The construction industry gets increasingly aware of the importance and value of people. Considering the nature of construction projects a certain level of collaboration is needed to successfully deliver a project. Throughout the complete project life cycle of large engineering projects, multiple actors are involved. As in any other industry and if not more, it is crucial to understand how people work and collaborate. Collaboration is positively associated with project performance. This research is conducted, from a managing contractor perspective, to study the formation of a coalition in the construction phase of a large engineering project. The coalition consists of the client, the managing contractor, and subcontractors. The coalition members are critical in finishing the project. The project management intervention is implemented to increase collaboration between coalition members. It should lead to increased organizational effectiveness. However, it remains unclear what the effect of a coalition is. Moreover, it is unclear how people, groups, and the project organization are affected by this intervention...

’What can be improved in the collaboration between general contractor and subcontractor to attain higher project performance and relationship continuity?’. This was the central question in this research. It is found that the design of the contract is basically abandoned. The contract is designed to have few inter-organizational relations, issues should be solved between counterparts which can each call upon their own organization. In practice there is a network of relations between Fluor and IREM. The organization has been divided into 5 clusters, based on which employees are expected to be most interrelated according to the contract’s design. These people (from the same clusters) are in practice, however, not most interrelated which underpins the conclusion, based on the number of ties, that a network structure is in place and that the design mentioned above is abandoned. An other conclusion is that the open communication factors (responsiveness, effectiveness and energy) could be improved between the construction- and office-cluster, within the construction-cluster (3 persons in particular) and one person in the preparation-cluster. After analyzing the perceptions about the collaboration between Fluor and IREM at these improvement areas, several trends have been identified. It has been found that people who consider collaborative practices and relational attitudes to be few or low, often respond slower when issues arise, have a lower conversation effectiveness and drain energy from their interlocutor. A trend has also been observed between their perception of teamworking quality and their responsiveness and effectiveness. The direction of this trend can however not be determined based on this research’s data, it could be self-enforcing. Based on the above mentioned conclusions, recommendations can be made on how to improve the collaboration between the general contractor and subcontractor. The above mentioned result have been gathered by conducting a valued social network analysis (SNA) and executing (and thereby testing) the relational capability (RECAP) tool of Suprapto (2016) in a setting between general contractor and subcontractor. Based on the results of the RECAP tool, it couldn’t be concluded that there are no significant differences between the clusters’ perceptions on collaboration. This, and the conclusion that the cluster structure is abandoned, lead to the conclusion that effort to increase collaboration, project performance and likelihood of relationship continuity, should be directed on company level.