Page 205 - Proceeding of Atrans Young Researcher's Forum 2019_Neat

“Transportation for A Better Life:
Smart Mobility for Now and Then”

23 August 2019, Bangkok, Thailand

the model is developed, the more it is included with in a study, catchment areas were found compatible
complex components such as demand and supply with transit-oriented development principles in
behaviors and uncertainties, especially with a strong terms of density and diversity [15]. According to this
focus on travel demand. study, these areas are characterized with declining
density gradients of population and employment
Based on these theories about the expanding from a station as its central point and a
relationship of supply location and its surrounding high level of mixed-use land. These features,
catchment area, the analysis of catchment area often together with intermodal connectivity, have positive
consists of two phases. The first phase is for figuring impacts on subway ridership, especially in areas
out its geographical border based on walkability within a short distance around the cores.
distance [13], as what Christaller discussed. The
second phase is for determining the potential number 3. Methodology
of commuters regarding additional information The research questions of this study
concerning travel demand to and from the defined concerning (1) the definition and categorization of
catchment area [13], as mentioned after Christaller’s the catchment areas of the stations of Metro Line 1
theory. and (2) urban transition of these areas through the
lens of population (2.1) and land cover (2.2).
For many years now, GIS has been using for Multiple methods are used to approach these
catchment analysis in several studies with various research questions as follow.
tools. The fundamental approach is Circular Buffer
which simply examines the catchment areas within For Research Question 1, data from relevant
certain radiuses from a central place [13], e.g. a stop reports on Metro Line 1 project are collected to build
of a metro line. Another popular approach is Service a model of route and stations in QGIS. Based on
Area, which can include geographical characteristics literature review, distance of 400-800 m is used for
as well as distance following road network [13], Circular Buffer approach to create the catchment
[14]. Data commonly used in these analyses include areas. Category method is applied then to group
population density, employment density, these areas based on its multi-characteristics.
topography, road network, travel demand, real-time
travel, public transport and so on. For Research Question 2.1, historical
demographic data within the surveyed catchment
Since catchment areas are determined by the areas was concerned to examine the population
walking distance that people are willing to take, it is movement and agglomeration with the presence of
generally referred to the pedestrian catchment area metro lines. The population data were mainly taken
(PCA) [15]. Various spatial ranges for PCA have from statistical yearbook and some other relevant
been used in analysis, depending on transit type and sources. Four periods of time were examined,
urban characteristics. A study in US ranged PCAs of namely 2000-2005, 2005-2010, 2010-2015, and
metro/ rail stations from 400 m for jobs to 800 m for 2015-2019, with an extension to 1999 for the first
populations [16]. Similarly, radius of 400 m and 800 period and a limitation to 2017 for the last period due
m was used for population to access bus/ tram stops to a lack of available data. Since data of employment
and train stations respectively in a study on public rate is absent, only this data of population was
transport at Melbourne [17]. Sydney plans a range considered.
between 400 m and 800 m as the straight-line
distance to reach rail line at daytime and nighttime For Research Question 2.2, three catchments
respectively, while Vancouver uses 400 m, Helsinki are first selected from the groups in the findings of
uses 300 m, and Perth uses 500 m [18]. Another Question 1, and four milestones are chosen from four
study classified PCA into 3 zones for the case of periods of time in the findings of Question 2.1.
subway in Seoul: core (within 300 m from the Referring from Open Street Map inserted into QGIS,
subway station), primary (between 300 m and 600 the 800-m-radius circular borders of the catchment
m), and secondary (between 600 m and 900 m) due areas are defined based on its relative position with
to the short distances between subway stations in this street networks. High resolution satellite images
dense city [15]. (Landsat data) are then exported from Google Earth.
Specifically, characteristics of catchment Photoshop is used then to buffer these catchment
areas are described in numerous studies. Particularly areas based on results from QGIS, as well as to

180