The Effect of Road Geometric Conditions on Route Realignment of the Trans Papua Highway, Jayapura–Wamena Section, Mamberamo–Elelim Segment

The Trans-Papua Highway is a vital transportation corridor connecting communities and improving regional accessibility in Papua, Indonesia. However, the Jayapura–Wamena section, particularly the Mamberamo–Elelim segment, crosses mountainous terrain with sharp horizontal curves, steep longitudinal grades, narrow road widths, and inadequate stopping sight distances. This study used a descriptive quantitative case study design to assess existing geometric conditions and determine the need for route realignment along a 41.3-km corridor from kilometer station 368+400 to 409+700. Existing horizontal and vertical alignments were evaluated against applicable geometric road design standards. Three route alternatives were compared using weighted multicriteria decision analysis. The results identified six critical road sections that failed to meet geometric design requirements. Eighteen horizontal curves had radii of 10–25 m, below the calculated minimum of 50.39 m. Longitudinal grades reached 10–15%, road widths ranged from 3 to 7 m, and available sight distances were approximately 20–30 m, below the required stopping sight distance of 45 m. The weighted evaluation ranked geometric-standard-based realignment first, scoring 5.00, followed by limited improvement at 3.00 and retention of the existing alignment at 1.45. The proposed realignment would reduce the combined length of the six critical sections from 15,498 m to 10,600 m, a reduction of 4,898 m or approximately 31.6%. These findings indicate that realignment is the preferred alternative based on the assessed geometric criteria, with potential benefits for alignment consistency, operational efficiency, and driving conditions along the corridor.