Taipei Mass Rapid Transit System Research Articles

Self-Tuning Inference Model for Settlement in Shield Tunneling: A Case Study of the Taipei Mass Rapid Transit System’s Songshan Line

Constructing tunnels in urban spaces usually uses shield tunneling. Because of numerous uncertainties related to underground construction, appropriate monitoring systems are required to prevent disasters from happening. This study collected the settlement monitoring data for Tender CG291 of the Songshan Line of the Taipei Mass Rapid Transit (MRT) system and considered that influential factors were examined to identify the correlations between predictor variables and settlement outcomes. An inference model based on symbiotic organisms search-least squares support vector machine (SOS-LSSVM) was proposed and trained on the collected data. Moreover, because the dataset used for this study contained far less data at the alert level than at the safe level, the class of the dataset was imbalanced, which could compromise the classification accuracy. This study also employed the probability distribution data balance sampling methods to enhance the forecast accuracy. The results showed that the SOS-LSSVM exhibited the most favorable accuracy compared to four other artificial intelligence-based inference models. Therefore, the proposed model can serve as an early warning reference in tunnel design and construction work.

Digital twins for managing railway maintenance and resilience.

Background: To improve railway construction and maintenance, a novel digital twin that helps stakeholders visualize, share data, and monitor the progress and the condition during services is required. Building Information Modelling (BIM) is a digitalization tool, which adopts an interoperable concept that benefits the whole life-cycle assessment (LCA) of the project. BIM's applications create higher performance on cost efficiency and optimal time schedule, helping to reduce any unexpected consumption and waste over the life cycle of the infrastructure. Methods: The digital twin will be developed using BIM embedded by the lifecycle analysis method. A case study based on Taipei Metro (TM) has been conducted to enhance the performance in operation and maintenance. Life cycles of TM will be assessed and complied with ISO14064. Operation and maintenance activities will be determined from official records provided by TM. Material flows, stocks, and potential risks in the LCA are analyzed using BIM quantification embedded by risk data layer obtained from TM. Greenhouse emission, cost consumption and expenditure will be considered for integration into the BIM. Results: BIM demonstrated strong potential to enable a digital twin for managing railway maintenance and resilience. Based on the case study, a key challenge for BIM in Taiwan is the lack of insights, essential data, and construction standards, and thus the practical adoption of BIM for railway maintenance and resilience management is still in the design phase. Conclusions: This study exhibits a practical paradigm of the digital twin for railway maintenance and resilience improvement. It will assist all stakeholders to engage in the design, construction, and maintenance enhancing the reduction in life cycle cost, energy consumption and carbon footprint. New insight based on the Taipei Mass Rapid Transit system is highly valuable for railway industry globally by increasing the lifecycle sustainability and improving resilience of railway systems.

Digital twins for managing railway maintenance and resilience

Background: To improve railway construction and maintenance, a novel digital twin that helps stakeholders visualize, share data, and monitor the progress and the condition during services is required. Building Information Modelling (BIM) is a digitalization tool, which adopts an interoperable concept that benefits the whole life-cycle assessment (LCA) of the project. BIM’s applications create higher performance on cost efficiency and optimal time schedule, helping to reduce any unexpected consumption and waste over the life cycle of the infrastructure. Methods: The digital twin will be developed using BIM embedded by the lifecycle analysis method. A case study based on Taipei Metro (TM) has been conducted to enhance the performance in operation and maintenance. Life cycles of TM will be assessed and complied with ISO14064. Operation and maintenance activities will be determined from official records provided by TM. Material flows, stocks, and potential risks in the LCA are analyzed using BIM quantification embedded by risk data layer obtained from TM. Greenhouse emission, cost consumption and expenditure will be considered for integration into the BIM. Results: BIM demonstrated strong potential to enable a digital twin for managing railway maintenance and resilience. Based on the case study, a key challenge for BIM in Taiwan is the lack of insights, essential data, and construction standards, and thus the practical adoption of BIM for railway maintenance and resilience management is still in the design phase. Conclusions: This study exhibits a practical paradigm of the digital twin for railway maintenance and resilience improvement. It will assist all stakeholders to engage in the design, construction, and maintenance enhancing the reduction in life cycle cost, energy consumption and carbon footprint. New insight based on the Taipei Mass Rapid Transit system is highly valuable for railway industry globally by increasing the lifecycle sustainability and improving resilience of railway systems.

Change in risk of hospital admissions for ischemic heart disease after the implementation of a mass rapid transit system in Taipei

ABSTRACT Numerous epidemiologic studies demonstrated an association between an increase in levels of fine particles (particulate matter less than 2.5 um in diameter, PM2.5) and elevation in the number of hospital admissions for cardiovascular diseases. Air pollution levels including PM2.5 clearly decreased in Taipei City after the mass rapid transit (MRT) system began operations in 1996. The aim of this study was to investigate the extent of changes in the risk of daily hospital admissions for ischemic heart disease (IHD) over a 17-year period after the installation of a MRT system in Taipei. The full study was divided into Period 1 (1997–2000), total track length 65.1 km; Period 2 (2001–2008), total track length 75.8 km; and Period 3 (2009–2013), total track length 121.3 km. A time-stratified case-crossover analysis was conducted to estimate relative risk (RR) of hospital admissions for IHD for each 10 ug/m3 increase in PM2.5 for different periods. On cool days, the associated RR of IHD for Period 3 was consistently lower compared to period 2 in both our single- and two-pollutant models. However, the daily risk for IHD admissions was found to be significantly higher for period 3 compared to period 2 in our single-pollutant model and in our two-pollutant models (PM2.5+ SO2) on warm days. The basis for this difference is unknown. Data suggests that an MRT system may provide substantial health benefits, a finding that may be helpful to urban communities, urban planners, and public health specialists.

Three-dimensional numerical study of long-term settlement induced in shield tunneling

The objective of this study is to examine the mechanism of the long-term settlement induced in shield tunneling. A series of finite element analysis were conducted using PLAXIS 3D on a well document shield tunneling case in Taipei Mass Rapid Transit System. Various simulation were executed assessing the impact of consolidation on long-term settlement using Soft Soil and Hardening Soil with Small-strain models. Simulation to assess the impact of the creep behavior of the soil on the long-term settlement was also executed using the Soft Soil Creep model. The computed surface settlements were compared to the field measurements. It was found from this study that the computed settlement matched the field measurement when creep behavior of the soft soil was considered but if creep was not accounted for, the computed settlement undervalued the field measurements. Finally, a series of parametric study was executed to examine the influence of various parameters on the long-term settlement. The results obtained from the parametric study of shield tunneling in thick clay clearly distinguished that mechanism of long-term settlement in shield tunneling is predominantly due to creep behavior of the soft soil since consolidation constitutes 5% of the total settlement while creep accounts for 80% of the total settlement.

Dominant Factors Influencing the Concentrations of Particulate Matters inside Train Carriages Traveling in Different Environments in the Taipei Mass Rapid Transit System

ABSTRACT Air quality inside metro systems is a critical issue for commuters and metro employees because of the considerable time they spend traveling or working in such systems. This study measured the PM10, PM2.5, particle number (PN), and CO2 levels and particle mass size distributions inside operating trains to reveal the factors influencing the concentrations and size distributions of particulate matter (PM) inside metro train carriages traveling in different environments. The measurement results demonstrated that the CO2 level was associated with ridership and that the PM levels and particle mass size distributions were highly affected by the immediate surroundings of the train, such as whether it was journeying through underground tunnels or on ground-level tracks as well as its direction of travel. Furthermore, the particle mass size distributions inside the metro train carriages exhibited a clear triple-mode pattern, whereas those for the ground-level and underground routes differed considerably due to different particle sources.

A constraint programming-based approach to the crew scheduling problem of the Taipei mass rapid transit system

This paper addresses the crew scheduling problem for a mass rapid transit (MRT) system. The problem is to find a minimum number of duties to cover all tasks while satisfying all the hard and soft scheduling rules. Such rules are complicated in real-world operations and difficult to follow through optimization methods alone. In this paper, we propose a constraint programming (CP)-based approach to solve the problem. The approach involves a CP model for duty generation, a set covering problem model for duty optimization, and alternative ways to identify the final solution in different situations. We applied the proposed CP-based approach to solve a case problem for the Taipei MRT. Case application results using real-world data showed that our approach is capable of reducing the number of daily duties from 58 to 55 and achieving a 5.2 % savings in labor costs. We also incorporated the soft rule considerations into the CP model in order to generate alternative optimum solutions that would improve the workload balance. The coefficient of variation of the work time distribution improves significantly, falling from 21 % to approximately 5 %. Given the CP model’s comprehensive coverage of various scheduling rules, our proposed approach and models would also be applicable to other MRT systems.

Comparisons of particulate matter, CO, and CO2 levels in underground and ground-level stations in the Taipei mass rapid transit system

As of 2010, the Taipei mass rapid transit (MRT) comprised 8 rapid transit lines stretching 90.5 km and linking 82 stations. Currently, over 1.4 million commuters a day travel on the Taipei MRT system. However, information related to the characteristics of indoor air quality at ground-level and in underground stations in the Taipei MRT system is limited. This study used portable monitors to measure the PM 10 , PM 2.5 , particle number (PN), CO, and CO 2 levels at an underground (UG) and two ground-level (AG1 and AG2) MRT stations on the same rapid transit line. All measurements were taken between August 20 and November 12, 2010. The mean PM 10 and PM 2.5 levels in underground environments (underground ticket hall and platform of the UG and underground platform of the AG1) are approximately 51–65 μg m −3 and 25–40 μg m −3 , respectively. Additionally, the mean PM 10 and PM 2.5 levels in ground-level indoor environments (ground-level ticket halls of the AG1 and AG2) are approximately 44–48 μg m −3 and 26–29 μg m −3 , respectively. Measurement results reveal that PM levels in underground environments are greater than those in ground-level indoor environments. PM levels in ground-level indoor environments are strongly associated with outdoor ambient PM levels, while PM levels in underground environments are less influenced by outdoor ambient conditions. The presence of coarse PM in the underground environments may have been generated internally through the mechanical friction processes or re-suspended by the movement of commuters, and fine PM is likely transferred from its source outside the station. The mean PM 2.5 -to-PM 10 ratios in underground environments are 0.45–0.79, and at ground-level indoor environments are approximately 0.58. Based on differences in the environment conditions among these selected locations, it is reasonable to assume that PM 2.5 -to-PM 10 ratios in underground and ground-level MRT stations will not be consistent, even those on the same metro line. Furthermore, low PN and CO levels are observed in underground environments. Mean PN and CO levels in underground environments are 9.5 × 10 3 –1.7 × 10 4 particles cm −3 and 0.30–0.48 ppm, respectively, and significantly lower than those in outdoor environments by approximately 0.3–0.6 times. However, the CO 2 levels in underground environments are 574–1051 ppm and significantly higher than those in outdoor environments, by approximately 1.3–2.4 times. The CO 2 in underground environments is likely elevated by the exhalation of commuters. ► Coarse PM in the underground environments may have been generated internally. ► Fine PM is likely transferred from its source outside the station. ► Low PN and CO levels are observed in underground environments.

Measurement and Characterization of Harmonics on the Taipei MRT DC System

The harmonics of the propulsion power supply system on the Taipei Mass Rapid Transit System (TMRTS) are characterized. This study applies a new measurement method based on the railway magnetic field measurement technique, to record the dc current harmonics of the TMRT system under various operating conditions. Analysis of the data obtained through these field measurements reveals the presence of both typical and atypical harmonics while the trains are running. The monitored information from the TMRTS during dynamic operation helps engineers (planners) to identify how many orders and levels of harmonics may be present.

Influence of platform screen doors on energy consumption of the environment control system of a mass rapid transit system: case study of the Taipei MRT system

This investigation studies how platform screen doors (PSD) affect the energy consumption of the environmental control system of a mass rapid transit (MRT) system in Taipei. The environmental parameter simulation was conducted using the subway environmental simulation (SES) program, while the associated air conditioning (A/C) cooling load was predicted with the carrier E20-II program. Results show that PSD can significantly decrease average and peak cooling load, thus reducing the capacity/size of cooling equipment and allowing the chiller cooling load to be abridged. However, electricity consumption by ventilation equipment increases notably when PSD are used, particularly the electricity consumption by the under platform exhaust (UPE) fan, and thus, ultimately, little difference exists in the overall energy consumption with and without UPE.

Simulation of ventilation and fire in the underground facilities

A revised fire outbreak and evacuation simulation model, MFIRE, is presented in the paper. The model provides information for setting up an emergency ventilation scheme, establishing safety procedures and minimizing damage in underground network systems. MFIRE simulates the interdependence between the ventilation system and its pertinent fans and structures, and the changes in ambient conditions and the heat source. A laboratory based fire simulation was conducted in a small physical tunnel network to verify the MFIRE. The rates of air flow and temperature distribution in each tunnel are compared with the simulated results obtained by MFIRE. Regarding air flow, the experimental rates correlate with the simulated results very well. Because of the reduced physical scale of the laboratory model, the simulated temperature distributions do not quite correlate with the laboratory data. MFIRE is employed to simulate a hypothetical fire outbreak in the Taipei Mass Rapid Transit System. The simulation is designed to investigate the direction and rate of air flow, temperature distribution and emergency ventilation responses. The results have confirmed that the proposed “push–pull” ventilation model can exhaust the high temperature air and smoke out of the underground facilities efficiently once the fire breaks out.

Contractor Selection Process for Taipei Mass Rapid Transit System

It is normal practice for developing countries to use a large industrial or technological project as a means to transfer foreign expertise and experience into the country, and the government of Taiwan has pursued this path in building the Taipei mass rapid transit system (MRTS). To satisfy the foregoing objective, the Department of Rapid Transit System (DORTS) set the following criteria for tendering contracts. Civil works that did not require a high level of technology were channeled to domestic firms. More complex projects were assigned to private and government-owned companies that had accumulated a higher level of expertise because of joint ventures and their active involvement in international projects during the past three decades. The most technically challenging projects are given to international consortia in the form of either joint ventures or technical collaboration agreements with domestic companies. This paper discusses the goals of DORTS during the past several years as they relate to promoting (1) increased domestic input, (2) technology transfer, and (3) a higher level of achievement.