On December 25, the world's largest rectangular pipe jacking machine with a large cross-section, "Kaotuo," independently developed and manufactured by China Railway Engineering Equipment Group Co., Ltd., rolled off the production line at the Dalian Qianyi Manufacturing Base. Luoyang Jiujiu Technology Co., Ltd. also contributed to the project by participating in its technical research and development efforts.

　　Gu Qiang, Director of the Dalian Changxing Island Economic Zone Management Committee; Cao Yanchun, Director of the China Railway Group Limited News Center; Chen Jiyan, Deputy Director of the Dalian Municipal State-owned Assets Supervision and Administration Commission; Ma Jinghang, Chairman of Dalian Metro Co., Ltd.; Li Huayi, General Manager of Dalian Urban Investment Company; Zhang Cunxu, Secretary of the Party Committee of China Railway Tunnel Group No. 3 Co., Ltd.; Tan Shunhui, General Manager of China Railway Engineering Equipment Group Co., Ltd.; and Jia Yongde, Chairman of Dalian Qianyi Group, attended the ceremony. The decoupling ceremony was hosted by Bu Zhaohua, Deputy Secretary of the Party Committee of China Railway Engineering Equipment Group Co., Ltd.

　　This rectangular pipe-jacking machine was developed by Tunnel Equipment Manufacturing Co., Ltd., a subsidiary of China Railway Engineering Equipment Group, which drew on its extensive construction experience to boldly innovate. The design features a unique two-layer arrangement with six cutterheads, where the cutting zones of adjacent heads overlap significantly, achieving a 95% cross-sectional excavation coverage rate. Thanks to the multi-cutterhead, small-scale excavation approach, the method minimizes ground disturbance, thereby substantially reducing surface settlement.

　　As society evolves and urbanization accelerates, more and more buildings are springing up across cities. Meanwhile, the competition for land is intensifying as numerous urban infrastructure projects vie for limited space above ground—making the shortage of available surface area an increasingly pressing issue. To address this challenge, "developing underground space" has emerged as a viable solution. By harnessing and expanding underground spaces, cities can shift some of their functions from the surface to beneath the ground, enabling a seamless transition from "two-dimensional" to "three-dimensional" urban planning. This approach not only significantly boosts the efficient use of urban land but also helps alleviate the growing tension between rapid city development and the scarcity of land resources. Among the technologies driving this transformation, shield-type pipe-jacking machines have gained popularity due to their simple and rapid excavation processes, coupled with high-quality tunneling outcomes. As a result, these machines are rapidly becoming the preferred choice for urban underground space development. They are already making significant inroads into various applications, including urban underground utility tunnels, city-level underpasses, subway station entrances and exits, pedestrian crosswalks, underground parking facilities, underground shopping malls, as well as civil defense projects and even large-scale gas storage caverns—showcasing vast potential and promising market opportunities ahead.