<![CDATA[The 11.7 km Kopo–Soreang Road is an important corridor connecting Bandung City and Bandung Regency and experiences traffic congestion during peak hours. This study aims to analyze the existing traffic conditions, design the pavement structure for road widening, evaluate the implementation of sustainable materials, and estimate the project cost. A quantitative approach was employed using traffic data, road inventory data, and *International Roughness Index* (IRI) measurements. Traffic performance analysis was conducted based on the 2023 Indonesian Road Capacity Guidelines (PKJI), while pavement design referred to the 2024 Pavement Design Manual (MDPJ). The results indicate that the existing Degree of Saturation (DS) ranges from 0.371 to 0.552, with a peak traffic volume of 1,741.40 pcu/h. The widening of the 4/2 Undivided Collector Road to a width of 14 m for a 20-year design life (ESA₅ = 2,191,493) resulted in a pavement structure consisting of a 40 mm AC-WC layer, 65 mm and 80 mm AC-BC layers, 200 mm Class A Aggregate Base, 150 mm Class B Aggregate Base, and a 40 mm AC-WC overlay based on an average IRI value of 2.21 m/km. Sustainable construction was implemented through the use of nickel slag, 50%–70% *Reclaimed Asphalt Pavement* (RAP), precast U-Ditch drainage, and a local Asphalt Mixing Plant (AMP), reducing embodied carbon by 42.45. Based on the 2026 Bina Marga AHSP, the sustainable alternative requires a total project cost of IDR 69,620,015,971.49, representing a 7.87% increase compared with the conventional alternative costing IDR 64,539,406,664.45.]]>
