This special issue is the first academic issue of the journal focused on high-speed railway technologies in English. Some of the researches related to high-speed railways have been selected for publication. This special issue covers: high-speed train aerodynamics, traction drives, braking, control, electromagnetic compatibility, line engineering, transportation organizations, and other technical fields.

Dynamic responses of track structure and wave propagation in nearby ground vibration become significant when train operates on high speeds. A train-track-ground dynamic interaction analysis model based on the 2.5D finite element method is developed for the prediction of ground vibrations due to vertical track irregularities. The one-quarter car model is used to represent the train as lumped masses connected by springs. The embankment and the underlying ground are modeled by the 2.5D finite element approach to improve the computation efficiency. The Fourier transform is applied in the direction of train’s movement to express the wave motion with a wave-number. The one-quarter car model is coupled into the global stiffness matrix describing the track-ground dynamic system with the displacement compatibility condition at the wheel-rail interface, including the irregularities on the track surface. Dynamic responses of the track and ground due to train’s moving loads are obtained in the wave-number domain by solving the governing equation, using a conventional finite element procedure. The amplitude and wavelength are identified as two major parameters describing track irregularities. The irregularity amplitude has a direct impact on the vertical response for low-speed trains, both for short wavelength and long wavelength irregularities. Track irregularity with shorter wavelength can generate stronger track vibration both for low-speed and high-speed cases. For low-speed case, vibrations induced by track irregularities dominate far field responses. For high-speed case, the wavelength of track irregularities has very little effect on ground vibration at distances far from track center, and train’s wheel axle weights becomes dominant.

Steel structures are widely used in railway infrastructures. Their stress state is the most important determinant of the safety of these structures. The elasto-magnetic (EM) sensor is the most promising for stress monitoring of in-service steel structures. Nevertheless, the necessity of magnetic excitation to saturation due to the use of a secondary coil for signal detection, keeps from its engineering application. In this paper, a smart elasto-magneto-electric (EME) sensor using magneto-electric (ME) sensing units to take the place of the secondary coil has been exploited for the first time. The ME sensing unit is made of ME laminated composites, which has an ultrahigh ME voltage coefficient and can measure the magnetic induction simply and precisely. Theoretical analysis and characterization experiments firstly conducted on the ME laminated composites showed that the ME sensing units can be applied in the EM sensor for improved performance in stress monitoring. A tension test of a steel bar was carried out to characterize our smart EME sensor and the results showed high accuracy and sensitivity. The present smart EME sensor is a promising tool for stress monitoring of steel structures in railway and other civil infrastructures.

Line planning is the first important strategic element in the railway operation planning process, which will directly affect the successive planning to determine the efficiency of the whole railway system. A two-layer optimization model is proposed within a simulation framework to deal with the high-speed railway (HSR) line planning problem. In the model, the top layer aims at achieving an optimal stop-schedule set with the service frequencies, and is formulated as a nonlinear program, solved by genetic algorithm. The objective of top layer is to minimize the total operation cost and unserved passenger volume. Given a specific stop-schedule, the bottom layer focuses on weighted passenger flow assignment, formulated as a mixed integer program with the objective of maximizing the served passenger volume and minimizing the total travel time for all passengers. The case study on Taiwan HSR shows that the proposed two-layer model is better than the existing techniques. In addition, this model is also illustrated with the Beijing-Shanghai HSR in China. The result shows that the two-layer optimization model can reduce computation complexity and that an optimal set of stop-schedules can always be generated with less calculation time.

In this paper, a modeling method for a pantograph-catenary system is put forward to investigate the dynamic contact behavior in space, taking into consideration of the appearance characteristics of the contact surfaces of the pantograph and catenary. The dynamic performance of the pantograph-catenary system, including contact forces, accelerations, and the corresponding spectra, is analyzed. Furthermore, with the modeling method, the influences of contact wire irregularity and the vibration caused by the front pantograph on the rear pantograph for a pantograph-catenary system with double pantographs are investigated. The results show that the appearance characteristics of the contact surfaces play an important role in the dynamic contact behavior. The appearance characteristics should be considered to reasonably evaluate the dynamic performance of the pantograph-catenary system.

The China’s high-speed railway is experiencing a rapid growth. Its operating mileage and the number of operating trains will exceed 45 000 km and 1500 trains by 2015, respectively. During the long range and constant high-speed operation, the high-speed trains have extremely complex and varied work conditions. Such a situation creates a huge demand for high-speed train on-board monitoring. In this paper, architecture for high-speed train on-board monitoring sensor network is proposed. This architecture is designed to achieve the goals of reliable sensing, scalable data transporting, and easy management. The three design goals are realized separately. The reliable sensing is achieved by deploying redundant sensor nodes in the same components. Then a hierarchal transporting scheme is involved to meet the second goal. Finally, an electronic-tag based addressing method is introduced to solve the management problem.

With the development of high-speed railways in China, more than 2000 high-speed trains will be put into use. Safety and efficiency of railway transportation is increasingly important. We have designed a high availability quadruple vital computer (HAQVC) system based on the analysis of the architecture of the traditional double 2-out-of-2 system and 2-out-of-3 system. The HAQVC system is a system with high availability and safety, with prominent characteristics such as fire-new internal architecture, high efficiency, reliable data interaction mechanism, and operation state change mechanism. The hardware of the vital CPU is based on ARM7 with the real-time embedded safe operation system (ES-OS). The Markov modeling method is designed to evaluate the reliability, availability, maintainability, and safety (RAMS) of the system. In this paper, we demonstrate that the HAQVC system is more reliable than the all voting triple modular redundancy (AVTMR) system and double 2-out-of-2 system. Thus, the design can be used for a specific application system, such as an airplane or high-speed railway system.

Compared to the current eddy braking patterns using a single magnetic source, hybrid excitation rail eddy brakes have many advantages, such as controllability, energy saving, and various operating models. Considering the large braking power consumption of the high-speed train, a hybrid excitation rail eddy brake system, which is based on the principle of electromagnetic field, is proposed to fulfill the needs of safety and reliability. Then the working processes of the mechanical lifting system and electromagnetic system are demonstrated. With the electromagnetic system analyzed using the finite element method, the factors such as speed, air gap, and exciting current have influences on the braking force and attractive force. At last, the structure optimization of the brake system is discussed.

Simulation models of traction driver systems were established using SIMULINK, according to the actual structure and parameters of China Railway High-Speed 2 (CRH2) and China Railway High-Speed 3 (CRH3) trains. In these models, the traction motor adopts transient current control and an indirect rotor magnetic field orientation vector control strategy, and the traction converter uses sinusoidal pulse width modulation (SPWM) and space vector pulse width modulation (SVPWM) methods. After these models are transformed in VC++ program, and a friendly interface and data processing system are constructed, simulation software is obtained for CRH2 and CRH3 traction driver systems. On this basis, the operational performance of a traction converter was simulated and analyzed at different train speeds and in different conditions. The simulation results can provide a reference for the actual design and production of a traction converter.

A switched-mode unit used in electric locomotive generates a strong high frequency conducted electromagnetic interference (EMI), which radiates electromagnetic energy through railway lines. Evaluation of magnetic field using analytical technique based on contour integral is presented, in order to assess the electromagnetic environment around a high-speed railway. Actual railway multiconductor finitely long overhead lines are represented by an infinitely long single line above two-layered earth, whose characteristic is different from homogeneous earth. Owing to the constraint of the GB/T 24338-2009 and the high frequency investigated (a few MHz), only the magnetic fields are examined. The magnetic fields consist of four components: the direct wave, the ideal reflected wave or image wave, the trapped surface wave, and the lateral wave. The calculation results proved that due to the presence of the trapped surface wave, the magnetic field of the observer point on the interface is strongly influenced, when the line is on or closed to the interface.

In order to study the unsteady aerodynamics effects in railway tunnels, the 3D Reynolds average Navier-Stokes equations of a viscous compressible fluid are solved, and the two-equation k-ε model is used in the simulation of turbulence, while the dynamic grid technique is employed for moving bodies. We focus on obtaining the changing tendencies of the aerodynamic force of the train and the aerodynamic pressures on the tunnel wall and train surface, and discovering the relationship between the velocity of the train and the intensity of the micro pressure wave at the tunnel exit. It is shown that the amplitudes of the pressure changes in the tunnel and on the train surface are both approximately proportional to the square of the train speed, so are the microwave and the drag of the train.

With the development of high-speed train, it is considerably concerned about the aerodynamic characteristics and operation safety issues of the high-speed train under extreme weather conditions. The aerodynamic performance of a high-speed train under heavy rain and strong crosswind conditions are modeled using the Eulerian two-phase model in this paper. The impact of heavy rainfall on train aerodynamics is investigated, coupling heavy rain and a strong crosswind. Results show that the lift force, side force, and rolling moment of the train increase significantly with wind speed up to 40 m/s under a rainfall rate of 60 mm/h. when considering the rain and wind conditions. The increases of the lift force, side force, and rolling moment may deteriorate the train operating safety and cause the train to overturn. A quasi-static stability analysis based on the moment balance is used to determine the limit safety speed of a train under different rain and wind levels. The results can provide a frame of reference for the train safe operation under strong rain and crosswind conditions.

The influence of sandstorms on train aerodynamic performance and safe running was studied in response to the frequent occurrence of sandstorm weather in north China. An Eulerian two-phase model in the computational fluid dynamic (CFD) software FLUENT, validated with published data, was used to solve the gas-solid multiphase flow of a sandstorm around a train. The train aerodynamic performance under different sandstorm levels and no sand conditions was then simulated. Results showed that in sandstorm weather, the drag, lift, side forces and overturning moment increase by variable degrees. Based on a numerical analysis of aerodynamic characteristics, an equation of train stability was also derived using the theory of moment balance from the view of dynamics. A recommended speed limit of a train under different sandstorm levels was calculated based on the stability analysis.

When aerodynamic braking works, the braking wings can change the flow field around the train, which may impact on the comfort and safety. Based on a sliding mesh, the pressure wave and flow field around high-speed trains with aerodynamic braking are analyzed. By comparing three typical intersection situations, the pressure wave of a high-speed train during braking (with or without aerodynamic braking) is studied. The analyses indicate that the pressure wave around the high-speed train body will change while using the aerodynamic braking, causing several pressure pulses on the surface of crossing high-speed trains. The distances between the pressure pulses are equal to the longitudinal distances of the brake wings, but the magnitudes of the fluctuations are less than those induced by the head of crossing trains. During the crossing, a train without aerodynamic braking will not impact the crossing train.