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sustainability

Article
Typological Differences in Railway Station Areas According to
Locational Characteristics: A Nationwide Study of Korea
Minho Seo * and Dongyoub Lee

                                           Urban Research Division, Korea Research Institute for Human Settlements, Sejong 30147, Korea; dy20@krihs.re.kr
                                           * Correspondence: mhseo@krihs.re.kr; Tel.: +82-44-960-0379

                                           Abstract: This study aims to explore whether railway station areas can be categorized according to
                                           locational characteristics on a nationwide level and whether the typological classification is valid
                                           for planning and development. Thirty-four railway station areas across Korea are analyzed and
                                           categorized using K-means clustering analysis. The results of the analysis prove that for all locational
                                           characteristics of land use, transit accessibility, and spatial form, station areas could be categorized
                                           into urban cores and suburbs. Moreover, the typological classification according to the location of
                                           urban cores and suburbs is valid in terms of development conditions and demand. This result implies
                                           that the role of the public and private sectors must be different in setting the space and size of areas
                                           of influence, and in forming and developing their use depending on the locational characteristics of
                                           station areas. This study contributes to the discussion on diversifying the planning and development
                                           of station areas as the heart of sustainable cities by verifying the types of station areas and their
                                           differences according to locational characteristics in East Asia, including Korea.

                                           Keywords: station area; land use mix; network analysis; K-means cluster; typology; TOD; Korea
         
         

Citation: Seo, M.; Lee, D. Typological
Differences in Railway Station Areas       1. Introduction
According to Locational                         With the growing interest in sustainability over the last few decades, constant efforts
Characteristics: A Nationwide Study
                                           have been made to reduce vehicle travel that leads to high carbon emissions, while increas-
of Korea. Sustainability 2021, 13, 4310.
                                           ing the use of environmentally friendly public transportation such as railways. In particular,
https://doi.org/10.3390/su13084310
                                           excluding Japan, which already has a dense railway network, many Asian countries such
                                           as China and Korea are making investments in transportation infrastructure that are as
Academic Editor: Giuseppe Inturri
                                           bold as their rapid economic growth, by quickly expanding their railroads. This change
                                           in spatial structure is expected to have a great impact on urban planning as well. Efforts
Received: 19 March 2021
Accepted: 7 April 2021
                                           to achieve transit-oriented development (TOD) with a focus on railway stations, such as
Published: 13 April 2021
                                           in the US and European countries [1,2], have been recently accepted as a fundamental
                                           premise for urban planning and development in not only Japan and Hong Kong [3], but
Publisher’s Note: MDPI stays neutral
                                           also in China and Korea [4,5].
with regard to jurisdictional claims in
                                                However, compared to countries that have been using TOD as a means of urban
published maps and institutional affil-    planning for a long time, such as the US and Japan, Korea is yet to diversify the use of
iations.                                   TOD in urban planning based on locational characteristics such as land use or the urban
                                           spatial structure of railway stations. The US has developed various types of TOD sites,
                                           such as centers, neighborhoods, and corridors, depending on the urban context in which
                                           the railway stations are located, actively considering these locations in urban planning [6].
Copyright: © 2021 by the authors.
                                           Japan is also using differentiated station area maintenance techniques that consider the
Licensee MDPI, Basel, Switzerland.
                                           relationship between railway stations and the surrounding urban spaces, density, and
This article is an open access article
                                           functions [7]. This implies that various types of TOD plans and project methods are needed
distributed under the terms and            to reflect the functions of the urban spatial structure or surrounding conditions so that
conditions of the Creative Commons         station area development can be pursued effectively.
Attribution (CC BY) license (https://           As argued by Sohn and Kim (2011) [8], Korea has been actively using the concept of
creativecommons.org/licenses/by/           TOD planning in station area development, but has been unable to establish a differentiated
4.0/).                                     plan and development model that can reflect the geographical status or land use of station

Sustainability 2021, 13, 4310. https://doi.org/10.3390/su13084310                                        https://www.mdpi.com/journal/sustainability
Typological Differences in Railway Station Areas According to Locational Characteristics: A Nationwide Study of Korea - MDPI
Sustainability 2021, 13, 4310                                                                                              2 of 16

                                areas or travel behavior characteristics. As a result, Korea is still seeking the development
                                of railway station areas in the form of building new towns in suburbs. Consequently, there
                                are many difficulties in the process of pursuing redevelopment or regeneration to utilize
                                railway station areas as the new growth centers of urban cores. This is a concern not only
                                in Korea, but also in many other Asian countries such as China [4]. Therefore, comparative
                                research is needed in Asian countries such as Korea on how railway station areas can be
                                categorized according to the urban context, and how approaches to urban planning and
                                development projects must vary according to the type of railway station area.
                                      This study investigates how railway station areas can be categorized in terms of land
                                use, transit accessibility, and spatial form, in the context of the spatial structure and location
                                of cities in Korea. In addition, it examines how development projects for the categorized
                                railway station areas must be approached differently based on the present and future
                                project conditions, such as development density or ridership. In Korea, major railway
                                stations that are connected nationally are divided into old railway stations that have served
                                as urban centers for decades, and new stations located in the suburbs that have mostly
                                been added after the 2000s with the implementation of high-speed railways. Therefore,
                                it is worth investigating whether the geographical location characteristics divided into
                                urban cores and suburbs can be typologically classified in association with land use, areas
                                of influence, and form of railway stations. In other words, this study suggests that railway
                                stations located in urban cores and suburbs vary in terms of general conditions related to
                                the urban context or station area development. Thus, the approach to urban planning or
                                development of station areas must also be differentiated.
                                      Accordingly, this study fulfills two major objectives. First, this study verifies whether
                                types of railway station areas hold valid in the urban context in countries where railroad
                                networks are rapidly expanding, such as Korea and China, in comparison to countries
                                like the US and Japan that categorize TOD through cumulative station area development
                                experience and use it in urban planning and development. Second, this study considers
                                the different approaches suggested for the categorization of railway station areas in such
                                developmental projects. Categorization considering the urban context can be used as a
                                policy decision-making tool by policymakers or urban planners to promote more effective
                                railway station area planning and development. Moreover, information on urban spaces
                                and functional differences in railway station areas can contribute to further theoretical and
                                academic endeavors.
                                      The remainder of this paper proceeds as follows and Figure 1 shows a flow of this
                                study. The next section reviews the key factors of consideration in the urban context for
                                the categorization of station areas and implications for urban planning and development
                                based on theoretical and empirical literature. The third section provides information on
                                the station areas included in the study, data, and analysis methodology for categorization.
                                The results of the analysis are provided in the fourth section, which discusses the typo-
                                logical characteristics of station areas and the differences in approaches to planning and
                                development. The suggestions based on the results and policy implications of this study
                                are presented in the final section.
Typological Differences in Railway Station Areas According to Locational Characteristics: A Nationwide Study of Korea - MDPI
Sustainability 2021, 13, 4310                                                                                                          3 of 16
Sustainability 2021, 13, x FOR PEER REVIEW                                                                                             3 of 16

                                                     Figure 1.
                                                     Figure 1. Study
                                                               Study flow
                                                                     flow diagram.
                                                                          diagram.

                                     Literature Review
                                  2. Literature  Review
                                  2.1. Station Area Scope Setting
                                  2.1. Station Area Scope Setting and
                                                                  and Location
                                                                      Location Functional
                                                                               Functional Characteristics
                                                                                          Characteristics
                                        In general,
                                        In general, station
                                                     station areas
                                                              areas are
                                                                    are geographical
                                                                         geographical areas
                                                                                        areas under
                                                                                              under the
                                                                                                      the influence
                                                                                                          influence of
                                                                                                                     of railway
                                                                                                                        railway station
                                                                                                                                 station
                                  areas  where  users   of that railway  station mostly  reside  or carry  out various  activities
                                  areas where users of that railway station mostly reside or carry out various activities          [9,10].
                                  The  process  of  analyzing    and  interpreting  the characteristics  of  station areas  begins
                                  [9,10]. The process of analyzing and interpreting the characteristics of station areas begins     with
                                  defining
                                  with       the physical
                                         defining            boundaries
                                                   the physical           of station
                                                                  boundaries          areas,areas,
                                                                                of station   as theasspatial structure
                                                                                                      the spatial       and functional
                                                                                                                   structure  and func-
                                  characteristics   of station  areas may   vary depending     on the  geographical
                                  tional characteristics of station areas may vary depending on the geographical      range.  Therefore,
                                                                                                                                  range.
                                  researchersresearchers
                                  Therefore,    generally define     station
                                                              generally       areas
                                                                         define     based
                                                                                 station    on the
                                                                                         areas      Euclidean
                                                                                                based            distance ordistance
                                                                                                        on the Euclidean      about 10–or
                                  15 min of walking time [11,12] and differentiate the physical boundaries of station areas
                                  about 10–15 min of walking time [11,12] and differentiate the physical boundaries of sta-
                                  based on the measure of the impact of public transportation and walking accessibility [13,
                                  tion areas based on the measure of the impact of public transportation and walking acces-
                                  14]. However, according to many studies (Table 1), the scope of station areas is difficult to
                                  sibility [13,14]. However, according to many studies (Table 1), the scope of station areas is
                                  define specifically through measures such as the Euclidean distance or walking accessibility.
                                  difficult to define specifically through measures such as the Euclidean distance or walking
                                  In order to determine the scope of station areas, it is important to consider their functional
                                  accessibility. In order to determine the scope of station areas, it is important to consider
                                  or locational context as well [15,16], and it is necessary to verify whether the characteristics
                                  their functional or locational context as well [15,16], and it is necessary to verify whether
                                  of the areas of influence vary significantly depending on physical boundaries.
                                  the characteristics of the areas of influence vary significantly depending on physical
                            Table boundaries.
                                  1. Studies on station area scope setting methods and spatial boundaries.

  Areas (Radius)                  TableResearches
                                        1. Studies on station area scope setting methods Contents
                                                                                         and spatial boundaries
                                                                                                  (Method)
                                                                                      Surveying light-rail users at transfer stations
     lessAreas
          than (radius) O’Sullivan and Morrall   Researches
                                                        (1996) [17];                               Contents (Method)
                                                                            (the points where the selection of walking as a mode sharply
       500 m                       Kim et al. (2001) [18]
                                                                                       Surveying light-rail  users at transfer stations
                                                                                                        decreased)
            less than              O’Sullivan and Morrall (1996) [17];
                                   Calthorpe   (1993)                                  (the points where the selection of walking as
              500 m                         Kim   et al.[19];
                                                          (2001) [18]                           Average   walkingdecreased)
                                                                                                                   distance
       500 m                   Ryan and Frank (2009) [12];                                      a mode sharply
                                                                                   (normatively stipulating walkable distance from a
      –1 km           Bertolini (1999) [20];Calthorpe
                                             Lee and Song     (2004)
                                                          (1993) [19];[21];                     Average    walking  distance
                                                                                    station/distance   reached  by 90%   walking trips)
              500 m                ChoiRyan
                                         et al.and
                                                (2008)  [22](2009) [12];
                                                     Frank                              (normatively stipulating walkable distance
     more than
              –1 km          Givoni  and
                             Bertolini    Rietveld
                                        (1999)  [20]; (2007)
                                                       Lee and[23];
                                                                 Song (2004) [21];        from a station/distance reached by 90%
                                                                                     Calculating railway service areas for bicycles
                                Debrezion Choi
                                            et al. et
                                                   (2009)
                                                      al.   [24]; [22]
                                                          (2008)                                        walking
       1 km                                                                  (modeling the joint access   mode trips)
                                                                                                                 and railway station choice)
                                 Lee and Leem (2010) [25]
                                     Givoni and Rietveld (2007) [23];                 Calculating railway service areas for bicycles
           more than
                                        Debrezion et al. (2009) [24];                  (modeling the joint access mode and railway
              1 km
                                         The
                                         Lee locational
                                              and Leem (2010)and functional
                                                                    [25]       contexts of station areas     have
                                                                                                       station     been generally analyzed
                                                                                                               choice)
                                  by categorizing the level of land use distribution or land use mix (LUM). Categorizations
                                  are decided    most generally
                                       The locational              by the difference
                                                         and functional     contexts ofinstation
                                                                                           locational
                                                                                                  areasconditions
                                                                                                         have beenbetween
                                                                                                                      generally urban   cores
                                                                                                                                   analyzed
                                  andcategorizing
                                  by   suburbs [19], thebut   this
                                                          level  ofdifference   can be subdivided
                                                                    land use distribution             evenmix
                                                                                             or land use      more  finelyCategorizations
                                                                                                                (LUM).      by the ratio of
                                  residence
                                  are decided ormost
                                                 density    of buildings
                                                       generally            when comparing
                                                                   by the difference            station
                                                                                       in locational      areas within
                                                                                                       conditions         a specific
                                                                                                                    between     urbancity  or
                                                                                                                                        cores
                                  limiting   the scope   to  urban   railway    stations [26,27].  LUM     is considered
                                  and suburbs [19], but this difference can be subdivided even more finely by the ratio of  first in  station
                                  area categorization
                                  residence   or densitybecause     land use
                                                            of buildings   whencorrelates with various
                                                                                   comparing              factorswithin
                                                                                                station areas      such as  accessibility
                                                                                                                          a specific        to
                                                                                                                                      city or
                                  commercial
                                  limiting       districts
                                            the scope       [28], walking
                                                        to urban   railwayactivity
                                                                             stations[29],  andLUM
                                                                                      [26,27].  surrounding      land value
                                                                                                      is considered    first in[30], thereby
                                                                                                                                station  area
                                  facilitating the because
                                  categorization    determination
                                                               land use of correlates
                                                                           locational with
                                                                                       characteristics.    Moreover,
                                                                                              various factors    such as many    studies on
                                                                                                                            accessibility   to
Sustainability 2021, 13, 4310                                                                                            4 of 16

                                station areas focus on discovering what kind of station area planning and development
                                will ultimately promote the use of public transportation and develop urban functions.
                                Therefore, analyzing the LUM of station areas allows for the investigation of the spatial
                                and functional characteristics of station areas to guide future planning and development,
                                and confirms the presence of other influencing factors such as ridership or travel behavior.

                                2.2. Travel Behavior Characteristics and Accessibility
                                      However, some studies have attempted to categorize station areas by focusing on
                                travel behavior characteristics. The travel purpose distribution and behavioral charac-
                                teristics of station users are effective in categorizing station areas [31], and the radius of
                                influence, which is the scope of station area planning and development, is determined
                                by the level of accessibility [14,15]. However, categorizing station areas in terms of travel
                                behavior patterns poses difficulties in verifying the implications of spatial structure, devel-
                                opment density, and functional distribution of urban spaces. Therefore, urban planning
                                studies on the use of station areas mostly adopt the method of setting the travelable radius
                                of influence and then employing a three-dimensional analysis of how LUM and spatial
                                structure affect ridership [32,33] and accessibility [34,35].
                                      As examined above, transit accessibility, such as land use characteristics or walking, is
                                an index used to comprehensively categorize station areas or determine their key charac-
                                teristics. However, existing researches using this index have several limitations, such as
                                their data being limited to specific cities, therefore these studies have failed to empirically
                                analyze the categorization patterns of station areas on a nationwide or metropolitan level.
                                Moreover, very few studies have specifically revealed whether types of station areas ac-
                                cording to physical influence or land use characteristics differ from those types that can be
                                used in planning and projects, or provided in-depth policy implications of the emerging
                                findings. Calthrope (1993) [11] and Cervero et al. (2002) [1] have provided information on
                                types of station area development on a nationwide level, but these types do not correspond
                                with categorizations based on land use and travel behavior characteristics. In particular,
                                most studies in Asian nations such as Korea have been limited to big cities like Seoul [5]
                                or been unable to attempt an overall categorization due to their analysis being limited
                                to individual evaluation indicators such as ridership [8,33], accessibility [29,36,37], and
                                land-use patterns [38,39]. Therefore, it is necessary to confirm whether the categorization
                                of station areas based on land use and transit accessibility is still valid on a nationwide
                                level. Furthermore, it is important to conduct additional research on whether the types of
                                station areas from the aforementioned method match the types of station areas according
                                to characteristics such as ridership and development density, which are directly linked to
                                planning or projects, and thus, can secure logical consistency.
                                      Adopting this perspective, this study categorizes major station areas in Korea at
                                a nationwide level by considering land use, transit accessibility, and spatial structure
                                characteristics. It further verifies whether the categorized types of station areas can be
                                equally categorized in terms of station area planning and development through analysis,
                                and what the direction of planning and development should be for the different categories
                                of station areas.

                                3. Data and Methods
                                3.1. Selecting Station Areas for Categorization
                                     This study addresses the question of whether railway station areas can be categorized
                                at a nationwide level. Studies on railway station areas in Korea have mostly focused on
                                urban railways, and comparative studies of railway station areas at a nationwide level
                                have been rare [15,21,39]. However, since the opening of the high-speed railways in Korea
                                in 2002, railway users have increased significantly, both on a nationwide and metropolitan
                                level. Consequently, there is an increasing interest in station area development around
                                major railway transfer points in big cities and provinces. Currently, there are 52 main
                                stations serving as transfer points and last terminals in Korea’s national railway network,
Sustainability 2021, 13, x FOR PEER REVIEW                                                                                    5 of 16

Sustainability 2021, 13, 4310                                                                                                 5 of 16
                                  level. Consequently, there is an increasing interest in station area development around
                                  major railway transfer points in big cities and provinces. Currently, there are 52 main sta-
                                  tions serving as transfer points and last terminals in Korea’s national railway network,
                                  including
                                  including high-speed
                                             high-speed rail.
                                                          rail. Of
                                                                Of these,
                                                                   these, 34
                                                                          34 stations
                                                                             stations currently
                                                                                      currently have
                                                                                                have plans
                                                                                                      plans for
                                                                                                            for the
                                                                                                                the station
                                                                                                                    station area
                                                                                                                            area or
                                                                                                                                 or
                                  development
                                  development projects. Accordingly, this study selected these 34 major railway stations as
                                                 projects. Accordingly,   this study  selected these 34 major  railway  stations as
                                  targets for analysis.
                                  targets for analysis.
                                       The railway station areas analyzed in this study are geographically distributed in
                                        The railway station areas analyzed in this study are geographically distributed in the
                                  the Korean national territory, as shown in Figure 2 and Table 2, comprising 17 urban core
                                  Korean national territory, as shown in Figure 2 and Table 2, comprising 17 urban core
                                  stations and 17 suburbs stations depending on location. Urban core stations are mostly
                                  stations and 17 suburbs stations depending on location. Urban core stations are mostly
                                  used in Seoul and big provincial cities such as Busan and Daejeon because of the formation
                                  used in Seoul and big provincial cities such as Busan and Daejeon because of the formation
                                  of urban cores around the existing railway stations and for user convenience. However,
                                  of urban cores around the existing railway stations and for user convenience. However,
                                  for other regions, large high-speed railway stations have been established in the suburbs
                                  for other regions, large high-speed railway stations have been established in the suburbs
                                  close to the city in the process of creating a high-speed rail network. As a result, stations
                                  close to the city in the process of creating a high-speed rail network. As a result, stations
                                  in the suburbs are distributed substantially in areas other than big cities, and station area
                                  in the suburbs are distributed substantially in areas other than big cities, and station area
                                  development in these areas remains an important pending regional issue.
                                  development in these areas remains an important pending regional issue.

      Figure 2.
      Figure 2. Major
                Major railway
                       railwaystation
                               stationareas
                                       areasininKorea
                                                 Koreaand
                                                       andtheir location
                                                            their        types.
                                                                  location      Railways
                                                                           types.        andand
                                                                                   Railways  nodes werewere
                                                                                                nodes   obtained using
                                                                                                            obtained   the 2019
                                                                                                                     using  the
      data from railway GISDB(Geographic Information System Data Base) provided by The Korea Transport Institute, Korea
      2019 data from railway GISDB(Geographic Information System Data Base) provided by The Korea Transport Institute,
      Transport Database (KTDB). The administrative boundary is obtained using the 2019 data of administrative districts pro-
      Korea Transport Database (KTDB). The administrative boundary is obtained using the 2019 data of administrative districts
      vided by the Ministry of Land, Infrastructure, and Transport.
      provided by the Ministry of Land, Infrastructure, and Transport.
Sustainability 2021, 13, 4310                                                                                                   6 of 16

                                Table 2. Names of each railway station area and their location types (n = 34).

         Location Type                                                              Station Area
                                              2 (Busan); 4 (Cheonan); 8 (Daegu); 9 (Daejeon); 10 (DMC, Digital Media City);
          Urban center                   11 (Dongdaegu); 13 (Gangneung); 14 (Geoje); 16 (Gwangju); 18 (Gyeongju); 23 (Mokpo);
                                                   26 (Seoul); 28 (Suncheon); 30 (Suseo); 32 (Wangsimni); 34 (Yongsan)
                                                  1 (Andong); 3 (Changwon-Jungang); 5 (Cheonan-Asan); 6 (Chuncheon);
             Suburb                              7 (Daegok); 12 (Donong); 15 (Gimcheon); 17 (Gwangmyeong); 19 (Iksan);
                                                20 (Jecheon); 21 (Jije); 22 (Kwangwoon University); 24 (Osong); 25 (Pohang);
                                                           27 (Singyeongju); 29 (Susaek); 31 (Ulsan); 33 (Wonju)
                                            Note: Railway station areas are listed in alphabetical order.

                                     3.2. Variables Included under Locational Characteristics and their Measurement Methods
                                           As mentioned in Section 2, the key variables that categorize the locational charac-
                                     teristics of station areas are land use, transit accessibility, and spatial structure form. In
                                     this study, the land use of station areas was analyzed based on LUM using the entropy
                                     index. Moreover, transit accessibility was obtained by analyzing the accessible walking
                                     time through network analysis, and the spatial structure form was analyzed using the
                                     flattening ratio.
                                           First, land was defined as an index to measure the diversity of two or more uses [40],
                                     and the most general index that verifies the land use patterns in the city [41,42]. LUM
                                     was indexed through the entropy index as in Equation (1); the entropy index had a value
                                     from 0 to 1, with a value closer to 1 indicating favorable LUM [43,44]. As can be seen in
                                     Equation (1):
                                                                                  ∑ny=1 Pu ln( Pu )
                                                                       LUM = −                                                  (1)
                                                                                       ln(n)
                                     where Pu represents the area ratio for u, and n denotes the number of types of use for
                                     analysis.
                                          This study classified the types of use into residential, commercial, business, public,
                                     cultural, and others. The areas of buildings for each use were obtained using the 2019
                                     data from the Internet Architectural Administration Information System provided by the
                                     Ministry of Land, Infrastructure, and Transport.
                                          Second, transit accessibility was based on accessible areas grounded on walking time
                                     and analyzed using network analysis. The radius of influence in railway station areas is
                                     measured in various ways, such as radius based on the Euclidean distance, living zone,
                                     or influence area of land use. However, the standard for this scope is defined differently
                                     among researchers or is merely set in physical boundaries. Thus, recent studies have
                                     generally analyzed pedestrian service areas using network analysis [45,46].
                                          Network analysis is a geographic information system (GIS) spatial analysis technique
                                     that analyzes the accessibility of amenities and the areas in which they are used by analyz-
                                     ing the connectivity and paths of networks such as roads [47]. A network is composed of
                                     nodes and links, and the service area is calculated by establishing a triangular irregular
                                     network (TIN) based on the limit point (Dk ) and network in a certain travel time with
                                     a focus on the starting point (O0 ) designated on the network, and adding TIN, which
                                     is the network path from the designated point to the limit point [48]. This is shown in
                                     Equation (2):
                                                                                                n
                                                                                   RA a =      ∑     ∆ti                           (2)
                                                                                               i=1

                                     where RA a represents the possible range of walking accessibility for Station a, ∆T represents
                                     the overall TIN established based on the pedestrian network, and ∆ti represents the TIN
                                     included in the social network distance (SND).
Sustainability 2021, 13, 4310                                                                                                   7 of 16

                                     The path from the center of the designated station (O0 ) to the limit point (Dk ) satisfying
                                a certain transit time is defined as O0 Dk , as shown in Equation (3):

                                                                                               j
                                                              O0 Dk = l1 , l2 · · · l j |    ∑     f ( li ) = M                    (3)
                                                                                             i=1

                                where l1 , l2 · · · l j represents the set of links that constitute the path O0 Dk , and f (li ) repre-
                                sents the transit time calibration function.
                                      The path O0 Dk is the sum of link sections (l1 , l2 · · · l j ), each of which comprises links
                                in which the sum of the transit time derived from the transit time calibration function ( f (li )
                                is M, thereby satisfying SND. In this study, the average walking speed of adults was set
                                to 4 km/h, and the standard walking time was measured at 5 min, 10 min, and 15 min to
                                calculate the walkable zone. The pedestrian network was obtained from the 2019 national
                                road network data based on the road name address system provided by the Ministry of
                                Land, Infrastructure, and Transport to reflect both vehicle roads and pedestrian roads.
                                ArcGIS 10.8 was used for network analysis.
                                      Third, the spatial structure of the station areas was analyzed using the flattening ratio.
                                The flattening ratio represents the flatness of an ellipse, calculated by subtracting the semi-
                                minor axis (the shortest distance from the center of the ellipse) from the semi-major axis (the
                                longest distance from the center of the ellipse) and dividing it by the semi-major axis. The
                                flattening ratio is an index used to verify the types of spatial forms under the assumption
                                that the actual station area of influence may not be determined in the form of simple circles
                                using the Euclidean distance. According to previous studies, the spatial form of station
                                areas is a major factor to be considered for future development potential [20], and many
                                actual station areas of influence are in oval or atypical polygonal shapes, suggesting the
                                need to distinguish squares and rectangles in setting the station areas [49]. Accordingly, this
                                study analyzed the flattening ratio to identify whether locational types can be distinguished
                                by the form of the station area’s spatial structure. The longest and shortest distances
                                derived from the service area of the network analysis were used as the semi-major axis and
                                semi-minor axis, respectively, of each station area.

                                3.3. K-Means Clustering Analysis for Categorization
                                     Clustering analysis is a technique used commonly in statistics and machine learning
                                for categorization as it uses similarity among independent variables without a dependent
                                variable. There are various methods of clustering analysis, such as hierarchical, K-means,
                                and DBSCAN (Density-Based Spatial Clustering of Applications with Noise); this study
                                used K-means clustering analysis to categorize station areas. K-means clustering can
                                determine the number of groups and is based on distance; thus, it can be used easily
                                without much consideration of the statistical values—such as the mean, variance, or
                                median—of the variables [50].
                                     K-means clustering analysis is an algorithm that groups the given data into k clusters,
                                minimizing the variance of each cluster and distance. Moreover, data within the cluster
                                have similar properties, whereas the data in different clusters have different properties.
                                In other words, grouping can be possible with just distribution of observed data, which
                                meets the purpose of this study, i.e., categorization of the station areas based only on
                                various locational characteristics without considering the dependent variables for specific
                                purposes.
                                     The analysis employed in K-means clustering is shown in Equation (4):

                                                                             N      K
                                                               argmin
                                                                 r, c        ∑ ∑            rnk || Xn − Ck || 2                    (4)
                                                                           n=1 k=1

                                     Assuming that the number of clusters (k) is determined in advance, rnk is expressed as
                                a binary variable with a value of 0 or 1 if the nth data belong to the kth cluster, Ck represents
Sustainability 2021, 13, 4310                                                                                                                          8 of 16

                                        the center of the kth cluster, and Xn represents an n number of d-dimensional data. Here,
                                        the distance was measured based on the Euclidean distance. This study standardized
                                        and used three variables of locational characteristics to eliminate bias caused by different
                                        variable units. The statistical program Stata 16.0 was used for K-means clustering analysis.

                                        4. Results and Discussion
                                        4.1. Results of Analyzing Station Area Categorization according to Locational Characteristics
                                              Table 3 summarizes the results of K-means clustering with locational characteristics as
                                        the variables. Two clusters were derived: Cluster 1 comprising 14 station areas, and Cluster
                                        2 comprising 20 station areas. The t-test revealed a statistically significant difference in
                                        all three locational characteristics, as shown in Table 4. Noteworthily, all station areas
                                        under Cluster 1 were located in urban cores, and most station areas under Cluster 2 were
                                        located in the suburbs, indicating the strong typicality of station areas depending on their
                                        location. More specifically, station areas categorized in Cluster 2 had a lower level of LUM
                                        and shorter walking accessibility radius per unit of time than station areas under Cluster
                                        1. In contrast, the station areas in Cluster 2 tended to have a high flattening ratio. This
                                        indicates that while station areas in urban cores are close to a circular shape and form a
                                        mix of various uses with relatively broad areas of influence, those in the suburbs are close
                                        to an oval shape and form less mixed uses with relatively smaller areas of influence.

                                                   Table 3. Clustering analysis results (N = 34).

         Type                                                        Station Area                                                             N
                                    2 (Busan); 4 (Cheonan); 8 (Daegu); 9 (Daejeon); 10 (DMC); 11 (Dongdaegu);
      Cluster 1                            13 (Gangneung); 16 (Gwangju); 18 (Gyeongju); 23 (Mokpo);                                           14
                                             26 (Seoul); 28 (Suncheon); 32 (Wangsimni); 34 (Yongsan)
                                      1 (Andong); 3 (Changwon-Jungang); 5 (Cheonan-Asan); 6 (Chuncheon);
                                7 (Daegok); 12 (Donong); 14 (Geoje); 15 (Gimcheon); 17 (Gwangmyeong); 19 (Iksan);
      Cluster 2                                                                                                                               20
                                    20 (Jecheon); 21 (Jije); 22 (Kwangwoon University); 24 (Osong); 25 (Pohang);
                                          27 (Singyeongju); 29 (Susaek); 30 (Suseo); 31 (Ulsan); 33 (Wonju)
                                              Note: Railway station areas are listed in alphabetical order.

                                                                Table 4. T-test results.

                  Variables.                       Cluster            Obs.1             Mean              SD 2               T                     P
                                                       1                14              −0.96                 0.79
                    LUM 3                              2                20              0.67                  0.39
                                                                                                                          −7.96               0.000 *

                                                       1                14              0.95                  0.63
      Walking Accessibility Radius                                                                                         7.73               0.000 *
                                                       2                20              −0.66                 0.57
                                                       1                14              0.82                  0.45
              Flattening Ratio                                                                                             5.51               0.000 *
                                                       2                20              −0.57                 0.86
             * p < 0.01, all variables were standardized for analysis. 1 Obs.: observations, 2 SD: standard deviation, 3 LUM: land use mix.

                                              The patterns of each cluster according to the locational characteristics are shown in
                                        Figure 3. First, based on the LUM variables, the average LUM of Cluster 1 was 0.72, while
                                        that of Cluster 2 was 0.55, and this difference was statistically significant. Considering that
                                        each cluster has a similar character based on the station areas’ location in either urban cores
                                        or suburbs, the LUM of station areas located in urban cores is diverse, whereas that of
                                        station areas located in suburbs tends to be homogeneous. In particular, station areas with
                                        a high level of LUM were big provincial cities such as Busan, Daejeon, and Gwangju; these
                                        station areas had a high level of LUM for residential, commercial, and business uses. In
                                        contrast, most station areas located in the suburbs had a relatively high ratio of functions
                                        and uses when planning and developing suburban station areas in the future.
Sustainability 2021, 13, x FOR PEER REVIEW                                                                                                     9 of 16

Sustainability 2021, 13, 4310                                                                                                                  9 of 16

                                      In contrast, most station areas located in the suburbs had a relatively high ratio of func-
                                      tions and uses when planning and developing suburban station areas in the future.

             Variables                                      Scatter Diagram                                               Box Plot

               LUM 1

     Walking Accessibility
           Radius

         Flattening Ratio

                            Figure 3. Cluster patterns according to locational characteristics. 1 LUM: land use mix.
                           Figure 3. Cluster patterns according to locational characteristics. 1 LUM: land use mix.

                                            Second,there
                                           Second,    therewas
                                                            wasaadifference
                                                                   differenceininthe
                                                                                   thedistribution
                                                                                        distribution ofof   areas
                                                                                                         areas  of of influence
                                                                                                                   influence       through
                                                                                                                               through          walk-
                                                                                                                                            walking
                                      ing  network   analysis   by cluster. The   average    radius   of  influence   of station
                                     network analysis by cluster. The average radius of influence of station areas in Clusters      areas   in   Clus-
                                      ters 1 and  2 was   787 m  and  580 m, respectively,     with  the   difference   between
                                     1 and 2 was 787 m and 580 m, respectively, with the difference between the two being           the  two    being
                                      statisticallysignificant.
                                     statistically  significant. Station
                                                                  Station areas
                                                                          areas inin Cluster
                                                                                     Cluster 22 showed
                                                                                                 showed consistent
                                                                                                             consistent results
                                                                                                                          results with
                                                                                                                                     with the
                                                                                                                                            the 500–
                                                                                                                                                  500–
                                      600  m  influence   areas set as station  areas   in many    studies    [11,13]. However,
                                     600 m influence areas set as station areas in many studies [11,13]. However, station areas       station    areas
                                      inCluster
                                     in  Cluster11proved
                                                     provedthat
                                                              thatthe
                                                                   theradius
                                                                        radiusofofinfluence
                                                                                    influence can
                                                                                                can be
                                                                                                     be expanded
                                                                                                          expanded to  to more
                                                                                                                          more than
                                                                                                                                  than 800800 m. m. In
                                                                                                                                                    In
                                      linewith
                                     line  withthe
                                                 thearguments
                                                      argumentsby  byBertolini
                                                                       Bertolini (1999)
                                                                                  (1999) [20]
                                                                                           [20] and
                                                                                                and Lee
                                                                                                      Lee and
                                                                                                            and Song
                                                                                                                 Song (2004)
                                                                                                                        (2004) [21],
                                                                                                                                 [21], for
                                                                                                                                        for station
                                                                                                                                              station
                                      areaslocated
                                     areas   locatedin inurban
                                                          urbancores
                                                                 coreswith
                                                                        withtightly
                                                                              tightly oror densely
                                                                                            densely packed
                                                                                                      packed urban
                                                                                                                 urban blocks,
                                                                                                                         blocks, such
                                                                                                                                    such asas inin the
                                                                                                                                                   the
                                      urban   spatial  structures  of Korea  or  Europe,    it might   be   more   valid  to set
                                     urban spatial structures of Korea or Europe, it might be more valid to set a larger radius ofa  larger    radius
                                      of influence.
                                     influence.      Moreover,
                                                  Moreover,       station
                                                               station    areas
                                                                        areas     located
                                                                               located   inin  thesuburbs,
                                                                                             the   suburbs,asasshown
                                                                                                                   shownin  inCluster
                                                                                                                               Cluster 2,  2, lacked
                                                                                                                                              lacked
                                     walking accessibility as the road network was not as densely created as those in urbanurban
                                      walking   accessibility   as the road  network      was   not  as  densely    created   as  those    in    areas.
                                      areas.
                                           Third, the spatial form of the station areas varied between clusters. The average
                                     flattening ratio of station areas in Cluster 1 was 0.57, while that of station areas in Cluster 2
                                     was 0.77. The closer the flattening ratio is to 0, the more a space is considered to resemble a
Sustainability 2021, 13, 4310                                                                                            10 of 16

                                perfect circle. The results show that station areas under Cluster 1 resembled a spatial form
                                closer to a more compressed ellipse than did station areas under Cluster 2. This may be
                                partially due to the topographical features of Korea, in which station areas located in the
                                suburbs such as Pohang Station, Chuncheon Station, or Geoje Station, are adjacent to the
                                mountains or waterfront.

                                4.2. Results of Identifying the Significance of Station Area Types Classified by
                                Locational Characteristics
                                      This study also identified the significance of the types classified by the locational
                                characteristics of station areas in planning and development. The analysis results proved
                                that there is a difference in land use, transit accessibility, and spatial form depending on
                                the type of station area. In terms of urban planning, reflecting this difference is sufficient to
                                partially improve the existing approach; however, it is important to come up with clearer
                                implications for each type to improve the development methods.
                                      Therefore, this study identified whether the types classified by locational characteris-
                                tics are still valid from the viewpoint of development, with a focus on a few key variables of
                                development. Seo et al. (2018) [51] provided an analytical framework that revealed project
                                tendency through expert group interviews with private developers and policy-making
                                authorities using the parameters of current project status and future latent demand. The
                                key indicators that determine the current project conditions in Korea include the total floor
                                area realization ratio compared to the regulated total floor area and officially appraised
                                land prices. This is because it is easy to carry forward the project in station areas with
                                relatively low total floor area realization ratios and land prices due to large density changes
                                from the development project as well as the low initial capital required [51]. Moreover, the
                                key indicators to estimate the future latent demand are represented by the ridership of the
                                station and the density of infrastructure such as roads. Since a considerable amount of
                                the profit from station area development is reinvested in maintaining the infrastructure,
                                the project feasibility can be improved by securing the infrastructure, and the estimated
                                number of station area users is the most important factor that determines project feasibility.
                                The judgment related to the effect of the station area development project based on these
                                indicators is consistent with the results of previous studies investigating this phenomenon
                                in Korea [15,38,52]. Therefore, this study used the total floor area realization ratio and
                                officially appraised land prices as the indicators representing the current project status, and
                                the ratio of roadway areas and the number of passengers as the indicators representing the
                                future latent demand, and verified whether similar typological characteristics are found in
                                the same station areas after standardization.
                                      The results showed that there was a clear tendency between station areas located in
                                urban cores and those located in the suburbs, as shown in Figure 4. More specifically, in
                                terms of current project status, station areas located in urban cores showed higher total
                                floor area realization ratios and officially appraised land prices than those located in the
                                suburbs. This may be due to the constant increase in demand and land value in business
                                and commercial districts and functions around railway stations during the process of the
                                expansion of urban sprawl around railway stations in the past [1,7]. Thus, station areas
                                located in the suburbs may seem relatively more favorable in terms of current project
                                feasibility. Meanwhile, in terms of future latent demand, station areas located in urban
                                cores showed a larger number of passengers and a higher density of infrastructure than
                                those located in the suburbs. Therefore, in terms of future latent demand, station areas
                                located in urban cores are relatively more favorable.
expansion of urban sprawl around railway stations in the past [1,7]. Thus, station areas
                                   located in the suburbs may seem relatively more favorable in terms of current project
                                   feasibility. Meanwhile, in terms of future latent demand, station areas located in urban
Sustainability 2021, 13, 4310      cores showed a larger number of passengers and a higher density of infrastructure11than
                                                                                                                        of 16
                                   those located in the suburbs. Therefore, in terms of future latent demand, station areas
                                   located in urban cores are relatively more favorable.

      Figure 4.
      Figure 4. Results
                Results of
                        of analyzing
                           analyzingthe
                                     thecurrent
                                         currentproject
                                                 projectstatus
                                                          statusand
                                                                 and  future
                                                                    future   latent
                                                                           latent   demand
                                                                                  demand of of station
                                                                                            station    areas.
                                                                                                    areas.    Statistics
                                                                                                           Statistics for for
                                                                                                                          eacheach
                                                                                                                                variable
      variable used in the analysis are presented in Appendix A.
      used in the analysis are presented in Appendix A.

                                         It is notable
                                         It is notable that
                                                        that Clusters
                                                             Clusters 11 and
                                                                          and 2,2, classified
                                                                                   classified byby locational
                                                                                                    locational characteristics
                                                                                                               characteristics of
                                                                                                                                of station
                                                                                                                                   station
                                   areas,   couldbebe
                                   areas, could          easily
                                                     easily      divided
                                                            divided          into cores
                                                                     into urban     urbanand cores    andrespectively.
                                                                                               suburbs,    suburbs, respectively.     This
                                                                                                                       This classification
                                   classification  is also  valid in  the  types  of   station  area  development    considering
                                   is also valid in the types of station area development considering project conditions and       project
                                   conditions    and demand.
                                   demand. Therefore,              Therefore,
                                                           in the urban   contextin ofthe  urban
                                                                                        Korea,  thecontext   of Korea,
                                                                                                     typological          the typological
                                                                                                                 classification of station
                                   classification  of station  areas into urban    cores  and  suburbs   can  be applicable
                                   areas into urban cores and suburbs can be applicable to locational characteristics        to locational
                                                                                                                                as well as
                                   characteristics
                                   to planning and  asdevelopment
                                                        well as to planning    and development conditions.
                                                                       conditions.

                                        Discussion on
                                   4.3. Discussion    ona aDifferential
                                                             DifferentialApproach
                                                                              Approachof theofStation Area Type
                                                                                                the Station   Areain Type
                                                                                                                     Planning    and Development
                                                                                                                            in Planning      and
                                   Development
                                         The above analysis results show several implications as follows. First, it may be
                                   difficult
                                         Thetoabove
                                               adoptanalysis
                                                        an approachresultssimilar
                                                                              showtoseveral
                                                                                        that of urban    cores for
                                                                                                  implications    asthe   allocation
                                                                                                                      follows.    First,ofitfunctions
                                                                                                                                              may be
                                   and usesto
                                   difficult when
                                               adopt planning     and developing
                                                        an approach       similar to station
                                                                                        that of areas
                                                                                                  urbanofcores
                                                                                                           the suburbs     in the future.
                                                                                                                for the allocation           Because,
                                                                                                                                       of functions
                                   in theuses
                                   and    urban   context
                                               when          of Korea,
                                                        planning     and station   areas located
                                                                            developing       stationin areas
                                                                                                       the suburbs
                                                                                                               of theare    based on
                                                                                                                        suburbs     in the
                                                                                                                                         thepremise
                                                                                                                                              future.
                                   of the formation    of  large-scale    new    satellite towns,    and  division   of the
                                   Because, in the urban context of Korea, station areas located in the suburbs are based    land  in large    blocks.
                                                                                                                                                   on
                                   Therefore,
                                   the premise of the formation of large‐scale new satellite towns, and division of the landthe
                                                it is better    to maintain       the  spatial   scope   at a  certain   level,   considering      in
                                   function
                                   large     of railway
                                          blocks.           stations
                                                    Therefore,     it in
                                                                       is the  process
                                                                           better         of planning
                                                                                    to maintain       theand   developing
                                                                                                           spatial   scope station      areas in
                                                                                                                               at a certain       the
                                                                                                                                                level,
                                   suburbs. It isthe
                                   considering     alsofunction
                                                         necessary of to  consider
                                                                       railway         designing
                                                                                   stations         theprocess
                                                                                               in the   scope ofofplanning
                                                                                                                     planningand  anddevelopment
                                                                                                                                         developing
                                   of station
                                   station    areasininthe
                                            areas        the suburbs.
                                                               suburbs in  It light  of their
                                                                               is also          expansion
                                                                                          necessary          in a longdesigning
                                                                                                       to consider       rectangle shape,
                                                                                                                                     the scope rather
                                                                                                                                                   of
                                   than recklessly setting it in a circular form, considering the surrounding topographical
                                   conditions. This is because in the case of railway station areas in the suburbs where
                                   pedestrians or the road network is not evenly formed, planning and developing the station
                                   area in a circular shape based on Euclid distance may be inefficient as it forms areas with
                                   weak accessibility.
Sustainability 2021, 13, 4310                                                                                            12 of 16

                                      In addition, even if the current business conditions are relatively unfavorable, station
                                areas located in urban cores have a high future latent demand and can be developed more
                                quickly if the regulations on building density are relaxed through incentives in terms
                                of urban planning. Japan, which has a similar urban space context as Korea, has been
                                applying this method for developing station areas in urban cores, such as those in Tokyo
                                and Osaka, and showing outcomes in development [3,7]. Therefore, it may be effective
                                to approach the planning and development of station areas located in urban cores by
                                attracting private sector entities to make investments, while the public sector focuses on
                                institutional support. In contrast, station areas located in the suburbs may have advantages
                                in the current project conditions, but it may be difficult to attract investment from the
                                private sector for these projects due to low future latent demand. Moreover, according to
                                the results of the clustering analysis, there is a low possibility of expansion in these station
                                areas in terms of LUM or infrastructure. Therefore, to encourage development in station
                                areas located in the suburbs, it is necessary for the public sector to first make investments
                                and improve land use with a focus on public functions; the effect of private investment
                                can then be anticipated within a limited range. Especially, since the station area in the
                                urban core has high potential demand in the future, the private sector should take the
                                initiative to expand public facilities and public spaces that are insufficient in the urban core,
                                while securing construction density and incentives for use in the public to secure business
                                feasibility. On the other hand, in the case of station areas in the suburbs, the private sector
                                does not have enough development feasibility to promote the project alone, so in the short
                                term, it is necessary to jointly secure anchor facilities in combination with public projects.
                                In addition, if demand expands in the future, a strategy to gradually expand the business
                                from a long-term perspective is expected to be effective.

                                5. Conclusions
                                      The goal of this study was to explore whether railway station areas can be categorized
                                on a nationwide level based on the urban context of East Asian countries, including Korea,
                                and whether categorization according to locational characteristics is still valid in planning
                                and development conditions. This study contributes to the discussion on station areas in
                                East Asia, especially Korea, where station areas are gaining importance with the expansion
                                of high-speed rail networks. Furthermore, it contributes to setting the direction for the
                                planning and development of station areas by investigating the typological characteristics
                                of station areas in terms of locational characteristics such as land use, walking accessibility,
                                and spatial form.
                                      In summary, a clear pattern that can classify the major railway station areas in Korea
                                into urban cores and suburbs was found for all three locational characteristics. Station
                                areas located in urban cores formed relatively broader areas of influence and had a high
                                level of LUM, while those located in the suburbs formed relatively smaller areas of influ-
                                ence and had a low level of LUM with a high ratio of residential use. There was also a
                                statistically significant difference between urban cores and suburbs in the form of station
                                areas. Moreover, both types showed a shape closer to an ellipse than a circle. This result
                                shows that it is necessary to take a differential approach to the planning and development
                                of station areas. Furthermore, the spatial location of urban cores and suburbs in the urban
                                context may be considered to have a considerable effect on the function and influence of
                                station areas.
                                      Categorization according to the locational characteristics of station areas was found to
                                be valid in terms of the project approach for development. The typological classification of
                                urban cores and suburbs showed a statistically significant difference in terms of the current
                                and future project conditions. Station areas located in urban cores had an advantage in
                                future latent demand, whereas those located in the suburbs had an advantage in the present
                                project conditions. These results imply that setting an effective policy direction for station
                                area development in the future should involve attracting private investment combined
                                with institutional support from the public sector for urban core station areas, attracting
Sustainability 2021, 13, 4310                                                                                                        13 of 16

                                     public investment, and securing optimum use for station areas in the suburbs. Above all, it
                                     is necessary to differentiate the planning and development strategies depending on the
                                     type of station area. For the station area in the urban core, it is effective for the private sector
                                     to lead planning and development by offsetting investment in public facilities that are
                                     insufficient with incentives such as density. In addition, for the station area in the suburbs,
                                     the private sector is effective to support public-led projects to secure anchor facilities first
                                     and expand demand and development areas in the long term.
                                            This study also had a few limitations, which need to be addressed in future research.
                                     First, while this study focused on analyzing station areas on a nationwide level, the
                                     typological pattern may be different if the spatial scope is limited to the city level. Therefore,
                                     it is necessary to identify whether the typological classification of urban cores and suburbs
                                     is still valid for intercity units that have been a major geographical measure in studies
                                     related to station areas. Second, it is necessary to identify how the typological characteristics
                                     of station areas in the context of Asian countries, including Korea, are different from those
                                     of station areas in the US, Japan, and Europe. Such international comparative studies
                                     can contribute to improving the planning model for station areas, including TOD and
                                     typological diversification of station area development strategies. Finally, since this study
                                     reflects the specific context of an Asian country undergoing rapid expansion of high-
                                     speed railways and cities, further research must verify the impact of the development of
                                     high-speed railways and cities in association with the changes in station areas.

                                     Author Contributions: M.S. designed this study, performed the analyses, and wrote the first draft;
                                     D.L. performed the analyses jointly and improved the methodological part. Both authors have read
                                     and agreed to the published version of the manuscript.
                                     Funding: This research was funded by a research grant entitled “The Revitalization of the Develop-
                                     ment Project and the Improvement of Legal System in the Station Area” from the Ministry of Land,
                                     Infrastructure, and Transport in Korea.
                                     Institutional Review Board Statement: Not applicable.
                                     Informed Consent Statement: Not applicable.
                                     Data Availability Statement: The data will be made available upon request to the corresponding
                                     author.
                                     Acknowledgments: This research is a part of a broader research entitled, “A Study on Facilitation of
                                     Urban Regeneration in Station Areas towards Energy Efficient Cities” to be published by the Korea
                                     Research Institute for Human Settlements at the end of 2019.
                                     Conflicts of Interest: The authors declare no conflict of interest.

Appendix A
      Cities and Counties Listed for Each of the Functional Urban Regions.

                          Table A1. Variable of the current project status and future latent demand of station areas.

                                                           Current Project Status                           Future Latent Demand
  Cluster Type           Station Area         Total Floor Area        Officially Appraised      Ratio of Roadway          Number of
                                                Realization                Land Price                 Areas               Passengers
                                                     (%)             (Thousand Won */m2 )              (%)              (Millions/Year)
                            Busan                   18.1                      4960                         30.1              24.13
                           Cheonan                  21.7                      1560                         25.0               6.02
                            Daegu                   18.3                      3060                         19.5               5.41
    Cluster 1
                           Daejeon                  18.1                      1510                         23.6              19.54
                            DMC                     19.4                      4150                         23.1              17.38
                          Dongdaegu                 30.1                      2080                          8.9              25.65
Sustainability 2021, 13, 4310                                                                                                      14 of 16

                                                               Table A1. Cont.

                                                         Current Project Status                           Future Latent Demand
  Cluster Type           Station Area      Total Floor Area         Officially Appraised           Ratio of Roadway     Number of
                                             Realization                 Land Price                      Areas          Passengers
                                                  (%)              (Thousand Won */m2 )                   (%)         (Millions/Year)
                          Gangneung               19.2                       420                         21.1               3.46
                           Gwangju                24.5                       910                         29.8              0.43
                           Gyeongju               11.5                       850                         9.1                0.98
                            Mokpo                 13.8                       320                         7.8                0.58
                             Seoul                26.1                      11210                        36.1              42.10
                           Suncheon               12.5                       320                         7.9                2.55
                          Wangsimni               21.1                      4720                         29.3              31.02
                            Yongsan               28.1                      13100                        19.3              34.72
                          Andong                  11.5                       710                         5.5               0.52
                        Changwon-
                                                  8.9                        210                         5.8               2.25
                          Jungang
                       Cheonan-Asan                9.4                       1030                        10.6               7.08
                        Chuncheon                  9.5                        310                        12.8               1.78
                          Daegok                   7.1                        310                        22.4               1.13
                          Donong                  11.5                       2010                        14.5              5.52
                            Geoje                 22.3                       1340                        26.8              1.19
                         Gimcheon                  9.3                        360                         8.6              0.57
                       Gwangmyeong                16.5                       2610                        12.0              10.06
      Cluster 2
                            Iksan                 10.6                       1240                        13.4               5.43
                          Jecheon                 16.8                        260                         7.7              1.42
                             Jije                 10.1                        320                        13.3               1.36
                      Kwangwoon Univ.             19.6                       1960                        17.6               4.81
                           Osong                   8.6                        610                         9.1              6.76
                           Pohang                  8.2                        510                         6.1              2.62
                        Singyeongju                8.1                        180                         6.8              0.87
                           Susaek                 17.5                       3630                        18.6              1.35
                            Suseo                 16.1                       7830                        10.9              15.12
                            Ulsan                  8.5                        460                         8.7               4.28
                           Wonju                  10.7                        620                         6.2               1.36
                                            * One thousand won is about 0.87 US dollars in 2019.

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