Investigating Cost, Quality, and Time Comparisons in Multi-Utility Tunnel Construction at Indonesia’s New Capital City

Abstract

The Multi-Utility Tunnel (MUT) constitutes a critical infrastructure component in the development of Indonesia’s New Capital City (Ibu Kota Nusantara, IKN), serving as the backbone of integrated underground utility networks. Accelerating MUT construction is essential to ensure timely support for subsequent infrastructure development phases. This study investigates and compares the phenolic hollow formwork and sliding formwork methods in terms of cost, quality, and time performance. The analysis is based on actual project implementation data obtained from the Pembangunan Jalan Lingkar Sepaku Tahap 2 project. Cost evaluation is presented as percentage deviations relative to the Owner’s Estimated Cost (RBP). The findings indicate that the sliding formwork method achieves higher productivity, improving work efficiency by approximately 30–50% compared with the conventional phenolic–hollow formwork system. However, sliding formwork results in a cost increase of approximately 5–6% per meter relative to the RBP, whereas phenolic–hollow formwork yields cost savings of 1–6%. In terms of quality, sliding formwork produces more uniform and precise concrete surfaces, thereby reducing the need for additional finishing work. Although the initial cost of sliding formwork is higher, its advantages in time efficiency and construction quality make it more suitable for long and repetitive MUT structures. These findings provide practical insights for selecting appropriate formwork methods in large-scale infrastructure projects, particularly in high-priority national development areas.