There are significant differences in the corrosion protection performance of commonly used cleaning agents for high-speed railways. In order to study the dual requirements of cleaning efficiency and corrosion inhibition, explore the differences in corrosion protection performance of cleaning agents, effectively protect metal substrates, and ensure the safe, economical, and environmentally friendly operation of high-speed railways, this study is hereby carried out.

This study investigated the corrosion behaviour of Q235 steel exposed to acidic, neutral, and alkaline cleaning agents through metallographic analysis, electrochemical testing, and scanning electron microscopy (SEM).

Electrochemical behaviour was assessed at concentrations of 5%, 10%, 15%, and 20% using electrochemical impedance spectroscopy (EIS) and Tafel tests. The results indicate that the protective efficacy of acidic, neutral, and alkaline cleaning agents follows the order: alkaline > neutral > acidic.

Microstructural analysis and energy-dispersive X-ray spectroscopy (EDS) surface element quantification reveal that acidic cleaning agents cause the most severe corrosion and offer the poorest protection for Q235 steel, whereas neutral and alkaline agents provide protective effects by retarding corrosion. Conducting in-depth research on the differences in corrosion protection performance of cleaning agents can effectively safeguard metal substrates, eliminate corrosion risks, and ensure the safe operation of high-speed railways.

To support the operational safety and lightning protection design of high-speed maglev railways, this paper quantitatively evaluates how suspension height and operating speed influence lightning susceptibility. It characterizes trends of the critical background electric field with respect to these two variables, tracks the evolution of surface hotspot distributions and identifies dominant attachment locations and their sensitivity.

A coupled procedure of “electrostatic field–aerodynamic flow field–scaled assessment” is proposed. The electrostatic model provides surface field-enhancement factors and their spatial distribution, while turbulent-flow simulations characterize near-wall density variations induced by speed. Under a unified leader height, a critical criterion based on a density-scaled breakdown field maps these two fields to a train-wise critical background electric field. Representative regions (nose, roof and bottom or tail) are used to build statistical metrics for hotspot migration and dominance with speed.

Increasing suspension height weakens electric-field coupling to ground, raises the critical background-field threshold and reduces the relative contribution of bottom and edge regions. At the same suspension height, a rigidly grounded train has a lower critical threshold than an electrically floating one. Within 0–500 km/h, the train-wise threshold decreases slowly with speed. Region-wise, roof-tail and bottom-mid sections show a decreasing trend with speed, while the nose stagnation point increases slightly; over the entire speed range, the dominant region remains the roof-tail section.

Within a unified framework, suspension height and operating speed affect lightning attraction through two distinct channels. Suspension height mainly modifies the threshold and hotspot distribution by changing geometric polarization, whereas speed alters discharge-initiation difficulty through aerodynamically induced density variations. The framework evaluates these effects separately and in combination, explaining the slow variation of the global threshold and the subtle evolution of hotspot locations and providing a physics-based reference for lightning protection design and operational safety assessment of high-speed maglev railway systems.

With the development of railway systems towards intelligence, informatization and networking, their architecture design becomes increasingly complex. Traditional safety analysis methods (such as failure mode and effects analysis (FMEA), fault tree analysis (FTA) and event tree analysis) can no longer realise integrated safety analysis across disciplines, domains and life cycles amid requirement drift, architecture iteration and operational scenario evolution. This paper aims to introduce a systematic, integrated, model-driven safety analysis framework for the entire life cycle of railway systems to address these complex safety challenges and improve the overall safety level of railway systems.

First, the paper conducts a literature review of traditional railway safety analysis techniques and their applications, and analyzes the technical framework, core elements (modelling languages, methods, and tools), and advantages of Model-Based Systems Engineering (MBSE). Then, it studies the integration of MBSE and system safety analysis, focusing on typical international research cases (e.g., the Methodology for the Description and Safety Analysis of Interoperable Systems (MeDISIS), the European Train Control System (ETCS) safety verification project SafeSysE, and the Reference Architecture for Model-Based System and Software Engineering in the Railway Domain (RAMSAS), etc.) and domestic research progress, and summarizes the core idea of integrating MBSE with safety analysis in the design process. Finally, it explores the key technologies of MBSE-based railway system safety analysis, including automatic mapping of architecture models to Fault Tree Analysis (FTA), dynamic linkage between behaviour models and Failure Mode and Effects Analysis (FMEA), multi-model collaboration and dynamic update, as well as technologies in three aspects: safety requirement analysis driven by railway operational tasks, integrated safety-function design analysis, and simulation-based safety verification via train-fleet operation modelling. The development and validation platform Platform for Integrated Systems and Mechatronic Engineering (PRISME) and tools such as the Dependability Engineering and Innovation System (DEIS), Behavior-Driven Development (BDD) frameworks, and International Business Machines (IBM) engineering suites were also utilized to support this research.

The MBSE-based railway system safety analysis technique embeds safety activities into the forward-engineering workflow of MBSE-driven development, enabling concurrent safety and functional design. It solves the problems of model heterogeneity, data silos and process discontinuities in traditional safety analysis and realises end-to-end traceability and consistency from system requirements to safety analysis results. This technique not only provides a rigorous foundation for standardised, efficient and accurate safety assessment of railway systems but also offers technical support for early identification of potential safety issues, reduction of late-stage design changes and continuous optimisation of system safety performance.

The innovation of this paper mainly includes three aspects:(1) It breaks the limitations of traditional document-driven safety analysis methods, constructs an MBSE-based integrated safety analysis framework covering the entire life cycle of railway systems and turns safety work from an ad-hoc add-on into a systematic, goal-oriented activity. (2) It proposes key integration technologies such as automatic mapping of SysML-based architecture models to FTA, dynamic linkage between behaviour models (state machine diagram/activity diagram) and FMEA and multi-model (FTA/FMEA/hazard and operability analysis) collaborative dynamic update, which guarantee the consistency and traceability of safety analysis data and improve the efficiency of safety analysis iteration. (3) It develops a set of MBSE-based railway safety analysis implementation paths, including task-driven safety requirement decomposition, integrated safety function failure propagation modelling and train-fleet operation simulation-based verification, providing a practical technical solution for the safety design and analysis of complex railway systems.

The rapid expansion of high-speed railway (HSR) networks in Western China has increased the exposure of linear infrastructure to active faults. This study establishes and applies a probabilistic fault displacement hazard analysis (PFDHA) framework to quantify both on-fault surface rupture and distributed offfault permanent ground deformation (PGD) hazards for HSR crossings of the Xiaojiang Fault Zone (XJFZ).

A PFDHA framework is developed, integrating a Poissonian seismicity model with spatial rupture randomness. The methodology is applied to the XJFZ, which crosses the Nanning- Kunming (NK) and Shanghai-Kunming (SK) HSR. Permanent displacement hazards are evaluated for 2 probability levels: 10% and 2% probability of exceedance in 50 years.

Through the evaluation of displacement hazards for 50-year exceedance probabilities of 10% and 2%, this study finds that for the NK and SK HSR, permanent displacements at a 10% probability of exceedance range from 1.0 m to 2.9 m, peaking at fault intersections. Comparative analysis shows that traditional deterministic estimates (1.3–2.0 m) generally align with the probabilistic results but fail to capture the full range of risk.

This work adapts PFDHA to linear infrastructure in a tectonically active region of China, explicitly considering both on- and off-fault displacement within engineering-relevant corridors. The integration of regional rupture scaling and segment-based constraints provides a reproducible basis for displacement hazard assessment in HSR planning and retrofit.

Interface management is the process of managing communications, responsibilities and coordination of project parties, phases or physical entities which are dependent on one another. Interface management is a crucial part of managing any construction project – but particularly important for high-speed railway projects that often have several contractual parties and stakeholders, very long project timelines and huge upfront cost overlays. This paper discusses how various project interfaces were managed during the design and construction of the civil engineering infrastructure for the High Speed Two (HS2) project in the United Kingdom.

The paper uses the case study methodology. Key interfaces on the HS2 project are grouped into various categories and the paper discusses how they were managed within the Area North Integrated Project Team (IPT) of the HS2 project made up of contractor Balfour Beatty VINCI (BBV), the Mott MacDonald SYSTRA Design Joint Venture (DJV) and client HS2 Ltd. 3 different case studies drawn from across the IPT are used, each of them highlighting different interfaces and how these interfaces were managed.

The paper shows how innovative technical designs and modern methods of construction were used to address some of the unique and peculiar challenges of designing a brand-new railway in the United Kingdom. Addressing the contrasting and often competing requirements of different stakeholders, coupled with challenging physical constraints of the very limited land available for the project and the use of a rarely used Act of Parliament in the delivery of the project required different approach to interface management. Collaboration and proactive stakeholder engagement are necessary for successful interface management on megaprojects. The authors posit that adopting an integrated approach to engineering and construction management is an essential ingredient for the successful delivery of high-speed railway projects.

With many high-speed railway projects around the world coming up in the next few years, understanding the context and challenges for each country will help engineering and design managers adopt appropriate approaches for their projects. The lessons learned on the HS2 project are also transferable to other mega infrastructure projects with complex project interfaces.

This paper provides a comprehensive analysis of the Brazilian freight railway system, examining the efficacy of the current concession renewal model in light of persistent structural problems such as market concentration, cargo dependence on export commodities and underutilization of the network. Situating Brazil within the broader international debate on railway reforms, the paper evaluates whether the ongoing early renewal of concessions can deliver a more diversified and competitive freight system.

The study adopts a sequential mixed-methods research design that integrates longitudinal quantitative analysis with qualitative institutional and policy evaluation. The quantitative component examines time-series indicators published by ANTT, DNIT and INFRA S.A. from 1999 to 2023 to identify structural patterns in traffic growth, investment, safety and market concentration. The qualitative component employs a process-tracing logic to reconstruct the evolution of concession renewals and the implementation of Railway Law 14.273/2021, drawing on concepts from regulatory economics, institutional theory and industrial organization. These empirical streams are synthesized through an analytical framework that connects three dimensions - regulatory design, market structure and system performance - allowing for a systematic assessment of how Brazil’s institutional configuration shapes incentives, competitive dynamics and network utilization.

The analysis confirms that the early renewal of concessions has successfully secured substantial private investment for capacity expansion on existing trunk lines. However, it has perpetuated the vertically integrated model, reinforcing the market power of incumbent operators and failing to significantly promote intramodal competition or cargo diversification. The system remains dominated by iron ore and agricultural commodities, with general cargo representing a minuscule share. The new authorization regime and short-line railway policies present a viable pathway for market opening but face significant operational and institutional barriers to implementation.

This research offers a timely and critical assessment of a pivotal moment in Brazilian railway policy. It moves beyond a simplistic evaluation of volume growth to a structural analysis of market failures and the interplay between concession renewal and regulatory innovation. The findings provide actionable insights for policymakers in Brazil and other emerging economies seeking to balance private investment with public interest goals in railway infrastructure, highlighting the necessity of complementary, pro-competitive measures alongside financial investment.

The utilization of alkali-free accelerators, primarily based on aluminum sulfate, in shotcrete often leads to significant shrinkage and cracking, jeopardizing long-term durability. This study aims to mitigate this issue by investigating the efficacy of silica fume (SF) and fly ash (FA), individually and combined, in controlling the shrinkage deformation of shotcrete.

Shotcrete mixtures were prepared with cement partially replaced by SF, FA, or their combination (SF-FA). Aluminum sulfate was used as an accelerator. The shrinkage behavior under sealed and dry conditions was monitored. The underlying mechanisms were elucidated through hardened airvoid analysis, mercury intrusion porosimetry (MIP), and internal humidity tracking.

Contrary to some previous studies, both individual and combined incorporation of mineral admixtures reduced the 28-day shrinkage. The SF-FA composite exhibited the most substantial reduction (23.72% sealed, 17.76% dry), followed by SF alone (18.11% sealed) and FA alone (11.35% sealed). Mechanism analysis revealed that the admixtures refined the pore structure, reduced the volume of harmful pores, and, crucially, optimized the air-void system by increasing the population of fine bubbles. This created an internal buffering effect that alleviates capillary stress. The synergistic effect in the SF-FA group is attributed to complementary pore-filling at dual scales.

This work demonstrates that, within an aluminum sulfate-accelerated shotcrete system, silica fume can effectively reduce shrinkage when its pore-refining effect is counterbalanced by a well-optimized micro-bubble network. It provides the first comprehensive evidence of the synergistic shrinkage-reducing mechanism of SF and FA in such systems, offering a practical strategy for mix design optimization to enhance the volume stability of shotcrete.

Association of American railroads (AAR) standard automatic couplers are designed for much higher capacity than the normal operating loads. However, failure of knuckles and coupler bodies is still a common occurrence. Recent studies have shown that fatigue is the main reason behind such failures below the expected load. Moreover, knuckle failures occur more frequently than coupler body failures, which cause operational disruptions and also influence overall coupler life because of nonconforming contact between a new knuckle and an old coupler. In addition to new and old counterparts, undesired contact conditions are often the case with the new assembly due to casting-based manufacturing inaccuracies.

A study is thus carried out in this paper to understand the variation of load transfer paths and its consequences caused by dimensional variability. A finite element model of an E-type coupler’s knuckle is developed and different possible contact conditions of the knuckle with the coupler head are simulated. Knuckles generally fail in pulling mode, during which the possible contacting elements of knuckle are pulling lugs, pin protector regions and pinholes. Due to dimensional variability, contact conditions may exist where an individual or a combination of these elements are in contact.

Simulation results indicate that under regular operational conditions, having only the pulling lugs in contact reduces the risk of knuckle failure and maintains assembly integrity even if the knuckle fails. However, under extreme loading conditions, the safest scenario is when both pulling lugs and pin protector regions are in contact.

These findings are believed to assist in defining the dimensional variability limits to ensure the desired contacts between the mating surfaces of the knuckle and coupler body of railway couplers of AAR type. This work contributes to understanding implications of dimensional variability in the railway couplers. The insight presented are useful in design, manufacturing and maintenance of railway coupler’s knuckle.

With the deepening integration of rail transit systems–encompassing urban rail, regional railways, trunk lines and medium-low capacity transportation–the four-network integration imposes higher demands on operation and maintenance systems regarding cross-modal coordination, full-element interconnectivity and dynamic responsiveness.

This paper, based on policy directives and engineering practices, analyzes the operational maintenance characteristics of urban rail traction systems from perspectives including device interconnectivity and fault data mining. A non-intrusive high-frequency diagnostic device independent of vehicle control is proposed, informed by practical onboard operation experience. This innovation significantly enhances diagnostic accuracy for components requiring high sampling frequency, while integrating “Flash” storage with far greater capacity than conventional control chips.

This article will systematically introduces the key points and diagnostic methods for typical faults in urban rail traction systems. Through rational diagnostic algorithms combined with high-precision, high-storage diagnostic instrumentation, the overall safety and reliability of urban rail traction systems have been improved. The proposed non-intrusive high-frequency diagnostic solution has been validated across multiple rail lines.

This paper introduces an innovative non-intrusive diagnostic device with a dual-channel design for multi-system compatibility and a high-speed acquisition architecture enabling 400 kHz sampling. Its originality stems from the independent, high-fidelity capture of microsecond-level transient faults like IGBT shoot-through and pantograph arcing; Validated in operational environments, this approach provides a significant leap in diagnostic precision, directly enhancing traction system availability and operational safety by enabling precise fault localization and intelligent, adaptive protection strategies.

This study investigates the impact of flagship trains on high-speed railway capacity utilization and develops a brand value-oriented optimization framework that balances service quality enhancement with operational efficiency.

A mathematical optimization model based on integer programming is developed, incorporating flagship train constraints into capacity optimization. Case studies compare scenarios with and without flagship train considerations using the Beijing–Shanghai High-Speed Railway data across 20 experimental groups.

Operating flagship trains with hourly departure constraints results in an average decrease of 0.9 trains and an 8.4% reduction in capacity utilization rate. When scheduling 2 flagship trains within a 2-h timeframe, capacity utilization decreases from 86.43% to 83.73%, quantifying the trade-off between brand positioning and operational capacity.

This research provides the first quantitative framework for brand value-oriented railway capacity optimization, establishing clear definitions for flagship trains and mathematical foundations for evaluating service quality versus efficiency trade-offs. The findings offer practical decision support for railway operators balancing competitive positioning with capacity maximization.