Railway Network In China Research Articles

Model for Intercity Railway Schedule Optimization Incorporating Metrorail Transfers

The promotion of multimodal coordination is of great significance for the joint development of diverse urban transportation systems. Focusing on a comprehensive urban passenger transport hub that converges both intercity modes and multiple inner-city modes, our study aims to incorporate intercity railway and Metrorail coordination into train scheduling optimization to enhance transfer efficiency and provide a seamless service for passengers in urban railway networks. By considering the variety of passenger demands in different transport modes (e.g., rail transit and traditional mainline railway), train loading capacity, and potential disruption scenarios, we specifically developed a mixed-integer nonlinear programming (MINLP) model to simultaneously generate the coordination strategies, arrival/departure times of trains at each station, and the number of carriages in service in the network. To enhance computational efficiency, we proposed several improvement strategies involving the model linearization to reformulate the MINLP model into a mixed-integer linear programming (MILP) model and the determination of appropriate big- M values. Finally, numerical experiments based on historical passenger data from a realistic urban railway network in China were implemented to verify the effectiveness of our approach. The results demonstrate that our intercity railway and Metrorail coordination strategies could, in practice, significantly improve passenger transfer efficiency by over 35% compared with the train schedule without coordination.

Railway network delay evolution: A heterogeneous graph neural network approach

Accurate delay evolution prediction plays a pivotal role in train rescheduling decision-making for the railway network. Existing studies on delay prediction predominantly centered around predicting delays for each train in the subsequent stations (i.e., following a train-oriented perspective). Furthermore, train operations in the railway network involve different types of entities (stations, trains, etc.), making the current graph/network models with homogenous nodes (i.e., the same kind of nodes) incapable of effectively capturing the interactions between the entities. This paper develops a network-oriented model to investigate the train delay evolution on railway networks, by predicting the delays of running trains in the network after a given time interval. The proposed model combines the GraphSAGE graph neural network (GNN) and the heterogeneous graph neural network (HetGNN) architecture, thus called SAGE-Het, enabling it to capture interactions between heterogeneous nodes (i.e., different types of nodes) based on different edges (e.g., edges between trains, trains, and stations). Additionally, SAGE-Het allows for flexible inputs in contrast to conventional machine learning techniques, whose inputs must meet the consistent dimension requirement (e.g., in the form of rectangular or grid-like arrays). The performance and robustness of the suggested SAGE-Het model are assessed in experiments on the data from two sub-networks of the China railway network. The experimental results demonstrate that SAGE-Het outperforms the existing delay prediction methods and some advanced HetGNNs used for prediction tasks in other domains; SAGE-Het demonstrates excellent scalability, capable of handling various types of nodes; the predictive performances of SAGE-Het under different prediction time horizons (10/20/30 min ahead) all exhibit better performance over other baselines; the accuracies are over 90 % under the permissible 3-minute errors for the three prediction time horizons. Specifically, the impact of train interactions on delay evolution is investigated based on the flexible input characteristic of the proposed model. The results illustrate that train interactions become subtle with the increase of train headways. This finding directly contributes to decision-making in situations where conflict resolution or train-canceling actions are needed.

Study on the structural characteristics of China's high-speed railway network and its coordination with economic growth based on Fractal theory

As one of the modern transportation modes, the high-speed railway network system has been a robust part of the comprehensive transportation system in China. An important topic emerges the exploration and optimization of its structural organization and coordinated relationship with the regional development, including urban form, land use, and economy. Therefore, supported by the integration of geographical information system (GIS) and fractal theory, this paper aims to carry out an investigation and discussion on the structural characteristics, including intensity (density), complexity, nonstationarity, and heterogeneity of the high-speed railway network in China (HSRNC) from the perspective of the whole country and specific regions, i.e., urban agglomerations. Moreover, based on the time-series data of network mileage expansion and economic output analysis, this study aims to evaluate and characterize the coordinated relationships between network development and economic growth in the context of the nationwide area and urban agglomerations. This study aims to explore and promote the spatial structural organization and morphology of the high-speed railway network in China, thus improving the coordinated development with the regional economic growth, for giving a new perspective to the future planning and evolution of the high-speed railway network in China.

An Integrated Optimization Method of High-Speed Railway Rescheduling Problem at the Network Level

For high-speed railway operations at the network level, unforeseen events that lead to operation interruptions are inevitable, which should be handled within a short period of time to reduce the influence of the events as much as possible. This paper introduces an integrated optimization method to deal with rescheduling problems at the railway network level under emergencies, rescheduling the train timetable, and utilizing the train sets. train set A three-objective optimization model is proposed with the aim of minimizing additional operation costs, total delay, and the number of transfer passengers. Then, an algorithm based on NSGA-III is proposed to solve the model. Computational experiments on real data are conducted to show the adaptability of the model and algorithm. The average optimization rate of the three objectives is 12.12%, 14.12%, and 10.57%, indicating the effectiveness of the method. Moreover, more experiments on a railway network in China are being conducted to analyze which section and which time have the greatest impact on the railway network when emergencies occur. According to the experiment, the bottleneck section is section 15, and the bottleneck time is 11:00 am. In addition, the importance of all the depots is discussed, and depot II is selected as the most important depot.

Train rescheduling for large-scale disruptions in a large-scale railway network

This paper studies the problem of rescheduling trains in a large-scale railway network with the characteristics of long distance, long time horizon and a large number of trains, where a disruption causes the paralysis of a significant part of the network for a long duration. As rescheduling measures we consider train reordering and retiming as well as the option of rerouting trains along alternative paths in the railway network. Although rerouting was not previously employed in large-scale long-distance networks, we show its benefit in reducing passenger delays. We formulate the problem as an integer linear programming (ILP) model on a space–time network with the goal of minimizing the total passenger delay and the number of passengers that could not reach their destination. In order to effectively solve the ILP model for real-world instances, we propose a heuristic algorithm (LR-H), based on the Lagrangian relaxation (LR) of a subset of constraints in the ILP model. LR allows decomposing the problem into a series of independent train-based subproblems which are easy to solve. Due to the large number of constraints and to cope with the real-time requirement, LR-H employs dynamic constraint-generation.We tested LR-H on railway networks of different sizes under several disruption scenarios: first, we compared the results obtained by LR-H on a small-size instance with those found by the general-purpose ILP solver GUROBI, showing that LR-H can find near-optimal solutions in significantly shorter computing times. Then, we applied LR-H to a real-world instance of a railway network in China with 350 trains in different disruption scenarios. The experimental results show that, LR-H can obtain near-optimal solutions with an average optimality gap of 2.27% in an average computing time of about 300 s.

Network periodic train timetabling with integrated stop planning and passenger routing: A periodic time–space network construct and ADMM algorithm

Designing a passenger-centric railway service is of great importance for railway companies to attract more passengers and increase their revenue. Focusing on the passenger-centric operational plans, this paper considers the problem of integrated periodic train timetabling and train stop planning in high speed railway networks. In view of the immediate dependency of passengers’ routes on the train timetable and stop plan, simultaneous passenger routing is included to directly shape the train stops and timetable in a passenger-friendly way. Besides travel time, ticket price is also considered in passenger utility to better depict passengers’ route choices in the railway network. A railway network-based time–space network with train stop-skip technique, periodic properties and detailed consideration of different train headways is designed, based on which a multi-commodity network flow model is developed. With a novel linearization technique of train capacity penalty term, the alternating direction method of multipliers (ADMM) is used to relax and decompose the track and train capacity constraints. Further, time deviation of regular train services is achieved by a new shortest path algorithm to design more flexible timetables, however its application is still limited to small instances due to computational efforts required. The algorithm is finally tested on the Shandong high-speed railway network in China, and demonstrates its capability of providing tighter lower bounds than Lagrangian relaxation method and generating good feasible solutions. Besides, the impacts of different cycle times on service quality and train cost are evaluated.

Spatiotemporal Evolution Analysis of the Chinese Railway Network Structure Based on Self-Organizing Maps

Delving into the spatiotemporal evolution of the railway network in different periods can provide guidance and reference for the planning and layout of the railway network. However, most of the existing studies tended to model the railway data separately and compare the network indices of adjacent periods based on the railway data of different periods, thus failing to integrate the railway network in different periods into a unified framework for evolution analysis. Therefore, this paper used the railway data from 2008, 2010, 2015, and 2019, and analyzed the spatiotemporal integration of the railway network evolution based on the complex network theory and the self-organizing maps (SOM) method. Firstly, this study constructed the geographical railway network in the four years and probed into how the network feature indices changed. Then, it used the SOM method to capture the spatiotemporal integration of the railway network evolution in multi-time series. Finally, it clustered the change trajectory of each city node and unveiled the relationship between the evolution of city nodes and the hierarchy of urban systems. The results show that from 2008 to 2019, the railway network feature indices showed an upward trend and that the expansion pattern of the railway network could be divided into the core–peripheral pattern, belt expansion pattern, strings of beads pattern, and multi-center network pattern. The evolution of the change trajectory of the city nodes was highly related to the hierarchical structure of the urban system. This study helps to understand the evolution process of the railway network in China, and provides decision-making reference for improving and optimizing China’s railway network.

Improving running safety of railway bridges during earthquakes by equipping vehicle with lateral fuse stopper

Ensuring the safety of the railway vehicles over bridges shaken by earthquakes is a practical issue in the seismic design of railway bridges. To improve the vehicle’s running safety on railway bridges during earthquakes, the stopper (or bump-stop) between the bogie and the car-body of the vehicle was modified as a fuse-type element, i.e., it was designed to break under large impact due to earthquake occurrence. The efficacy of the fuse stopper was illustrated by a full-scale vehicle-track shake table test. The fuse stopper element was introduced to the vehicle-bridge interaction model, whose accuracy was also demonstrated by comparison with the test results. The fuse stopper was designed to remain intact under service level earthquakes (SLE) to avoid frequent replacement or repair, while it should fuse to improve vehicle safety on a group of bridges under design basis earthquakes (DBE). The bridge group includes 24 simply-supported bridges with pier heights ranging from 6m to 60m, covering the most simply-supported bridges in the China railway network. A total of 10 ground motion records were used in the analysis to account for the uncertainty of ground motions. Through vehicle-bridge incremental dynamic analysis (IDA) simulation, the optimal fusion strength of 188 kN and the extended gap of 0.04 m were proposed for the fuse stopper at DBE intensity, in which the bridge group can achieve derailment-free. The design procedure of the fuse stopper may provide a cost-effective way to improve the vehicle’s running safety on a group of bridges during earthquakes.

Analysis of structural evolution and its influencing factors of the high-speed railway network in China's three urban agglomerations

Development of HSR network has an important impact on the evolution of urban spatial structure. However, quantitative discussions on influencing factors of HSR network evolution are still lack. This study explores the structural evolution and influencing factors of HSR network consisting of three urban agglomerations. The main results are as follows: (1) The HSR network in Beijing-Tianjin-Hebei (BTH) had maintained a stable twin-city structure, while Yangtze River Delta (YRD) and Pearl River Delta (PRD) presented a balanced and polarized structure respectively. (2) The community structure of HSR network in BTH and YRD had become complex and diversified, while that in PRD was simple and stable. (3) The overall level of HSR connections in PRD has grown at the first and that in BTH has dropped at the bottom in 2019.The overall level of connectivity of HSR network in PRD continued to rise, and it continued to decline in YRD. That in PRD has significant small-world feature. (4) The interaction intensity of tourism, income, technology, and investment of cities significantly affects HSR network structure. This article helps to adjust HSR network structure from the demand of residents' travel between cities, and optimize the service supply of inter-city high-speed travel. • The structure and evolution of HSR network in Chinese three urban agglomerations are analyzed. • The reverse impact of social economy on HSR network structure is discussed based on bottom-up thought. • A new method is used to analyze the impact of social economy on HSR network structure. • The connections of tourism, income, technology and investment between cities significantly affect HSR network structure. • Understanding the influence mechanism of HSR network structure will help adjust spatial structure of urban agglomerations.

The Integrative Development of Cultural Tourism Industry in the Areas along Sichuan-Tibet Railway from the Perspective of Field: Based on the Cultural Reproduction Theory

Sichuan-Tibet Railway, the second railway into Tibet built by China after the Qinghai-Tibet Railway, is an important bond of the "eight vertical and eight horizontal" high-speed railway network in China, which is of great significance to the economic development along the line. This paper based on the field perspective of reproduction theory as well as the actual development of the cultural tourism industry along the Sichuan-Tibet Railway, this paper will provide practical theoretical recommendations for the integrative development of the cultural tourism industry along the Sichuan-Tibet Railway.

A Line Planning Optimization Model for High-Speed Railway Network Merging Newly-Built Railway Lines

This paper is devoted to developing a line-planning approach for high-speed railway networks merging newly built railway lines, which result in the change of the network’s original structure and some passengers’ travel routes. In order to exactly describe the choice of time-varying passengers and the operation of the trains, a passenger travel network with time information is constructed based on the pre-generated candidate train set. Following this, a line-planning optimization model for optimizing trains on both the existing railway network and the merged new railway line is established under the considered constraints, such as transportation resources on the network. It does not aim to only provide higher service level for passengers and increase revenue of railway enterprise, but also to ensure the continuity of the existing trains to facilitates passengers and train organization. A framework of the Simulated Annealing Algorithm is designed to solve the proposed model by combining the neighboring solution search strategies with evaluation method based on the allocation of passengers. The case of a partial high-speed railway network in China is studied to test the practicability and validity of the proposed approach.

Vulnerability Analysis of Geographical Railway Network under Geological Hazard in China

As the passenger railway network is expanding and improving, the internal connections and interdependence in the network are rising. Once a sudden geological hazard occurs and damages the network structure, the train service is prone to large-scale halt or delay. A geographical railway network is modeled to analyze the spatial distribution characteristics of the railway network as well as its vulnerability under typical geological hazards, such as earthquakes, collapses, landslides and debris flows. First, this paper modeled the geographical railway network in China based on the complex network method and analyzed the spatial distribution characteristics of the railway network. Then, the data of geological hazards along the railway that occurred over the years were crawled through the Internet to construct the hazard database to analyze the time–space distribution characteristics. Finally, based on the data of geological hazards along the railway and results of the susceptibility to geological hazards, the vulnerability of the geographical railway network was evaluated. Among these geological hazards, the greatest impact on railway safety operation came from earthquakes (48%), followed by landslides (28%), debris flows (17%) and collapses (7%). About 30% of the lines of the geographical railway network were exposed in the susceptibility areas. The most vulnerable railway lines included Sichuan–Guizhou Railway, Chengdu–Kunming Railway and Chengdu–Guiyang high-speed Railway in Southwest China, Lanzhou–Urumqi Railway and Southern Xinjiang Railway in Northwest China, and Beijing–Harbin Railway and Harbin–Manzhouli Railway in Northeast China. Therefore, professional railway rescue materials should be arranged at key stations in the above sections, with a view to improving the capability to respond to sudden geological hazards.

Integrated optimization of transfer station selection and train timetables for road–rail intermodal transport network

In this study, we investigate the integrated optimization of container transfer station selection and train timetables for a road–rail intermodal transport network based on the transport organization mode of improved passenger-like container trains. The aim is to achieve a prompt response from train timetables for freight transportation needs to improve the quality of the timetable. The problem is formulated as a mixed-integer nonlinear programming problem, and a multiobjective bi-level optimization model is proposed with the objectives of increasing the average utilization ratio of the rail capacity and decreasing the number of road–rail transfer stations, transport costs, and transport delay penalty costs. To improve the quality of the Pareto solutions, a grid-based adaptive artificial bee colony (GBA-ABC) algorithm is designed to solve the model of a road–rail network with multicommodity flows. As a case study, the model is applied to the high-speed railway network in China and the China–Europe transcontinental railway network. The results show that the integrated optimization approach yields train timetables that can simultaneously reduce the transportation costs and the transportation delay penalty costs, with a rail capacity utilization rate of above 79.57%. Concurrently, it is beneficial for solving robust solutions under different case scales, demonstrating the effectiveness of the model and the algorithm. Finally, the proposed algorithm is experimentally compared with other multiobjective metaheuristics algorithms and is found to exhibit superior performance.

Semi-automatic construction of pile-supported subgrade adjacent to existing railway

The rapid expansion of the high-speed railway network in China leads to an increasing number of connections between new constructed infrastructures and existing ones. The construction of the infrastructure extremely adjacent to existing high-speed railways significantly threaten the operation safety of the high-speed trains. To guarantee the operation safety of the existing high-speed railways in this sensitive zone, a developed Benoto pile-plank-supported subgrade and a set of specially designed construction equipment are proposed. A fiber-optical monitoring system for foundation deformation and structural internal forces is employed to provide a data basis for parameterization of the construction equipment. In this way, an integrated semi-automatic construction system is established. The application effect of the construction system is tested in a real construction project of a pile-supported subgrade adjacent to an existing high-speed railway track. In-situ measurement data reveal that the deformation of the existing high-speed railway subgrade can be well controlled.

Urban land use effects of high-speed railway network in China: A spatial spillover perspective

In the past decade, China’s high-speed railway (HSR) system has expanded rapidly and become the longest and most complex network in the world. To fully exploit the HSR dividend, many cities have constructed HSRs in new locations, triggering urban land use change, especially around the HSR stations. This study has used the difference-in-difference (DID) method to explore the effect of HSRs on urban land use using long-term nighttime light (NTL) data. The main conclusions are that the operation of HSRs has increased the intensity of urban land use by about 4.4%, with the land use effect of the “renewed HSR stations” being significantly higher than that of the “newly-built stations”; further the development of tertiary industry has promoted a siphoning effect, that is the spillover of HSR stations in large cities is strengthened relative to that for small cities. Based on these results, the study further analyzed the performance of areas with new HSR installations and the factors controlling the inter-city heterogeneities.

Analyzing the Formation Mechanism of Cross-City Transportation Network Resilience

The formation mechanism of cross-city transportation network resilience occupies an important position in cross-city transportation network resilience management. This study analyzes the constituent elements of the cross-city transportation network and their interrelationships, and the connotation of cross-city transportation network resilience is defined from the general meaning of system resilience. Combining with the connotation of cross-city transportation network resilience, the specific formation process of cross-city transportation network resilience is analyzed and summarized from three stages, including resisting disturbance, absorbing disturbance, and function recovery. Taking cross-city transportation network nodes and systems as specific objects, the static and dynamic formation path of cross-city transportation network resilience is condensed. Based on the standard linear solid model, a theoretical model is constructed and solved for revealing the formation mechanism of cross-city transportation network resilience. Finally, the theoretical model of cross-city transportation network resilience proposed in this study is used for analyzing the China railway network resilience.

Integrating traffic routing optimization and train formation plan using simulated annealing algorithm

An essential problem encountered in a railway freight transport system is determining the best formation plan on a capacity-constrained physical network. The formation plan is not only the foundation of railway operations, but also the basis of train scheduling, yard and terminal management, and infrastructure resource planning. An integrated optimization of the traffic routing and train formation plan aims at designing a globally optimal train service network to decide: between which pairs of reclassification yards (terminals) should provide a block, the frequencies of the train services, the physical paths of traffic, and the block sequences of shipments. This study proposes a non-linear binary programming model to address the integrated problem to minimize the total costs of accumulation, reclassification, and travel distances while satisfying various practical requirements. An efficient simulated annealing based heuristic solution approach is developed to solve the mathematical model. We use a penalty function method to tackle the capacity constraints and a customized method for the operational requirements. The feasibility of the solving approach is tested using a numerical case study based on the east-west railway channel of China. The computational results of a national-scale example based on the China railway network consisting of 235 nodes indicates that the proposed model and approach can achieve good quality solutions within an acceptable computing time.

Ground-Based Radar Interferometry for Monitoring the Dynamic Performance of a Multitrack Steel Truss High-Speed Railway Bridge

With the continuous expansion of the high-speed railway network in China, long-span railway bridges carrying multiple tracks demand reliable and fast testing procedures and techniques. Bridge dynamic behavior analysis is a critical process in ensuring safe operation of structures. In this study, we present some experimental results of the vibration monitoring of a four-track high-speed railway bridge with a metro–track on each side: the Nanjing–Dashengguan high-speed railway bridge (NDHRB). The results were obtained using a terrestrial microwave radar interferometer named IBIS-S. The radar measurements were interpreted with the support of lidar point clouds. The results of the bridge dynamic response under different loading conditions, including high-speed trains, metro and wind were compared with the existing bridge structure health monitoring (SHM) system, underlining the high spatial (0.5 m) and temporal resolutions (50 Hz–200 Hz) of this technique for railway bridge dynamic monitoring. The detailed results can help engineers capturing the maximum train-induced bridge displacement. The bridge was also monitored by the radar from a lateral position with respect to the bridge longitudinal direction. This allowed us to have a more exhaustive description of the bridge dynamic behavior. The different effects induced by the passage of trains through different tracks and directions were distinguished. In addition, the space deformation map of the wide bridge deck under the eccentric load of trains, especially along the lateral direction (30 m), can help evaluating the running stability of high-speed trains.

Optimizing train frequencies and train routing with simultaneous passenger assignment in high-speed railway network

In a high speed railway line plan (LP), train frequencies, train routing and passenger assignment problems are usually solved sequentially, which may lower the quality of the line plan. To bridge the gap, a bi-level multi-objective mixed integer nonlinear programming model for simultaneously obtaining the optimal plan of passenger assignment and train routing is developed in this paper. The upper level model is an integer programming (IP) model with an objective of minimizing both the total train travel time and the average capacity utilization rate, while the lower level one is a model with an objective of minimizing the total travel time of passengers and maximizing the average train attendance rate for all sections. In order to obtain the solution in relatively short time, a particle swarm approach is adopted to solve the model in a large scale railway network. As a case study, the model is applied to a high speed railway network in China. The results show that the total travel time of passengers and trains obtained from the simultaneous optimization model can be reduced by 0.9% in comparison with the two problems solved sequentially, which indicates that the model and the solution algorithms could be useful in practice.

Social equity-based timetabling and ticket pricing for high-speed railways

High-speed railways are expanding rapidly over the world, providing fast, convenient, and comfortable transport. It is therefore important to ensure that people are not excluded from high-speed railway use due to relatively high ticket prices. We aim to develop a railway timetable according to passenger requirements that explicitly considers social equity by applying variable ticket prices to trains. Specifically, we want to optimize ticket prices for trains operating during off-peak hours to improve accessibility for low-income passengers to improve social justice. A mixed integer linear programming model is formulated to solve our problem. In this timetabling-based model, we not only minimize the total general travel cost from a passenger perspective but also ensure that the revenue of the train company is no less than a specified value and that social equity is maintained at a specific level. To do this, we consider the social equity constraint and the minimum revenue requirement constraint, in addition to the traditional passenger-centric (-oriented) train timetabling-related constraints. Finally, we test our model on both a hypothetical high-speed railway network and the Guangzhou–Nanning and Guangzhou–Guilin high-speed railway network in China. The results demonstrate that the proposed optimization framework can provide a convenient timetable for passengers, adequate revenue for train companies and enhance social equity to meet government targets.