THE GEOMETRIC DESIGN OF HORIZONTAL ALIGNMENT: A CASE OF BOJONGGEDE-KEMANG SECTION ROAD, WEST JAVA INDONESIA

Published: January 17, 2023 Roads are one of the basic infrastructure facilities in the development of an area. With the construction of roads, they can be used as access to transportation and as a driving force for an area's economy to grow better. The purpose of geometric planning on the Bojonggede-Kemang section road at STA 0 + 000 STA 1 + 200 is to obtain a design that prioritizes user safety and comfort. The method used in this study is a manual method that refers to the 2021 Road Geometric Design Guidelines (PDGJ). The data used in this study used Google Earth. The results of the study obtained a class III primary local type road. The plan speed of 60 km / h was obtained based on the criteria design. Then, using values, the horizontal alignment of the Bojonggede-Kemang road section is of type S-C-S.R = 150 m.


INTRODUCTION
Roads are one of the infrastructures needed by humans that are used to travel and for activities to deliver goods from one place to another. Road infrastructure plays an essential role by providing mobility for the efficient movement of people and goods and providing accessibility to various commercial and social activities. Transportation by road is the only mode to provide full service to everyone. As a result, roads have a more significant influence than other infrastructure in boosting economic growth (Ng, Law, Jakarni, & Kulanthayan, 2019); (Nugraha, Prayitno, Situmorang, & Nasution, 2020).
Indonesia has abundant natural resources opening opportunities to become a developed country. Indonesia's national economy is expected to snowball after a decade of significant investment in public infrastructure projects emphasizing new roads, railways, ports, airports, power plants, distribution, water supply and sanitation, schools, and hospitals. Three main challenges of infrastructure development in Indonesia have been identified: land clearing, project planning and preparation, and financing. The uncertainty and scarcity of available funds for road infrastructure investment and competing priorities present challenges to the planning and execution of government infrastructure (Chan & Personal, 2022); (Salim & Negara, 2018); (Ben, 2019).
The Bojonggede-Kemang section road, located in Bogor Regency, West Java, is planned to be a link between Jalan Raya Parung in Kemang District and Jalan Tegar Beriman in elements in each design speed. The type of road and the terrain are influential in determining the speed of the initial plan .

Alignment Road
Road Alignment is a projection of an arc on the geometric road. There are two types of alignment on the road: Horizontal Alignment and Vertical Alignment. Road alignment is a concern for designers and researchers worldwide because there are often accidents on the alignment of a road. Therefore, there is a need to measure, using the appropriate safety parameters in the elements of road design, the design's influence on road users' safety .
A vertical alignment, commonly referred to as a descent or climb, is an arc that is a projection of a line against an elevation or height in a collection of y-axis points. The height of these waypoints is usually determined by the need to provide the right level of driver safety, comfort, and drainage. In vertical alignment, there are two types of slump, namely positive (climb) and negative (derivative), and there are also two types of curvature, namely concave and convex arch (Mannering & Washburn, 2020).
Horizontal alignment or commonly referred to as bends or turns, is a curve that is a projection of a line against the points of the z and y axes. There are several types of horizontal alignment, namely Spiral-Circle-Spiral (S-C-S), Full Circle (F-C), and Spiral-Spiral (S-S). Spiral-Circle-Spiral (S-C-S) is the intersection of two lines connected by a combination of fixed radius curves (Circle) R combined with an intermediate form (Spiral). A full Circle (F-C) is one of the horizontal arches that connects two lines with the curvature of one circle. In comparison, the Spiral-Spiral (S-S) is one of the horizontal arches that connects two lines with two arch switches. Roads with this type of arch usually have a high design speed. In addition, poor visibility on the horizontal arch affects the increased risk of accidents due to lack of visibility (Papadimitriou, Eleonora, & al, 2019). It is fundamental research to optimize the road's horizontal alignments to improve the safety and economy of the designed horizontal alignment (You, Yu, Huang, & Hu, 2022).

Road Classification
Determining the classification of roads helps determine the type of road to be built to fit its function. In Indonesia, road grouping is explained in Law No. 38 of 2004 and Government Regulation No. 34 of 2006 concerning road designation, system, function, and status. By grouping a road, it is expected to follow the purpose for which a road is built. It is hoped that this grouping is also following the needs of a region to support activities and run the economic wheels of a region.
The construction of a road is also given some exceptions. Due to several factors, road construction can be carried out in stages. One of them is the limited funds owned by the government or private agencies authorized to build the road. The gradual development is expected to be born the development of the wheel of life of an area. Bojonggede-Kemang Section Road is planned as Primary Local Road. Primary local roads serve to connect the National Activity Center (PKN) with the Environmental Activity Center (PKL), the Wilaya Activity Center (PKW) with the Environmental Activity Center (PKLing), between (PKL) or (PKL) with (PKLing). With the characteristics of serving medium-distance traffic trips, medium average speed with Vd at least 20 km / h, a capacity more significant than the average traffic volume, a road width of at least 7.5 meters, the number of driveways is not limited (Road Geometric Design Guidelines, 2021).

Road Geometric Design Guidelines
Some countries have guidelines for the geometric design of a road. It is because each country has differences in various factors. Both from the habits of different drivers, vehicle standards, weather, and others. Traffic accidents involve human, vehicle, and environmental and road factors. It previously had its own standard for the geometric design of intercity roads in Indonesia, namely "Geometric Planning Procedures for Intercity Roads, No. 038/TBM/1997". The Directorate General of Wildlife Development created the standard in 1997. Currently, the latest road design standard is the Road Geometric Design Guidelines (PDGJ) 2021 (Elfandari, Amadea, & Siregar, 2021).
This PDGJ describes ways of geometrically designing roads which include design criteria, general provisions, road geometric technical provisions, and road geometric design procedures, in designing horizontal road paragraphs, vertical road paragraphs, road cross sections, and coordination of horizontal and vertical alignment of roads, for Highways, Medium Roads, Minor Roads, and Freeways, both serving Intercity traffic and inner-city traffic. This guide is mainly designed so that users can estimate the traffic behavior of a facility in specific traffic conditions, geometry, and environmental conditions (Isradi & Primary, 2020). Some parameters form the basis of geometric design: the vehicle's size, the plan's speed, the volume and capacity, and the level of service the road provides (Džambas, Ahac, & Dragčević, 2017).

METHOD
This study was in the Bojonggede-Kemang Section, Bojonggede District, Bogor Regency, West Java Province, Indonesia. The road was planned as a Primary Local road III. The plan to develop a new road functioning local primary III, a district ring, and a through road between border districts/cities includes the Rumpin -Ciseeng -Parung -Tajurhalang -Bojonggede -Cibinong (Tegar Imanman) -Citeureup section. Geographically, the location of the Bojonggede -Kemang road plan is located 2 km next to the embers of the Bogor Regency Government Office complex in Cibinong, which extends to cut the Parung Highway -Ciseeng Highway, with coordinates at 106°43'30" BT and 06°28'00" LS, administratively located in three sub-district areas, namely, Kemang District, Tajurhalang District, and Bojongede District. The systematic scientific research process must begin with identifying the right problem. Data is one of the main strengths in compiling scientific research and modeling. The primary data used in this study used data from Google Earth to find coordinates. In addition, there were secondary data on traffic volume carried out by the predecessor researcher and other parameters following the applicable rules (Rifai, Hadiwardoyo, Correia, & Pereira, 2016); (Rifai, Hadiwardoyo, Correia, Pereira, & Cortez, 2015).
Geometric Planning of the Bojonggede-Kemang Road Section uses manual methods and procedures and design references using the 2021 Road Geometric Design Guidelines (PDGJ).

RESULTS AND DISCUSSION
The On-road planning based on the Indonesian Road Geometric Design Guidelines  Table. The determination of Design Speed is a fundamental element in the road design used to select other geometric design parameters. Speed Design considers road users to be able to pass safely and comfortably at the specified speed limit in every possibility, such as all weather conditions, timing, traffic flow conditions, and interference from the driveway or others. Therefore, Design Speed is selected as the highest value from the allowed Design Speed range. Used Design Speed = 60 /ℎ.

b. Determining Technical Design Criteria
This technical design criterion refers to road technical data as well as all significant design criteria following the parameters of the latest regulation of the Director General of Highways, namely the Road Geometric Design Guidelines (PDGJ) 2021. For Design Clock Traffic Flow, data obtained through previous researchers is used. First, the Environmental Survey Team results in 2010, which received the average daily volume in the current year, rounded up. Then with a planned design life of 15 years and a traffic collision factor of 10%, the average annual daily traffic volume of the design was obtained. It is planned that the road will be very congested, then the K value for the design hour factor is 11%.    The value of the super-elevation of roads in Indonesia both for outside cities and in cities varies, namely 2%, 4%, 6%, 8% and 10% (Procedures for geometric planning, Directorate General of Highways, 2021). However, according to Highways, the maximum e value for inner-city roads is 8% and 10% for out-of-town roads. Meanwhile, according to A Policy on Geometric Design of Highways and Streets, AASHTO, 2004 the maximum e value for all types of roads is 4%, 6%, 8%, 10% and 12%.