Urban Rapid Transit Research Articles

Study on the influence of intermediate airshafts on the aerodynamic effect of urban rapid rail transit

This study explores how intermediate airshafts affect the aerodynamics of urban rapid transit trains in tunnels. It employs a three-dimensional turbulence model to simulate train-tunnel interactions, specifically examining airshafts’ impact on transient pressure variations along surfaces. The model’s accuracy and reliability are confirmed by comparing results with full-scale experimental data. The results show that airshafts effectively mitigate peak tunnel wall pressures, with the lowest peak overpressure observed at the airshaft location. With the airshaft-reflected expansion wave arriving ahead of the train, the pressure between the train front and tunnel wall decreases compared to scenarios without airshafts. Similar transient pressure changes at the tunnel entrance and rear half suggest the emergence of a “secondary compression wave” due to the train’s transit.

Improvements in Urban Rapid Transit Boarding and Alighting Safety during System Modernization

Urban rail transport has advantages that determine its particular usefulness. However, despite decades of technical development, it is still difficult to speak about satisfactory solutions. Safe, independent access to this transport and public infrastructure for passengers with reduced mobility (PRM) is an essential element of civil rights and an interesting subject of scientific research. In relation to that, the interface between rail vehicle and platform, despite multiple efforts aiming at improving this situation, is one of the hardest problems to overcome. This paper presents a summary and analyses of distinctive features of selected transit systems that are interesting from the viewpoint of finding various solutions to improve the safety of passengers on platforms. This analysis led to preparation of a new, improved standard of the vehicle–platform interface, illustrated with an example of the city of Wrocław, as discussed further in this paper. Some of the main conclusions of this paper are that insufficient progress has been made with developing the vehicle–platform interface, there are a multitude of systems and ways of (more or less effectively) ensuring independent access for PRM, and further research and development work is needed to optimize engineering solutions in this domain so they are both sustainable and economical.

Application of Failure Mode Effects Analysis for Maintenance of Turnout System on Serviced Urban Rapid Transit

Over the past 25 years, maintenance processes for the wooden sleeper turnouts of sleeper floating tracks (known as STEDEF) have been insufficient, lacking accurate maintenance history and failure cause analyses. Currently, damaged parts are repeatedly replaced without an analysis of the cause of their failure. Therefore, it has been difficult to predict potential damages due to the lack of maintenance history data on the replaced items and the timing of the turnout component. This study proposes a turnout maintenance plan using the failure mode and effects analysis (FMEA) technique to analyze the turnout maintenance history data for a period spanning 10 years. The maintenance damage type of the turnout was classified to confirm the cause of damage and the damage frequency. Additionally, components that could lower the occurrence score were selected based on a risk analysis of the turnover. Therefore, it was possible to reduce the risk occurrence score by improving the size of the turnout top plate and the number of bolts.

Nonparametric Passenger Flow Monitoring using A Minimum Distance Criterion

Monitoring real-time passenger flow in urban rapid transit systems is very important to maintain social stability and prevent unexpected group events and system failure. To monitor passenger flow, data are collected by sensors deployed in important stations and many existing control charts can be applied. However, because of unknown complex distributions and the requirement to detect shifts of all ranges effectively, conventional methods may perform poorly. Nevertheless, while there are certain charting schemes that truncate the log-likelihood ratio (LLR) function to detect large shifts more quickly, they can cause massive loss of information by truncation, and can only handle particular distributions, leading to unstable online monitoring. In this article, we propose a nonparametric CUSUM charting scheme to monitor passenger flow dynamically. We propose a novel minimum distance criterion is proposed to minimize the functional distance between the objective function and the original LLR function while maintaining its monotonically increasing property. By integrating this concept with kernel density estimation, our proposed chart does not require any parametric process distribution, can be constructed easily in any situation, and is sensitive to shifts of all sizes. Theoretical analysis, simulations and a real application to monitoring passenger flow in the mass transit railway (MTR) in Hong Kong show that our method performs well in various cases.

Study of Noise and Vibration Impacts to Buildings Due to Urban Rail Transit and Mitigation Measures

The developments in urban rail transit (URT) construction are associated with the benefits of moving people efficiently and the negative impacts of noise and vibrations caused to surroundings. Despite a proliferation of studies conducted throughout the world, very few studies employed the field measurement approach due to various limitations. Using a metropolitan city, Tianjin (China), as an example, field measurement was set up to monitor the indoor vibration and noise spectrum in buildings near urban rapid transit lines to establish a baseline as well as the effectiveness of corresponding mitigation measures, namely wheel-rail polishing and train speed reduction. While our study suggests a maximum 6 dB reduction in indoor vibration, the effectiveness of noise and vibration reduction measures depends on the attenuation of the main frequency corresponding to the secondary radiation noise of the indoor vibration excitation in the building. In our field test, the peaks of the frequency spectrum were found to be 40, 50, 63 and 80 Hz. The secondary radiation noise attenuation and vibration were invariant to the change in frequency spectrum. Mitigation measures such as polishing may cause vibration frequency to peak in non-main frequency spectrums. URT speed reduction will lead to vibration and noise attenuation energy being concentrated at around 50 Hz. Given the presently inconsistent and widely varying industrial and international standards, this study can provide important field measurement data supporting future development in standards, regulation and legislation with respect to URT development, especially in mature townships.

Minimization of Energy Consumption for Urban Rapid-Transit Traction

Minimization of Energy Consumption for Urban Rapid-Transit Traction

Production planning, monitoring and review: comparison between the practices in an urban rail transit megaproject with the Last Planner System

PurposeMegaprojects are typically very expensive public-centred projects that leave little space for any mismanagement or deficient planning, which could affect the project adversely. The Last Planner™ System (LPS) is a lean construction planning and control tool that functions to reduce waste and increase performance. Given the benefits, the application of the LPS in megaprojects is still scarce, especially in Malaysia. Hence, this study aims to compare the current production planning, monitoring and review practices in a megaproject with the LPS in order to explore the possibilities of adapting the LPS to the current practices.Design/methodology/approachThis longitudinal case-based study has first explored the current practices implemented in an infrastructure megaproject, which is an urban rapid transit (URT) project, which was then compared to the standard LPS practices. The case study has adopted several research methods such as observation, interview and document review.FindingsFindings from the study highlight that the current production planning, monitoring and review practices in the URT project mostly differs from the standard LPS practices with only slight similarities found in the major planning phases. The comparative study, which based on five reference points through master, phase, look-ahead, weekly work plan and measure, and learning has resulted in several key elements, representative of the different planning phases, such as collaborative programming, reverse planning, reliability, dependability and continuous learning.Practical implicationsThis study provides an alternative perspective to rail planners, as well as other types of project planners in considering the use of the LPS to enhance the quality of planning, monitoring and review in projects. The framework that highlights the core values and key elements for the related planning phases enables project teams with no lean background to partially adapt their current practices to the LPS with minimal disruption.Originality/valueThis study first contributes to the body of knowledge, where limited study was found comparing and contrasting current production planning practices against the LPS, particularly in rail-based megaproject. The results from the comparison are the key elements representing each of the planning phases that was rooted back to the core values (teamwork, involvement and collaboration, communication and transparency, and continuous improvement) necessary to enhance the current practices.

Robust optimal predictive control for real-time bus regulation strategy with passenger demand uncertainties in urban rapid transit

The bus is inevitably affected by various factors during the trip, which causes that the phenomenon of bus bunching often occurs. This paper proposed a nonlinear optimal control model with passenger demand and disturbance uncertainties for the real-time bus regulation in urban rapid transit. The aim of this model is to assure the stability of bus headway in the line, reduce passengers’ waiting time and improve bus service level. Considering the system uncertainties and the real-time control requirement of bus regulation, a robust optimal predictive control algorithm is put forward to generate the real-time optimal bus regulation strategy based on updated delay feedback of buses by a rolling horizon strategy. Simultaneously, by using continuous interval number to describe the uncertain parameters, the robust counterpart of the formulated robust optimization model is obtained using the duality theory, which is further converted to a mixed integer convex quadratic programming problem by a linearization method, which can be easily solved to obtain the robust solution with a good performance for any value of uncertain parameters. Finally, some numerical experiments are conducted to verify the validity of the presented optimization model in improving the stability of the bus headway.

The Food-Trade Associated Spreading of COVID-19 Outbreak from a Contaminated Super Wholesale Food Market in Beijing

Background: The re-emerging outbreak of COVID-19 in Beijing China in summer of 2020 was originated from a contaminated super food wholesale market. The transmission mechanism was analyzed. Methods: We hypothesized that the Xinfadi outbreak was associated with activities of food-trade. Therefore, all the confirmed cases were divided into groups of sellers, buyer, seller transmitted and buyer transmitted. Data for each case were georeferenced and aggregated to the 500m-spaced hexagon grids using geodata and base maps, road networks, urban points of interest from OpenStreetMap. The Xinfadi-related trade activity data were derived using Python crawling scripts. The spatial association of the outbreak was studied with Moran’s I statistic method and a Susceptible-Infected-Recovered (SIR) coupled Agent-Based Model (ABM). Findings: Of 335 cases reported, 177 (45·3%) were sellers who worked for the Market, 83 (23·7%) were buyers who visited the Market, and 74 were transmitted by either of the infected buyers or sellers. The Market was the outbreak center, which were spreading along the urban rapid transit lines. The areas with a high incidence were concentrated across neighborhoods in the southwest of Beijing's Fifth Ring Road and the west section of the Fourth Ring of southwestern Beijing, and the west portion of Fuxing Road. The highest number of seller transmission hubs were located in Market neighborhood, however the buyer transmission hubs extended to cover more than three different districts. Our SIR-ABM model analysis suggested that the trade-distancing strategy effectively reduced the R0. The retail shops closure strategy reduced nearly half number of visitors to market. The Buy-local policy option reduced more than 70% infection in total. Interpretation: The Xinfadi outbreak was associated contaminated super food market by people's movements for food-trade, including their interactions in related activities. Therefore, the retails closures and buy-local policy could reduce size of the outbreak and prevent possible outbreak in future.Funding Statement: Ministry of Science and Technology China (Grant number 2018ZX10712001-017 and 2018ZX10712001-018), Chinese Academy of Medical Sciences (2018RU010), Chinese Academy (2020-XZ-37) and the National Natural Science Foundation of China (71603253 and 72074209).Declaration of Interests: All authors declare no competing interests.

Analysis of Metro Station Ridership Considering Spatial Heterogeneity

This study aims to explore the role of spatial heterogeneity in ridership analysis and examine the relationship between built environment, station attributes and urban rapid transit ridership at the station level. Although spatial heterogeneity has been widely acknowledged in spatial data analysis, it has been rarely considered in travel behavior studies. Four models (three global models-ordinary least squares (OLS), spatial lag model (SLM), spatial error model (SEM) and one local model-geographically weighted regression (GWR) model) are estimated separately to explore the relationship between various independent variables and station ridership, and identify the influence of spatial heterogeneity. Using the data of built environment and station characteristics, the results of diagnostic identify evidence the existence of spatial heterogeneity in station ridership for the metro network in Nanjing, China. Results of comparing the various goodness-of-fit indicators show that, the GWR model yields the best fit of the data, performance followed by the SEM, SLM and OLS model. The results also demonstrate that population, number of lines, number of feeder buses, number of exits, road density and proportion residential area have a significant impact on station ridership. Moreover, the study pays special attention to the spatial variation in the coefficients of the independent variables and their statistical significance. It underlines the importance of taking spatial heterogeneity into account in the station ridership analysis and the decision-making in urban planning.

Strategic network expansion of urban rapid transit systems: A bi‐objective programming model

AbstractWith the development of urbanization and the extension of city boundaries, the expansion of rapid transit systems based on the existing lines becomes an essential issue in urban transportation systems. In this study, the network expansion problem is formulated as a bi‐objective programming model to minimize the construction cost and maximize the total travel demand covered by the newly introduced transit lines. To solve the bi‐objective mixed‐integer linear program, an approach called minimum distance to the utopia point is applied. Thus, the specific trade‐off is suggested to the decision makers instead of a series of optimal solutions. A real‐world case study based on the metro network in Wuxi, China, is conducted, and the results demonstrate the effectiveness and efficiency of the proposed model and solution method. It is found that the utopia method can not only provide a reasonable connecting pattern of the network expansion problem but also identify the corridors with high priority under the limited budget condition.

Urban Services on Regional Rail: Local and Network-Based Methodologies for Evaluating New Stations in Toronto

The Greater Toronto and Hamilton Area’s regional GO Rail network is undergoing a substantive upgrade to provide a two-way, all-day, electrified, 15-min service. These investments have led to discussions about the nature of the service and calls to add new stations, particularly within the City of Toronto. This paper explores the methodology used to evaluate specific new station locations in the City of Toronto and beyond, along with a concurrent analysis of the impacts of a package of new stations on the network performance and hierarchy. Both assessments used a multi-faceted business case framework. Travel-time impacts, land use, costs, feasibility, and other factors influenced the recommendation of sites intended to optimize the substantial investment in network infrastructure, and address city-building objectives like encouraging development and providing access to underserved communities. Network analysis points to new stations within the city shifting the traditional three-tier network hierarchy comprised of regional rail, urban rapid transit, and local transit to a hybrid network in which regional rail serves some intermediate functions.

Estimating the influence of common disruptions on urban rail transit networks

With the continuous expansion of urban rapid transit networks, disruptive incidents—such as station closures, train delays, and mechanical problems—have become more common, causing such problems as threats to passenger safety, delays in service, and so on. More importantly, these disruptions often have ripple effects that spread to other stations and lines. In order to provide better management and plan for emergencies, it has become important to identify such disruptions and evaluate their influence on travel times and delays. This paper proposes a novel approach to achieve these goals. It employs the tap-in and tap-out data on the distribution of passengers from smart cards collected by automated fare collection (AFC) facilities as well as past disruptions within networks. Three characteristic types of abnormal passenger flow are divided and analyzed, comprising (1) “missed” passengers who have left the system, (2) passengers who took detours, and (3) passengers who were delayed but continued their journeys. In addition, the suggested computing method, serving to estimate total delay times, was used to manage these disruptions. Finally, a real-world case study based on the Beijing metro network with the real tap-in and tap-out passenger data is presented.

The Research of Event Detection and Characterization Technology of Ticket Gate in the Urban Rapid Rail Transit

Making events recognition more reliable under complex environment is one of the most important challenges for the intelligent recognition system to the ticket gate in the urban rapid rail transit. The motion objects passing through the ticket gate could be described as a series of moving sequences got by sensors that located in the walkway side of the ticket gate. This paper presents a robust method to detect some classes of events of ticket gate in the urban rapid rail transit. Diffused reflectance infrared sensors are used to collect signals. In this paper, the motion objects are here referred to passenger(s) or (and) luggage(s), for which are of frequent occurrences in the ticket gate of the urban railway traffic. Specifically, this paper makes two main contributions: 1) The proposed recognition method could be used to identify several events, including the event of one person passing through the ticket gate, the event of two consecutive passengers passing through the ticket gate without a big gap between them, and the event of a passenger walking through the ticket gate pulling a suitcase; 2) The moving time sequence matrix is transformed into a one-dimensional vector as the feature descriptor. Deep learning (DL), back propagation neural network (BP), and support vector machine (SVM) are applied to recognize the events respectively. BP has been proved to have a higher recognition rate compared to other methods. In order to implement the three algorithms, a data set is built which includes 150 samples of all kinds of events from the practical tests. Experiments show the effectiveness of the proposed methods.

日本の鉄道事業者に対する効率性分析

This paper measures the technical efficiency of joint public-private venture railways and private railways in Japan using the Stochastic Frontier Analysis. We compare the following four groups using student’s t-tests: Group 1 is composed of rural railways operated by joint public-private ventures, Group 2 is composed of rural railways operated by the private sector, Group 3 is composed of urban rapid transit railways operated by joint public-private ventures, and Group 4 is composed of urban rapid transit railways operated by the private sector. The results show that the null hypothesis of no difference between Group 1 and Group 2 in mean efficiency is not rejected, and the null hypothesis of no difference between Group 3 and Group 4 in mean efficiency is not rejected.JEL Classification: R32, L33, H42

철도차량용 금속계 소결마찰재의 조성에 따른 트라이볼로지 특성

Graduate School of Railroad, Seoul National University of Science and Technology(Received September 22, 2014; Revised November 10, 2014; Accepted November 17, 2014)Abstract − Sintered metallic brake pads and low alloy heat resistance steel disks are applied to mechanical brake sys-tems in high energy moving machines that are associated with recently developed 200km/h trains. This has ledto the speed-up of conventional urban rapid transit. In this study, we use a lab-scale dynamometer to investigatethe effects of the composition of friction materials on the tribological characteristics of sintered metallic brakepads and low alloy heat resistance steel under dry sliding conditions. We conduct test under a continuous pressureof 5.5 MPa at various speeds. To determine the optimal composition of friction materials for 200 km/h train, wetest and the evaluate frictional characteristics such as friction coefficients, friction stability, wear rate, and thetemperature of friction material, which depend on the relative composition of the Cu-Sn and Fe components. Theresults clearly demonstrate that the average friction coefficient is lower for all speed conditions, when a largequantity of iron power is added. The specimen of 25 wt% iron powder that was added decreased the wear ofthe friction materials and the roughness of the disc surface. However when 35 wt% iron powder was added, thedisc roughness and the wear rate of friction materials increased By increasing the amount of iron powder, thesurface roughness, and temperature of the friction materials increased, so the average friction coefficientsdecreased. An oxidation layer of Fe

디스크 질량 변화에 따른 철도차량용 제동디스크의 마찰 특성

Low alloy heat resistant brake disk and sintered brake pad are applied to mechanical brake system for the speed-up of urban rapid transit. In this research, we analyzed how the frictional characteristics between brake disk and pad are influenced by the disk mass. At a high disk mass, the friction stability was the lower value as a result of the lack of tribofilm formation at the disk surface. Wear rates of friction materials showed the higher value at a low disk mass and wear rates of 10 mm and 15 mm showed the similar level. Average friction coefficient was the lower value at the 10 mm disk thickness and range of variation of average friction coefficient was also the smaller value at the 10 mm disk thickness. However, there were no significant changes in the friction coefficients under any of test conditions. Surface roughness of a disk showed the highest value at the 5 mm disk and surface roughnesses of 10 mm and 15 mm showed the similar level. As a result, friction characteristics of disk mass influenced the friction stability, as well as the wear rate of friction pad and disk, but not the friction coefficient.

Urban rapid rail transit and gentrification in Canadian urban centres: A survival analysis approach

Despite the existing knowledge that urban rapid rail transit has many effects on surrounding areas, and despite some attempts to understand the links between transit and gentrification, there remain methodological gaps in the research. This study addresses the relationship between the implementation of urban rapid rail transit and gentrification, which is conceived of as an event. As such, an event analysis approach using ‘survival analysis’ is adopted as the statistical analytical tool. It tests whether proximity to rail transit is related to the onset of gentrification in census tracts in Canada’s largest cities. It is found that proximity to rail transit, and to other gentrifying census tracts, have a statistically significant effect on gentrification in two of the three cities analysed. By providing a methodological framework for the empirical analysis of the impact of urban rail transit on gentrification, this paper is a reference for both researchers and transportation planners.

Long-Term Deformation Monitoring of Metro-Tunnel Airshaft Excavation during Construction Stage

The project of Hangzhou Metro Line 1 is the first metro line of the urban rapid rail transit system in Hangzhou, China, which is one of the largest municipal projects of Hangzhou and is being constructed commencing from March 28, 2007 and expected to be completed by October 1, 2012. This metro line has a total length of 48 km and 34 stations, connecting Hangzhou downtown with the suburban area of the city. Owing to the complex geological condition, harsh construction situation, and immature computational methodology, construction of metro systems is often subjected to considerable sources of uncertainties. To ensure the safety of the adjacent building structures, it is a vital necessity to monitor deep excavations of metro tunnels at their in-construction stage. This paper introduces the instrumentation system for settlement monitoring of a metro-tunnel airshaft of the project of Hangzhou Metro Line 1 during the construction of deep excavation. The long-term settlement data monitored by the measurement markers installed at the surface ground and in the depth direction of the airshaft excavation construction site are analyzed and presented in detail. The obtained results indicate that the settlements at the instrumented locations of the construction site during different construction steps vary steadily in an allowable variation range.

The Trade-Offs of Transferring Demand Risk on Urban Transit Public–Private Partnerships

There is a long history of ridership on urban rapid transit projects failing to meet predevelopment forecasts. This article examines the trade-offs for government associated with transferring the financial risk of ridership demand shortfalls to the private sector through public–private partnerships (PPPs). First, the article develops a theory of the way that PPPs are designed to clamp down on the causes of transit ridership shortfalls. Second, it outlines technical, planning, and financial trade-offs associated with transferring ridership demand risk to the private sector. Third, examples are presented to show how these trade-offs manifest in the most popular models of allocating ridership demand risk in PPPs. The article concludes that transit projects have particular characteristics that challenge the effective transferring of ridership demand risk to the private sector. Governments should instead focus on project procurement models that encourage risk sharing between the partners.