国内最长，成功架设！

Core Points - The successful installation of the longest railway concrete box girder in China marks the commencement of the superstructure construction phase for the Hangzhou Bay Cross-Sea Railway Bridge [3] - The installed box girder has a span of 80 meters, significantly exceeding the 70-meter span of other notable cross-sea bridges, indicating advanced engineering capabilities [3][5] - The Hangzhou Bay Cross-Sea Railway Bridge is a critical project for the Tongsu-Jia-Ning High-Speed Railway, with a total length of 29.2 kilometers and a design speed of 350 km/h, expected to be operational by the end of 2027 [5] Construction Challenges - The record-breaking length and weight of the box girder present significant construction challenges, necessitating the use of specialized equipment such as the "Tianyi" transport and erection vessel [5] - A digital twin system has been developed, incorporating 85 intelligent sensors to monitor various data points in real-time, ensuring risk management throughout the girder installation process [5]