Cause of Claims in one of Iran's underground Design and Build project (tunnel and underpass project in Tehran)

In most projects with different Delivery systems, it is possible for claims to be made. On the other hand, faster operation of projects has led to the need to use Design-Build Delivery system. However, the implementation of projects in this way in Iran, compared to other existing methods, is new and the parties of the projects are little familiar with it; For this reason, disputes are inevitable, especially in underground projects that are complex in nature. In the present study, by examining the documents of the Tehran Tunnel and Underpass project and conducting 10 semi-structured interviews with representatives of the main pillars of the project, some claimants have been identified. After analyzing the data, which was performed using qualitative content analysis and shown through Gantt chart, it was found that sometimes the claims lead to each other during the project in a chain. Also, showing the time of occurrence of claims by five project management process groups shows that most claims occur in the executing process group, which is rooted in the initial and planning process groups.