Development Of Rail Transit Research Articles

Aerodynamic shape optimization of an urban maglev train

With rapid development of urban rail transit, maglev trains, benefiting from its comfortable, energy-saving and environmentally friendly merits, have gradually entered people's horizons. In this paper, aiming at improving the aerodynamic performance of an urban maglev train, the aerodynamic optimization design has been performed. An improved two-point infill criterion has been adopted to construct the cross-validated Kriging model. Meanwhile, the multi-objective genetic algorithm and complex three-dimensional geometric parametrization method have been used, to optimize the streamlined head of the train. Several optimal shapes have been obtained. Results reveal that the optimization strategy used in this paper is sufficiently accurate and time-efficient for the optimization of the urban maglev train, and can be applied in practical engineering. Compared to the prototype of the train, optimal shape benefits from higher lift of the leading car and smaller drag of the whole train. Sensitivity analysis reveals that the length and height of the streamlined head have a great influence on the aerodynamic performance of the train, and strong nonlinear relationships exist between these design variables and aerodynamic performance. The conclusions drawn in this study offer the chance to derive critical reference values for the optimization of the aerodynamic characteristics of urban maglev trains.Graphic abstract

Impact of Urban Rail Transit Network on Residential and Commercial Land Values in China: A Complex Network Perspective

Urban rail transit can improve a city’s accessibility. However, high construction and operation costs restrict the development of urban rail transit. Value capture recoups the additional value that the investments of urban rail transit confer to local land and is considered to be an effective measure to alleviate this financial problem. Understanding the land value uplift effects of urban rail transit is essential for understanding value capture. This study applied a Space-P model of urban rail transit network based on complex network theory and demonstrated the influence of urban rail transit network characteristics on residential and commercial land prices. The model was tested with eight metropolises in China, using the 2003 to 2022 timeframe as the context. The results showed a significant positive correlation between the number of nodes and the land prices, the average clustering coefficient was highly positively correlated with the land prices, and there was a significant negative correlation between the average path length and the land prices. This study provides theoretical support for value capture, is beneficial for urban rail transit planning, and supports improvements in the development quality of urban rail transit networks.

Research on Evaluation Method of Gas Environment in Metro Station

With the development of rail transit, subway has become one of the main means of transportation in most cities. However, the particularity and tightness of the subway station, the continuous growth of passenger traffic has also brought some negative environmental problems, such as the comfort and safety of subway station staff and passengers. In this paper, a comprehensive evaluation model of gas environment for metro station is proposed. The micro environment quality evaluation index of metro station is divided into two parts, one is the air quality evaluation index, the other is the thermal comfort evaluation index. From the construction and calculation of these two indexes, the comprehensive evaluation of gas environment of metro station is realized. In order to verify the applicability of the proposed method, we collected the environmental parameter data of six subway stations and evaluated them by using the environmental assessment method. The results show that the proposed method can not only realize the evaluation and monitoring of the station environment, but also has great significance for the improvement and decision-making of public transport environment.

Intelligent Recognition of Safety Risk in Metro Engineering Construction Based on BP Neural Network

With the rapid development of urban economy, the development of urban rail transit is becoming more and more rapid. As an energy-saving, land-saving, and environment-friendly green travel mode, the subway provides realistic and feasible solutions to the increasingly prominent traffic environment and other urban diseases in our country and brings a booming development in the subway construction industry with efforts to promote and build in many large cities. For a large number of subway constructions, it is particularly important to judge the construction safety status in time during the entire safety management process. Regularly conducting safety risk assessments on subway construction status can accurately predict and judge the types of accidents that occur. In order to solve the current safety risk assessment problems in the process of subway construction in our country, this paper is based on the BP neural network to intelligently identify the safety risks of subway construction, choosing from three aspects: human factors, management factors, and risk factors. We evaluate the construction safety of subway projects under construction through the model, predict the types of accidents that may occur, so that the construction unit can take corresponding preventive and improvement measures, improve the relevant safety technology of subway construction in a targeted manner, and propose corresponding reductions. We provide suggestions and measures for risk probability, to ensure that the construction unit discovers the danger in time and takes safety measures. The rectification measures provided theoretical basis and guidance.

Impacts of light rail transit development on neighborhood health: A scoping review through a social determinants of health lens

IntroductionLight rail transit (LRT) has become a popular intervention for addressing the social and economic complexities associated with urban growth. LRT development can exert influence on neighborhood characteristics, such as property values, employment opportunities, and service access. Many of these changes can impact the health of nearby residents by influencing their exposure to the social determinants of health (SDOH). This study maps the literature on LRT development through an SDOH lens and comments on gaps and implications for neighborhood health and transit planning. MethodsThe Arksey and O'Malley scoping review methodology was used to examine existing literature on neighborhood-level impacts of LRT development related to the SDOH. Peer-reviewed articles were included if they focused on an LRT project in an urban center in Canada or the United States, reported on a neighborhood-level impact related to the SDOH, and were published in English between 2004 and 2019. Standardized information was extracted from each included article and thematic analysis was applied to generate impact themes. ResultsA search of three databases yielded 767 non-duplicate records and 29 studies were included in the review. Six impact themes were identified: property values, neighborhood demography, economy, development, transit, and neighborhood perceptions. LRT development was associated with residential property value increases, high-density residential development, new business openings, and increases in neighborhood household income. Articles had limited recognition of the role of LRT development in creating health disparities. ConclusionsThis review demonstrates that transit development can influence the living conditions and resource availability of surrounding areas. Since many of the impacts identified in this study can further social stratification or have differential effects by socioeconomic status, LRT development can be conceptualized as a driver of health inequities. In order to design more effective and equitable transit policy, future research should position transit development as an SDOH.

Optimization Design of Rail Station Signal Monitoring System Based on Role Autonomous Decentralized System

Online-expansion, online maintenance and fault tolerance are vital functions of rail signal monitoring system, which can guarantee the system always in working status and satisfy the sustainable development of rail transit. Due to the limitations of traditional centralized system structure, it is necessary to optimize the design of rail station signal monitoring system to make the system possess these functions. In this research, the novel concept of Role on Autonomous Decentralized System (RoADS) is adopted to optimize the design of rail signal monitoring system. On the one hand, RoADS has the characteristic of role dynamic conversion which is essential to realize the special function of online-expansion, online maintenance and fault tolerance. On the other hand, RoADS also can support the basic function of data collection. In order to verify the validity of the proposed method, a case study has been performed on ZPW-2000 track circuit monitoring system which is the subsystem of rail signal system mainly responsible to monitor the track circuit. The results clearly indicate that the optimized system based on RoADS can not only realize the function of data collection, but also possess the function of online-expansion, online maintenance and fault tolerance. Consequently, the proposed method based on RoADS can improve the safety level of rail transit and reduce the cost operation which is of great significance for maintaining the sustainable urban development of rail transit.

Fire emergency evacuation model of light rail station based on BIM technology

Urban light rail undertakes the mission of escorting passengers to arrive safely. Once a fire accident occurs, it will inevitably have a great negative impact. Therefore, how to effectively carry out emergency evacuation tasks in fire accidents has become one of the problems facing the development of urban rail transit. Based on this, this article first introduces the relevant characteristics of BIM technology and the corresponding advantages, and further its use in urban light rail stations. The application advantages of emergency evacuation strategies are briefly analyzed; then the requirements for the construction of BIM emergency evacuation models are studied; finally, through field investigations, a specific urban rail transit light rail station is taken as an example to construct a BIM building information model for this light rail station. Applying BIM technology to fire protection work in light rail stations, it is expected to improve the efficiency of emergency evacuation of passengers in light rail stations.

A novel wind energy harvesting system with hybrid mechanism for self-powered applications in subway tunnels

With the rapid development of urban rail transit, the safety maintenance of subway tunnels has attracted attention in various countries. Tunnel safety monitoring systems are used to ensure the safety of subway operation. This paper presents a new type of self-powered system for WSN nodes in tunnels to solve the power supply problem in subway tunnel safety monitoring systems. This new self-powered system collects wind energy in subway tunnels and converts it into electrical energy for storage and utilization. The system is composed of three parts: electromagnetic wind energy acquisition module, piezoelectric wind energy acquisition module, and power generation energy storage module. The electromagnetic wind energy acquisition module uses the principle of electromagnetic induction to convert wind energy into electrical energy. The piezoelectric wind energy acquisition module uses piezoelectric patches to convert wind energy into electrical energy. The power generation energy storage module converts the collected AC power into DC power, stores it in the supercapacitor, and supplies power to the WSN nodes. Experimental data shows that the energy output power of the system at a wind speed of 7 m/s is 59.31 mW. The Chengdu subway line 2 was selected for case study; the energy consumed by WSN nodes accounts for 49.4%–59.8% of the energy collected by the system. The proposed system can provide continuous and stable power for WSN node systems in subway tunnels.

Numerical simulation platform for slab track systems subjected to a moving vehicle

With the rapid development of high-speed and urban rail transit, ballastless slab tracks have been widely used in many areas. The work on construction, design, and mechanics of ballastless slab tracks is abundant and achievements have been made. However, a platform for numerical simulation and dynamic analysis of slab track systems subjected to a moving train still needs to be probed into. In the MATLAB®, effective and easily programable methods are presented to guide the construction of the vehicle-slab track interaction system and the realization of long length computation in this present study. Based on previous studies, the formulation of slab track dynamics in the framework of finite element theory is founded with simplicities, and then the wheel-rail coupling matrices totally derived from the nonlinear wheel-rail normal contact/tangential creep forces using the energy variation method are presented. Following the dynamics modeling construction, an improved method for long or infinite length computation is proposed. With an implementation of this method, the effect of the spatial variability of track properties on vehicle-track system dynamic performance can be evaluated conveniently. Using this numerical simulation platform, extensive studies have been conducted to model and analyze the influence of spatial variability of filling layer support stiffness, the track slab finite element type and support type of steel spring for floating-slab tracks, etc.

Analysis of Three-Dimensional Vibration Characteristics of Single-Circle Double-Track Subway Tunnel under Moving Load

With the development of urban rail transit, subway lines are becoming more and more denser, the departure time interval is short, and the probability of subway trains meeting is high. The impact of vibration caused by double-line subway meeting on the surrounding environment cannot be ignored. Taking the typical cross-section of a single-circle double-track subway tunnel as an example, a single running scenario and three typical meeting scenarios, namely, 4 s meeting, 6 s meeting, and 8 s meeting scenarios were considered, and a track-tunnel-foundation three-dimensional ABAQUS finite element model was established. The dynamic response of monitoring points at different distances between the center of the track bed and the center line of the track was analyzed. Results showed that due to the consistent load action period, the center acceleration of the track bed increases significantly during the meeting, the main frequency of vibration and the peak value of the 1/3 octave spectrum were increased by about 5 Hz, and the vibration level at the dominant frequency was increased by about 7 dB. The center displacement of the track bed and the peak compressive strain increased significantly under the 4 s meeting and 6 s meeting working scenarios; while the 8 s meeting and 4 s single running scenarios were basically the same, only the action time was doubled. The dynamic response of the 4 working scenarios decreases with the increase of distance, and the attenuation rate gradually decreases and has gradually stabilized within 15–19 m above the vault.

Research and design of data communication subsystem of urban rail transit CBTC system

With the intensive development of urban rail transit in China, urban rail transit has increasingly become the preferred mode of transportation for citizens due to its convenience and speed. The design and construction of an efficient and highly reliable urban rail transit system has become an urgent requirement for urban rail transit construction. This article mainly introduces the research and design of the data communication subsystem of the urban rail transit CBTC system, and intends to provide some ideas and directions for studying the data communication subsystem of the urban rail transit CBTC system. This article uses a variety of methods, such as consulting literature and information research on trademark system suppliers. The development status of CBTC system and data communication subsystem is analyzed, and the importance of data communication subsystem and the necessity of the entire CBTC system are analyzed. The experimental results of this article show that in the design, development and application engineering of the CBTC system, the DCS subsystem accounts for 55%, the system is complex, and the environment is changeable, occupying an important position. When the DCS has a problem, it may cause drive failure, affect normal functions, cause greater losses, and even cause huge safety accidents. Therefore, the reasonable, reliable and safe design of the DCS subsystem is of great significance.

Research on Obstacle Detection Method of Urban Rail Transit Based on Multisensor Technology

With the rapid development of urban rail transit, passenger traffic is increasing, and obstacle violations are more frequent, and the safety of train operation under high-density traffic conditions is becoming more and more thought-provoking. In order to monitor the train operating environment in real time, this paper first adopts multi-sensing technology based on machine vision and lidar, which is used to collect video images and ranging data of the track area in real time, and then it performs image preprocessing and division of regions of interest on the collected video. Then, the obstacles in the region of interest are detected to obtain the geometric characteristics and position information of the obstacles. Finally, according to the danger level of the obstacles, determine the degree of impact on train operation , the automatic response mode and manual response mode of the signal system are used to transmit the detection results to the corresponding train to control train operation. Through simulation analysis and experimental verification, the detection accuracy and control performance of the detection method are confirmed, which provides safety guarantee for the train operation.

Load and response quantification of direct fixation fastening systems for heavy rail transit infrastructure

Ballastless track (i.e. slab track) systems are used extensively in passenger rail applications for improved track stability, alignment control, vibration, and life cycle cost (LCC) benefits. These systems regularly rely on Direct Fixation (DF) fasteners to connect the rail to the structure. Field performance observations have indicated that even under similar track geometry and train operating conditions, the DF fasteners useful life varies widely. Meanwhile, a review of literature reveals that there is limited prior research to guide optimization of DF fastener designs for heavy rail transit. Therefore, researchers at the University of Illinois at Urbana-Champaign (UIUC) conducted a field investigation at three sites on a United States legacy heavy rail transit system to quantify wheel-rail interface loading demands and DF fastener response. Track response variance across similar track geometry was found. Wheel loads ranged between 2.7 to 18.2 kip (12.0 to 81.0 kN) and 0.9 to 12.4 kip (4.0 to 55.2 kN) for vertical and lateral loads, respectively. Lateral rail head displacements ranged between −0.05 to 0.16 inches (−1.27 to 4.06 mm) while dynamic lateral stiffness ranged from 42 to 62 kip/in. (7.3 to 10.8 kN/mm), indicating a low stiffness ratio for the DF fastener studied. Differences in behavior are attributed to dynamic vehicle-track interaction, the relationship between balanced and operating speeds, and differences in track gauge between sites. A comparison of vertical loading results with two additional heavy rail transit agencies shows Burr distributions that accurately represent the loading demands. Results from this study provide quantitative information that can be leveraged to improve heavy rail transit DF fastening system design and development of representative design validation testing protocols.

Research on Regional Development of Rail Transit -- Taking Guangfo Metro as an example

The shortest path model is selected to evaluate the regional traffic accessibility. Three index factors, gross regional product, total retail sales of consumer goods, and the number of permanent residents in the region, were selected, and the weight sum was given by entropy weight method to evaluate the regional economic intensity. The gravity model adding the regional accessibility index considering traffic factors is selected to evaluate the regional linkages. By integrating the three indexes, an evaluation index system of rail transit benefits is formed to study the utility of rail transit to the economic development of surrounding areas, and to provide scientific theoretical basis and guidance for the government to carry out urban construction and rail transit management.

Analysis on the Development of Tokyo Rail Transit and Its Enlightenment to Chengdu

With the introduction of the intensive urban development model, urban rail transit, as a rapidly developing inter-city spatial association network, has become increasingly prominent in promoting social and economic development and has an important influence on the shaping of regional spatial structure. Taking the practical experience of Japan’s rail transit development as an example, this article first combs its development history and summarizes the three organizational characteristics of its development model: diversified business entities, TOD model, and efficient use of underground space. On this basis, it summarizes Japan’s success. Experience and design techniques for the utilization of underground space, and put forward several optimized development suggestions based on the current status and problems of the development of urban rail transit hub in Chengdu, providing reference and reference for building a multi-mode, multi-level, and coordinated regional integrated rail transit system For reference, in order to better play the supporting role of rail transit network on the development and growth of urban agglomerations in our country.

Rail Transit Development Experience of World-class Multi-airport System at Abroad

The advanced development experience of rail transit in foreign world-class multi-airport systems is studied and refined. Based on the fact that China’s world-class multi-airport systems will consolidate the development pattern of rail transit as the backbone distribution mode, and based on the perspective of spatial structure and traffic mode of foreign world-class urban agglomerations, the Pacific coast multi-airport system of Japan, the northwest European multi-airport system and the London multi-airport system of Britain are selected as objects of reference for rail transit development experience. Systematically sorting out the current situation of rail transit development of the selected world-class multi-airport systems, from the point of view of development model, hub level, integrated hub, interconnection, true service and so on, this paper studies and summarizes the beneficial enlightenment which is helpful to the development of rail transit of world-class multi-airport systems in our country.

Study on commuter travel of urban workers——Analysis of coordination between ground bus and rail transit in Beijing

At present, with the advancement of China’s urbanization construction process, China’s urbanization rate has gradually increased in recent years, and the population in the suburbs and surrounding towns and rural areas continue to pour into large cities, which inevitably leads to a series of social problems in the process of China’s urban economic development. In the process of population gathering in large cities, traffic problems have a great impact on urban workers. With the increase of urban population and the rising stock of private cars, the efficiency of ground transportation continues to decline; the population aggregation in big cities, the poor travel experience of public transport system in the morning and evening rush hours on weekdays, and the long commuting time and distance of workers restrict the long-term development of large cities in China to a certain extent. This paper studies the coordination between ground public transport and rail transit in Beijing with reference to the coordination of the development of ground public transport and rail transit. Finally, based on these problems, this paper puts forward some suggestions for the long-term coordinated development of public transport in Beijing.

Research progress of lightweight metallic materials and their processing technologies for modern transportation

With the rapidly development of automobile, rail transit and aviation, the lightweight of modern transportation is becoming the common choice to conserve energy and reduce emission. At present, the...

Rail Transit Obstacle Detection Based on Improved CNN

With the continuous development of rail transit fully automatic operation, the urgent need to improve train operation safety makes obstacle detection become the research focus. In this work, a flexible and efficient multiscale one-stage object detector FE-YOLO was proposed for image obstacle detection. The feature extraction network is composed of attention module, downsampling module, residual block, spatial pyramid pooling (SPP) module, and so on. A repeatable bidirectional cross-scale path aggregation module was designed as the core of the feature fusion network. The dataset RT2021 of rail transit obstacles was constructed based on the real scene. The mean of average precision (mAP), detection time, iteration time, parameters, and anti-interference ability were used to compare FE-YOLO with other classic object detectors. The results showed that FE-YOLO has the best comprehensive performance. The mAP can reach 92.57%, and the single-frame detection time on the onboard embedded device is up to 0.0989 s. The ablation experiment verified the effectiveness of each module of FE-YOLO and has the best generalization performance on the PASCAL VOC dataset. Finally, a rail transit obstacle detection system was developed, and multiple sensors were used to improve the detection accuracy. Experiments showed that the detection system can work normally in different environments.

Research on Preparation and Performance of Clay‐Based Shield Tunnel Nonsintered Bricks

With the rapid development of rail transit in China, the number and scale of underground engineering construction have increased significantly, and a large amount of shield muck has been generated, which has brought great challenges to the urban environment. The reuse of shield muck has become an important research direction in underground engineering construction. In this paper, a nonsintered brick is prepared with shield muck soil as the matrix. The influence of different doping amounts of lime, fly ash, cement, and polyvinyl alcohol on porosity, density, water absorption, saturation coefficient, compressive strength, and other properties was explored to realize the resource utilization of shield dregs and at the same time obtain excellent performance nonsintered bricks. Through research, it is found that when the lime doping amount is 10% and the cement doping amount is 5%, with the increase of the fly ash doping amount, the overall compressive strength increases significantly, and the maximum compressive strength can reach 13.69 MPa. Although the doping of trace amounts of polyvinyl alcohol reduces the compressive strength, it can significantly reduce the compressive strength and mass loss rate after 15 freeze‐thaw cycles.