This paper explores how the ÖNORM B 2203-1 model can complement the FIDIC Emerald Book contracts in conventional tunnel construction projects, specifically focusing on cooperation, project management, reimbursement, and dispute resolution. The complex technical nature of such projects requires collaborative stakeholder engagement, efficient project management, and effective dispute resolution mechanisms. This article enhances the current body of literature by undertaking a qualitative comparative analysis of the FIDIC Emerald Book and the ÖNORM B 2203-1 model within the specific context of conventional tunnel construction projects. The findings demonstrate that specific areas in the FIDIC Emerald Book exist where supplementary guidance is required. Compared to the FIDIC Emerald Book, the ÖNORM model offers a more extensive range of project management aspects, reimbursement guidelines, dispute resolution provisions, and comprehensive technical specifications, all supported by contractual provisions. The major limitation of this study is its focus on a literature review. Thus, including the qualitative analysis in an actual project and applying the study results would be advantageous for verifying the findings.