Optimalization of Geometric Design on Nagreg Ring Road STA 1+925 S.D. STA 3+200, Bandung Regency, West Java Provincy

The first phase construction in Nagreg Ring Road in the construction from STA 0+000 to STA 1+925 (not yet functioned) and STA 4+600 to STA 5+266 (functioned). The next phase will be from STA 1+925 to STA 3+950 (phase II plan) and STA 3+950 to STA 4+600 (phase III plan) and it has not been constructed. The Nagreg Ring Road is planned to be an Arterial Road which National status. Based on the technical data, the Nagreg Ring Road type is one way two lanes. The evaluations result mentioned that the geometric design from STA 1+925 to STA 3+200 doesnt fulfil the specification for rural road especially the vertical alignment which has the maximum grade more the 12 %. The discussion for this paper is begun from STA 1+800 to STA 3+500 with the idea to have the best connection either with the previous or the following steps. Three alternatives were made in trying to achieve the specification. Then the earth work volume derived from those alternatives are calculated. The relative smallest earth work volume is chosen include the fill volume and the earth work operation between cut and fill. Nagreg is a hilly area that force the geometric design to surround it to fulfil the vertical alignment demand and it results a long curving road and a large volume of cut and fill will be needed. To overcome this problem there will be some alternatives considerations to design a bridge over the extreme fill and tunnelling instead of extreme cut. This type of design may shortened, fastened, and straightened the road route to achieve a more safe and comfortable travelling for the road needs. Beside it the environment surrounding will be saved. Key