Value Engineering in Temporary Cofferdam Works: The Impact of Using Type II Steel Sheet Piles on Cost and Time Efficiency in the Palu IV Bridge Reconstruction Project

Abstract

Temporary cofferdam works in post-disaster infrastructure projects require rapid, safe, and cost-effective technical decisions. This study evaluates the use of Steel Sheet Pile (SSP) Type II as an alternative to SSP Type IV in the temporary cofferdam works of the Palu IV Bridge Reconstruction Project. The study aims to examine the effects of stakeholder perception, material availability, and ease of implementation on cost efficiency; to analyze the effect of cost efficiency on work completion time; and to assess the implementation impact of SSP Type II in terms of material requirements, driving volume, technical control, and direct costs. A descriptive quantitative approach was applied through a survey of 36 project respondents and Structural Equation Modeling-Partial Least Squares (SEM-PLS). The SEM-PLS results show that stakeholder perception significantly affects cost efficiency (O=0.664; t=5.034; p<0.001), material availability significantly affects cost efficiency (O=0.912; t=2.397; p=0.017), ease of implementation significantly affects cost efficiency (O=1.151; t=3.484; p=0.001), and cost efficiency significantly affects project time (O=0.766; t=10.500; p<0.001). Technically, the 18 m SSP Type II system with HB 350x350x12x19 cross bracing met the criteria for stability, deflection, bending moment, and stress ratio based on the project design review. In the pier works, SSP Type II reduced the number of sheets from 420 to 400 units, decreased the driving length from 8,610 m to 7,200 m, and produced cost savings of IDR 11,938,147,636.30 or 64.84% compared with SSP Type IV. These findings indicate that value engineering can improve cost efficiency and provide volume-based time efficiency indications when supported by technical justification, stakeholder coordination, and effective implementation control.