Risk Allocation at Engineering Interfaces in Construction Contracts: A Case Study of the Taiwan High Speed Rail Project

Large-scale infrastructure projects routinely divide construction responsibilities across several specialized contractors whose scopes are simultaneously independent and mutually reliant, producing boundary zones where design changes, remedial obligations, and contractual disputes repeatedly emerge. This study examines how interface-related risks are distributed between civil construction contractors and core system contractors, drawing on fieldwork conducted within the Taiwan High Speed Rail (THSR) project. Questionnaire surveys were administered to 38 practitioners who held direct THSR involvement or comparable experience in analogous multi-party infrastructure projects, yielding a valid response rate of 63.3%. Using a weighted influence scoring approach, 37 risk factors grouped into seven interface categories were evaluated. Results show that Variation (top-ranked item A07, score 290/300), Care of Works (B01, 284/300), and Cooperation and Coordination (D04, 285/300) represent the three most consequential risk domains. Analysis of risk-initiation patterns indicates that project owners are the predominant source of variation-related risks, while core system contractors most frequently trigger care-of-works incidents. Structured comparison of FIDIC (1995), AIA/A201 (1997), NEC/ECC (1995), ENAA (1996), and THSR contractual documents uncovers a shared shortcoming: no examined standard form contains explicit provisions tying risk liability to the party whose conduct gave rise to the risk. Evidence from three documented THSR dispute cases is consistent with the survey data and illustrates the real-world consequences of this drafting gap. On this basis, the study proposes a risk-trigger principle as a potential framework for improving interface risk allocation in future multi-party infrastructure contracts.