This article outlines the use of operational planning and simulation modeling as a lean tool within Perkins+Will, to determine the room utilization and staffing for a large trauma center, based on current and projected volumes and turnaround times. A specific area of focus was the Resuscitation Rooms and their location within the emergency department (ED). In its most recent year, this facility had 64,000 patient visits. Projections estimate that approximately 75,000 annual patient visits within 63 exam rooms will be needed in this emergency department in 10 years. This study began with a process map of the patient flow within the ED. A simulation model was built to mimic the patient flow in the design of the new emergency department. Patient wait times, census, and staffing ratios were the key metrics to assess the efficacy of the ED design. The results of this revealed that the medical resuscitation rooms that were planned were better used when integrated with the emergent rooms in the main ED versus an area decentralized and adjacent to the main ED. The results also revealed that staffing of the ED within specific staff roles (RN’s and Technicians) and specific ratios could reduce patient wait times.