Urban Rail Transit Construction Research Articles

Node Importance Evaluation of Urban Rail Transit Based on Signaling System Failure: A Case Study of the Nanjing Metro

Assessing the importance of nodes in urban rail transit systems helps enhance their ability to respond to emergencies and improve reliability in view of the fact that most of the existing methods for evaluating the importance of rail transit nodes ignore the disturbance effect of signaling system failures and are unable to objectively identify critical stations in specific disturbance scenarios. Therefore, this paper proposed a method for evaluating the importance of urban rail transit nodes in signaling system failure scenarios. The method was based on the research background of the signaling system failure that occurs most frequently and analyzed the network failure mechanism after the occurrence of a disturbance. The node importance evaluation indices were selected from the network topology and network operation performance in two aspects. The variation coefficient–VIKOR method was employed to comprehensively assess the significance of urban rail transit stations during signaling system failures. The Nanjing Metro network was also used as an example to evaluate the importance of network stations. The results showed that under the attack method of signaling system failure, most ECC and interlocking stations experienced significantly higher network performance losses compared to the original attack method, and a few interchange stations showed smaller performance losses. The critical stations identified based on the proposed method are mainly distributed in the passenger flow backbone of the Nanjing Metro and were constructed in the early stage; of these, 85% are ECC stations or interlocking stations, which are easily neglected in daily management, in contrast to interchange stations with heavy passenger flow. The results of this study can provide an important reference for the stable operation and sustainable construction of urban rail transit.

Pantograph fault prediction of urban rail transit vehicles based on edge feature extraction and detection

Nowadays, as an indispensable part of urban infrastructure, urban rail transit (URT) vehicles have also developed rapidly. A large amount of manpower, material resources, and financial resources need to be invested in the construction process of URT. For URT vehicles, research on more accurate fault prediction methods can save a lot of maintenance costs and improve the reliability of URT construction. As an important electrical equipment for urban rail transit vehicles to obtain electric energy from the catenary, the operation of rail transit vehicles puts forward higher performance requirements for the pantograph. For solving the problems of low accuracy of fault prediction, over reliance on practical experience and high cost of fault prediction in the application of traditional URT vehicle pantograph fault prediction model. Combining sensor network and artificial intelligence algorithm, this paper analyzed the traditional rail transit vehicle pantograph fault prediction model, and verified it through comparative experiments. Through the comparative analysis of the experimental results, this paper can draw a conclusion that compared with the traditional rail transit vehicle pantograph fault prediction model, the rail transit vehicle pantograph fault prediction model has higher fault prediction accuracy, less model response time, lower risk of pantograph failure, higher model application satisfaction, and the accuracy of fault prediction increased by about 6.6%. The rail transit vehicle pantograph fault prediction model can effectively improve the accuracy of vehicle pantograph fault prediction, which can greatly promote the safety of URT and promote the intelligent process of URT.

A Comprehensive Review of the Development Characteristics and Future Trends of TOD in Chinese Urban Rail Transit

The transit-oriented development (TOD) concept has become a significant catalyst for urban development in China, which has undergone rapid urbanization and has actively participated in the development of public transportation networks over the past 20 years. TOD not only guides the transformation of transportation modes but also leads the development of urban spaces. The extensive construction of urban rail transit in China highlights the universal patterns of TOD and reflects the uniqueness of Chinese practices. This paper analyzes the characteristics of urban development and TOD in developed countries, summarizing the common laws driving TOD in theoretical research. It then compares China, which is in a period of rapid rail transit construction, to identify the unique developmental laws of transit-oriented development of rail transit in China (TOD-RTC). The paper further examines the developmental characteristics of TOD-RTC in practice, considering both temporal and spatial aspects, and explores the reasons behind the formation of individual differences in TOD-RTC. Finally, it discusses the new value and potential that TOD brings to urban development, along with predicting future development trends.

Complex stress mechanism and design method of urban rail prestressed concrete U‐beams based on finite element simulation

SummaryTo explore the complex stress mechanism of prestressed concrete U‐beams in urban rail transit, in order to improve the safety of urban rail transit construction and the economy of beam structures. The study first analyzed the complex stress mechanism of U‐beams and obtained a tension compression rod model through finite element analysis. Then, experimental research was conducted on the vertical three‐dimensional finite element stress of U‐beams, and strain cloud maps were obtained and compared with calculated values. The experimental data show that the beam can still recover to its original state after the second cycle, and the beam will not crack. This recovery mechanism means that U‐beams have high crack resistance and stability under complex stress processes. In the vertical deformation cloud map of the U‐beam, the deflection of the mid span section is the largest, with a maximum displacement of about 20.4 mm, which is very close to the measured value of 20.3 mm. In the measured data of concrete strain measuring points and the results of finite element calculation, the difference rate between measured values and calculated values of some measuring points is within 10%. The results indicate that the U‐shaped beam tension and compression rod model combined with finite element analysis has a high degree of conformity with the actual situation, and can provide technical reference for the construction of urban rail transit. The stress mechanism and design method proposed in the study have high reliability and are suitable for the design and construction of prestressed concrete U‐beams in urban rail transit construction.

The Externality Impact of Urban Rail Transit on Urban Real Estate Prices in China

China has the largest and fastest growing urban rail transit system in the world. The system plays an important role in China's urbanization process, city governance and residents' daily commutes. The development of urban rail transit (URT) has influenced China's urban spatial structure and real estate supply, and has produced externalities on real estate value, including both positive and negative externalities. The research shows a positive correlation between URT and China’s real estate prices in general. The closer rail transit systems are, the greater the premium on real estate prices. In addition, the impact of rail transit on real estate prices shows a trend of first increasing and then decreasing. Different land use types and urban areas will also be affected. The research also found that the three stages of URT construction: planning, engineering construction and traffic operation have different effects on housing prices. At the same time, the impact of URT on land price will also change with China's economic situation and urbanization process. These influencing mechanisms above between URT and real estate prices may be linked to some factors. This research attempts to explain it by introducing urban spatial and land rent transformation, changes in real estate supply and demand, gentrification process, and different employment and housing pattern. This research points out the shortcomings and possible research directions of existing studies. In order to provide a reference for academic research and government policy making.

Research on the Resilience Evaluation of Urban Rail Transit Construction Organization Based on the Cloud Matter-Element Model: A Case Study of Nanchang West Station

In the construction of urban rail transit projects, the disturbance of equipment, sudden failure, rainstorms, and other emergencies may bring serious safety risks. Resilience theory emphasizes the ability of the system to resist, adapt, absorb, and learn from risks in the whole process before, during, and after the occurrence of risks. It is introduced into the safety management of construction organization of urban rail transit projects to describe the ability of urban rail transit projects to cope with risks in the whole process of dealing with construction risks. This study defines the connotation of the resilience of the project construction organization and uses the literature frequency statistics method to determine the resilience evaluation indexes. The game theory combination weighting method is used to determine the index weights, and the cloud matter element model is used to establish the evaluation model of construction organization resilience of urban rail transit projects. Taking Nanchang West Station of Phase 1 Project of Nanchang Line 2 as an example, the validity and accuracy of the model are verified. The results show that the resilience grade of the construction organization of the project is “higher resilience,” which is consistent with the actual survey situation, and the evaluation model is reasonable. In addition, in the evaluation results, the key indexes and risk indexes of the project are determined, and the safety management measures of the construction organization of the project are put forward according to the key indexes and risk indexes.

Calculation of greenhouse gas emissions of urban rail transit systems in China

In China, the total energy consumption and greenhouse gas (GHG) emissions will reach considerable levels based on the current speed of urban rail transit system development. Based on the life-cycle assessment theory, this research constructs an urban rail transit system GHG emission assessment method, calculates emission outputs based on resource inputs from actual investigated data and makes a quantitative analysis of GHG emissions. The results show that in recent years, the GHG emission of urban rail transit construction and operation in China is between 2000 × 104 and 4200 × 104 tonnes of carbon dioxide equivalent (tCO2e) per year. The proportions of the construction and operational phases in this emission are 57 and 43%, respectively. In the construction phase, the GHG emission intensity per unit mileage of shield tunnels and per unit area of stations is about 1.3 × 104 tCO2e/km and 3.71 × 104 tCO2e/ha, respectively. In the operational phase, the GHG emission intensity per unit trip is 0.084 kg carbon dioxide equivalent/passenger-km. The entire life-cycle GHG emission per kilometre of urban rail transit systems is 11.69 × 104 tCO2e (with a service life of 50 years) in China. The construction phase and operation phase generated about 18.73 and 81.27% of this emission, respectively. The preliminary conclusions of this study may help shed light on the emission reduction potential of urban rail transit systems and the emission reduction targets in China.

Reliability-aware failure recovery for cloud computing based automatic train supervision systems in urban rail transit using deep reinforcement learning

As urban rail transit construction advances with information technology, modernization, information, and intelligence have become the direction of development. A growing number of cloud platforms are being developed for transit in urban areas. However, the increasing scale of urban rail cloud platforms, coupled with the deployment of urban rail safety applications on the cloud platform, present a huge challenge to cloud reliability.One of the key components of urban rail transit cloud platforms is Automatic Train Supervision (ATS). The failure of the ATS cloud service would result in less punctual trains and decreased traffic efficiency, making it essential to research fault tolerance methods based on cloud computing to improve the reliability of ATS cloud services. This paper proposes a proactive, reliability-aware failure recovery method for ATS cloud services based on reinforcement learning. We formulate the problem of penalty error decision and resource-efficient optimization using the advanced actor-critic (A2C) algorithm. To maintain the freshness of the information, we use Age of Information (AoI) to train the agent, and construct the agent using Long Short-Term Memory (LSTM) to improve its sensitivity to fault events. Simulation results demonstrate that our proposed approach, LSTM-A2C, can effectively identify and correct faults in ATS cloud services, improving service reliability.

Experimental study on stress distribution characteristics of a shield tunnel under passive failure

Urban rail transit construction will inevitably encounter tunnel working conditions with extremely complex surrounding environment and buried deep shield tunnel, and the stability of the tunnel surface cannot be ignored. A series of passive instability geotechnical model tests were carried out on the tunnel faces at different burial depths. The earth pressure, lateral earth pressure coefficient and soil arch area evolution law caused by passive instability of the tunnel face in sandy cobble stratum were studied. Once the preset position is reached, the rotation is stopped using the cutterhead and the screw excavator and the shield machine continues the jack, simulating passive instability of the tunnel face. The results show that the soil pressure in the horizontal earth pressure is significantly more affected by the passive instability of the tunnel face than the vertical direction. The soil in front of the excavation caused by the ejection of the shield machine is squeezed and moved forward, resulting in a decrease in horizontal earth pressure perpendicular to the direction of shield tunnel excavation. The results of the passive instability region obtained by numerical simulation are larger than those obtained by model experiments, because the numerical simulation method fails to consider the compacting effect caused by the extrusion of sandy cobble formations. It can be found that the uplift value of C/D = 1.0 is significantly greater than that of C/D = 1.5, which also confirms the conclusion that the instability area with a relatively small burial depth is larger and develops farther to the front of excavation.

Quality Risk Evaluation of Urban Rail Transit Construction Based on AHP–FCE Method

The demand for urban transport is increasing globally, and urban rail transit is an important infrastructure for meeting this demand. The objectives of this study were to effectively control and prevent all types of risks in the construction of metro projects and improve the quality and safety control of urban metro project construction. First, 20 index factors were selected from the five dimensions of “man–machinery–materials–methods–environment” and constructed an index system for assessing urban metro construction quality risks. Second, the analytic hierarchy process (AHP) and fuzzy comprehensive evaluation (FCE) methods were used to comprehensively evaluate the construction quality risks of subway projects, and the weights of the secondary indices were determined. Finally, the importance of secondary indicators was evaluated using the integrated AHP–FCE method, and the model was applied to engineering practice for validation. The results indicated that the comprehensive AHP–FCE method has good adaptability and rationality and has practical application value for metro project construction quality and safety risk assessment. It can help prevent urban metro construction quality accidents and provides a novel idea for metro project construction quality risk assessment.

Fixed-point excitation prediction method for environmental vibration of urban rail transit

In urban rail transit construction, the empirical prediction equation is generally used to predict the environmental vibration along the line after its operation. It is used as the basis for whether to adopt a vibration-damping track or which vibration-damping track to use. Due to the superposition of complex factors such as geological conditions, differences in vehicles, and their running foundations on the prediction results, the track implementation should be considered at least with a design margin of 3 dB. However, there are still a large number of environmental vibration complaints. Therefore, an ecological vibration prediction method with higher prediction accuracy is proposed. The construction of the track-foundations, such as tunnel, bridge, and roadbed is completed. Before the track system is constructed, a fixed-point excitation load simulating the passage of trains is applied on the track-foundation, and the vibration-sensitive points around the line are directly measured by the actual measurement—environmental vibration prediction evaluation. The fixed-point vibration source function model for simulating train passing is deduced as the excitation load applied to the track-foundation; the fixed-point vibration source foundation finite element model and vehicle-track-foundation coupled dynamic model with the same track-foundation and foundation model have been established. The vibration response of the track-foundation and foundation surface when the train passes through is calculated separately. The results corresponding to different prediction methods of environmental vibration are compared and analyzed. The comparison between the theoretical prediction value of vibration response, the prediction value of the empirical equation, and the measured value shows that the vibration response waveform of the foundation surface is the same as that of the actual train passing under the action of the fixed-point vibration excitation source function. The vibration prediction error is much smaller than the empirical equation predicts the result. It shows that the prediction accuracy of the fixed-point excitation prediction method for environmental vibration is higher than that of the existing practical equation method. Because the fixed-point vibration source device is simple to implement and the ecological vibration field testing method is mature, it is beneficial to the field application of the fixed-point vibration excitation prediction method for urban rail transit environmental vibration.

Elements of the core area transport system oriented to station–city integration

Currently, China's urban rail transit construction projects are faced with several challenges including inconsistent planning and execution, lack of alignment with urban development, overly protracted timelines for some projects, sub-optimal land utilization rates, and significant wastage of precious urban resources. To mitigate these issues, it is essential to enhance land utilization around stations, implement scientific planning, and adopt intelligent management for underground space development. Moreover, all parties involved in construction must adhere strictly to planning guidelines during project execution. This study investigates the integrated development strategy of urban rail transit stations and their correlating cities, with the primary objective of enhancing the land utilization of stations and their surrounding areas. This involves fortifying the functionality of transportation, commerce, offices, residences, entertainment, and leisure in these areas, thereby catering to the varying needs of residents for travel, work, or entertainment activities. This type of an approach is anticipated to ease the pressure on urban road traffic, stimulate the economic growth of the stations and the areas along the routes, decrease environmental pollution, conserve urban space resources, and address issues associated with urban rail transit development. The insights gained from this research offer a valuable reference for future rail transit construction endeavors, carrying substantial practical significance.

Image-Processing-Based Subway Tunnel Crack Detection System.

With the increase in urban rail transit construction, instances of tunnel disease are on the rise, and cracks have become the focus of tunnel maintenance and management. Therefore, it is essential to carry out crack detection in a timely and efficient manner to not only prolong the service life of the tunnel but also reduce the incidence of accidents. In this paper, the design and structure of a tunnel crack detection system are analyzed. On this basis, this paper proposes a new method for crack identification and feature detection using image processing technology. This method fully considers the characteristics of tunnel images and the combination of these characteristics with deep learning, while a deep convolutional network (Single-Shot MultiBox Detector (SSD)) is proposed based on deep learning for object detection in complex images. The experimental results show that the test set accuracy and training set accuracy of the support vector machine (SVM) in the classification comparison test are up to 88% and 87.8%, respectively; while the test accuracy of Alexnet's deep convolutional neural network-based classification and identification is up to 96.7%, and the training set accuracy is up to 97.5%. It can be seen that this deep convolutional network recognition algorithm based on deep learning and image processing is better and more suitable for the detection of cracks in subway tunnels.

ISM-MICMAC based safety risk sources analysis and control measures for underground engineering of urban rail transit projects

Vigorously developing urban rail transit projects lowers the growing pressure on public transport in densely populated cities. However, accidents frequently occur due to the complex construction environment and diverse risk source factors emerging in urban rail transit construction. Existing research on the causes of urban rail transit construction accidents is mostly limited to the analysis of individual factors. This has negatively affected risk control of projects where risk factors for accidents have mutual influence. This paper adopted an integrated ISM-MICMAC approach to analyze and control urban rail transit construction accident risks. Through the analysis of China’s urban rail transit construction accidents (N = 134) from 2001 to 2019, this study 1) identified 18 risk source factors and their influencing relationships, 2) established a five-level Interpretive Structure Model (ISM) with 38 causal paths, and 3) classified the risk source factors using the Cross-Impact Matrix Multiplication Applied to Classification (MICMAC) procedure. All causal paths starting with the driver factors were then analyzed. Truncation factors and control measures were proposed to prevent accidents. Globally, China’s urban rail transit projects are large in number and size and cover a wide range of geological conditions. The analysis and control of accident risks in these projects provide valuable insights into risk management of urban rail transit construction in other countries.

Experimental Research on Vibration Dynamics Performance of Type B Metro Vehicles

In recent years, due to the acceleration of urban rail transit construction, the cumulative length of urban rail transit lines in China has also continued to grow. As one of the typical representatives of urban rail transit, the subway is an excellent choice for the general public due to its energy saving, environmental friendliness, large transportation capacity, and high punctuality rate. However, this also imposes stricter requirements on the operational safety and smoothness of subway vehicles. The vibration generated by subway vehicles in operation will affect the riding experience of passengers and subway vehicles to varying degrees. Vibration research is an important part of the research on rail transit vehicles. In this paper, a dynamic performance test of a B-type subway vehicle is carried out. According to GB/T5599-2019 and other standards, the operation safety and stability of the vehicle under no-load and overloaded loads and the vehicle vibration characteristics are studied, which provides reliable experimental data for the subsequent research of the vehicle.

Analysis of the Impacts of Passenger Demand on the Profitability of Different Types of Urban Rail Transit

With the rapid development of urban rail transit (URT) in China, a contradiction between high costs and low passenger demand becomes prominent. Complete analysis of the impacts of passenger demand on the profitability of URT can be difficult to conduct, due to the multifaceted impact of passenger demand with multidimensional characteristics. To this end, we propose a strategy that helps to analyse the profitability of different types of URT, taking into account the spatial and temporal characteristics of demand. Based on data of the Shunde (SD) district in China, the profitability of metro, light rail transit (LRT), monorail and tram was evaluated. Results show the profitability under different demand levels. Tram might be the best choice at low demand levels. At medium demand levels, LRT and monorail are competitive. At high demand levels, LRT with medium to high capacity and low cost is a good alternative to metro, though the capacity of metro is higher. Utilizing the URT with high capacity under insufficient demand can aggravate the burden of depreciation, and make it hard to achieve profit. The spatial characteristics of the demand described in this paper reflect the problem of insufficient demand in marginal areas due to the diversified construction of URT.

Research on construction data association management of Urban Rail Transit Based on BIM

With the continuous expansion of the scale of urban rail transit construction projects, it is difficult to improve the coordination in construction and the relevance of construction data. In order to solve the problem of data association in construction, an urban rail transit construction data association management system oriented to BIM Technology is proposed. BIM is used to build a dynamic workflow collaboration architecture to manage the data in urban rail transit construction, so as to realize construction collaborative scheduling. In the test and analysis of the system, the comprehensive ability test of the system shows that the minimum response time of the system can be reduced to 1.2 ms. At the same time, the system has ideal visualization effect and obvious practical value in practical application. Therefore, the urban rail transit construction data association management system based on BIM can show ideal results in complex construction environment, which is of great significance to China's urban construction.

Land Premium Effects of Urban Rail Transit and the Associated Policy Insights for TOD: A Case of Ningbo, China

With considerable investments, mainly from local government budgets, the construction and operation of urban rail transit (URT) can exert significant spillover effects on the surrounding land use and land prices. In particular, China’s local governments are actively committed to developing their URT systems and promoting large-scale transit-oriented development (TOD) projects under the public land leasing policy. However, the connection between the land premium effects and TOD policy and practice is still lacking, particularly in the local government contexts, which exhibit significant policy and spatial heterogeneity. Thus, this research represents an attempt to better address this issue using the city of Ningbo as a case study. First, the premium effects of URT on land prices are examined, after which three crucial policy insights (land value capture [LVC], public–private cooperation [PPC], and urban regeneration) are proposed to enhance the effectiveness and efficiency of TOD, demonstrating its strong connection with the potential premium effects. The findings demonstrate that (1) local governments have adopted different innovative policies—with the ambition—to implement LVC; (2) assisted by PPC, the local rail transit authority can significantly amplify the premium effects, although it must still address the fair distribution of premiums across multiple stakeholders; and (3) transit-oriented urban regeneration can significantly influence land prices/land rents and subsequently generate significant gentrification, which will be further addressed by the TOD policy and practice.

Computer-Aided Analysis of Small Clear Space Intersection Tunnel and Heavy Load Railway Surrounding Rock Structure Dynamic Response Characteristics Analysis under Intelligent Manufacturing

Among many tunnel construction projects, small clear tunnels have been the focus of urban rail transit construction in recent years. The purpose of this research work is to study the dynamic response characteristics of the surrounding rock structure of a heavy-duty railway with a small clearance crossing tunnel. It is proposed to analyze the dynamic response characteristics of the surrounding rock structure through the frequency response function. The vertical acceleration, tensile force, stress, and internal strength of the pipe section are specifically analyzed. The influence of the pipe joint and the assembly method on the dynamic response is also analyzed. The influencing factors of stability are analyzed from buried depth, clear distance, and surrounding rock grade. Studies have shown that the minimum clear distance of crossing tunnels increases nonlinearly with the increase of tunnel depth and gravity, and decreases nonlinearly with the increase of cohesion, internal friction angle, calculated internal friction angle, and lateral pressure coefficient. When other parameters are the same and when the side pressure coefficient is less than 1, the minimum clear distance is larger than that of the side pressure coefficient when it is equal to 1. When the vibration frequency exceeds 100 Hz, the coherence coefficient is basically close to 1, indicating that the frequency response function response result of this section is the most reliable. It is hoped that it can provide a reference for the dynamic stability analysis of the surrounding rock structure of the heavy-duty railway surrounding rock structure and the surrounding stratum and the research of structural vibration reduction technology for the small clearance crossing tunnel in the future.

Research on the Coupling Coordination Relationship between Urban Rail Transit System and Sustainable Urban Development

With the accelerating urbanization and steady economic development in China, the urban built-up area is expanding and the population in the core area is proliferating. The pressure of insufficient urban infrastructure, especially public transportation capacity, is becoming increasingly evident, and urban rail transit (URT) systems are crucial to the sustainable development of cities. This paper collects data related to URT and sustainable urban development (SUD) in 42 cities in China in 2020, constructs a comprehensive evaluation index system, and quantitatively analyzes the coupling coordination degree of the two systems using the TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution) method and coupling coordination degree model. Then, the influencing factors of the coupling coordination degree of URT and SUD are analyzed by combining the grey correlation analysis method. The results of this study show that: (1) There are significant differences between URT system development and SUD in 42 cities in China. (2) The average coupling coordination between URT development and SUD is 0.4406. More than half of the cities are in the slightly unbalanced category. (3) Factors, such as resident population, income level and urban built-up area, significantly influence the coupling and coordination level of URT and SUD. It is hoped that the research in this paper will advance the in-depth research on the level of coordination between URT and SUD coupling, provide a solid basis for future URT planning and construction in China and even other countries in the world, and make the planning and construction of URT in China more scientific and reasonable, to promote the sustainable development of cities.