Cause Analysis of Rework in Skytrain Construction Projects: Case Studies in MRT Green Line (North) and SRT Red Line Construction Project

Abstract

The objectives of this research are to investigate the problems of defects and to analyze the causes of reworks due to the defects of 2 skytrain construction projects. The data are collected from 4 construction contracts which have similar characteristics. The defect issues from Non-Conformance Reports (NCR) that have effect on direct cost of solving the problem have been ranked by employing Pareto theory. Then, 6 construction project managers are interviewed. The projects are divided into two parts; Substructure and Superstructure, each consists of 5 main factors.  The result shows that; For Substructure, there are top 3 problems that have accumulated cost greater than 80 percent, they are 1.) Bored piles do not pass integrity testing 2.) Concrete pouring of bored piles. 3.) Eccentric of bored piles. For Superstructure, there are top 3 problems that have accumulated cost greater than 80 percent, they are 1.) Installing prestressed concrete cross beams to support the station 2.) Damages of Viaduct Segments 3.) Damages of concrete plank slab station floor. Finally, the researchers summarize a guideline to prevent the future problems for quality control department, new project managers or site engineers who are interested in Skytrain construction projects.