Core Viewpoint - The successful installation of the first steel box girder marks a significant milestone in the construction of the Shuangshan Tunnel and its associated extension project, indicating the transition to the bridge superstructure construction phase [1][3]. Group 1: Project Overview - The Shuangshan Tunnel and its associated extension project is a key hub for traffic upgrades in the eastern urban area of Qingdao, featuring a new bridge approximately 4.8 kilometers long with a total of 52 steel box girders weighing around 15,485 tons [3]. - The first steel box girder was installed at the intersection of Fuzhou North Road and Tai Liu Road, an area characterized by limited space and dense surrounding road networks, posing significant challenges for traffic organization and construction safety [3]. Group 2: Construction Techniques and Management - The installation utilized a construction technique of "factory prefabrication, modular assembly, and segmented hoisting," emphasizing multi-party collaboration, precise measurements, and comprehensive safety management throughout the process [5]. - The project team implemented a "one girder, one checklist" verification system to ensure meticulous control over each construction phase, employing BIM technology for simulations of transportation routes, lifting angles, alignment, and protective measures [3][5]. Group 3: Future Plans and Impact - The project is progressing according to schedule, with significant advancements in the construction of the Huaren Interchange and the main bridge on Heilongjiang Road, where the average progress of piers and caps has surpassed 50% [5]. - The Shuangshan Tunnel and its associated extension are critical for the connectivity of the backbone road network in Qingdao, facilitating multi-level connections and enhancing the rapid transit network, which will improve traffic flow across a 5.6-kilometer stretch of Heilongjiang Road [5].