High-speed Railway In China Research Articles

Railway Polygonized Wheel Detection Based on Numerical Time-Frequency Analysis of Axle-Box Acceleration

The increasing need for repairs of polygonized wheels on high-speed railways in China is becoming problematic. At high speeds, polygonized wheels cause abnormal vibrations at the wheel-rail interface that can be detected via axle-box accelerations. To investigate the quantitative relationship between axle-box acceleration and wheel polygonization in both the time and frequency domains and under high-speed conditions, a dynamics model was developed to simulate the vehicle-track coupling system and that considers both wheel and track flexibility. The calculated axle-box accelerations were analyzed by using the improved ensemble empirical mode decomposition and Wigner-Ville distribution time-frequency method. The numerical results show that the maximum axle-box accelerations and their frequencies are quantitatively related to the harmonic order and out-of-roundness amplitude of polygonized wheels. In addition, measuring the axle-box acceleration enables both the detection of wheel polygonization and the identification of the degree of damage.

Train schedule optimization based on schedule-based stochastic passenger assignment

In this study, we propose a new schedule-based itinerary-choice model, the mixed itinerary-size weibit model, to address the independently and identically distributed assumptions that are typically used in random utility models and heterogeneity of passengers’ perceptions. Specifically, the Weibull distributed random error term resolves the perception variance with respect to various itinerary lengths, an itinerary-size factor term is suggested to solve the itinerary overlapping problem, and random coefficients are used to model heterogeneity of passengers. We also apply the mixed itinerary-size weibit model to a train-scheduling model to generate a passenger-oriented schedule plan. We test the efficiency and applicability of the train-scheduling model in the south China high-speed railway network, and we find that it works well and can be applied to large real-world problems.

Mixed Logit Model Based on Improved Nonlinear Utility Functions: A Market Shares Solution Method of Different Railway Traffic Modes

In recent years, with the development of high-speed railway in China, the railway operating mileages and passenger transport capacity have increased rapidly. Due to the high density of trains and the limited capacity of railways, it is necessary to solve market shares of different railway traffic modes in order to adjust the operation plans appropriately and run railway passenger transport products in line with passenger demand. Therefore, the purpose of this paper is to calculate market shares by formulating a mixed logit model based on improved nonlinear utility functions taking different factors into consideration, such as seat grades, fares, running time, passenger income levels and so on. Firstly according to maximum likelihood estimation, the likelihood function of this mixed logit model is proposed to maximize utility of all passenger groups. After that, we propose two improved algorithms based on the simulated annealing algorithm (ISAA-CC and ISAA-SS) to estimate the unknown parameters and solve the optimal solution of this model in order to enhance the computational efficiency. Finally, a real-world instance with related data of Beijing–Tianjin corridor, is implemented to demonstrate the performance and effectiveness of the proposed approaches. In addition, by performing this numerical experiment and comparing these two improved algorithms with the traditional Newton method, the ant colony algorithm and the simulated annealing algorithm, we prove that the improved algorithms we developed are superior to others in the optimal solution.

Inserting Extra Train Services on High-Speed Railway

With the aim of supporting future traffic needs, an account of how to reconstruct an existing cyclic timetable by inserting additional train services will be given in this paper. The Timetable-based Extra Train Services Inserting (TETSI) problem is regarded as an integration of railway scheduling and rescheduling problem. The TETSI problem therefore is considered involving many constraints, such as flexible running times, dwell times, headway and time windows. Characterized based on an event-activity graph, a general Mixed Integer Program model for this problem is formulated. In addition, several extensions to the general model are further proposed. The real-world constraints that concerning the acceleration and deceleration times, priority for overtaking, allowed adjustments, periodic structure and frequency of services are incorporated into the general model. From numerical investigations using data from Shanghai-Hangzhou High-Speed Railway in China, the proposed framework and associated techniques are tested and shown to be effective.

The impact mechanical characteristics of steam-cured concrete under different curing temperature conditions

In order to clarify the influence of curing temperature on the dynamic properties of steam-cured concrete, series of SHPB tests were conducted to investigate the impact mechanical characteristics of a typical steam-cured concrete applied in prefabricated components of high-speed railway in China. The index of fineness modulus was proposed to evaluate the degree of concrete breakage under different strain rates. The results showed that the peak stress of steam cured concrete increased with increasing the strain rate, while the peak strain showed a decreasing trend, the fineness modulus of broken concrete particles decreased, and the degree of fracture increased obviously. As curing temperature increases, the peak stress of steam-cured concrete decreased significantly, and the concrete specimens showed a stronger strain rate sensitivity. A statistical damage constitutive model considering the strain rate was established and agreed well with the experimental stress–strain curves. Higher temperatures lead to an increase in internal defects of concrete, which makes the impact mechanical properties different from that of normal temperature cured concrete.

Automated Visual Inspection of Multiple Missing Fastening Bolts on the Sides of High-Speed Train Body in Railway Maintenance

The rapid development of China Railway High-speed (CRH) has provided safe and comfortable transportation for many people. The fastening bolts (FB) on the sides of CRH fall off occasionally, which might cause serious traffic accidents. However, the automatic inspection of multiple missing FBs on the sides of CRH is seldom conducted. In this study, an automated visual inspection system based on space-scale normalization is proposed to inspect the status of FBs on the sides of CRH. To locate the missing FBs in sequence images, the exact alignment of the target image and its reference image must be ensured. This problem can be solved by normalizing the target image according to its reference image. First, the FBs are located in a specific CRH region, which is called the region of interest (ROI). The target image is cropped according to the size of the ROI. Second, the keypoints are extracted and matched by using the gradient-enhanced scale-invariant feature transform (GESIFT). Furthermore, the horizontal shift between the target image and its reference image is obtained during keypoint matching. Third, the target image and its neighboring image are stitched according to the horizontal shift. Then, the target image is resegmented according to its reference image to complete the normalization of the target image. Finally, the normalized target image can be exactly aligned with its reference image. We propose an image subtraction method to locate the potential missing FBs. The FBs that may be lost are finally determined according to prior knowledge, and the state of the FBs is determined by using high-level image understanding knowledge. Experimental results show that our presented method performs excellently in monitoring the missing FBs on the sides of CRH.

Research on the Maintenance and Management Mode of High-speed Railway Infrastructure in China

China has preliminarily built a modern high-speed railway network, and the huge scale of the network has put forward higher requirements on infrastructure maintenance and management. In order to achieve high quality and efficient development of high-speed railway, this paper conducts research on the maintenance and management model of China's high-speed railway infrastructure. This article describes the characteristics of infrastructure maintenance management in developed countries of high-speed railways such as Japan, France and Germany; summarizes the technical characteristics of China's high-speed railways and analyzes the factors influencing infrastructure maintenance management in China. Based on the theory of organizational structure, the article systematically analyzes the differences in the work content, work methods, and means of high-speed railway infrastructure inspection and monitoring, routine maintenance, and specialized repair operations, so as to put forward the maintenance management mode of the separation of "inspection, maintenance, repair". This model mixes together the specialization of technical management and the comprehensive integration of production organization. On this basis, a comprehensive maintenance system for high-speed railway infrastructure was designed and a comprehensive maintenance organizational structure and working mechanism was proposed. Practice has shown that a comprehensive maintenance system for high-speed railway infrastructure is conducive to improving emergency response capabilities, reducing operating costs and achieving optimal resource allocation.

Low-Frequency Instability Induced by Hopf Bifurcation in a Single-Phase Converter Connected to Non-Ideal Power Grid

With the high-density operation of China Railways High-speed (CRH) series vehicles in railways, a large number of power electronic converters are connected to the traction network. Due to the nonlinear characteristics of power electronic converter, it is easy to cause the low-frequency oscillation (LFO) in the single-phase vehicle-grid system of high-speed railways when the converter is connected to a non-ideal power grid. In order to solve this problem, the time domain nonlinear dynamic average model is proposed in this paper. Given Jacobian method to probe into the low-frequency stability of single-phase vehicle-grid system based on Hopf bifurcation, the characteristics and applicability of this method is summarized. The effects of electrical and control parameters can be analyzed with this model. In addition, with the emergence of LFO, the stability boundary leading to catastrophic bifurcation is discussed in detail. In the end, theoretical analysis results are verified by simulations and hardware-in-the-loop (HIL) platform.

High-Speed Railway EMUs’ Circulation Plan Optimization: A Two-Stage Optimization Algorithm Based on Column Generation

Considering the characteristics of China's high-speed railway network and the allocation structure of Electric Multiple Units (EMUs), the EMUs operation management mode provides an effective technical route for EMUs route planning optimization. To reduce the number of EMUs, key factors such as the EMUs mileage, time limit, maintenance model, maintenance capability, night accommodation capacity, maintenance management mode, and train tasks are considered as constraints. The number of maintenance tasks is also the objective so that the EMUs route planning solution method is more integrated with actual production needs, and an optimization model of EMUs route planning is established to overcome the shortcomings of previous studies that did not sufficiently consider EMUs maintenance. To verify the feasibility and effectiveness of the proposed model and method of the proposed two-stage optimization algorithm based on column generation, a case study on the preparation of EMUs circulation planning for the Beijing-Shanghai high-speed railway network is conducted, and the results are analyzed.

Field Test Research and Numerical Simulation on Aerodynamic Deloading Characteristics of V-Shaped Noise Barrier

With the rapid development of the high-speed railway in China, the problems of the noise pollution induced by passing trains emerge. Theoretically, the V-shaped noise barrier is of pretty good performance of noise-reduction and load-shedding. To assess the practical aerodynamic deloading characteristics of the V-shaped noise barrier, a full-scale field test was carried out at three measuring-sections equipped with noise barriers of different heights. In order to quantify the research work, the impact strength and deloading rate were selected as indicators. The effects of train speeds, train types and barrier heights are studied. This study includes the variations of impact strength and deloading rate in vertical directions. Meanwhile, 2D numerical simulation research is conducted to analyze the experimental results from the angle of mechanism. It is observed that the aerodynamic load acting on the surface of the V-shaped noise barrier was weaker and more uniform compared with conventional barrier. The flow field distribution influenced the deloading characteristics of the V-shaped noise barrier significantly. Moreover, the load-shedding effect of V-shaped noise barrier, when CRH380AM passed by, was slightly better than CRH380A. The deloading rate improved with the increasing of the noise barrier height in general.

Dynamic Performance of High-Speed Electric Multiple Unit within Multi-Body System Simulation

Background: With the rapid development of the high-speed railway, the dynamic performance such as running stability and safety of the high-speed train is increasingly important. This paper focuses on the dynamic performance of high-speed Electric Multiple Unit (EMU), especially the dynamic characteristics of the bogie frame and car body. Various patents have been discussed in this article. Objective: To develop the Multi-Body System (MBS) model of EMU, verify whether the dynamic performance meets the actual operation requirements, and provide some useful information for dynamics and structural design of the proposed EMU. Methods: According to the technical characteristics of a typical EMU, a MBS model is established via SIMPACK, and the measured data of China high-speed railway is taken as the excitation of track random irregularity. To test the dynamic performance of the EMU, including the stability and safety, some evaluation indexes such as wheel-axle lateral forces, wheel-axle lateral vertical forces, derailment coefficients and wheel unloading rates are also calculated and analyzed in detail. Results: The MBS model of EMU has better dynamic performance especially curving performance, and some evaluation indexes of the stability and safety have also reached China’s high-speed railway standards. Conclusion: The effectiveness of the proposed MBS model is verified, and the dynamic performance of the MBS model can meet the design requirements of high-speed EMU.

Displacement Characteristics of Shallow-Buried Large-Section Loess Tunnel with Different Types of Pre-Supports: A Case Study of New Badaling Tunnel

Three-bench seven-step excavation method (TSEM) has been widely used in large-section loess tunnels for high-speed railway in China. As the most commonly applied pre-supports, pipe roofs and leading ductules are broadly used in the ground reinforcement of loess tunnels. Their application is to ensure face stability and prevent tunnel collapse during construction. This study focused on the impacts of the TSEM on the ground surface settlement (GSS), as well as the tunnel displacement characteristics for the high-speed railway tunnels with large cross-sections in loess ground. Furthermore, the reinforcement effects of the two kinds of pre-supports were compared in this study. In-situ tests for a total of 12 sections were conducted to reveal the GSSs and displacement characteristics for the shallow-buried large-section loess tunnels. The monitoring results showed that the excavation process plays a significant role on the GSSs and tunnel displacements. A maximum value was observed for the tunnel displacement rate at the excavation of the upper and middle benches, where the face instability or collapse were prone to occur. The GSS trough curves were deviated to the early excavation side, with no conformation to the Gauss distribution. After a series of comparisons, we concluded that the pre-reinforcement effect of the pipe roof is better than that of the leading ductule for the loess tunnels.

An experimental approach to evaluating the long-term performance of segmental linings

There have been numerous engineering projects involving shallow buried metro tunnels underneath the subgrade of high-speed railways in China, and the metro tunnel inevitably bears the dynamic load induced by the high-speed trains above. Thus, the long-term performance of segmental linings cannot be negligible. An experimental model is an important method for evaluating the segmental linings. In the experiment, three key problems must be solved to ensure the strict similarity between the prototype and the model in terms of the structural form, initial earth pressure and fatigue behaviour of the segmental linings. A series of key points to maintain the similarity of the model is put forward, including the presentation of the standard joint-staggered model, the principle of a reserved displacement constraint device and the equivalence of fatigue life between the prototype and model materials. Based on similarity theory, a 1/10-scale model experiment is designed, and the stress and strain states are measured. The results show the model experimental design can be approximately consistent with the theoretical calculation and numerical simulation. The study provides a sufficient experimental basis for evaluating the long-term performance of segmental linings.

Investigating college students’ choice of train trips for homecoming during the Spring Festival travel rush in China: results from a stated preference approach

ABSTRACT This study is to investigate college students’ choice of train trips for homecoming during the Spring Festival travel rush, which is triggered by two facts in China that the annual Spring Festival travel rush has been challenging the national transportation system and that the high-speed railway in China has made a great progress in the latest years. To this end, a stated choice experiment was designed, where four hypothetical train trips (two conventional and two high-speed train trips) consisted of a choice set. A survey based on this design was carried out, where 2768 valid observations were collected. Given the potential correlations within alternatives and the heterogeneity of respondents’ preferences, a latent class nested logit model was established and estimated, in which two classes were identified that one payed more attention to economy while the other cared more about services. The estimation results answered the questions that which determinants and to what extent of these determinants have influence on college students’ choice of homecoming train trips and who are more likely to choose high-speed train trips. In addition, this study also provides analysis of willingness to pay and market share changes.

Dynamic Elastic Modulus and Damping Ratio of Unsaturated Red Clay

Dynamic modulus of elasticity and damping ratio are two important parameters of dynamic properties of soil. These two parameters were extensively studied in the laboratory. However, there has been little research on these two parameters of the unsaturated red clay which is located in the southwest of Hunan, China. With the rapid development of high-speed railway in China, it is urgent to identify the dynamic properties of the unsaturated red clay to provide reference for the civil engineering industry. In this paper, DDS-70, an electromagnetic type dynamic tri-axial testing system, was used to study the effects of water content, dry density, confining pressure, over-consolidation ratio and loading frequency on dynamic elastic modulus and damping ratio of unsaturated red clay. The result shows that within the phase of small strain the influences of water content, dry density, confining pressure, over-consolidation ratio and loading frequency on dynamic modulus of elasticity are obvious. Dynamic modulus of elasticity increases with the increase of dry density, confining pressure and over-consolidation ratio under the same strain, whereas dynamic modulus of elasticity decreases with the increase of water content and loading frequency. Moreover, the effects of these factors on damping ratio are also significant during the phase of small strain. With the increase of strain, damping ratio increases with the decrease of dry density, confining pressure and over-consolidation ratio under the same dynamic strain. There is no clear relationship between damping ratio and loading frequency. It is concluded that the influence of above factors on the dynamic modulus of elasticity and damping ratio is significant.

Interval sliding mode observer-based fault accommodation for non-minimum phase LPV systems with online control allocation

This paper proposes an interval sliding mode observer (ISMO)-based sliding mode actuator fault accommodation (FA) framework for non-minimum phase linear-parameter-varying (LPV) systems involving online control allocation (CA) problem. Firstly, a specifically designed coordinate transformation is introduced to deal with the non-minimum phase issue. Then, an ISMO is proposed to estimate the set of admissible values for the states of the faulty LPV systems, which combines the interval observer technique and the sliding mode observer technique. A fault-tolerant control (FTC) law with an online CA scheme is subsequently designed by stabilising the ISMO instead of the original faulty LPV system. Finally, a simulation for an inverter used in China Railway High-speed (CRH) is presented to illustrate the effectiveness of the proposed framework.

A Quantitative and Comprehensive Evaluation of China’s Ecological High-speed Railway Development Based on DSR Model

This paper evaluates the development status of China’s high-speed railway from 2010 to 2018 based on the DSR (Driving force, State and Response) model, and further evaluates the ecological development status of China’s high-speed railway in the future by using the analytic hierarchy process. The results demonstrate the overall trend of the development of ecological high-speed railway in China is good, but the driving force is insufficient, the proportion of state indicators decreases year by year, and the response indicators indicate an upward trend. According to the research and analysis, some suggestions are put forward for the development of ecological high-speed railway.

Study on Evaluation of Beijing-Shanghai High-speed Railway Operation Safety

The study aims to evaluate operation safety level of Beijing-Shanghai High-speed Railway in China. In order to do so, this research establishes a safety assessment index system of Beijing-Shanghai HSR based on AHP firstly. Then based on the fuzzy matter-element theory, with the concept of the Euclid approach degree (EAD), compound fuzzy matter-element for safety level evaluation is established. The results show that Beijing-shanghai HSR is a better operation safety level in China. According to the results, some suggestions on improving Beijing-shanghai HSR operation safety are proposed.

Analysis of the bearing behaviour of a screw-pile foundation in silt soil

Screw-pile composite foundations have been widely implemented on multiple high-speed railways in China. Their distinctive design with variable sections makes the bearing behaviour of screw piles far more complex than that of common smooth piles. The bearing behaviour of a screw-pile composite foundation was analysed in silt soil on a national key construction project. A comparative analysis of the bearing characteristics of composite foundations of smooth piles and screw piles was performed through model tests. The results showed that, in a single-pile composite foundation and with the same pile diameter and length, the ultimate bearing capacity of the screw pile was 67% higher than that of the smooth pile. The smooth pile showed an area of negative frictional resistance at the top of the composite foundation. The screw pile had a negative friction area below the junction of the smooth section and the screw section in the screw-pile composite foundation.

Analyzing the Key Drivers of Contractors’ Temporary Competitive Advantage in the Competition of International High-speed Rail Projects

After temporary competitive advantage (TCA) being proposed, this concept has received a lot of attention from academia and industry. For international HSR contractors, how to form their TCA and win out over the competition for new projects is crucial, while only a few studies focus on this issue. This research aims to develop a TCA system that reflects the characteristics of high-speed rail (HSR) contractors in the corporation and project levels. At first, exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) was conducted to explore and examine the key drivers and their relationships with contractors’ TCA. The results revealed that experience-mining advantage was the most critical factor of the six common factors. Next, common factors were divided into three dimensions and discussed in-depth, including resource-based TCA (i.e., technical resource and social image) which had the highest significance, followed by performance-based TCA (experience-mining advantage and risk-controlling performance), and action-based TCA (i.e., funding strategy and organizational management). Finally, two case study projects were selected to investigate the competitive situation between CRH (China Railway High-speed) and Shinkansen (Japan) in the international HSR market. This study not only provides suggestions for contractors to improve their TCA in international HSR projects, but also contributes to the theoretical framework for the TCA theory.