• Earthquakes and Structures
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• v.24 no.4
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• pp.303-316
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• 2023

Rapid post-earthquake damage estimation of subway stations is particularly necessary to improve short-term crisis management and safety measures of urban subway systems after a destructive earthquake. The conventional Performance-Based Earthquake Engineering (PBEE) framework with constant earthquake occurrence rate is invalid to estimate the aftershock risk because of the time-varying rate of aftershocks and the uncertainty of mainshock-damaged state before the occurrence of aftershocks. This study presents a time-varying probabilistic seismic risk assessment framework for underground structures considering mainshock and aftershock hazards. A discrete non-omogeneous Markov process is adopted to quantify the time-varying nature of aftershock hazard and the uncertainties of structural damage states following mainshock. The time-varying seismic risk of a typical rectangular frame subway station is assessed under mainshock-only (MS) hazard and mainshock-aftershock (MSAS) hazard. The results show that the probabilities of exceeding same limit states over the service life under MSAS hazard are larger than the values under MS hazard. For the same probability of exceedance, the higher response demands are found when aftershocks are considered. As the severity of damage state for the station structure increases, the difference of the probability of exceedance increases when aftershocks are considered. PSDR=1.0% is used as the collapse prevention performance criteria for the subway station is reasonable for both the MS hazard and MSAS hazard. However, if the effect of aftershock hazard is neglected, it can significantly underestimate the response demands and the uncertainties of potential damage states for the subway station over the service life.

• Journal of Environmental Health Sciences
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• v.20 no.1
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• pp.28-38
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• 1994

The objective of this study were to measure concentrations of indoor pollutants in public transportation systems to provide importance of indoor air quality in transportation systems to policy makers. Indoor air quality of the pollutants (CO, CO$_2$, PM-10) and environmental sources (temperature, humidity) were measured at subway, seat-type bus, and city-type bus in the Seoul area from April to September 1992. The same pollutants and environmental sources were also measured at selected bus stops and subway stations during October 1991-September 1992. The mean concentrations of indoor pollutants in the public transportation systems were showed 115.5 $\mu$g/m$^3$ in PM-10, 6.8 ppm in CO, and 2167.9 ppm in CO$_2$, respectively. The mean values of PM-10 and CO showed below the U.S. 24 hour standard value of PM-10 and the Korea ambient CO standard, while the mean concentrations of CO$_2$ exceeded the Korea CO$_2$ standard. The highest levels of indoor concentration at public transportation systems were PM-10 of 134.6 $\mu$g/m$^3$ in the subway, CO of 8.9 ppm in the city-type bus, CO$_2$ of 2,511.1ppm in seat-type bus, respectively. The results showed that indoor air quality in bus and subway seemed likely to be affected by number of passengers and outdoor air infiltrated from exhausted gases of automobiles.

• Journal of the Korean Professional Engineers Association
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• v.42 no.3
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• pp.41-46
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• 2009

A new subway, line 9 linking Western and Eastern Seoul began its services for citizens between Gimpo airport and Gangnam area within 30 minutes by express transit service. Seoul Metro Line 9 Corporation plans to operate both local transit service which will stop at every station, and express transit service that will stop at several key stations including junctions. The passengers on line 9 will be able to transfer to lines 2, 3, 5, 8, Bundang and Incheon International Airport. The Line 9 is expected to disperse the demand for line 2, having the most number of subway users, and will provide passengers with less crowded travel. The new line will also help residents in southern Seoul outskirts and Gyeonggi provincial cities including Bundang vicinity, and Gangdong area commuters get better access to Gimpo and incheon Airports. The Corporation expects to transfer 560,000 passengers daily by the subway line 9. Seoul Development Institute conducted network reshuffle study for Seoul Metro system to sort out congestion problem due to its irrational line alignments and inconvenient transfer. Among several candidate plans of network reshuffling, the direct connection of line 9 with line 5 was chosen as a pilot study. The study found that direct connection of the 2 lines is essential for enhancing transit utility and reducing automobile commuters.

• Fire Science and Engineering
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• v.22 no.5
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• pp.1-8
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• 2008

The study is to perform numerical analysis of train fire characteristics in an underground subway tunnel, depending the different locations of ventilation facility. To study the characteristics of train fire, two kinds of worst-case scenarios are selected, based on escape distance, escape time, and fire zone, and trends and thermal environments of tunnel are analyzed by changing the locations of ventilation facility for times. Fire characteristics is calculated by using FLUENT v.6.3.26, and turbulent flow is calculated by using the standard k-${\varepsilon}$ model. The numerical results show distribution of carbon monoxide concentration, temperature, and velocity. The results of this study will contribute to building the most suitable ventilation systems when designing subway stations and tunnels.

• Journal of Environmental Health Sciences
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• v.19 no.1
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• pp.37-43
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• 1993

The airborne concentrations of Sulfur Dioxide and Total Suspended Particulates were investigated in 4 subway lines in Seoul at early summer, 1990 and early summer, 1991. The results of the study were as follows: 1. The airborne concentrations of SO$_2$ and TSP were 0.022 ppm, 445.7 $\mu$g/m$^3$ respectively. And percents of over annual air quality standard of WHO was that SO$_2$ and TSP were 41.7%, 100% respectively. 2. Airborne SO$_2$ concentrations by subway lines were that line 1 was 0.025 ppm, line 2 was 0.023 ppm, line 3 was 0.020 ppm, and line 4 was 0.017 ppm. And TSP concentrations by subway lines were that line 2 was 533.8 $\mu$g/m$^3$, line 1 was 516.5 $\mu$g/m$^3$, line 4 was 371.6 $\mu$g/m$^3$, and line 3 was 369.3 $\mu$g/m$^3$ 3. Annual variation of concentration of TSP was not significant statistically (t=0.327), and that of SO$_2$, in 1990 was slightly higher than that in 1991 (t=1.433, p<0.1). 4. Coefficients of correlation between TSP and SO$_2$ by years were that early summer, 1990 was r=0.277 (p>0.1), and early summer, 1991 was r=0.32 (p>0.1).

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1567-1574
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• 2006

To prevent safety accidents such as injury or death from falling by blocking platforms from trains, the Seoul Metropolitan Subway Corp. have gradually installed screen doors in platforms of 115 subway stations in Seoul on lines 1, 2, 3, and 4. Installation in nine areas among those has been completed and screen doors are being operated as a model operation. Traffic signs should be clear for users. The essential functions of signs should be fully investigated from the aspect of user as well as the visual beauty and recognition. Signs should be able to provide users with information regarding location, position, directions, etc. Particularly, safety and convenient signs should be visually and sensually correlated. However, the entire screen doors in platforms installed in line 2 subway in Seoul are used for commercial advertisement, consequently, the functions and roles as public signs are not fulfilled aggravating inconvenience for users. In this study, cases have been studied to investigate requirements for user-oriented sign system in platform and public sign space to fulfill the functions of sign system in platform. Using an anthropometry approach, the study aimed to obtain the space to install the sign system and to systemize necessary and sufficient conditions for user-oriented system for platform in which screen doors have been installed using. The study suggests fundamental information to obtain the space of public sign system on the entire screen door.

• Journal of the Korean Society for Railway
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• v.10 no.3 s.40
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• pp.290-295
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• 2007

The Seoul Metropolitan Subway Corp. have gradually installed screen doors in platforms of 115 subway stations in Seoul on lines 1, 2, 3, and 4. Installation in nine areas among those has been completed and screen doors are being operated as a model operation. Traffic signs should be clear for users. The essential functions of signs should be fully investigated from the aspect of user as well as the visual beauty and recognition. Signs should be able to provide users with information regarding location, position, directions, etc. Particularly, safety and convenient signs should be visually and sensually correlated. However, the entire screen doors in platforms installed in line 2 subway in Seoul are used for commercial advertisement, consequently, the functions and roles as public signs are not fulfilled aggravating inconvenience for users. In this study, cases have been studied to investigate requirements for user-oriented sign system in platform and public sign space to fulfill the functions of sign system in platform. Using an anthropometry approach, the study aimed to obtain the space to install the sign system and to systemize necessary and sufficient conditions for user-oriented system for platform in which screen doors have been installed using. The study suggests fundamental information to obtain the space of public sign system on the entire screen door.

• The Journal of the Acoustical Society of Korea
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• v.40 no.6
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• pp.615-625
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• 2021

Prior to proposing appropriate standard for subway station platform, this study conducted field measurements to examine characteristics of room acoustics on platform of two subway stations. As a result of analyzing the longitudinal length of the platform, Sound Pressure Level (SPL) decreased (maximum difference : 14 dB), Reverberation Time (RT) tended to increase (maximum difference of 0.8 s ~ 1.5 s), and C50 and D50 were decreased (maximum difference: 5.9 dB ~ 9.1 dB and 31.8 % ~ 37.6 %, respectively) as measurement positions moved away from the sound source. The Interaural Cross-correlation Coefficient (IACC) did not show clear tendency, but it was lower than 0.3 in entire points. It is judged that the subway platform has non-uniform sound field characteristics due to various combinations of direct and reflective sound even though it is finished with a strong reflective material.This indicates that the room acoustic characteristics of the near and far sound field are clearly expressed depending on the source-receiver distances in the subway platform having a long flat shape with a low height compared to the length.Therefore, detailed architectural and electric acoustic design based on the characteristics of each location of speaker and sound receiver in the platform is required for an acoustic design with clear sound information at all positions of the platform.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.5
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• pp.100-111
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• 2019

The existing selected station analysis (SSA) method analyzes the link transfer mode data between origin and destination of individuals passing through stations from a microscopic standpoint. As such, existing SSA is insufficient as it uses integrated analysis using macroscopic data such as subway lines. This research builds a line chain OD based on path search of individual passenger's movement through the subway, and explores means to utilize the findings. First, a method is proposed that searches the traversed subway path from the linked passage modes that the passenger uses and applies the results to SSA line analysis. Compared to the existing SSA, this method provides for analysis of commonly conflicting features such as the line on which the station is passed, and the stations included on the line thanks to the presence of complete information of the individual passenger's traversed path. It also allows for integrated observation of the line chain OD that approaches a certain station. For enhanced understanding, Seoul Metro Line 9 is used as a case study to demonstrate the integrated formulation concept of line chain OD centered around a certain station as well as the macroscopic features of the traversed path that approaches stations included on the line.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.6D
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• pp.541-552
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• 2010

The light rail transit (LRT) having bus lines as subsystem is being constructed or planned in the suburban area of metropolitans and medium size cities. However, there is difficulty in establishing the service coverage (SC) of the LRT because the LRT is a completely new transit mode in Korea. The purpose of this study is to provide the basic data and techniques to be used for establishing the SC of the future LRT by understanding the SC characteristics of buses and subways and building models to estimate the walking distances of their users. Busan City is selected as the study city and the SC's of buses and subways are surveyed simultaneously. A total of 9 variables for 82 stations are collected and the cluster analysis is conducted about the variables. The station areas are divided to three types of CBD (Central Business District), sub-CBD and regional center based on the analysis. A station in each area is selected as the study station. At the walking distance (WD) analysis for each mode, the 80 percentile WD of the subway is 672 m and that of the bus is 472 m. In comparing the SC's of both modes by the type of station areas, there are not significant differences between the SC's of sub-CBD and regional center except CBD. At analysis of the relationship between the personal attributes and the WD, for subway users the WD of female is longer than that of male and apartment residents use subway more positively than single house residents do. For the models to estimate the walking distances, the simple regression models were built employing the income as independent variable by dividing the stations into CBD abd non-CBD stations.