Core Insights - The construction of the Xixiang Expressway, which includes nine major super-engineering projects, has entered a comprehensive construction phase, with the Yuanbao Hub underground interchange being recognized as the world's largest scale underground interchange in mountainous areas [2] - The project has a bridge-to-tunnel ratio of 73.4%, with a total estimated investment of 58.738 billion yuan and a per-kilometer cost of approximately 25.1 million yuan [2] - The Lugu Lake Grand Bridge, a key component of the expressway, holds three world records, including the largest span of a space cable-stayed bridge and the largest span of a steel truss cable-stayed bridge in mountainous areas [2] Project Overview - The Xixiang Expressway was initially planned in 2011 but faced delays due to high construction difficulty and investment costs until it was included in the National Highway Network Planning [2] - The project officially commenced in 2022 and is now in a large-scale construction phase [2] - The expressway features nine super-engineering projects, including three bridges, five tunnels, and one interchange, which is rare in highway construction [2] Engineering Challenges - The Lugu Lake Grand Bridge was selected after evaluating 16 potential bridge sites, balancing geological challenges, construction costs, and traffic convenience [2] - The project employs innovative designs, such as the U-shaped tunnel anchor, which reduces concrete usage by 20% and enhances stability in soft rock conditions [2] - The construction of the Salt Source Tunnel, the second-longest tunnel in the province, utilizes a specially developed TBM to shorten the construction period from seven years to four years [3] Technological Innovations - The Yuanbao Hub interchange incorporates 11 different excavation methods and 36 types of engineering structures, showcasing a wide range of tunneling techniques [3] - The project management utilizes advanced technologies, including AI-assisted monitoring and drone management, to ensure real-time tracking of construction progress [3] - The completion of the Xixiang Expressway will enhance the transportation network in Liangshan Prefecture, integrating with multiple existing highways to form a comprehensive traffic hub [3]