In the last years, Floating Car Data (FCD) has risen as a technology that has the potential to replace legacy sensors, reduce associated installation and maintenance costs and offer new possibilities in the field of traffic management. FCD refers to the use of sources such as in-vehicle systems with network connectivity or road users’ mobile phones to collect relevant traffic information (e.g. vehicle speed or intensity). There is extensive literature on the feasibility of using FCD for traffic management purposes and on the added value of fusing legacy sensors data with FCD. These studies have been mostly experimental and a literature review shows that there is no academic work on how to deploy and integrate legacy sensors data and FCD in an actual live setting. This research aims to fill that gap by designing a flexible ICT Architecture that integrates FCD into Rijkswaterstaat’s Traffic Management and Information Systems. Taking an architecture point of view to address this challenge is not only novel but also appropriate because it provides a comprehensive view of what changes need to take place at different levels of the organization (business, information systems and technology) for this to happen. This research follows a design science research approach, where four main phases can be distinguished: (1) Problem formulation, (2) Building, (3) Reflection and learning and (4) Formalization of learning. The Building phase is further subdivided into the specification of design principles and requirements and the development of the solution ICT Architecture. The outcomes of this research are relevant not only to Rijkswaterstaat but also to other organizations looking to integrate FCD in their traffic systems, to design science researchers and to ICT architects.