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[Objective] In order to ensure the running safety of trains with a speed of 400 km/h and above when passing through tunnels and improve the passenger ride comfort, it is necessary to adopt the numerical simulation method to study the characteristics of the pressure on the train body surface when passing through tunnels. [Method] The one-dimensional flow theory and the method of characteristic lines of generalized Riemann variables are introduced and verified through dynamic model tests. The influence patterns of different train running speeds and different tunnel lengths on the train body surface pressure when an 8-car marshalling train passes through the tunnel are explored, and the distribution characteristics of surface pressure on different vehicle bodies are analyzed. [Result & Conclusion] When the train running speed is 400 km/h and the tunnel length is 0.7 km, the maximum positive pressure value, the maximum pressure amplitude, and the maximum negative pressure value on the train surface all reach their peak values. When the tunnel length exceeds 0.7 km, the maximum positive pressure value basically does not change with the increase of tunnel length, while the maximum negative pressure value and the maximum pressure amplitude gradually decrease as the tunnel length increases. With different train running speeds, the pressure values on the train surface gradually increase with the increase of train running speed. For the same train running at a speed of 400 km/h, the different parts of the train in descending order of the maximum positive pressure value and the maximum pressure amplitude on their surfaces are the head car, the intermediate car, and the end car, while in ascending order of the maximum negative pressure are the head car, the intermediate car, the end car. Numerically, the maximum positive pressure value, the maximum negative pressure value, and the pressure amplitude on the train body surface all gradually decrease as the distance of the measuring points from the nose tip of the train head increases. [ABSTRACT FROM AUTHOR]

The ballastless track subgrade is the foundation that bears the weight of the upper track structure and the dynamic train loads. Solving the internal stress-strain state of subgrade under moving load is a key aspect of subgrade dynamics research. To accurately calculate the vertical dynamic stress and displacement of the subgrade under moving train loads, a numerical model of the CRTS III-type slab ballastless track-subgrade-foundation was established. The wheel-rail excitation force expression was improved and secondary development of the load subroutine within finite element software was used to simulate the dynamic train load. A series of dynamic explicit numerical calculations were carried out. The results showed that the subgrade surface generated dynamic response peaks corresponding to the wheel-rail forces, with the maximum value occurring when the third bogie load passed. Stress concentration occurred at the contact position between the subgrade and the concrete baseplate edge. The vertical dynamic displacement was uniformly distributed beneath the track structure; The vibration induced by the train load attenuated along the depth direction and superposed toward the track centerline. The vertical dynamic stress and displacement at the bottom of subgrade were 8 kPa and 0.89 mm, respectively. As train speed increased, the dynamic stress and displacement of the subgrade increased significantly. Increasing the subgrade height effectively improved its load buffering capacity, but the attenuation trend of dynamic displacement and stress gradually slowed down. Comprehensive analysis indicated that the soil strength at the baseplate edge and the central area of the embankment would require attention. [ABSTRACT FROM AUTHOR]

［Objective］ In order to ensure the running safety of trains with a speed of 400 km/h and above when passing through tunnels and improve the passenger ride comfort, it is necessary to adopt the numerical simulation method to study the characteristics of the pressure on the train body surface when passing through tunnels. ［Method］ The one-dimensional flow theory and the method of characteristic lines of generalized Riemann variables are introduced and verified through dynamic model tests. The influence patterns of different train running speeds and different tunnel lengths on the train body surface pressure when an 8-car marshalling train passes through the tunnel are explored, and the distribution characteristics of surface pressure on different vehicle bodies are analyzed. ［Result & Conclusion］ When the train running speed is 400 km/h and the tunnel length is 0.7 km, the maximum positive pressure value, the maximum pressure amplitude, and the maximum negative pressure value on the train surface all reach their peak values. When the tunnel length exceeds 0.7 km, the maximum positive pressure value basically does not change with the increase of tunnel length, while the maximum negative pressure value and the maximum pressure amplitude gradually decrease as the tunnel length increases. With different train running speeds, the pressure values on the train surface gradually increase with the increase of train running speed. For the same train running at a speed of 400 km/h, the different parts of the train in descending order of the maximum positive pressure value and the maximum pressure amplitude on their surfaces are the head car, the intermediate car, and the end car, while in ascending order of the maximum negative pressure are the head car, the intermediate car, the end car. Numerically, the maximum positive pressure value, the maximum negative pressure value, and the pressure amplitude on the train body surface all gradually decrease as the distance of the measuring points from the nose tip of the train head increases.

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Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To study the influence of the lateral deformations of a simply-supported beam bridge on the safety of high-speed railway train operations under earthquake action, this study adopted a three-span simply-supported beam bridge with 32-m spans as an example. Finite element software ANSYS and multi-body dynamics software SIMPACK were used to establish a coupled train-bridge dynamic model subjected to seismic excitations. By adopting different ground motions and changing the peak ground acceleration (PGA) and the train speed, the effects of different earthquakes and train speeds on the train driving safety were analyzed. Several conclusions were obtained. First, the trends in train derailment coefficient, wheel load reduction rate, lateral horizontal wheelset forces, vertical accelerations of the car body, lateral accelerations of car body, and other dynamic indices were similar under different ground motions, but the actual values were different. Second, the PGA had a significant impact on the train derailment coefficient, wheel load reduction rate, lateral horizontal wheelset forces, and lateral accelerations of the car body, but little effect on the vertical accelerations of the car body. Third, the train speed affected the train derailment coefficient, wheel load reduction rate, lateral horizontal wheelset forces, vertical accelerations of the car body, and lateral accelerations of the car body, and these dynamic performance indices were positively correlated with the train speed. Fourth, in case of the earthquake with a PGA of 0.3 g, a high-speed train would have to travel slower than at 280 km/h to ensure the safety and comfort of the ride. [ABSTRACT FROM AUTHOR]

Purpose – The design goal for the tracking interval of high-speed railway trains in China is 3 min, but it is difficult to achieve, and it is widely believed that it is mainly limited by the tracking interval of train arrivals. If the train arrival tracking interval can be compressed, it will be beneficial for China's high-speed railway to achieve a 3-min train tracking interval. The goal of this article is to study how to compress the train arrival tracking interval. Design/methodology/approach – By simulating the process of dense train groups arriving at the station and stopping, the headway between train arrivals at the station was calculated, and the pattern of train arrival headway was obtained, changing the traditional understanding that the train arrival headway is considered the main factor limiting the headway of trains. Findings – When the running speed of trains is high, the headway between trains is short, the length of the station approach throat area is considerable and frequent train arrivals at the station, the arrival headway for the first group or several groups of trains will exceed the headway, but the subsequent sets of trains will have a headway equal to the arrival headway. This convergence characteristic is obtained by appropriately increasing the running time. Originality/value – According to this pattern, there is no need to overly emphasize the impact of train arrival headway on the headway. This plays an important role in compressing train headway and improving high-speed railway capacity.

In order to study the dynamic response of high-speed railway bridge under flood, a two-span high-speed railway simple-supported beam bridge with unequal 32-meter pier height is studied. A three-dimensional hydrodynamic model of the substructure and a finite element model of the bridge under flooding are built up to analyze the law of flow field distribution around and the hydrodynamic pressure. The influences of the change of velocity and height of flood and the foundation scour depth on the dynamic response of bridge and internal force of pile foundation are revealed. The study shows that: (1) The law of flow field distribution is basically the same when the bridge substructure is impacted by the flood with different velocities; (2) When the flood velocity exceeds 3 meters per second, the influence of the hydrodynamic pressure on the substructure cannot be ignored, and the pressure is positively correlated with velocity and height of the flood; (3) The depth of foundation scour has a significant influence on the hydrodynamic pressure. But when the depth of foundation scour is increased after the bearing platform is exposed, the increase of the pressure is not obvious; (4) When the bridge is impacted by the flood, the overall law of the dynamic response of the bridge with time is basically the same. The response is as follows: When t = 1.06 s, the lateral vibration acceleration of pier top reaches the peak value; When t = 1.16 s, the lateral displacement of pier top reaches the peak value. After the lateral displacement and vibration acceleration reach their peak values, they both tend to attenuate decay rapidly and periodically. With the velocity and height of flood increasing, the peak values and final stable values of displacement and acceleration at prier top as well as the pile bending moment increase; (5) With the increase of foundation scour depth, both the dynamic response and the pile bending moment increase, but the negative bending moment area of pile foundation is more sensitive to the impact of foundation scour depth. [ABSTRACT FROM AUTHOR]

During the long-term operation of high-speed railway in our country, affected by various factors such as surrounding environment changes and human engineering activities, large lateral deviation occurs in some line bridge sections, which seriously affects the normal and safe operation of the train and needs to be rectified urgently. Based on the analysis of the principle of bridge rectification by high pressure jet grouting, the theoretical calculation model of bridge rectification is established, and the differential equations of pile deflection, rotation angle, bending moment and shear force under the high pressure jet grouting rectification mode and the analytical formula of pier top displacement are deduced based on the elastic foundation beam theory. Then,by comparing the calculated displacement at the top of the pier with the actual offset of the line,the feasibility of high pressure jet grouting technology for bridge rectification is analyzed, and the rectification effect is verified by typical engineering cases on site. Research shows that the top displacement of pier is related to foundation coefficient and excess pore water pressure generated by high pressure jet grouting; when foundation coefficient and excess pore water pressure take 1 MPa/ m and 80.3 kPa respectively,the top theoretical calculated displacement of pier is 81.8 mm,which is much larger than the actual deviation of ballastless track line of common high speed railway;In the bridge rectification project of a high speed railway Songjiang Grand Bridge,the displacement at the top of the pier calculated by the average value of the measured excess pore water pressure 30.4 kPa 6. 4~31. 0 mm,which is also greater than the maximum deviation 18.2 mm of the line, indicating that the high pressure jet grouting technology is feasible for bridge rectification theoretically;After rectification construction,the bridge and track structure are stable,the line alignment is smooth,and there is no abnormality in the normal speed operation for many years. The theory and practice have proved that the high pressure jet grouting method is a practical and feasible technical measure for bridge rectification. [ABSTRACT FROM AUTHOR]

In the red-bed areas of southwestern China, subgrade uplift deformation poses a serious safety concern for high-speed trains. However, the subgrade uplift mechanisms are still not well-defined, and there is a lack of effective prediction methods for addressing this issue. The objective of this study is to build prediction model of subgrade uplift using three machine learning techniques (MLTs): artificial neural network (ANN), random forest (RF), and support vector machine (SVM). The Chengdu-Chongqing passenger dedicated line (CCPDL) was selected as the research object, and a total of 200 cuttings along the CCPDL were randomly divided into two groups: a training set (70%) and a testing set (30%). The subgrade uplift mechanism was concluded by conducting the laboratory test, field investigation and mathematical statistics. Then six subgrade uplift-conditioning factors were identified, including subgrade excavation height, subgrade excavation width, dip angle, interbedded characteristics between sandstone and mudstone, mudstone rheology, and mudstone swelling. To assess the model performance, various evaluation metrics were employed, including receiver operating characteristic curve (ROC), area under the curve (AUC), accuracy, precision, recall, specificity, and F1 score. The results demonstrate that the RF model outperforms the other MLTs in predicting subgrade uplift. Notably, among the six factors considered, subgrade excavation height was identified as the most influential factor. These findings provide valuable insights into the prediction of subgrade uplift and offer guidance for mitigating the risks associated with subgrade uplift during the construction of high-speed railways. [ABSTRACT FROM AUTHOR]

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Purpose – The purpose of this study is to introduce the top-level design ideas and the overall architecture of earthquake early-warning system for high speed railways in China, which is based on P-wave earthquake early-warning and multiple ways of rapid treatment. Design/methodology/approach – The paper describes the key technologies that are involved in the development of the system, such as P-wave identification and earthquake early-warning, multi-source seismic information fusion and earthquake emergency treatment technologies. The paper also presents the test results of the system, which show that it has complete functions and its major performance indicators meet the design requirements. Findings – The study demonstrates that the high speed railways earthquake early-warning system serves as an important technical tool for high speed railways to cope with the threat of earthquake to the operation safety. The key technical indicators of the system have excellent performance: The first report time of the P-wave is less than three seconds. From the first arrival of P-wave to the beginning of train braking, the total delay of onboard emergency treatment is 3.63 seconds under 95% probability. The average total delay for power failures triggered by substations is 3.3 seconds. Originality/value – The paper provides a valuable reference for the research and development of earthquake early-warning system for high speed railways in other countries and regions. It also contributes to the earthquake prevention and disaster reduction efforts.

Improving the aging resistance and elasticity of rubber materials can increase the service life of rubber pads and reduce railway operation costs. The purpose of this work was to improve aging resistance, decrease compression set and ratio of dynamic stiffness to static stiffness (Rd/s) of railway rubber pads by using environmentally friendly accelerators N‐t‐butyl‐2‐benzothiazole sulfenimide (TBSI) and tetrabenzylthiuram disulfide (TBzTD). The influence of the curing system on the properties of rubber pads was assessed using multiple techniques. Compared to sulfur/tetramethylthiuram disulfide (TMTD) /N‐cyclohexyl‐2‐benzothiazole sulfenamide (CZ), compression set of S/TBSI/TBZTD decreased to 29.5% from 35.7%, retention of elongation at break after hot air aging increased to 77.7% from 66.1%, and Rd/s decreased to 1.82 from 1.85. Thermogravimetry (TG) and derivative thermogravimetry (DTG) analysis indicated that maximum thermal decomposition temperature of TBSI/TBZTD was higher, which was the reason for the good aging resistance and low compression set results. Rubber processing analysis (RPA) demonstrated that the loss factor of TBSI/TBZTD was smaller. The rubber cured by TBSI/TBZTD had a higher crosslinking density and smaller loss factor, which decreased the Rd/s. This study provides a reference for preparing of environmentally friendly rubber pads with a low Rd/s and long service life. [ABSTRACT FROM AUTHOR]

In this paper, we evaluate the role of the high speed railway (HSR) project, one of the largest transportation infrastructure projects in the world, in poverty alleviation in China. This study combines county-level data from the China County Statistical Yearbooks with HSR data from the China Railway Yearbooks. The method of difference-in-differences is applied to examine the HSR connection effect on government expenditure in poverty alleviation across Chinese poverty counties over the period of 2010-2018. The results show that the HSR connection has a significantly positive impact on reducing government expenditure in poverty alleviation. Our results, which are based on alternative measurement of poverty alleviation and possible bias arising from endogeneity issue, are robust. This paper highlights that HSR can help achieve accessibility of rural area and poverty alleviation simultaneously. An understanding of the effect is critical for policymakers to promote intra-regional development, balancing efficiency and regional equality. [ABSTRACT FROM AUTHOR]

Copyright of Railway Signalling & Communication Engineering is the property of Railway Signalling & Communication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Signalling & Communication Engineering is the property of Railway Signalling & Communication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

High-speed railway bridge piers with large stiffness, structure and construction are different from those of highway and municipal bridges and we need to conduct in-depth and systematic research to ensure whether a large number of existing highway and municipal bridge pier research results are applicable to socket type railway piers. The nonlinear finite element models of socket and castin-place double column hollow piers are established, and the correctness of the modeling method is verified by combining with the existing test results. By simulating the mechanical behavior of the pier under the quasi-static reciprocating action, the force-displacement curve of the hollow pier is obtained. The difference of hysteretic behavior between the socket pier and cast-in-place pier is compared. The reasonable range of the socket depth is determined based on the strain permeability effect and the development length of longitudinal reinforcement, and the calculation formula of the minimum socket depth is proposed. The results show that the bearing capacity difference between socket pier and cast-in-place pier is very small, the maximum difference is 2. 8% when the pier height is 5m and 10m. The stiffness degradation law of socket pier and cast-in-place pier is basically the same, the stiffness decreases with the increase of lateral displacement, and the stiffness degrades faster when the displacement is small, and it slows down when the displacement is large. The longitudinal reinforcement yields in the plastic hinge area and the strain permeation area below the cap top, and the strain decreases rapidly in the range of 400 mm below this area, the strain permeation area is the vulnerable part of the cap and socket pier. According to the calculation formula of the minimum socket depth proposed in this paper, the design value of the minimum socket depth of the hollow high-speed rail pier is 0. 5D(D is the outer diameter of the pier column). In order to ensure the safety of cap and plug bridge pier, reasonable structural measures should be taken to ensure the seismic performance of the pier in the strain permeation section, and it is recommended that the bearing depth of bridge pier in high intensity area should be greater than 0. 5D. [ABSTRACT FROM AUTHOR]

In the red-bed areas of southwestern China, subgrade uplift deformation poses a serious safety concern for high-speed trains. However, the subgrade uplift mechanisms are still not well-defined, and there is a lack of effective prediction methods for addressing this issue. The objective of this study is to build prediction model of subgrade uplift using three machine learning techniques (MLTs): artificial neural network (ANN), random forest (RF), and support vector machine (SVM). The Chengdu-Chongqing passenger dedicated line (CCPDL) was selected as the research object, and a total of 200 cuttings along the CCPDL were randomly divided into two groups: a training set (70%) and a testing set (30%). The subgrade uplift mechanism was concluded by conducting the laboratory test, field investigation and mathematical statistics. Then six subgrade uplift-conditioning factors were identified, including subgrade excavation height, subgrade excavation width, dip angle, interbedded characteristics between sandstone and mudstone, mudstone rheology, and mudstone swelling. To assess the model performance, various evaluation metrics were employed, including receiver operating characteristic curve (ROC), area under the curve (AUC), accuracy, precision, recall, specificity, and F-1 score. The results demonstrate that the RF model outperforms the other MLTs in predicting subgrade uplift. Notably, among the six factors considered, subgrade excavation height was identified as the most influential factor. These findings provide valuable insights into the prediction of subgrade uplift and offer guidance for mitigating the risks associated with subgrade uplift during the construction of high-speed railways.

Purpose – The purpose of this paper is to summarize the status and characteristics of rail technology of high-speed railway in China, and point out the development direction of rail technology of high-speed railway. Design/methodology/approach – This study reviews the evolution of high-speed rail standards in China, comparing their chemical composition, mechanical attributes and geometric specifications with EN standards. It delves into the status of rail production technology, shifts in key performance indicators and the quality characteristics of rails. The analysis further examines the interplay between wheels and rails, the implementation of grinding technology and the techniques for inspecting rail service conditions. It encapsulates the salient features of rail operation and maintenance within the high-speed railway ecosystem. The paper concludes with an insightful prognosis of high-speed railway technology development in China. Findings – The rail standards of high-speed railway in China are scientific and advanced, highly operational and in line with international standards. The quality and performance of rail in China have reached the world’s advanced level. The 60N profile guarantees the operation quality of wheel–rail interaction effectively. The rail grinding technology system scientifically guarantees the long-term good service performance of the rail. The rail service state detection technology is scientific and efficient. The rail technology will take “more intelligent” and “higher speed” as the development direction to meet the future needs of high-speed railway in China. Originality/value – The development direction of rail technology for high-speed railway in China is defined, which will promote the continuous innovation and breakthrough of rail technology.

Purpose – This method will become a new development trend in subgrade structure design for high speed railways. Design/methodology/approach – This paper summarizes the structural types and design methods of subgrade bed for high speed railways in China, Japan, France, Germany, the United States and other countries based on the study and analysis of existing literature and combined with the research results and practices of high speed railway subgrade engineering at home and abroad. Findings – It is found that in foreign countries, the layered reinforced structure is generally adopted for the subgrade bed of high speed railways, and the unified double-layer or multi-layer structure is adopted for the surface layer of subgrade bed, while the simple structure is adopted in China; in foreign countries, different inspection parameters are adopted to evaluate the compaction state of fillers according to their respective understanding and practice, while in China, compaction coefficient, subsoil coefficient and dynamic deformation modulus are adopted for such evaluation; in foreign countries, the subgrade top deformation control method, the subgrade bottom deformation control method, the subsurface fill strength control method are mainly adopted in subgrade bed structure design of high speed railways, while in China, dynamic deformation control of subgrade surface and dynamic strain control of subgrade bed bottom layer is adopted in the design. However, the cumulative deformation of subgrade caused by train cyclic vibration load is not considered in the existing design methods. Originality/value – This paper introduces a new subgrade structure design method based on whole-process dynamics analysis that meets subgrade functional requirements and is established on the basis of the existing research at home and abroad on prediction methods for cumulative deformation of subgrade soil.

In the emergency scenario of abnormal high speed railway operation, dispatchers need to quickly and correctly handle the emergency response to the emergencies, which plays a decisive role in the safe operation of trains. The cognitive decision-making process of high speed railway dispatchers was took as the research object, using the laboratory simulation experiment platform and facing the emergency scenario of abnormal driving, the structure of the cognitive decision-making mechanism model and the data collection method corresponding to the measurement model were designed. Based on the information processing model, combined with the concept of perceptual load theory and situational awareness, adding elements of mental load, a cognitive decision-making mechanism model for high speed railway dispatchers was established. Aiming at the evaluation of mental load, a particle swarm optimization algorithm for joint optimization was designed and adopted to optimize the training process based on multi-source physiological signals, comprehensively using signal processing theory and mathematical methods to extract the data characteristics. Fitting the structural equation model and studying the relationship between mental load and attention and working memory are of more practical value for the later optimization of dispatchers workload and job adaptability. [ABSTRACT FROM AUTHOR]

This paper presents a proposal to cut the longitudinally connected slab ballastless track structure into discrete units with a certain length so as to control the damage caused by excessive temperature rise and accordingly reduce the risk of instability of track structure. The temperature deformation of the unit track structure needs to be constrained by some measures. By two displacement-limiting measures such as planting rebar and installing pressing device, the temperature deformation and damage of longitudinally connected slab ballastless track with different segment lengths are investigated in a numerical way. Results show that for the longitudinal deformation of both ends of the segment, the effect of planting rebar is more obvious than that of installing pressing device. For the longitudinal deformation of the slab corner of the segment end, the effects of two displacement-limiting measures are very close; The planting rebar is better to overall control the relative longitudinal displacement between the track slab and the CA mortar layer, and the installing pressing device has control advantage at the slab corner. When the rebar is planted, the segment length has little influence on the concrete damage of the rebar holes; While the pressing device is installed, the influence of the segment length on the concrete damage of slab corner is small under the overall temperature lower 5 °C, and becomes significant after the overall temperature rise over 5 °C. After the rebar is planted, the tensile damage first appears at the wall of the rebar hole, and the damaged area expands laterally with the temperature rising. After the pressing device is installed, the compressive damage first appears on the bottom surface of the track slab. As the temperature rises, the damage area expands upwards to the top surface of the track slab. For the interface damage, the differences in the influence between the two displacement-limiting measures are remarkable. The total delamination area reduced by planting rebar measure is larger, while delamination at the slab corner is better controlled by the installing pressing device measure. The temperature deformation and damage are controlled by choosing 3 slabs as a segment and using planting rebar measures. [ABSTRACT FROM AUTHOR]

Distributed acoustic sensing (DAS) using existing optical fiber cables facilitates high‐density seismic observation. However, few studies have examined the reliability of the seismic waveform amplitude recorded by DAS. In this study, a DAS network was connected to optical fiber cables installed over a distance of 75 km along a high‐speed train (Shinkansen) railway in the Kumamoto prefecture, Japan. We successfully observed strong motions of the Mj6.6 earthquake (approximately 150 km from the fiber) on 22 January 2022, in Hyuga‐nada, in addition to several small local earthquakes. The observed strong motions from the Mj6.6 earthquake, using DAS, exhibited cycle skipping (clipping) issues due to dynamic range limitations at numerous channels. To address this, we estimated the shaking map, representing maximum strain distributions for Mj6.6, by replacing the clipped data with information from nearby unclipped channels and scaling their RMS amplitudes based on S‐coda (unclipped). Furthermore, we verified the reliability of the amplitude information obtained from DAS by estimating the distance attenuation of seismic waves while correcting for the differences in the structure type and coupling as much as possible. The distance attenuation property of local earthquakes was consistent with that of the peak ground velocities obtained from seismometers, indicating that DAS data acquired using fibers installed on infrastructure (various structures) can also be utilized to assess the spatial distribution of the relative amplitude values along the fiber. Obtaining high‐density seismic motion distributions is important for earthquake early warning and accurate damage estimation of strong motions. Plain Language Summary: In the past decade, the use of distributed acoustic sensing (DAS) for seismological purposes has grown rapidly. By utilizing existing dark fibers, such as telecommunication cables, high‐density seismic observation networks can be established in residential areas. In this study, DAS was applied to an existing optical fiber cable installed along a railway line, which recorded strong ground motions of Mj6.6 originating from a subduction zone, as well as numerous regional earthquakes. Although the technique uses optical phase differences for strain measurements and therefore has a poor response to strong ground motions, we resolve this issue using the correct data from neighboring stations as a reference and estimated the shaking distribution every 5 m along 75 km of the railway line. Additionally, when we analyzed the distance attenuation of small regional earthquakes, we found that the attenuation characteristics were similar to those obtained from permanent seismometers. These findings will significantly impact society in the future, particularly as the fiber cables replace conventional seismic observation networks. As a result, ultra‐high‐density observation networks will be capable of issuing more accurate earthquake early warnings and estimating damage following earthquakes. Key Points: We successfully observed strong motion from the Mj6.6 earthquake in Hyuga‐nada using Distributed acoustic sensing (DAS) over 75 km along railwayThe shaking map of the Mj6.6 was estimated by replacing the clipped channels with nearby unclipped channels and scaling their RMS amplitudes of S‐codaDistance attenuation property of local earthquakes of DAS consistent with that of peak ground velocities from continuous seismometers [ABSTRACT FROM AUTHOR]

During train travel, various factors, such as body vibration, uneven contact lines, and hard spots on carbon sliding plates and over electric neutral zones, often lead to brief separation between the pantograph and the contact line, i.e., the pantograph catenary contact loss phenomenon. With the continuous increase in train speed and traction power, the probability of pantograph catenary contact loss occurrences rises with a gradual increase in the energy of electromagnetic radiation, making the pantograph catenary arc a primary source of interference affecting the electromagnetic safety of high-speed railways. Understanding the mechanism, characteristics, and influencing factors of electromagnetic interference caused by pantograph catenary contact loss discharges is of utmost importance for analyzing and resolving on-site equipment interference faults. Our analysis of the physical process of pantograph catenary contact loss reveals that when the distance between the pantograph and catenary is significant and the duration is lengthy, high-voltage breakdown occurs within the pantograph catenary gap as it comes close again after the complete extinguishing of the arc. To investigate the electromagnetic radiation characteristics resulting from high-voltage breakdown discharge arcs in the pantograph catenary contact loss process, we established a laboratory test platform for assessing the electromagnetic disturbance characteristics of high-voltage pantograph discharge. We designed a test procedure utilizing fixed-gap breakdown discharge to evaluate the impact of the arc zero-crossing stage on electromagnetic radiation disturbances. Our research indicates that when the pantograph catenary spacing remains constant, an increase in voltage level leads to an elevation in the current within the discharge circuit, resulting in an increased intensity of impulse radiation generated during pantograph catenary contact loss events. During the moment of gap breakdown, the antenna records the highest amplitude of electromagnetic radiation. Also, during the steady-state arc ignition phase of the pantograph catenary gap, the zero-crossing stage generates pulsed discharge currents within the circuit, accompanied by substantial electromagnetic radiation. As the arc current increases, the zero-crossing time shortens, and the pulse current during the zero-crossing process decreases, accompanied by a reduction in the excited electromagnetic radiation. These observations reveal novel characteristics of electromagnetic radiation disturbances during steady-state arc ignition. The outcomes of our study provide valuable insights that can contribute to our understanding of the characteristics and influencing factors of electromagnetic radiation in pantograph catenary contact loss discharges and offer theoretical guidance for the resolution of pantograph catenary contact loss interference faults. [ABSTRACT FROM AUTHOR]

Long tunnels of high-speed railway need to be covered according to GSM-R redundancy networking scheme. At present, GSM-R network can use two kinds of digital relay equipment: digital repeater and distributed base station. Both of the equipment have a variety of networking solutions. This paper analyzes the fault response capability, carrier frequency utilization, construction cost and other aspects, compares various GSM-R digital relay equipment redundancy networking schemes in high-speed railway tunnels, and proposes the application scope and performance advantages and disadvantages of various schemes. [ABSTRACT FROM AUTHOR]

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Chongqing University of Technology (Natural Science) is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study estimated the effects and mechanisms of high-speed rail (HSR) connectivity on the city air quality in China. The Difference-in-Difference model are used to explore the effects, we found that on average, the city's PM2.5 concentration declined by 2.8 % after the opening of HSR, however, this impact varies depending on whether the city is part of the Ecological Economic Zone and the marketization degree. We further explored that HSR can affect local PM2.5 concentrations by changing firm's technical level. In instrumental variables regression and robustness testing, the conclusion remains unchanged. The results highlight the significance of considering firm responses to HSR in understanding the spatial patterns of air pollution in China. [ABSTRACT FROM AUTHOR]

This article discusses the outcomes of a study conducted to explore new power supply sources for subway trains. The power supply system for traction is an integral and inseparable component of subway rail infrastructure, encompassing both its management and operation. As a result, the specific choice of a power supply type has a lasting impact, either positive or negative, on the overall performance of a subway system. Consequently, researching power supply for traction presents a considerably more intricate challenge when compared to other railway transportation systems. In this study, the results obtained shed light on the pros and cons of utilizing the 25,000 V / 50 Hz system in comparison with the 1,500 V DC system, with a particular focus on traffic capacity and the efficiency of supplying traction power. [ABSTRACT FROM AUTHOR]

There has been no consensus on post‐earthquake operating plan for high‐speed railway trains. In this paper, two three‐dimensional coupling model of track‐bridge system without and with trains for high‐speed railways were developed, and their performance were verified based on shaking table tests. The equivalent method of design seismic track irregularity for random structures was discussed, and the amplitude response spectra of design seismic track irregularity for all levels of seismic intensity were proposed. In addition, the rationality of design seismic track irregularity was evaluated based on engineering case analysis, providing a theoretical foundation of formulating post‐earthquake contingency plans for high‐speed railways. The results show that when span number increases, the design seismic track irregularity amplitude increases and then tends to be stable; when the span number reaches 9, the train dynamic response gradually becomes stable; the random structures with arbitrary span numbers are equivalent to a specific 9‐span structure when constructing design seismic track irregularity. When the seismic intensity is low, there is no significant difference in shape and amplitude between the measured pre‐earthquake and post‐earthquake track alignment irregularities, and the train can normally run with no significant deceleration required. The train dynamic response under the design post‐earthquake track irregularity is greater than that under the measured post‐earthquake track irregularity, indicating that the design seismic track irregularity has a reasonable safety margin and a good feasibility in engineering practice. [ABSTRACT FROM AUTHOR]

Running trains on a long-span bridge under earthquake is an inevitable problem for the high-speed railway in seismic regions. This paper aims to investigate the seismically random dynamic behavior of train–cable stayed bridges interaction system using the probability density evolution method (PDEM). The system simultaneously involves the multi-effect of random multi-point earthquake excitations with traveling waves and random track irregularity. The multi-point earthquake excitations, composed of lateral and vertical positions, are generated by stochastic harmful functions (SHFs) and uniformly modulated into nonstationary random processes. The motion equation of such a system is established by coupling the 38-degree vehicles and bridges through the refined random wheel/rail contact relationship and accounting for the phase-lags of seismic travelling waves between pier excitations. PDEM is proven to be applicable to such time-dependent systems and is then used to transform the random excitations into a series of deterministic representative excitations with initial probability. By solving for the corresponding deterministic probability responses, various nonstationary random responses, including the time-dependent probability density evolution functions of random responses, mean values curves and standard deviations, can be obtained easily. A case study based on the cable-stayed bridge is then presented, and the results show the effectiveness and accuracy of the proposed method by comparison with Monte Carlo Simulation. Additionally, the influence of train speed and seismic intensity on the safety and reliability of trains is discussed. [ABSTRACT FROM AUTHOR]

This paper studied the impact of high-speed railway linesonagricultural outputin the regions along their routes. It also investigated the heterogeneity of this impactbased on the terrain characteristics. The results of empirical testsusing county-level data show that ahigh-speed railway line can bring higher agricultural "dividends" to counties along the line. Notably, low altitude areas and regionswith gentle terrain exhibit a more pronounced promotional effect on local agricultural output. High-speed railways mainly promote agricultural output by promoting the mechanization of agriculture in counties along the route, thus reinvigorating the agricultural population and the development of specialty agriculture. Ourfindingsprovide quasi-microscopic evidence of the potential benefits of transportation infrastructure construction to break down geographical barriers and facilitate production factor flow, and providesa theoretical basis for the economic spillover effects of high-speed railway construction. Plain Language Summary: This paper studied the impact of high-speed railway lines on agricultural output in the regions along their routes. It also investigated the heterogeneity of this impact based on the terrain characteristics. The results of empirical tests using county-level data show that a high-speed railway line can bring higher agricultural "dividends" to counties along the line. Notably, low altitude areas and regions with gentle terrain exhibit a more pronounced promotional effect on local agricultural output. High-speed railways mainly promote agricultural output by promoting the mechanization of agriculture in counties along the route, thus reinvigorating the agricultural population and the development of specialty agriculture. Our findings provide quasi-microscopic evidence of the potential benefits of transportation infrastructure construction to break down geographical barriers and facilitate production factor flow, and provides a theoretical basis for the economic spillover effects of high-speed railway construction. [ABSTRACT FROM AUTHOR]

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)