From Fragmentation to Integration: An Empirical Study on Enhancing Design–Construction Interface Management in EPC Landscape Projects

The EPC model is currently the mainstream implementation approach for landscape projects, but fragmented management of the design–construction interface constrains project performance. Addressing issues such as cost overruns and schedule delays caused by ambiguous responsibility allocation, inefficient information transfer, and frequent design changes in EPC landscape projects, this paper focuses on the Xiaoyalong Wetland Park project in Kashi, Xinjiang, as a core case study. Combined with research on 12 representative projects, it identifies 16 interface management factors across four dimensions: contract management, organizational coordination, technical support, and ecological–artistic integration. Employing a mixed-methods approach combining questionnaire surveys (186 valid samples) and semi-structured interviews, validated through SPSS and structural equation modeling, this study confirms that early collaborative design serves as a core driver. Based on empirical findings, it derives and proposes a three-tiered optimization strategy: “foundation at the root layer, coordination at the transition layer, and assurance at the direct layer”. Pilot application of this strategy demonstrated significant effectiveness, reducing design change rates by 32%, shortening coordination time by 28%, and lowering cost overrun rates by 15%. This study enriches the theoretical framework of interface management in landscape engineering EPC projects and provides practical guidance for similar projects in arid regions.