There is an increasing application of Systems Engineering in the construction industry. This paper investigates the effects of a Systems Engineering approach on project management performance, prerequisites for success, and which elements contribute to effectiveness from a technical contractor and sub-contractor perspective. First, we find a positive perception of Systems Engineering's effect on time, cost, and quality. Second, we provide and rank a list of 12 prerequisites for success. Third, we quantify the perceived importance of five elements of the systems engineering process. Finally, we find a disconnect between what seems to be essential processes and prerequisites and what gets done in practice. To improve Systems Engineering performance, we recommend improving Systems Engineering competence and capabilities, increasing the formality of requirements analysis and documentation, and front-loading the effort and allocation of resources in projects.