally formed layer, namely interlayer, can contain different quantities of fine particles, becoming more or less sensitive to changes in water content. As the water content changes are governed by the hydraulic behavior of the interlayer soil, assessing the influence of fine particle content on the hydraulic behavior of interlayer soil is of importance. To this end, the hydraulic behavior of an interlayer soil taken from Sénissiat (near Lyon, France) was investigated using two infiltration columns, a large-scale column equipped with tensiometers and a time domain reflectometer (TDR) for suction and volumetric water content measurements, respectively, and a smaller column equipped with high-capacity tensiometers only. Different fines contents were considered and wetting–drying cycles were applied to the soil specimens. The hydraulic conductivity was determined by applying the instantaneous profile method. The results obtained showed that (i) hysteresis exists for both the soil water retention curve and the hydraulic conductivity changes with suction; (ii) the effect of wetting–drying cycles is insignificant; (iii) adding 10% fine particles to the natural interlayer soil gives rise to changes in the soil water retention curve but does not induce significant changes in hydraulic conductivity; (iv) the unsaturated hydraulic conductivity of interlayer soil with 10% fine particles added is close to that of soil sieved at 2 mm, suggesting that the unsaturated hydraulic conductivity of interlayer soil is mainly governed by fine particles through the suction effect. By contrast, in a saturated state, the value for the interlayer soil with 10% fine particles added was found to be higher, suggesting that in this case the hydraulic conductivity is mainly governed by the water transfer through macropores.

Ground vibration reduction analysis using a frequency-domain finite element approach

A finite element model combined to the thin layer method is used to model ground wave propagation in the frequency domain. This coupled model allows the waves to transmit through the lateral boundaries of the computational domain so that it simulates the semi-infinite extent of the medium. Unstructured triangular mesh grids are used in the model allowing consideration of complicated geometries involved in such problems. The efficiency of this approach is first assessed against known analytical models. Then the effectiveness of various shaped wave barriers in reducing surface ground vibration is examined. Last, examples of ground vibration due to railway loading are presented including a conventional railway embankment and highly compacted geomaterials embankment with vertical Retaining Walls.

High speed rail passenger segmentation and ticketing channel preference

A multi-channel strategy for the purposes of marketing and ticketing has been widely employed in various fields, including the transportation industry, yet few transportation studies have investigated ticket channel-related issues. This study thus adopts Taiwan High Speed Rail (THSR) as a case study to identify passengers’ perceptions regarding key factors that affect the channel preference through which they receive their services, particularly across a four-stage ticket purchasing process, including information enquiry, booking, payment, and ticket pick-up. To investigate these key factors, we base the framework of our research model upon customers’ perceived value perspective, adopting a multinomial logit model to examine the influence of channel attributes on HSR passengers’ preferences. The relationship among the decisions made by these passengers at each ticket purchasing stage is also examined. The findings of our study demonstrate that perceived risk, perceived benefit, and perceived ease of use are critical factors influencing passengers’ channel preference throughout the ticket-purchasing process. Perceptual differences are proven to exist due to various demographic factors and trip characteristics. The conclusions of this study have implications for THSR management to design appropriate ticketing channel services for certain types of passengers and can also be generally applied to multiple distribution channels in conventional railway system and intercity bus services.

Investigation of interlayer soil behaviour by field monitoring

As opposed to the new ballasted railway tracks where a sub-ballast layer is often emplaced, the conventional railway tracks were constructed with ballast directly emplaced on the natural sub-soils. Thereby, a layer of mixed materials, namely interlayer, was formed over time mainly by interpenetration between ballast and sub-soils. As this layer plays an important role in transmitting load to the sub-soils, its behaviour under the effects of dynamic loading and climate changes is of primary importance for the stability of tracks. In order to understand the behaviour of the material in such interlayers, field monitoring was performed at a selected site in France, namely Moulin Blanc. Firstly, site investigation was done by borehole, allowing the interlayer location to be identified. Secondly, the interlayer was instrumented with suction probes, temperature sensors and accelerometers at different depths. Two piezometers were also installed for water table monitoring, and a weather station was installed for air data monitoring. The data recorded allowed the suction changes with water evaporation and the behaviour of tracks under the effect of temperature to be analysed. Moreover, the recorded data of acceleration allowed assessing the double-integration method for different kinds of train. It was observed that the site is out of the hazards related to freeze/thaw and the double-integration method can be applied to determine the particle velocity and displacement provided that appropriate filters are used. Note however that further study is needed to confirm this point with comparison between the measured particle displacement and the calculated one.

Measurements and analysis of track irregularities on high speed maglev lines

Track irregularities have an obvious effect on the running stability and ride quality of maglev trains traveling at high speeds. We developed a measurement principle and data processing method which were applied to the high speed maglev line operating. The method, which includes partial filtering, integration, resampling of signal, and a low pass Butterworth filter, was used to calculate the irregularities of the maglev line. The spectra of the sample space were evaluated. A 7-parameter power spectrum density (PSD) function of line irregularities was fitted, based on the measured data. Analysis of the results showed that the maglev stator plane irregularities were better than conventional railway vertical rail irregularities when the wavelength was 5–100 m, and worse when the wavelength was 1–5 m. The PSD of maglev guidance plane irregularities was similar to that of cross level GRSHL (German railway spectra of high irregularity) when the wavelength was 10–100 m. The irregularities were clearly worse than cross level rail irregularities in a conventional railway when the wavelength was 1–10 m. This suggests that short-wavelength track irregularities of a maglev line caused by deviation and inclination of the stator plane should be minimized by strictly controlling the machining error of functional components during construction and maintenance.

Simulating train moving loads in physical model testing of railway infrastructure and its numerical calibration

Ballastless high-speed railways have dynamic performances that are quite different from those of conventional ballasted railways. The essential dynamic characteristics of high-speed railways due to passing train wheels, such as the cyclic effect, moving effect, and speed effect, were put forward and discussed. A full-scale accelerated railway testing platform for ballastless high-speed railways was proposed in this study. The feasibility of the sequential loading method in simulating train moving loads, and the boundary effect of the proposed physical model of ballastless railways, was investigated using three-dimensional finite element models. A full-scale physical model, 5 m long, 15 m wide, and 6 m high, was then established according to practical engineering design methods. Using a sequential loading system composed of eight high-performance hydraulic actuators, loads of a moving train with highest speed of 360 km/h were simulated. Preliminary experimental results of vibration velocities were presented and compared with field measurements of the Wuguang high-speed railway in China. Results showed that the experimental results coincided with the field measurements, demonstrating that the full-scale accelerated railway testing platform can simulate the process of a moving train and realistically reproduce the dynamic behaviors of ballastless high-speed railways.

고무차륜형 경전철 고가구조물 설계기준에 관한 현장 계측 시험 연구(1): 제동하중

국내에 건설 운영 중인 경전철 고가구조물은 설계 당시 경전철 고가구조물 설계기준이 마련되어 있지 않아 일반 철도교 설계기준 및 국외 차량제작사에서 제시한 설계기준을 참조하여 설계된 관계로, 고가구조물이 과다 설계되어 비경제적으로 건설된 주된 이유가 되고 있다. 본 연구에서는 고무차륜형 경량전철이 고가구조물 위를 각각 50km/h, 60km/h, 70km/h의 속도로 주행 중 5개 제동 지점별로 제동 시 고가 하부구조물에 작용하는 제동하중을 현장 계측시험을 통해 분석하였고, 현재 설계시 반영되고 있는 철도설계기준과 비교하였다. 본 연구에서 제시된 제동하중 시험분석 결과는 향후 경전철 고가구조물 설계기준 제정 시 참조될 수 있다. Due to the absence of design guidelines for elevated light-rail structures in Korea, most elevated light-rail structures have been designed and constructed based on the design codes of conventional railway bridges and on the codes recommended by foreign vehicle manufacturers. This is the main reason why most elevated light-rail structures are massive or over-designed or poorly constructed economically. In this paper, the authors carried out field tests to analyze the braking forces caused by braking a train running at speeds of 50km/h, 60km/h, and 70km/h, acting on the elevated structures of rubber-wheeled Light Rail Transit (LRT) trains. The authors also briefly describe the analyzed results of the braking force acting on the substructures of elevated light-rail structures. The test-results presented here in this paper can be referenced when establishing design guidelines or standards for elevated structures of LRT systems.

Annoyance and activity disturbance induced by high-speed railway and conventional railway noise: a contrastive case study

BackgroundHigh-speed railway (HR, Electrified railway with service speed above 200 km/h.) noise and conventional railway (CR, Electrified railway with service speed under 200 km/h.) noise are different in both time and frequency domain. There is an urgent need to study the influence of HR noise and consequently, develop appropriate noise evaluation index and limits for the total railway noise including HR and CR noise.MethodsBased on binaural recording of HR and CR noises in a approximate semi-free field, noise annoyance and activity disturbance induced by maximal train pass-by events in China were investigated through laboratory subjective evaluation. 80 students within recruited 102 students, 40 males and 40 females, 23.9 ± 2.1 years old, were finally selected as the subjects. After receiving noise stimulus via headphone of a binaural audio playback system, subjects were asked to express the annoyance or activity disturbance due to railway noise at a 0-100 numerical scale.ResultsThe results show that with the same annoyance rating (A) or activity disturbance rating (D), the A-weighted equivalent sound pressure level (LAeq) of CR noise is approximately 7 dB higher than that of HR noise. Linear regression analysis between some acoustical parameters and A (or D) suggests that the coefficient of determination (R2) is higher with the instantaneous fast A-weighted sound pressure level (LAFmax) than that with LAeq. A combined acoustical parameter, LHC = 1.74LAFmax + 0.008LAFmax(Lp-LAeq), where Lp is the sound pressure level, was derived consequently, which could better evaluate the total railway noise, including HR and CR noise. More importantly, with a given LHC, the noise annoyance of HR and CR noise is the same.ConclusionsAmong various acoustical parameters including LHC and LAeq, A and D have the highest correlation with LHC. LHC has been proved to be an appropriate index to evaluate the total railway noise, including both HR and CR. However, it should be pointed out that this study provides suggestive evidence, rather than a final proof. Further study is expected to elucidate conclusions above by additional measurements.

Assessment of conventional French railway sub-structure: a case study

A statistical study was firstly undertaken on problems that occurred in a period of more than 1 year and were related to train circulation in the entire conventional French railway network. Emphasis was put on the degradation of track components. The analysis evidenced the particular importance of sub-grade quality in the performance of the whole track. After this general analysis, a conventional railway line in the West of France was investigated. In the sub-structure of this line, an interlayer was identified that was created mainly by interpenetration of ballast and sub-grade. In the analysis, the degradation rate of this line was correlated with different parameters, such as the nature of sub-grades involved along the line and the thickness of different layers. The results showed that the degradation rate is correlated to the thickness of various layers. Furthermore, it was observed that the interlayer plays an important role in the performance of tracks, as it represents a transition layer for the train-induced stress transmission to the sub-grade.