Today’s airport terminals face a critical problem of traffic congestion in the terminal area partly caused by uncoordinated shuttle operations. The congestion near pick-up and drop-off points negatively affects passenger traffic leading to unnecessary idling, delays and congestion with negative impact on air quality and mobility. The need for an intelligent shuttle management system becomes more urgent with the development of information technologies, battery electric shuttles and autonomous vehicles. In this project, the authors developed a centrally coordinated shuttle scheduling and routing management system for mixed fleets of diesel and electric shuttles using a digital twin of LAX to LA downtown traffic road network by optimizing the total combined cost of energy consumption and travel time. A Co-Simulation Optimization method is used to solve the problem. The objective is to reduce congestion at the designated pick up and drop off points due to different shuttles showing up at these points during overlapping time windows which exceed the curb capacity. Another objective is to integrate into the system mixed fleet of shuttles that include diesel and battery operated. The proposed centrally coordinated shuttle scheduling and routing management system takes into account the characteristics of mixed shuttle fleets and is shown to reduce the operational cost such as energy consumption and delays. The results also suggest the deployment of electric shuttles in order to reduce emissions and improve air quality further.