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High-speed railways (HSRs) have been widely deployed all over the world in recent years and China has entered an era with both high investments and rapid expansion of HSR transport infrastructure. One of the most challenging issues is how to keep the security and safety of millions of HSR infrastructures. Meanwhile, the emerging sensing and wireless sensor network (WSN) technologies for infrastructure health monitoring (IHM) are being substituted for traditional tethered monitoring systems. This paper presents a two-layer architecture of WSN which will be appropriate for infrastructure health monitoring of HSR. The upper layer is named as tree access network and the lower layer is called star detection network. By adapting to the special characteristics of IHM network, we design a short network address and an optimized communication frame structure, which can satisfy the actual requirements and special characteristics of the IHM network. In order to implement a better transmission performance, we propose a novel transmission power based method which adopts the knowledge update mechanism to detect the optimization result. In the end, the details of address assignment and network construction are discussed, and the effectiveness of the proposed method is validated by a practical instance. [ABSTRACT FROM AUTHOR]

• The high-speed railway network is modeled as a three-layer network. • Network-specific characteristics are considered in performance evaluation instead of pure complex network analysis. • Railway stations are prioritized and compared within different layers of the network. • The current physical rail network in China is generally sufficient to satisfy the requirements of its transportation accessibility. • Management implications are provided to facilitate the rail network planning, transportation organization and operations. High-speed railways, as dominant transportation patterns, constitute a large-scale complex network. Network performance is critical for high-level transportation services in transportation management. However, existing studies generally adopt pure topological indicators to evaluate performance in a single network and without considering the specific characteristics of rail transportation. This paper modeled the high-speed railway as a three-layer network including topological, functional, and service layers and assessed the integrated network performance from the view of transportation accessibility. In addition, the rail stations were prioritized and their performances in different layers were compared to analyze whether the total integrated performance was restricted by its connection abilities, functional capacities, and transportation service level. Finally, a case study of the high-speed rail network in China and comparisons with other traditional evaluation methods were conducted to verify the feasibility and superiority of the model. The findings of this study enable to provide management implications for rail transportation planning, organization, and operations. [ABSTRACT FROM AUTHOR]

Aimed at the complicated problems of attraction characteristics regarding passenger flow in urban rail transit network, the concept of the gravity field of passenger flow is proposed in this paper. We establish the computation methods of field strength and potential energy to reveal the potential attraction relationship among stations from the perspective of the collection and distribution of passenger flow and the topology of network. As for the computation methods of field strength, an optimum path concept is proposed to define betweenness centrality parameter. Regarding the computation of potential energy, Compound Simpson’s Rule Formula is applied to get a solution to the function. Taking No. 10 Beijing Subway as a practical example, an analysis of simulation and verification is conducted, and the results shows in the following ways. Firstly, the bigger field strength value between two stations is, the stronger passenger flow attraction is, and the greater probability of the formation of the largest passenger flow of section is. Secondly, there is the greatest passenger flow volume and circulation capacity between two zones of high potential energy. [ABSTRACT FROM AUTHOR]

Greening of the railway energy supply chain is an irreversible trend, and photovoltaics (PVs) provide the most suitable type of renewable energy to integrate with railways. The integration of variable and uncertain PV power generation with the dynamic loads on a railway increases the flexibility needed to maintain load-generation balance. A new evolutionary model of a railway energy supply system (RESS) for railway PV integration systems (RPISs) is proposed by constructing a three-in-one "traction-storage-information integrated station" (TSIIS). A flexibility evaluation approach is proposed to estimate the system flexibility of both the individual TSIIS and the banded featured microgrid group through energy storage capacity configuration and dynamic scheduling via a multileader multifollower Stackelberg game. Finally, the Lanzhou-Xinjiang Railway is taken as an example to calculate the emission reduction and flexibility. The results show that through application of the storage configuration and scheduling strategy to the TSIIS network, the flexibility index of the Lanzhou-Xinjiang Railway increased by 8.40%, which promoted a corresponding decrease in carbon dioxide emissions and increase in PV permeability. In addition, with the gradual construction of PV and energy storage systems, an RPIS can basically achieve self-consistent energy utilization, offering environmental benefits and strong flexibility. [ABSTRACT FROM AUTHOR]

Considering the complexity of the urban rail transit system (URTS), it is necessary to systematically identify the critical factors and their relationships to avoid or prevent urban rail transit accidents. In response to the problems few previous studies have modeled networks for the whole system components of URTS and have focused too much on the identification of specific component states or behaviors without quantitative analysis of inter-component relationships. This paper proposed a risk network construction and analysis method based on complex network theory to identify the critical accident causative factors and their relationships of the URTS system. Firstly, the accident is defined as the combination of a sequence of risk incidents occurring in a certain order and their resulting consequences, and the definitions of risk point and risk incident were given. Secondly, a risk network construction and analysis method based on the combination of accident reports and complex network theory was proposed to obtain the critical factors and their relationships in the process of the accident. At last, this paper constructed the urban rail transit risk point set containing 39 risk points, built the risk network based on 201 accident reports of URTS in China and analyzed the critical risk points and risk relationships. The results show that this study can provide a new perspective for identifying the critical causative factors of URTS accidents and their relationships for practical application in risk analysis and accident prevention. • The new definitions of risk points and incidents are put forward. • A critical risk analysis framework are proposed by complex network theory. • Critical risk points and relationships are identified in the urban rail transit system by the risk network. [ABSTRACT FROM AUTHOR]

China's railway has been experiencing rapid growth recently. The achievement of solar energy for the increasing electricity consumption in the rail sector attracts significant attentions. In this paper, the available solar energy on the covered land and trackside land in the rail itself is assessed for further utilization. The development of the railway electrifications is briefly presented. In the split- and co-phase AC electrifications, AC and DC microgrids are introduced to constitute the solar-powered rail transportation. This approach offers both the on-site access and the local consumption of the available solar energy alongside railways. Focused on the solar power regulation, an individual phase current control (IPCC) strategy is developed without extractions between sequences. This strategy can achieve a flexible current provision for both powering single-phase locomotives and feeding back to the three-phase grid. Finally, the solar-powered rail transportation contributes to a sustainable future of both the rail and solar energy sector and a win-win situation in both the economy and environment in China. • Assessments of the available solar energy along railways for further utilization. • Scenarios for the on-site access and local consumption of solar energy. • Flexible current regulation method with a hybrid current reference. • Solar-powered rail transportation contributes to the rail's sustainable future. [ABSTRACT FROM AUTHOR]

According to the International Energy Agency (IEA)'s forecast, China will fully electrify its railway system by 2050. However, the development of electrified railways is limited in the weak areas of China's power grid. To surpass these limitations, we turn our attention to new railway energy sources, among which the most suitable is photovoltaic power generation. To evaluate the feasibility of integrating railway systems and photovoltaic power generation in China, this paper analyzes the geographical conditions and railway layout of China, gives a potential method for evaluating railway asset energy transformation measures and asset energy transformations that are suitable for China's national conditions, and proposes an application of railway system energy transformation on this basis. Then, this method is used to evaluate the potential of a substation section of the Lanxin high-speed railway in China for reference. The results show that the green energy potential and scheduling potential of China's railway assets are great and can effectively alleviate the energy anxiety of China's railway system. [ABSTRACT FROM AUTHOR]