High-speed Railway Research Articles

The threshold effect and driving path of the rapid transit system on tourism eco-efficiency in China

Rapid transit is important for the green development of China’s tourism industry because it profoundly affects the optimal structural layout and rational allocation of elements that impact regional tourism. Based on provincial panel data from 2009 to 2020, the entropy weight method, tourism carbon emission measurement model, Super efficiency slacks-based measure model and threshold regression model were used to determine the impact of the rapid transit system on tourism eco-efficiency in China. The findings showed that rapid transit system has increased steadily, while tourism eco-efficiency has fluctuated significantly, and the relative development characteristics of rapid transit system and tourism eco-efficiency gradually changed from “lagging rapid transit system” to “lagging tourism eco-efficiency.” In addition, the rapid transit system and the highway and civil aviation have a nonlinear relationship with tourism eco-efficiency, while the high-speed railway has not passed the threshold effect test, and at the regional level, the impacts of rapid transit system have heterogeneous characteristics. As the deepening construction of rapid transit system, its threshold effect on tourism eco-efficiency will change from positive “V” to positive “U” type, promoting the more efficient development of environmentally friendly tourism.

Влияние параметров мостовых сооружений высокоскоростных железнодорожных магистралей на динамические свойства системы «мост — бесстыковой путь»

Objective: to determine the influence on the frequencies and shapes of free vibrations of multi-span bridge structures of high-speed railways of such factors as the longitudinal modulus of elasticity of the connection of the rail with the sub-rail base, the stiffness of the supports in the direction along the bridge and the massiveness of the intermediate supports. Methods: the article considers a four-span bridge with a jointless path modeled as an elastic beam on an elastic base, for which the oscillation forms and their corresponding natural frequencies are determined for various parameters of the bridge-jointless path system. Results: the data presented in the article make it possible to take into account the presence of a jointless track on the bridge and its participation in the work of the bridge structure when designing bridge structures on high-speed railways, which makes it possible to make constructive decisions of the elements of the object more reasonably. Practical significance: since the dynamic reaction of a structure is entirely determined by its dynamic properties, it becomes extremely important to identify the spectrum of natural frequencies and oscillation patterns of a bridge structure when taking into account the operation of a jointless track on a bridge, which unites the structure into a single system, ensuring the compatibility of the elements of the bridge-jointless track system under longitudinal train and temperature influences, which It makes it possible to reflect the actual operation of the structure and, ultimately, allows you to build more economical bridge supports.

О грузоперевозках на существующем главном ходу Октябрьской железной дороги после ввода в эксплуатацию ВСМ Москва — Санкт-Петербург

Objective: to study the change of passenger and freight traffic on the Oktyabrskaya Railway “main route — the way around” and to show the need to continue research, taking into account the construction in 2028 high-speed railway Moscow — St. Petersburg (HSR). Methods: analysis of published research results, study of the main regulatory documents, reports and other sources taking into account the reflection of the key tasks of the development of railway transport, including the HSR network, according to the Transport Strategy of the Russian Federation until 2030 with a forecast until 2035. Results: it was found that after switching cargo traffic from the main route to the way around in Russia, tariffs and the delivery time of goods by rail have increased. With the growth of the total volume of container traffic towards the ports of the North-West, the goods are transported by road. There is a strong competition between Sapsan trains and air transport in the fight for passengers on the Moscow — St. Petersburg route. The upgraded railway track for the Sapsan speed service is operating at the capacity limit. This confirms the relevance of the construction of HSR in this route and makes it important of research of passenger and freight traffic on the Oktyabrskaya Railway “main route — the way around”. Practical importance: the use of research results will increase the competitiveness of railways in comparison with auto and airtransport in the Oktyabrskaya Railway “main route — the way around”.

Detection and Assessment of Seismic Response of High-Speed Railway Bridges Based on Smartphone Public Participation

The seismic response detection and operational safety assessment of high-speed railway (HSR) bridges play a crucial role in ensuring HSR systems’ operational safety and reliability. Smartphones have introduced intelligent inspection tools for structural health detection, becoming a new tool for intelligent structural inspection. Combining the public and smartphones is the key to public participation in structural health detection. This study utilizes smartphone-based structural seismic response inspection technology to investigate the framework of public participation in earthquake response inspection and assessment. This system comprises the Smart Bridge Brain (SBB), which integrates data from multiple sources and systems, an assigning mechanism for public participation inspection tasks, and smartphone-based HSR bridge structural seismic response inspection technology. At the same time, the Unreal Engine 5.0 software is used to create a mixed-reality virtual simulation experimental environment to validate the feasibility of this framework. The results indicate that the intelligent optimization of task allocation by the SBB successfully assigns detection tasks to each public participant. Public participants can promptly reach predefined damage structure detection targets and rapidly inspect bridge structural seismic response indicators using smartphones. In addition, this paper also conducts a comprehensive evaluation and analysis of the detection of the work efficiency index (WEI) within the system. Furthermore, optimization strategies for the efficient execution of detection tasks are proposed based on WEI variations influenced by different factors. The system framework is expected to enhance cluster-based HSR bridges’ intelligent disaster prevention and mitigation capabilities.

The Characteristics of Long-Wave Irregularities in High-Speed Railway Vertical Curves and Method for Mitigation.

Track geometry measurements (TGMs) are a critical methodology for assessing the quality of track regularities and, thus, are essential for ensuring the safety and comfort of high-speed railway (HSR) operations. TGMs also serve as foundational datasets for engineering departments to devise daily maintenance and repair strategies. During routine maintenance, S-shaped long-wave irregularities (SLIs) were found to be present in the vertical direction from track geometry cars (TGCs) at the beginning and end of a vertical curve (VC). In this paper, we conduct a comprehensive analysis and comparison of the characteristics of these SLIs and design a long-wave filter for simulating inertial measurement systems (IMSs). This simulation experiment conclusively demonstrates that SLIs are not attributed to track geometric deformation from the design reference. Instead, imperfections in the longitudinal profile's design are what cause abrupt changes in the vehicle's acceleration, resulting in the measurement output of SLIs. Expanding upon this foundation, an additional investigation concerning the quantitative relationship between SLIs and longitudinal profiles is pursued. Finally, a method that involves the addition of a third-degree parabolic transition curve (TDPTC) or a full-wave sinusoidal transition curve (FSTC) is proposed for a smooth transition between the slope and the circular curve, designed to eliminate the abrupt changes in vertical acceleration and to mitigate SLIs. The correctness and effectiveness of this method are validated through filtering simulation experiments. These experiments indicate that the proposed method not only eliminates abrupt changes in vertical acceleration, but also significantly mitigates SLIs.

Flatness warping of CRTS III track slabs during curing phase

At present, there is a problem of excessive flatness warping in high-speed railway CRTS III type ballastless track slabs on certain railway lines. To analyze the evolution of flatness warping in track slabs and propose effective solutions, this study measured the compressive strength of the concrete used in track slabs, and the flatness warping of track slabs during the water curing and wet curing stages. A comparative experiment was also conducted to evaluate six improvement designs of track slabs. A model was developed to calculate the flatness warping of track slabs during the natural curing stage. The primary findings are as follows: (1) After the demoulding of the track slab, central upward arching deformation occurs at all stages due to the combined effects of drying shrinkage, thermal shrinkage, prestressing, and creep. The flatness warping generated during steam curing stage is a prerequisite; (2) During the curing phase, the primary factors causing excessive flatness warping in track slabs are drying shrinkage and thermal shrinkage; (3) The issue of excessive flatness warping of track slabs can be effectively resolved by employing secondary water spraying and setting a 0.5 mm reverse arch. Additionally, when the temperature is below 0℃ and the relative humidity is less than 0.55, it is necessary to apply insulation and moisturizing measures to the track slabs during the natural curing stage.

Subgrade uplift prediction along a high-speed railway using machine learning techniques in Sichuan, China

Subgrade uplift prediction along a high-speed railway using machine learning techniques in Sichuan, China

Seismic response prediction and fragility assessment of high-speed railway bridges using machine learning technology

Nowadays, reliable and accurate prediction of the seismic response of high-speed railway bridges and then rapid assessment of their seismic fragility is crucial for the risk assessment of regional high-speed railway bridges. However, the traditional seismic fragility assessment based on nonlinear time history analysis (NTHA) has a characteristic of high computational cost. Therefore, this study explores different machine learning (ML) methods to develop a reliable rapid seismic fragility assessment framework for high-speed railway bridges. Taking a typical high-speed railway continuous (HRC) bridge as a case, a large number of numerical model and ground motion pairs considering various structural and ground motion features are established. Then, the two types of models including six popular ML methods are investigated, in which Lasso regression, artificial neural network (ANN) and support vector machine (SVM) are single models, and random forest (RF), extreme gradient boosting (XGBoost) and light gradient boosting machine (Light GBM) are ensemble models. A database containing a large number of seismic responses of different components is established through the NTHA to develop prediction models, and the optimal hyperparameters of different ML models are determined by ten-fold cross-validation and grid search. The study results show that the ensemble model can reliably predict the seismic response of the HRC bridge compared with the single model, and the XGBoost model is recommended for seismic fragility assessment. On this basis, the optimal ML model obtained by the performance evaluation is applied to develop seismic fragility curves of the HRC bridge, which are compared with the fragility curves based on NTHA. The results indicate that the XGBoost model can effectively replace the traditional NTHA for rapid seismic fragility assessment of the HRC bridge, which can achieve a sufficient assessment level while saving calculation costs.

Monitoring and analysis of side-slope deformation along Changgan high-speed railway based on time-series InSAR and BDS techniques

Monitoring and analysis of side-slope deformation along Changgan high-speed railway based on time-series InSAR and BDS techniques

WITHDRAWN: Artificial-intelligent-powered safety and efficiency improvement for integrated railway systems

The multi-mode integrated railway system, anchored by the high-speed railway, caters to the diverse travel requirement both within and between cities, offering safe, comfortable, punctual, and eco-friendly transportation services. With the expansion of the railway networks, enhancing the efficiency and safety of the comprehensive system has become a cricual issue in the advanced development of railway transportation. In light of the prevailing application of artificial intelligence technologies within railway systems, this study leverages large model technology characterized by robust learning capabilities, efficient associative abilities, and linkage analysis analysis, to propose an AI-powered railway control and dispatching system. This system is elaborately designed with four core functions, including galobal optimum unattended dispatching, synergetic transportation in multiply modes, high-speed automatic control, and precise maintenance decision and execution. The deployment pathway and essential tasks of the system is further delineated, alongside the challenges and obstacles encountered. The AI-powered system promises a significant enhancement in the operational efficiency and safety of the composite railway system, ensuring a more effective alignment between transportation services and passenger demands.

Aerodynamic study of high-speed railway tunnels with variable cross section utilizing equivalent excavation volume

High-speed railway tunnels, being critical components of transportation infrastructure, are subject to various aerodynamic effects that can impact train operations and passenger comfort. To address these challenges, the concept of tunnels with variable cross sections offers a promising solution, allowing for non-uniform adjustments to tunnel geometry along its length. By employing the notion of equivalent excavation volume, this paper aims to provide a comprehensive aerodynamic analysis of variable cross section tunnels, focusing on different rates of cross section variation (CR). The simulation of high-speed trains (HSTs) passing through tunnels is conducted using the compressible, unsteady Reynolds-Averaged Navier–Stokes model, and the accuracy is confirmed through experimental validation. The transient pressure and peak distribution, slipstream characteristics, micro-pressure waves, and aerodynamic loads acting on trains are fully evaluated. The results indicate that variable cross section tunnels can alleviate the negative pressure on train surface, particularly with streamlined heads and tails exhibiting superior effects, whereas its influence on positive pressure is minimal. The mitigation of both positive and negative pressures on the tunnels is promising, with the maximum peak-to-peak pressures exhibiting a quadratic decrease as the CR increases, resulting in a maximum relief of 17.7%. However, variable cross section tunnels have certain adverse effects on slipstreams and transient loads when HSTs passing through front junctions. Therefore, it is necessary to choose an appropriate CR to control these effects during design process. The findings of this research contribute novel insight for optimizing tunnel design and engineering practices to enhance operational efficiency and passenger comfort.

Transport capacity optimization for high-speed rail network considering flexible train composition and additional capacity pool

To balance the limited capacity and constantly changing demand in the high-speed rail network, a transport capacity optimization problem is investigated by adjusting train composition through uncoupling/coupling operations at the origin station, scheduling additional trains from the capacity pool, and optimizing the seat allocation among ODs. To make joint decisions, a two-stage stochastic programming model is formulated to minimize both operating cost and penalty cost for unsatisfied passengers, while incorporating various constraints such as flow conservation, loading capacity, flexible composition, etc. The two-stage model is linearized into a mixed-integer linear programming model, which can be effectively solved for small networks but is still intractable to solve for realistic networks. Therefore, a Lagrangian relaxation algorithm is proposed integrating parallel computing and sub-gradient method. Finally, two sets of case tests, including a toy network and a real-world case of a high-speed rail network in China, are implemented to show the performance of the proposed approach. The results illustrate that the parallel heuristic algorithm could generate a high-quality solution with a slight discrepancy from the optimal solution, while achieving a commendable computation time. Furthermore, the findings emphasize the advantages of applying flexible train composition and additional capacity pool in the high-speed railway system for cost-saving and supply–demand matching.

The effect of fastener clip fatigue for high-speed railway on vehicle-track dynamic interaction: Numerical analysis and probabilistic evaluation

To investigate the vehicle-induced fatigue damage evolution of fastener clips and their impact on the vehicle-track (VT) system, a numerical dynamic model is established to achieve probabilistic evaluation. The “rain flow” counting method is adopted to describe the stress cycles of the hazard area of the clips, and the S-N curve is used to predict the fatigue life of the clips. The solution of the dynamic equation of motion is obtained by the time-domain Green's function method, which is an effective method to improve computational efficiency. A versatile iterative algorithm is adopted to solve the nonlinear system considering the damaged clips. In the probabilistic evaluation framework, a novel random field method is employed to depict the spatial variability of clips’ strength. The applicability of the model established in this work in aspects of expressing random damage of fasteners and evaluating the dynamic behavior of the system is demonstrated by different numerical examples. The results show that the dynamic responses of the train and track system significantly exacerbate as the number of train cycles increases, which is closely related to the variability and non-uniform damage of the fasteners. The probability of cumulative damage to the fasteners induced by the train follows a three-stage rule, and the fatigue damage of the non-uniform fastener system caused by the train is greater than that of the uniform situation. In addition, the short wave components of track irregularity will significantly exacerbate the damage to fasteners and therefore degrade the status of the railway line. As the driving speed increases, the damage to the fasteners also increases, but the impact of vehicle speed on the fastener damage is smaller than that of track irregularity, especially in the range of fatigue damage greater than 0.9. Therefore, maintaining the geometric smoothness of the track, controlling the uniformity of the mechanical properties of the fasteners, and reducing the driving speed are feasible measures to extend the service life of the fastener system, thereby ensuring the operation of high-speed trains.

Damage characteristics and mechanical properties of CRTS III track structure in curved sections under longitudinal uneven subgrade settlement

This paper first presents a CRTS III track structure (TS) model specifically designed for curved sections, highlighting its adjustable superelevations feature that enhances adaptability to various high-speed railway curve profiles. The model considers the distribution of steel bars within the TS, concrete damaged plasticity, as well as contact nonlinearity. Afterward, the intricate impacts of longitudinal uneven subgrade settlement (LUSS) position (7 positions), amplitude (5–30 mm), wavelength (5–30 m), and TS superelevation (15–175 mm) on structural damage, stress, deformation, and interlayer gap are studied. The findings reveal that: 1) Under different LUSS positions, the concrete base (CB) experiences the most severe damage, particularly on its thick side. For the TS with 175 mm superelevation, in the wavelength range of 10–20 m, the maximum damage value of CB exceeds 0.9 when LUSS amplitude reaches 20 mm. With the movement of LUSS position, the main damage position of CB changes obviously. When the concrete stress reaches the tensile strength, the steel bars located in adjacent positions progressively assume the primary role in load-bearing. 2) The influence of LUSS on TS deformation and interlayer gap is inevitably associated with the distance between settlement center and expansion joints. Interlayer gaps vary among structural components, which are primarily distributed near settlement center, expansion joints, and settlement edges. 3) As the amplitude increases, both CB and self-compacting concrete layer (SCCL) damage are aggravated. Increasing wavelength initially causes damage to increase, then decrease, and 10–20 m is the most unfavorable wavelength range for most cases. 4) The effect of superelevation on TS damage is complex, varying with structural components and settlement characteristics. In most cases, as superelevation increases, the damage to CB increases, whereas the deformation decreases.

Understanding the Synergistic Effects of Walking Accessibility and the Built Environment on Street Vitality in High-Speed Railway Station Areas

The high-speed railway (HSR) has profoundly influenced individuals’ lifestyles and travel behaviors. The development of HSR stations and their surrounding areas plays a critical role in urban growth, enhancing both transport efficiency and urban functionality. This study investigates the development of HSR station areas, with a particular focus on Shanghai Hongqiao station, emphasizing the enhancement of street vitality as essential for integrated urban development. Street vitality in station areas is closely associated with individuals’ activities and travel behaviors, influenced by walking accessibility and the built environment. Understanding these factors is crucial for improving the efficiency and attractiveness of HSR station areas. Although extensive research has examined the separate impacts of the built environment and walking accessibility on street vitality, a significant gap remains in comprehending their synergistic effects. This study employs GPS and point-of-interest (POI) data to analyze the stay time of HSR passengers in station areas. Utilizing machine learning algorithms and geographic information system (GIS) tools, this research models the impact of walking accessibility and the built environment on passengers’ stay time. The results indicate that passengers are more inclined to remain within areas accessible by a 7 min walk from the station. Furthermore, the synergistic effects of walking accessibility and the built environment can inform the spatial planning of various functions. These findings provide valuable insights for urban planners and policymakers aiming to enhance the development and efficiency of HSR station areas.

Ultrasonic dynamic plane wave imaging for high-speed railway inspection

The detection of internal defects within railway tracks stands as a critical aspect of ensuring transport security, given its potential to precipitate severe accidents. Phased array ultrasonic testing methods have gained extensive usage in rail inspection owing to their remarkable precision and expansive coverage. Traditional ultrasonic inspection techniques typically require either a fixed relative position between the transducer and the specimens or a gentle movement of the transducer to beamform. However, the unavoidable vibration stemming from the vehicle–rail coupled interactions often results in time-variant media, significantly impacting the beamforming. This paper presents a refined wavenumber-domain plane wave imaging technique tailored to enable real-time dynamic imaging, specifically accommodating the vertical vibrational movement of the transducer. Real-time calculation of the transmission focal law is achieved by numerical fitting. The wavenumber-domain technique is utilized to realize real-time accurately reconstructed images. The efficacy of the proposed method is assessed through simulations and experiments performed on a convex cylindrical specimen and a rail head sample, respectively. It can be seen that this approach can achieve a frame rate of 83.3 fps with a pipeline architecture in this study, demonstrating the capability to reconstruct images in vibrating environments, such as during the high-speed inspection of railways.

Determining the effect of additional tank volume and air pressure in the spring on the dynamic indicators of a pneumatic system of spring suspension in high-speed railroad rolling stock

The object of this study is the pneumatic system in the spring suspension of rolling stock under conditions of high-speed movement from 170 to 250 km/h. Based on the thermodynamic model of the pneumatic spring suspension system, the influence of volume of the additional tank and the initial pressure in the pneumatic spring on the nature of change in the spring's dynamic stiffness, energy losses, and damping coefficient was studied. Based on the built "force-deformation" dependences for the pneumatic spring, it was established that the change in the volume of an additional tank has a slight effect on the deformation of the pneumatic spring at different speeds of the high-speed rolling stock. It was established that in the range of rolling stock speeds of 170–250 km/h, the diameter of the connecting pipeline is 30 mm, and the volume of the additional tank is from 30 to 60 l, the maximum change in the dynamic stiffness of the pneumatic spring up to 15.5 % occurs at the pressure in the spring of 6.5 bar. Dependences of energy loss and damping coefficient during the operating cycle of the pneumatic spring suspension system were derived. It was established that an increase in the volume of the additional tank and the initial pressure in the pneumatic spring leads to an increase in the energy loss during the operation cycle of the pneumatic system. The maximum values of the damping coefficient over the entire considered range of variable parameters are 1.16–1.29. It was established that with the volume of the additional tank in the range from 30 to 50 liters, the maximum values of the damping coefficient are observed at a diameter of the connecting pipeline of 25 mm and a speed of movement from 200 to 250 km/h. And with an additional tank volume of 60 liters – with a diameter of 30 mm and a speed of 170 to 250 km/h

Evaluation of energy performance and environmental benefits for transcritical CO2 thermal system in high-speed trains

The conventional air conditioning system used in high-speed railways has limitations in heating performance and environmental impact, necessitating the exploration of alternative refrigerants. The transcritical CO2 system has gained popularity due to its exceptional heating efficiency and environmental benefits. This study aims to evaluate the energy and environmental potentials for transcritical CO2 systems in high-speed trains based on four-vertical-and-four-horizontal railway lines within different climatic regions of China. A high-fidelity transcritical CO2 system model was first developed and validated through experiments. Then, a comprehensive energy and environmental evaluation method was proposed and applied to the four-vertical-and-four-horizontal railway lines. The results indicated that the transcritical CO2 system had a superior heating performance and competitive cooling performance based on daily and annual operations. Furthermore, the transcritical CO2 system exhibited significant environmental advantages with lower total life cycle climate performance for all lines, with an average emissions reduction ratio of 17.6% and a maximum emissions reduction ratio of 26.98%. These findings highlight the competitive energy performance and outstanding environmental benefits offered by transcritical CO2 systems as promising alternatives to air conditioning systems in railway transportation.

Null Phase Assumption-Based Technique for Constructing the Target Model of Seismic Irregularity on High-Speed Railways

High-speed railways are “lifeline projects” that shoulder the heavy responsibility of transporting relief supplies and medical forces for the first time after earthquakes. To ensure the train’s safety after earthquakes, it is of great urgency to ascertain a post-earthquake speed threshold. To that end, a target model for seismic irregularity emerges as a key parameter. In this paper, a null phase assumption-based technique for the mutual conversion between evolutionary power spectral density and non-stationary signal was proposed. Taking a high-speed railway track-bridge system as the research object, the target model of seismic irregularities was constructed based on the proposed technique. The rationality of the target model of seismic irregularities was verified, and the construction parameter settings were discussed. Moreover, a simplified frequency-domain fitting method for the target model of seismic irregularities was proposed based on the spectral decomposition theory. According to the research findings, the null phase assumption-based technique is capable of performing interconversion between seismic irregularity and its evolutionary power spectral density with satisfactory accuracy. It is recommended to set the minimum number of seismic irregularities, spatial sampling interval, hop size, and length of window function as 50, 0.25[Formula: see text]m, 1, and 40 to 100, respectively.

The impact of nozzle parameters and water injection pressure on the application effect of hydraulic punching enhanced permeability technology in high ground stress coal seam

High-stress coal seams are different from ordinary coal seams in terms of their low hardness, low permeability, and certain degree of fluidity, making them more difficult to enhance permeability. Hydraulic punching enhanced transmission technology can quickly create voids in coal seams, but existing hydraulic punching techniques are suitable for shallow coal seams, and the effect of creating voids is greatly reduced when applied to high-stress coal seams. To optimize the application effect of hydraulic punching enhanced transmission technology in high-stress coal seams, theoretical research was conducted on the parameters of hydraulic punching nozzles and injection water pressure. A simulation model was established using COMSOL numerical simulation software to optimize the nozzle parameters and explore the combined effect of nozzle parameters and injection water pressure on enhancing permeability. Field experiments were conducted in the Zhaotong Tunnel of the China high-speed railway to determine the optimal combination of nozzle parameters and injection water pressure, thereby increasing the overall permeability of the coal seam and improving gas extraction efficiency. The results indicate that: (1)Through theoretical calculations, numerical simulations, and experimental verification, it has been proven that the perforation effect of a jetting device with three the long oblique nozzle with an oblique length of 15 mm and a size of 3 mm × 6mm is the best among the comparative results under a water injection pressure of 5 MPa；(2)Compared to the perforation effect before optimization, the water consumption for perforation after optimization is reduced to 0.6 times that before optimization, and the perforation efficiency after optimization is 3.556 times that before optimization. The perforation efficiency has been effectively improved；(3)The similarity between the theoretical results, simulation results, and experimental results in this study is all above 85%. The consistency of the results provides mutual verification and has certain engineering guidance significance.