甬舟铁路是国家《中长期铁路网规划(2016—2030年)》的重大项目，线路全长76.4公里，设计时速250公 里。项目建成运营后将结束舟山群岛不通铁路的历史，长三角唯一不通高铁的地级市舟山市将接入全国 铁路网，对促进长三角一体化发展等具有重要意义。(完) 中新网杭州9月22日电(王逸飞 许文峰 余剑波)9月22日，在浙江省宁波与舟山间的金塘水道海平面下65 米深处，国产超大直径盾构机"甬舟号"掘进里程突破2470米，标志着世界最长海底高铁隧道——甬舟铁 路金塘海底隧道宁波侧掘进过半，建设取得阶段性进展。 建设者庆祝"甬舟号"盾构机掘进过半。马婧波 摄 金塘海底隧道是甬舟铁路全线控制性工程，西起宁波市北仑区，东至舟山市金塘镇，全长16.18公里， 其中盾构段长11.21公里。 该隧道采用"甬舟号""定海号"两台盾构机从宁波和舟山两侧同时始发、相向掘进，在穿越高水压及多种 复杂地层后，最终将在海底实现精准对接。其中，由中铁十四局承建的宁波侧盾构段长4940米，使用开 挖直径14.57米的国产"甬舟号"超大直径盾构机由西向东掘进。 金塘海底隧道沿线地质条件极为复杂，需穿越海堤、码头和航道等多项风险源，海底最大埋深7 ...

Core Viewpoint - The approval of the feasibility study report for the Ningbo Qijia Mountain to Zhoushan Jintang section of the Ningbo-Zhoushan Expressway double line marks a significant step forward for the construction of the world's longest underwater dual-direction six-lane highway tunnel, indicating that the second channel of the Ningbo-Zhoushan Expressway will commence full construction [1][3]. Group 1: Project Overview - The total investment for the Ningbo-Zhoushan Expressway double line is approximately 31.4 billion yuan, with a total length of about 46 kilometers, designed to a dual-direction six-lane highway standard and an overall design speed of 100 km/h [3]. - The project consists of three segments, with the Jintang to Dasha segment (rail and road combined bridge) costing about 10.9 billion yuan and expected to be completed by 2028, the Ningbo Qijia Mountain to Zhoushan Jintang segment (underwater tunnel) costing about 15.7 billion yuan and expected to be completed by 2030, and the Beilun Haosifang to Qijia Mountain segment costing about 4.8 billion yuan and expected to be completed by 2029 [3]. Group 2: Technical Details - The approved section of the Ningbo-Zhoushan Expressway double line is 18.1 kilometers long, featuring the world's longest underwater dual-direction six-lane highway tunnel, the Jintang Underwater Tunnel, which is 11.6 kilometers long and utilizes 16-meter shield tunneling technology [3]. - The construction of the tunnel presents significant technical challenges, including "super large, super long, super deep" characteristics, complex geological conditions, underwater precision alignment, and underwater tunnel dismantling [3]. Group 3: Strategic Importance - The construction of this project is crucial for improving the national highway network, promoting high-quality development in Zhejiang, accelerating the construction of the Yangtze River Delta urban agglomeration, and enhancing the transportation and emergency response capabilities of the Ningbo-Zhoushan cross-sea passage [4]. - Once the double line is fully completed, the total length of the Zhoushan connected island expressway will reach 120 kilometers, further solidifying its status as China's longest connected island expressway [4].