Railway Operation Research Articles

Strategic Siting of Hydroelectric Power Plants to Power Railway Operations with Renewable Energy

The present study explores the strategic siting of hydroelectric power plants, focusing on the Miyanaka Intake Dam (MID) and Shinano River Hydroelectric Power Station (SHP). Built in 1939 to support Tokyo’s railway electrification, these facilities demonstrate the complexities of balancing renewable energy production with ecological conservation. Despite the high costs and energy losses associated with transmitting power from the Sea of Japan side, the SHP has effectively powered Tokyo’s rail system for over 80 years, owing to advanced transmission technologies and the region’s abundant water resources. However, river-crossing structures such as dams disrupt fish migration and habitats, necessitating the implementation of fishways. The MID fishway, continually improved since its construction, emphasizes the importance of integrating ecological considerations into hydropower projects. Our findings highlight the higher power generation efficiency on the Sea of Japan side and stress the need for careful site selection to ensure sustainable hydroelectric power while preserving river ecosystems. In conclusion, hydropower sites should be chosen based on both environmental impacts and future development potential to maintain the ecological balance and support long-term renewable energy goals.

Research on an Evaluation Method of Snowdrift Hazard for Railway Subgrades

The objective of this study is to investigate the potential risks posed by snowdrifts, a prevalent cause of natural disasters in northern China, on railway subgrades, and to assess their risk level. As a wind-driven process of snow migration and redeposition, snowdrifts pose a significant threat to the safety of transportation infrastructures. This study focuses on the Afu Railway in Xinjiang, situated on the northern slopes of the Eastern Tianshan Mountains, where it experiences periodic snowdrifts. We employed a combination of the Analytic Hierarchy Process (AHP) and fuzzy comprehensive evaluation (FCE) to construct an integrated evaluation system for assessing the risk of snowdrift to railway subgrades. The results indicate that subgrade design parameters and regional snowfield conditions are two key metrics affecting the extent of snowdrift disasters, with topography, vegetation coverage, and wind speed also exerting certain impacts. The evaluation method of this study aligns with the results of on-site observations, verifying its accuracy and practicality, thereby providing a solid risk assessment framework for snowdrifts along the railway. The scientific and systematic hazard assessment method of railway subgrades developed in this research provides basic data and theoretical support for future research, and provides a scientific basis for relevant departments to formulate countermeasures, so as to improve the safety and reliability of railway operations.

Flexible yard crane scheduling for mixed railway and road container operations in sea-rail intermodal ports with the sharing storage yard

The sea-rail intermodal port, serving as the “cornerstone” supporting the seamless connection of landside and quayside transportation, plays a crucial role in determining the service level of the container multimodal transport through port’s operational organization efficiency. With on-dock rails, the physical integration between railways and water transport is smoothly achieved. However, within the port, the diversity in container flows adds complexity to operational organization and decision-making. In this paper, we formulate a flexible crane scheduling model to reduce the mutual interference during the mixed operations of railway containers and road containers in the sharing yard. The model addresses the time window constraints of railway containers required by train schedule, and the uncertain scenarios of external truck arrivals. To solve this problem, we design a two-stage approach that encompasses a task reassignment phase and a sequential decision-making phase. Furthermore, we test the model and algorithm performance through various experiments of different scales. Our results show that the designed algorithm designed solves instances of 20 tasks in 18.7 s, compared to 3600 s for the model solver. It efficiently handles real-world instances with over 200 tasks and 100 scenarios. Finally, sensitivity analysis is carried out to capture the influence of railway container ratio, truck arrival patterns, and train time windows on yard operations. Under intensive operation, we find that road containers, following a uniform arrival pattern, are least affected by railway container operations when the proportion of railway containers in the sharing block ranges from 70% to 80%. We also observe that the flexibility of crane service increases as the time window for railway container operations becomes more lenient.

A refined track dynamic model considering the bending properties of iron pad: Proposal and validation

Iron pads are crucial components in rail fastening systems, characterized by their load-bearing and force-transmitting capabilities. This study presents and validates a track dynamic model considering the bending properties of iron pad, offering a comprehensive analysis of their dynamic performance under train loads. The primary aim is to employ iron pads as key elements for monitoring and detecting potential defects throughout the track’s service life. Initially, the construction of the track dynamic model is outlined, followed by an in-depth explanation of how the iron pads integrate with the track model. This involves introducing an enhanced Kelvin-Voigt three-element model and elaborating on the parameter selection for the spring element using a nonlinear spring model that accounts for voids and their relevant conditions. Subsequently, a systematic comparative analysis is performed to evaluate the accuracy of simulating iron pads using solid, shell, and beam elements, along with a proposed strain correction method. Finally, the established model and methods are employed to simulate and analyze the dynamic response of iron pads under typical defect conditions. These results indicate that iron pads can effectively reflect the failure conditions of the railway track system, making them ideal sensing elements for the dynamic monitoring of track structures. The enhanced model developed in this study holds significant theoretical and practical value, contributing to the safety monitoring and defect analysis of railway operations.

The Analysis of Electric Phase Separation and Common Technical Issues of High-speed Railway System in China

The electric railway, as a vital economic transportation artery, offers high efficiency and effectiveness compared to other modes of transportation. The characteristics of efficient transport, comfortable ride and environmental friendliness have effectively driven regional economic construction and industrial economy along the route, which has significantly enhanced cultural and economic exchanges between different regions, becomes the preferred mode of transportation for medium-distance and long-distance travel, and plays an irreplaceable role in China’s current transportation system. Under the increasing demand for passenger flow, the high-speed and high-density tracking operation of trains has become the new normal of high-speed railway operation management. In the background of national science and technology innovation development strategy, how to further shorten the train tracking interval to improve transportation efficiency and further reduce the energy consumption of train operation to improve the energy utilization level of the railway industry is the focus of the current electric railway construction and operation management department. The electric phase separation is a special and intricate part of the traction power supply system in China’s electric railway, and it is an indispensable component. The article describes that some main techniques relating to electrical phase separation are utilized extensively in China’s high-speed railway, by studying the technologies of electric phase separation, a few new methods were given and shared, which will solve the issues of high energy consumption, increased breakdowns, large equipment loss, and the lower speed, to better serve economic and social development and people’s travel.

A pantograph-catenary arcing detection model for high-speed railway based on semantic segmentation and generative adversarial network

ABSTRACT Pantograph-catenary arcing refers to an abnormal phenomenon occurring in pantograph-catenary system due to poor contact or other factors, which significantly impacts the normal operation of high-speed railway. Therefore, the detection of arcing occurrences holds significant importance for the intelligent maintenance of pantograph-catenary systems. However, the scarcity of arcing data in pantograph-catenary datasets limits the efficacy of supervised learning methods for arcing detection. To address this issue, we propose a novel pantograph-catenary arcing detection model that integrates semantic segmentation with generative adversarial networks. The model first modifies the loss function of the U 2 -Net network to tailor it specifically for pantograph-catenary semantic segmentation. To generate finer normal pantograph-catenary images, attention mechanism is incorporated into the SPADE-based pantograph-catenary scene generation model. Finally, an improved differencing method is employed to compute the arcing image by subtracting the generated normal pantograph-catenary image from the actual pantograph-catenary image. The experimental results validate the effectiveness of the method for pantograph-catenary arcing detection in the absence of prior arcing knowledge, with a recall rate of 75.3% and an F1-Score of 69.63%. Compared to other advanced pantograph-catenary arcing methods, this method exhibits superior performance.

Study on Deformation of New Tunnels Overcrossing Existing Tunnels Underneath Operating Railways

With the increasing utilization of urban underground space, new tunnels frequently intersect with existing tunnels and operational railways. However, sometimes the excavation and unloading of new tunnels can cause deformation of adjacent existing tunnels and railways, significantly affecting their normal operation. We used finite element software to predict the influence of new tunnel construction on overcrossing existing tunnels and down-traversing operational railways by a dynamic tunneling model based on a connection channel project of the east and west squares of a railway station. This article is not only control the distance between the two tunnels, but the new tunnel and the existing tunnel, as well as the new tunnel and the operation of the railway, the positional relationship between the three, the deformation laws of existing tunnels and operational railways during the construction of new tunnels with different buried depths are analyzed. The results show that the deformation curves of existing tunnels and operational railways present a normal distribution. The maximum deformation position is at the intersection with the new tunnel upon completion of the new tunnel excavation construction. Moreover, an increase in the buried depth of the new tunnel increases the deformation of the operational railway and the existing tunnel. The influence of the depth change of the new tunnel on the settlement of the operational railway is greater than that of the existing tunnel.

A Performance Evaluation Method for Long and Steep Uphill Sections of Heavy-Haul Railway Lines

Any system for evaluating the safety service performance of heavy-haul railway lines must effectively reflect the real-time service status of the line. The working conditions of heavy-load lines are complex and diverse, particularly on uphill sections. Existing evaluation systems struggle to accurately reflect the service conditions of long and steep uphill sections bearing heavy loads, posing a significant threat to the safe operation of these lines. To address this problem, we propose a new method for evaluating the safety service performance of long and steep uphill sections of heavy-haul railway lines by establishing a scoring system based on the Analytic Hierarchy Process (AHP). First, damage indicators for heavy-haul lines are categorized into three groups: track geometry status indicators, track structure status indicators, and track traffic status indicators. Using data from existing heavy-haul lines and maintenance experiences, we determine a score deduction standard, classifying lines into four levels based on their safety service quality. Next, we establish a coefficient table for the service performance of long and steep uphill sections after the corresponding scores are deducted. Using data for the length and elevation grade of the actual uphill section, we adjust the deducted scores of the track structure status indicators, enhancing the evaluation system’s accuracy in describing the working conditions. Finally, we verify the stability of the entire system by conducting a sensitivity analysis of the indicator evaluation results using the One-At-a-Time (OAT) method. This method fills a critical gap in the safe operation and maintenance of heavy-haul railways and provides a safety guarantee for the operation of long uphill sections of heavy-haul railways.

High-speed railway in developing countries: mind the gap -lessons from Morocco-

ABSTRACT Conducted prior to the launch of the High-Speed Railway (HSR) in Morocco, this study aims to be the first research to assess the HSR project through the estimation of the value of travel time savings. We focused on inter-urban routes to assess the HSR project impact. We conducted a Discrete Choice Experiment in the cities impacted (directly or indirectly) by the HSR project, which are Tangier, Kenitra, Rabat, Casablanca and Marrakesh. Our results show that at the sample average points of each mode of transport, the values of travel time savings are approximately 94MAD/h for car users, 27MAD/h for train users and 25MAD/h for bus users. We performed a simulation for the Tangier-Casablanca route and obtained satisfactory results (93MAD/h, 26MAD/h and 24MAD/h, for private car, train, and bus journeys respectively). Finally, our results show that the pricing strategies of the national railway operator (Office National des Chemins de Fer) present a potential risk of eviction, which could counterbalance the positive impact of the time savings.

Evaluation of Indian Railway’s Supply Chain Parameters for Improved Sustainability Under Industry 4.0 Transformation: An Application of AHP and TOPSIS

Indian Railways (IR) is India’s major public transportation system and one of the world’s largest and busiest rail networks. The Indian government is in charge of owning and running it. This paper presents an alternative approach to measuring the overall operational performance of the Indian Railway supply chain. The operation of Indian railways from a supply chain perspective needs to be analyzed to improve customer service and inventory management.Industry 4.0 is used for the easy processing of individual transportation components efficiently and safely. The study is useful for the Indian Railways because it enables the classification of various issues related to government procurement. A supply chain model is proposed to assess service expectations and quality. Various issues (such as the integration system, financial behavior, and management perspective) related to supply chain management have been identified, and various factors affecting availability, railway service quality, and reliability have been analyzed for managing its supply chain. The Analytical Hierarchy Process (AHP) and TOPSIS have been used to examine inventory-related difficulties and make recommendations for the public procurement environment. The result of the AHP method showed that Model 1 (Integration System) has the highest Max_C_weight of 0.5348, followed by Model 2 (Financial Behavior, 0.381695) and Model 3 (Management Perspective, 0.399443). The consistency ratio (CR) for all three models was also less than 0.1. Further, the TOPSIS method was used to validate the accuracy of AHP results and found that the model is significant. This result will help the decision-makers at Indian Railways design an assessment and relationship management model that will help them make procurement the driving force behind their supply chain.As per COP27, Industry 4.0 will help to achieve net zero emissions. The net carbon emissions will be reduced to zero, which will result in a clean environment.To improve sustainability within the framework of the Industry 4.0 transition, the research aimed to evaluate the Indian Railway’s supply chain metrics. Analytical Hierarchy Process (AHP) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) are methodologies used in this assessment.

Thermo-mechanical response of near-pearlitic steel heated under restriction of thermal expansion

Railway wheels experience high temperatures during operation, especially during severe block braking. The thermal expansion of wheel rim material due to frictional heating is limited by the wheel's geometry and size. This study investigated the impact of this combined mechanical and thermal loading on the mechanical properties and microstructure in the tread surface of an ER7T steel railway wheel.The material response below the austenitisation temperature is comprehensively evaluated through thermal cycling at peak temperatures of 300, 400, 600, and 650 °C, simulating severe block braking cycles with varying degrees of thermal dilatation (25 %, 50 %, 75 %, and 100 %). An initial plastic deformation was observed during the first heating cycle for the two lower temperatures at lower restrictions, followed by a predominantly elastic response. However, at higher restrictions, the material showed time-dependent relaxation during heating, and some plastic deformation was observed during cooling. Notably, even at the lowest level of restriction, similar observations were made at higher peak temperatures. Increasing the restriction resulted in large strains and a wider hysteresis loop. The test bars exposed to the two higher temperatures retained large tensile stresses after cooling. This indicates a risk of a significantly altered residual stress state in the rim of an overheated railway wheel, which could adversely affect its fatigue properties. The study's outcomes will aid in designing and calibrating constitutive material models for severe block braking. Furthermore, it will significantly contribute to research into the thermo-mechanical behaviour of pearlitic/near-pearlitic materials during railway operations and maintenance.

LCC-based approach for design and requirement specification for railway track system

AbstractLife cycle cost (LCC) analysis is an important tool for effective infrastructure management. It is an essential decision support methodology for selection, design, development, construction, maintenance and renewal of railway infrastructure system. Effective implementation of LCC analysis will assure cost-effective operation of railways from both investment and life-cycle perspectives. A major setback in the successful implementation of LCC analysis by infrastructure managers is the availability of relevant, reliable, and structured data. Different cost estimation methods and prediction models have been developed to deal with this challenge. However, there is a need to include condition degradation models as an integral part of LCC model to account for possible changes in the model variables. This article presents an approach for integrating degradation models with LCC model to study the impact of change in design speed on key decision criteria such as track possession time, service life of track system, and LCC. The methodology is applied to an ongoing railway investment project in Sweden to investigate and quantify the impact of design speed change from 250 to 320 km/h. The results of the studied degradation models show that the intended change in speed corresponds to correction factor values between 0.79 and 0.96. Using this correction factor to compensate for changes in design speed, the service life of ballasted track system is estimated to decrease by an average of 15%. Further, the expected value of LCC for the route under consideration will increase by 30%. The outcome of this study will be used to support the design and requirement specification of railway track system for the project under consideration.

Cost Inefficiency of Japanese Railway Companies and Impacts of COVID-19 Pandemic and Digital Transformation

The outbreak of the COVID-19 pandemic seriously affected railway businesses. The motivation of this study is to provide vital information to railway company management and policymakers by quantitatively assessing the cost efficiency of railway operations. We examine the efficiency of Japanese listed railway companies by applying stochastic frontier analysis to their operational and financial data from 2005 to 2020. Then, we classify the companies into four groups by cost efficiency levels and identify the characteristics of the best-practice companies. Furthermore, we analyze the factors influencing cost efficiency before and during the pandemic. Finally, we discuss the sustainable business practices and measures of digital transformation (DX) that can be applied to improve efficiency and survive severe events like the pandemic. From the results, we reveal that cost-efficient companies succeeded in securing profits through the creation of new services by proactive DX investments. The practical contributions of this study are threefold: quantifying the deterioration in efficiency due to the pandemic; identifying characteristics of best-practice companies; and examining the relationship between cost efficiency levels and concrete measures and investments for sustainable business practices. This study proposes a new analytical framework that combines conventional methods.

Analysis of Non-Road Mobile Machinery Homologation Standards in Relation to Actual Exhaust Emissions

This article presents issues related to the current approval procedures in the group of off-road vehicles. Our research aimed to demonstrate significant differences between actual railway vehicle operation and stationary homologation tests regarding exhaust emissions. The research cycle consisted of analyzing emissions of toxic compounds from exhaust systems under real operating conditions, supplemented by a temporal share analysis based on the denormalized NRTC test upon which the tested object was homologated. Based on the conducted analyses, a significant difference was found between the actual operation of the tested railway vehicle and the stationary homologation test. By interpreting emission intensities within the parameter ranges of the propulsion unit’s operation, key areas with a significant impact on the vehicle’s overall emissions were identified. Based on the obtained results, a critical opinion is expressed regarding current homologation standards for the off-road vehicle group and the necessity for further empirical research in the area of actual operation of the tested vehicle group.

An Improved Target Network Model for Rail Surface Defect Detection

Rail surface defects typically serve as early indicators of railway malfunctions, which may compromise the quality and corrosion resistance of rails, thereby endangering the safe operation of trains. The timely detection of defects is essential to ensure the safe operation of railways. To improve the classification accuracy of rail surface defect detection, this paper proposes a rail surface defects detection algorithm based on MobileNet-YOLOv7. By integrating lightweight deep learning algorithms into the engineering application of rail surface defect detection, a MobileNetV3 lightweight network is used as the backbone network for YOLOv7 to enhance both speed and accuracy in complex defect extraction. Subsequently, the efficient intersection over union (EIOU) loss function is utilized as the positional loss function to bolster system resilience. Finally, the k-means++ clustering algorithm is applied to obtain new anchor boxes. The experimental results demonstrate the effectiveness of the proposed method, achieving superior detection accuracy compared with traditional algorithms.

The Influence of Seasonal Effects on Railway Vertical Track Modulus

Adequate vertical track support is essential for safe and efficient railway operations. Insufficient support leads to distorted track geometry, increased dynamic loads, component stress, poor ride quality, rolling stock damage, and derailment risks. Current inspection practices focus on assessing the condition of the track components and geometry, rather than the root causes of degradation. To improve this condition, this study presents the use of a methodology that utilizes an autonomous vertical track deflection measurement system mounted on a loaded rail car (36 tonnes/axle) to support track maintenance decisions in a heavy haul railroad located in southeast Brazil. The system continuously measured substructure stiffness along the railway line. Over one year, data were collected from over 8000 km of track. The study highlighted seasonal effects on track degradation over time, identifying areas with significant deflections and high deflection rates, which contribute to issues such as differential settlement and reduced lifespan of track components. Additionally, the study revealed seasonal effects, with deflections peaking during wet weather and decreasing during dry cycles. A method to classify weak track areas was developed, facilitating monitoring and enabling more effective maintenance planning, contributing to the reduction of overall track maintenance costs and enhancing safety and operational efficiency.

The Management of Railway Operations during the Planned Interruption of Railway Infrastructure

A planned interruption of railway infrastructure is a situation where the operation of the track line or the operation of railway transport is limited. If there is also a restriction on the railway infrastructure, it means there will be complications not only for passengers but, above all, for railway undertakings operating freight transport. However, because of the planned railway infrastructure interruption, the quality of services provided not only to passengers but also to freight transport is decreasing. The aim of this paper is to propose effective planned maintenance works based on the analysis and evaluation of the processes performed during the planned railway infrastructure interruption or restriction. The research describes the process of affected railway infrastructure from technical, cost, and safety points of view. A methodological procedure is proposed under the condition of the Czech infrastructure manager. The main method is the calculation of the costs for the railway infrastructure manager and railway operator during the infrastructure interruption. The application part is undertaken using two interrupted lines according to the established alternative timetable in the area of České Budějovice.

Study of flood protection water levels for railway projects in the plains river network area

The Taihu Lake basin is characterised by a developed water system and a longitudinal river network, which is prone to flooding during the flood season. This poses a threat to the construction and operation of river-related railways, bridges, and other infrastructures, and therefore the design value of the water level of the river channel must be provided prior to the construction of roads and bridges in the basin. The Yanyi Railway traverses numerous river systems without the benefit of measured hydrological data. In order to address this deficiency, two methods were constructed using the Taihu Lake basin model: the historical water level frequency analysis method and the typical design storm method of the basin. These methods were employed to calculate the flood protection water level of each river under different design schemes and to analyze the reasons for the differences in the results. The results indicate that the water level results of the historical water level frequency analysis method are also applicable to the construction of the Yanyi Railway, provided that an economic perspective is taken.

Energy efficiency and indoor thermal comfort of railway carriages: Development of an innovative passenger-centric-control framework for HVAC systems

The railway sector's energy impact is increasing, and this trend is expected to persist over the next decade. Particularly, the energy consumption of Heating Ventilation, and Air Conditioning (HVAC) systems is significant among various services provided on board (30 % of total energy requirements) due to the rising attention to passengers' thermal comfort. In this framework, this research proposes an innovative method for enhancing indoor thermal comfort while also studying the associated energy consequences. It consists of an advanced passenger-centric-control framework for HVAC systems that prioritizes comfort, utilising optimized indoor air setpoints, which surpasses the rule-based control logic proposed by the existing standards. To analyse the proposed control framework, a novel mathematical model for the energy, economic, and environmental performance analyses of train HVAC systems, which can incorporate weather data associated with actual railway paths, is developed and validated. To prove the potential of the proposed method, a proof-of-concept analysis is conducted. In particular, for an existing railway coach operating in Italy, the standard and the innovative control logic are tested and compared. The results show an interesting thermal comfort hours increase (≃+1000 h) and energy savings (−27 % yearly), proving the benefits potentially achievable by adopting the proposed method.

Early Detection and Stability Assessment of Hazardous Rock Masses in Steep Slopes

The assessment of slope stability plays a critical role in the prevention and management of slope disasters. Evaluating the condition and stability of hazardous rock masses is essential for predicting potential collapses and assessing treatment effectiveness. However, conventional measurement techniques are inadequate in high slope areas, which lack sufficient spatial data to support subsequent calculations and analyses. Therefore, this paper presents a method for the early identification and evaluation of unstable rock masses in high slopes using Unmanned Aerial Vehicle (UAV) digital photogrammetry and geographic information technology. By considering nine evaluation indices including geology, topography, and induced conditions within the study area, weights for each index are determined through an analytic hierarchy process. A semi-automatic approach is then utilized to extract and analyze rock mass stability. The reliability of this early identification method is confirmed by applying the limit equilibrium principle. The findings reveal that 17.6% of dangerous rock masses in the study area fall into the unstable category (W4, W6, W10). This method effectively assesses slope rock mass stability while providing technical support for disaster monitoring systems, warning mechanisms, and railway infrastructure safety defense capability to ensure safe mountain railway operations.