Infrastructure Development of Road Network for Regional Development Based on Accessibility Concept

Penukal Abab Lematang Ilir (PALI) District is a new district in South Sumatera Province, Indonesia which has been established since 2013 and has five subdistricts and 72 villages. PALI district continuously implements regional development to improve the living standard and economy of the community. Consequently, the infrastructure development of road network based on needs of improvement of accessibility and the spatial area is a precondition for economic and regional development and improvement of competitiveness of PALI district in South Sumatera Province. This research aimed to study the needs of infrastructure development of road network in PALI District regarding the economic and regional development and other sectors based on accessibility measurement. The data of existing infrastructure and regional condition and spatial area plan are activity centres, spatial patterns, and strategic area to be fundamental in determining the infrastructure development of road network for either internal or external accessibility of PALI District area. The existing condition based on the accessibility values show that several villages which are the priority of development have low accessibility so that the development of road infrastructure networks is needed. The simulation of scenarios of road network development was conducted to get the best accessibility score in order to support the plan of the existing economic and regional development. The result of the study is the plan of infrastructure development of road network of PALI District that can really support economic growth and regional development in PALI District. Keywords— accessibility measurement; road infrastructure development; infrastructure; spatial area accessibility.


I. INTRODUCTION
Penukal Abab Lematang Ilir (PALI) District is a new district in South Sumatra Province having exceptionally good at agriculture, plantation, and mining sectors which are expected to develop fast from time to time. Hasan, M. [1] explained in his book the eds of infrastructure to support area development. The infrastructure construction to support the needs of the movement of people and goods continues to be carried out along with the development of the district to exploit the potential of the region optimally. Having fast regional development, PALI District is faced with challenges, particularly those related to the provision of regional transportation infrastructure.
The spatial planning has planned the points of regional development and strategic area plan embodied in the spatial plan of PALI District, where the centers of economic, cultural and other development have been mapped in the spatial plan. In spatial planning, it needs road network development as a connection of the analyzed strategic areas to the accessibility and mobility parameters. This is the main indicator needed in road network infrastructure development, particularly for a region of a new autonomy such as PALI District. The high accessibility level in one area will improve the competitiveness of that area. The connectedness and accessibility reaching centers of utility make it easy to have productive activities. Man, T. et al. [2] studied the spatial impacts of infrastructure constructions in improving accessibility in Romania. Marinos, PD [3] revealed how to elaborate spatial development to sustainable in relation. The productivity combination of each zone will positively affect the improvement of competitiveness of a region.
The development of supporting infrastructure for movement activities that accommodate the needs of movement will be directly proportional to economic activity because good accessibility in a region is the key and the prerequisite of economic development in that region. Accessibility development which one of them is with road network development must be based on accessibility analysis, development plan, and regional spatial plan. Because PALI is a new district where its infrastructure condition has not been optimal in supporting regional development, it is necessary to have a road network development plan in PALI District. The study aimed to evaluate the accessibility of the existing network and develop the alternative of road network development in supporting the regional development plan of PALI District.
A. The concept of Regional Development Mahi, A.K [4] studied the spatial development, the concept of regional development, among others, consists of the concept of the growth poles, the development of small towns, the development of integrated space and the development of agropolitan.
The concept of growth poles is a development aimed at economic growth with an efficiency that emphasizes the growth of new equity that is expected to be duplicated in other regions. The concept of small-town development is that of developing the center of growth in a location that can spur economic improvement geographically and attract investment in the area concerned. The concept of integrated space is a development that aims to improve economic and equity simultaneously with the relevance of activities with land use expected to occur in the production system integration and community participation so that the development is both tops down and bottom up. The concept of agropolitan is that of harmonizing the agropolitan activities whose agricultural development is with industry optimally at the location of the development area. The concept of regional development selected for PALI District is that of integrated space development (functional integration) combined with the agropolitan concept. It is since the regional characteristics and potential are focused on agricultural sectors (plantation, fishery, and agriculture food crops). The concept of regional integration development of Penukal Abab Lematang Ilir District aims to develop an integrated city system which is supported by the development of adequate transportation and infrastructure system, and the sustainable agriculture activities are developed in the rear areas of the cities.

B. Area Accessibility
Tamin Z. O. [5] points out that accessibility is a concept combining a system of geographical land use arrangement with the existing transportation network system. Jan Scheurer [6] states that indicators of regional accessibility comprise 7 categories of regional accessibility measurement as follows: 1.Spatial Measurement; 2. Contour Measurement; 3.Gravity Measurement; 4.Competition Measurement; 5.Time Span Measurement; 6.Utility Measurement; 7.Network Measurement.
In the measurement of accessibility of new autonomous regions, there will be network measurement in which calculating the degree of ease of reaching a destination location is based on an intersection between paths within the network. The formula of accessibility calculation developed by Jan Scheurer as follows In measuring the accessibility, the procedure was as follows: • Identifying link and meeting point in the existing network • Defining connectivity matrix • Calculating accessibility matrix The following are the phases of the calculation process of accessibility matric: • Arrange the initial network matrix based on the road network map and name it C 1 on the matrix. Specify Matrix T = C 2 and initial value n = 1. Then check if each element on the matrix T has no zero value. If not, then m = 1 and directly proceed to step 5 • Calculate m = n + 1 dan C m = C 1 xC 2 • Calculate T + C m • Iteration is stopped when the matrix T has no elements of 0 value • Calculation of accessibility value The road network development of PALI District is carried out by: • The existing accessibility condition for each area connected by the existing road network. • Road network development scenario of improving regional accessibility for a plan of activity center and strategic areas. • Selected road network development plan.

A. Plan of Area Development
Based on the spatial planning of PALI District (2016) [12], there are planned development points in several categories, namely: • Centre of Local Activity (CLA) • Centre of Promotion Local Activity (CPLA) • Centre of Regional Services (CRS) • Centre of Environment Services (CES) CLA is a central area of major growth center area with government orientation and trade of government and industry. CPLA is a central area of subdistrict-scale trades, services, and distribution. CRS is developed to be a center of production and industries of subdistrict-scale plantation and agriculture to support the city. CES is centers of agriculture production at local-scale villages which are planned to be an urban area. Fig. 2 shows planned development areas and plan of activity center development is shown in Table 1.

B. Plan of Strategic Areas
Strategic areas are large-scale cultivation areas/certain areas and have national and regional roles. The plan of the strategic regions is grouped into 2, namely economic strategic areas and living environmentally supportive strategic areas. Strategic areas of PALI District are shown in Figure 3. The plan of strategic area development for economic growth of PALI District is shown in Table 2.

C. Existing Condition
The existing network condition of PALI District is a description of the road network that accommodates the need for movement of people or goods within the area of PALI District, and then the level of accessibility on the existing network is analyzed. Fig. 4 shows the existing road network of PALI District. Table 3 shows the accessibility level of the existing network of 27 nodes and 26 connectors.   Table 3 shows that villages/towns needing accessibility improvement are Tanah Abang Selatan, Tempirai Utara, Harapan Jaya, and Sukaraja due to having accessibility ratings against lower areas. Tanah Abang Selatan village is an entrance and exit point of the District and a transit point to tourism objects of Bumi Ayu village and economy corridor of Subdistricts of Tanah Abang and Penukal Utara, while Tempirai Utara is an area of plantation and entrance and exit point of the District from the northwest. Harapan Jaya village has agricultural cultivation whereas Sukareja village is located on the border between PALI and Prabumulih City accessible through Harapan Jaya village. Also, other areas needing accessibility improvement are those of Tempirai Selatan, Air Itam, and Betung, the three of which are not connected as the supports of fishery and plantation activities of these three villages.

D. Road Network Development
Based on the spatial of PALI District [12]. The plan of road network development is divided into 2 scenarios as follows: • Primary collector road development • Development system of the transport infrastructure network

E. Central Activity Development
The scenario of district class primary collector road development is a development plan aimed to support the economic movement activities of people and goods at the villages connected by planned roads. Scenario 1 is described as follows: • Talang  Ayu village which has great tourism objects and potential The two developed scenarios to improve regional accessibility and locations or strategic areas are shown in Figures 5 and 6 representing the development scenarios 1 and 2. The result of the analysis of the accessibility level of each scenario is shown in Table 4.   Tampui  -33  30   14  Sungai Baung  14  13  10  33  Muara Ikan  -32  34   15  Handiyanimulya  15  12  14  34  Tambak  -31  36   16  Talang Bulang  16  17  16  35  Sukamanis  -37  33   17  Tanjung Kurung  17  15  15  36  Purun  -38  35   18  Karang Agung  18  16  18  37  Sukarami  -36  38   19  Air Itam Timur  19  19  17  38  Sukamaju  -35  37 The above Table 4 shows that the result of the accessibility improvement of scenario 2 area is better than that of scenario 1. Pendopo becomes level 1 as the capital city of the District; Air Itam village is number 6 as an area of plantation and mining, Tempirai village is number 8 with its plantation potential, Talang Bulang village remains number 16 as entrance access of the District, Bumi Ayu village having tourism potential is number 27, Kartadewa is number 21 as an industrial area, and Spanta Jaya village as an economic corridor crossing.

IV. CONCLUSION
The existing condition shows that the development of the primary regions of activity centers needs accessibility improvement of villages such as Tanah Abang Selatan, Tempirai Utara, Harapan Jaya, Sukareja. The scenario of area development 2 using an area accessibility level is expected to be able to improve economic and regional development by performing: Connecting villages of Spantan Jaya and Panta Dewa; Construction of road connecting villages of Gunung Menang and Betung; Connecting villages of Tempirai Utara -Tempirai Lubuk Tampui -Muara Ikan and Tambak; Construction of road connecting Subdistricts of Talang Ubi and Tanah Abang; Construction of road connecting Subdistricts of Tanah Abang and Penukal; Construction of road connecting Subdistricts of Penukal and Penukal Utara; Construction of road connecting Subdistricts of Penukal Utara and Talang Ubi; Construction of ring road within the territory of PALI District; Construction of new road to tourism access of Bumi Ayu.