For an efficient seaport terminal, we propose a novel operational model, namely, a double container-handling operation among operating machines, such as automated guided vehicles (AGVs), automated transfer cranes (ATCs), and quay container cranes (QCCs), in a seaport terminal system. In addition, a passing lane is provided in a container storage yard in order to activate the container-handling operation by the AGVs and ATCs. In this paper, the effect of the double container-handling operation and passing lane on the system utilization is examined. Finally, the effectiveness of the proposed operational model with a passing lane is discussed on the basis of the operating time and obtained number of operating machines for a given demand in consideration of a mega-container terminal.