The management of aging road infrastructure is increasingly challenged by climate change impacts, financial constraints, and the demand for digital transformation. While proprietary software dominates the sector, its limitations in interoperability and transparency have sparked interest in open-source alternatives. This study provides a state-of-the-art overview of open-source technologies, standards, and data for road asset management, focusing on documented applications within or in collaboration with Public Administrations. A systematic literature search across Google Scholar and Scopus identified case studies utilising tools such as QGIS and CloudCompare, and standards including IFC and CityGML. The findings are synthesised through a four-layer Digital Twin framework to assess current capabilities in data acquisition, modelling, analysis, and visualisation. Results indicate that while individual open-source tools offer robust solutions for specific tasks like bridge monitoring or traffic simulation, a lack of integrated workflows and standardised data pipelines remains a significant barrier. The study concludes that leveraging the collaborative nature of open-source ecosystems can enhance resilience and cost-effectiveness but requires concerted efforts to improve documentation, interoperability, and training for asset managers. Future directions include the development of seamless open-source toolchains and open educational resources to bridge the gap between technical potential and operational adoption.