This INFORMS RAS webinar will discuss the challenges and opportunities in developing an open-source ecosystem for state-wide and national intermodal transportation systems modeling and optimization. The webinar will explore the practicality of constructing a digital twin system, harnessing the power of open-source models and open data, and bridging the gap in multiresolution modeling. The first part of the webinar will focus on General Modeling Network Specification (GMNS) and machine learning for real-time system replication and optimization. The second part will present recent advancements in open-source optimization, benchmarking, and open data ecosystems for RAS communities, including the development of two open-source transportation engines, Path4GMNS and TransOMS. The aim is to establish a high quality modeling ecosystem for transportation researchers, planners, and software vendors in national intermodal freight transportation systems modeling.