Accessibility to Location of Activities in Denpasar City, Bali-Indonesia
Putu Alit Suthanaya
Civil Engineering Department, Engineering Faculty, Udayana University Jl. Kampus Bukit Jimbaran, Bali-Indonesia
email: suthanaya@rocketmail.com
Keywords: accessibility, activity, Hansen index, Z-score
Abstract. Denpasar City is the capital of Bali Province with the population of about 0.9 million.
Denpasar City has experienced high increase in private vehicles use and long trip distance to reach activity locations. The objective of this study is to investigate the accessibility of residents to several activities location in Denpasar City. The activities considered in this study included shopping centers, schools and health facility. Accessibility values were calculated based on Hansen’s Index.This study found that the activities in Denpasar City were not evenly distributed. Several zones mainly located in the center of the city had high accessibility values whilst zones located in the north of Denpasar City had low accessibility values. This has caused long average trip distance travelled by resident of Denpasar City to reach location of activities. In order to reduce the average trip distance, a policy intervention is required to re-arrange location of activities in Denpasar City in the future in the form of mix-used development.
Introduction
Many cities have initiated efforts in the achievement of sustainable cities through transport policies. Land-use planning has a key role to play in the attainment of these objectives [1].Creating asustainable and low-carbon society through the urban development has been a general trend [2]. However, in recent years, Asian region is consuming increasing amounts of energy. In 2030, theincrease of energy consumption in Asia is estimated to account for 46% in the total world energyincrease [3].Sustainable transportation has become an important issue that need to be considered in developing transportation infrastructure. A comparative analysis of transportation sustainability in 29 OECD Countries using the sustainable transportation indicators has been made and outlined in the Korean Sustainable Transportation and Logistics Development Law [4]. They found that transportation sustainability in some countries have been getting progressively worse. The majority of cities in developing countries such as Indonesia have been identified to move toward unsustainable city.
Cities in Indonesia have faced the increasing traffic congestion and air pollution. Environmental degradation has continued to occur from year to year. This condition is influenced by poor public transport service and increasing dependence on using private vehicle especially motor cycle [5]. Car dependence is a fundamental problem in the sustainability of cities with low density suburban sprawl [6]. By applying preference function to analyze travel behavior and Moran’s I spatial statistic to evaluate the spatial association, it was found that the commuting preferences of residents in Sydney City, Australia, have moved towards distance maximization [6]. Similar condition has also occurred in Indonesian cities.This condition are becoming an issue of concerns for urban governments and citizens in Indonesian cities include Denpasar City.Denpasar City is the capital of Bali Province and has been identified as one of cities in Indonesia that has poor traffic condition. Bali is one of the most famous tourist destination. This poor traffic condition has become an important issue that may reduce the attractiveness of Bali. According to study conducted by Denpasar City Department of Transport [7], it has been identified that almost 50 percent of the road capacity in Denpasar City has been exceeded. The population has reached 0.9 million and livedwithin the limited area of Denpasar City.
Motor vehicle ownership has increased at the rate of 10 percent per year [8]. The activities such as business and government office, shopping center, hospital, school, etc., have been developed with scatter form. This has created a complex traffic flow pattern with relatively long journey travelled by residents to reach the activity location. Spatial distribution of activities relative to housing location will influence vehicle trip length, traffic congestion, energy consumption and air pollution level. Therefore, it is necessary to evaluate relative housing-activities location by measuring accessibility of the residents to activities in a city. Accessibility concept can be used to analyze relative housing-activities location. The objective of this study is to investigate the accessibility of residents to several activities location in Denpasar City.The results of the analyses will provide a basis for the government to plan the location of housing and activities in the future in order to reduce trip length.
Literature Review
Accessibility is defined and operationalized in severalways, and thus has taken on a variety of meanings.These include such well-known definitions as ‘the potentialof opportunities forinteraction’ [9]. One way to measure proximity of housing-activities location in a city is by measuring the accessibility of the residents to activities. The concept of accessibility has been widely used in various research in various field such as in transportation, urban planning, geography, and sociology. It was considered as the same concept of the mobility in early researches, but the limitation is that it simply defines the accessibility as the transportation effect of land-use, as it defines the traffic demand as the transportation effect of land development[10].Land-use development is related to accessibility, which he described as a measurement of the spatial distribution of activities about a point, adjusted for the ability and desire of people or firms to overcome spatial separation.The Hansen-based job accessibility index is used in this study and expressed as follows [9]:
= . (1)
where,
Ai : Accessibility of area i
Ej : Number of employer in area j D ij : Distance from area i to area j β : Constanta (β > 0)
In the field of studies concerning optimum commuting allocation solutions, it was found that a reduction in the length of worktrip through efforts to bring about changes in journey-to-work travel characteristics [11, 12]. Numerous progresses have been made and applied to derive the determining factors of theresidential choice behavior of households. The accessibility is one of the mostimportant factors which influence on the location choice decision. In particular, regional accessibility is very important in employment location choicedecision [13].
In this study Z-Score is used to evaluate distribution of accessibility value. The standard normal curve helps to simplify the calculation of probabilities for normally distributed populations. Because not all normally distributed random variables have µ = 0 and σ = 1, it is needed to transform the variable so that µ = 0 and σ = 1. It can be done by using the Z-score, which is calculated as follows [14]:
Z = X - µ (2) σ
Methodology
consists of 4 sub-regions and 43 districts. The area of Denpasar City is 127.78 km2 or 2.27% of the area of Bali Province. The population is about 0.9 million. The study area was divided into 43 zones, where 11 zones were in the sub-region of West Denpasar, 11 zones in East Denpasar, 11 zone in North Denpasar and 10 zones in South Denpasar as shown in Fig.1.
Fig.1. Study Area Zoning System in Denpasar City, Bali-Indonesia
The primary data used in this study is travel time data, whilst the secondary data (number of activities) were obtained from Denpasar Bureau of Statistic [8]. The number of motor vehicles have increased at the rate of about 10 percent per year. Denpasar City has continued to become the central of economic development in the Province of Bali. Microsoft Access was used to compile relevant cross-tabulations and summaries. Tabulations were then converted to Microsoft Excel spreadsheets to allow presentation and modification of format. The activities considered in this study included shopping centers, schools and health facility.The number of activities were obtained from Denpasar Bureau of Statistics. Accessibility values were calculated based on Hansen’s Index for each activity types. Based on the latest census data and the average change in both accessibility values and travel time variables over time, a Z-score is calculated. To facilitate a visual inspection, a scatter-plot for this Z-score is developed. The zones were then grouped into low, medium and high accessibility zones based on percentile values.
Results and Discussions
Accessibility to Shopping Centers. Based on accessibility value to shopping centers in Denpasar,
PenatihDanginPuri, PeguyanganKaja, KesimanKertalangu and Kesiman which have a low accessibility values both based on 2012 data and the growth rate values.
Accessibility to HealthFacilities. Basedonaccessibility to healthfacilities,
itwasfoundthathighaccessibilityvalueswereexperiencedbyresidents living in thewest of Denpasar City. Residents living in thenorth and south of Denpasar City had médium accessibilityvalues. Residents living in theeast of Denpasar City experiencedlowaccessibilityvalues.Fig.3 shows Z Score diagram for accessibility to health facilities. From 43 zones evaluated, only Panjer District was found to have high accessibility value in 2012 and high average increase in accessibility values.Districtswithlowaccessibilityvalueswithtendency of decreasingvalueover time werePenatih, PenatihDanginPuriandKesimanKertalangu.
Fig.2. Z-Score Diagram of Accessibility to Shopping Centers
-2.5
Accessibility to School. Based on accessibility to schools in Denpasar City, it was found that several zones located in the city center were identified to have a high accessibility values such as zone 1, 3, 4, 17, 18, 28, 35 and zone 36. Mainly zones in the middle and south of Denpasar had medium accessibility values whilst zones in the north of Denpasar were in low accessibility category. Fig.4 shows Z-Score diagram based on the 2012 accessibility to school values and the average increase of accessibility values per year. Panjer District was found to have a high accessibility to schools value with the tendency of increasing over time. On the other hand, DauhPuri District was identified to have the lowest accessibility value both based on the 2012 data and the average increase in accessibility value per year.
Accessibility values were then classified into low, medium and high value. DauhPuriKangin, DanginPuri, and Panjer Districts were in high accessibility groups as these districts are located in the center of Denpasar City. On the other hand, Sanur, PenatihDanginPuri, Penatih, KesimanKertalangu, UbungKaja and PeguyanganKaja were in a low accessibility group.
Summary
Policies for sustainable urban development should include measures to reduce the need for movement and to provide favorable conditions for energy-efficient and environmentally friendly forms of transport. In order to reduce distances travelled by residents in a city, policies to re-arrange housing-activities location are important to be considered such as in Denpasar City. By measuring accessibility to shopping centers, health facilities and schools, this study found that the activities in Denpasar City were not evenly distributed. Several zones mainly located in the center of the city had a high accessibility values whilst zones located in the north of Denpasar City had a low accessibility values. For example,DauhPuriKangin, DanginPuri, and Panjer Districts were in high accessibility groups as these districts are located in the center of Denpasar City. On the other hand, Sanur, PenatihDanginPuri, Penatih, KesimanKertalangu, UbungKaja and PeguyanganKaja were in a low accessibility group. This has caused long average trip distance travelled by resident of Denpasar City to reach location of activities. In order to reduce the average trip distance, a policy intervention is required to re-arrange location of activities in Denpasar City in the future in the form of mix-used development. Development of activities need to be given priority in the region that
have a low accessibility value with a decreasing trend over time such as around zones located in the north of Denpasar City.
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