Product development (PD) and engineering design processes are often characterized by the
information flowing among activities. In PD, this flow forms a complex activity weba process
that can be viewed as a complex system. Most literature on the subject of information flow in
PD focuses on a single project, where precedence information constraints (based solely on
necessary information and possible assumptions) determine the execution sequence for the
activities and the resultant project lead-time. In this paper, we consider multiple PD projects that
share a common set of design resources. Especially in this setting, precedence information
availability is insufficient to assure that activities will execute on time. We extend the
information flow modeling literature by including resource availability. We model several PD
projects as a portfolio, where activity execution is based on both information and resource
availability. We demonstrate the effects of accounting for resource constraints on both
individual projects and portfolio lead-time distributions
