In April 2015, Suzhou passed the review with a high score of 94.29 and became one of the first 10 national pilot cities for underground comprehensive utility tunnel construction. Suzhou solemnly promised to complete the construction of 5 underground comprehensive utility tunnel pilot projects with a total length of about 34 kilometers within the next 3 years.

　　Nearly 3 years later, the original blueprint has been realized. The Sangtian Island utility tunnel, Chengbei Road utility tunnel, Chengyang Road utility tunnel, Wuzhong Taihu New City startup area utility tunnel, and Wuzhong Taihu New City utility tunnel (Phase II) stretch under the city, providing a safe and efficient new home for various urban "lifelines." It is expected that the first batch of nine major categories of pipelines will be installed in the tunnels before the Spring Festival in 2018.

　　Over 1,000 days and nights, Suzhou's utility tunnel builders overcame difficulties, pioneered trials, and dared to innovate, providing a referable "Suzhou model" for advancing national utility tunnel construction.

　　The Longxiang Road utility tunnel under construction by the East Taihu Lake in Wuzhong District.

　　Fierce competition for the national pilot; careful preparation for the "final" and a high-score victory

　　Recalling the moment 3 years ago when Suzhou was selected as one of the first 10 national pilot cities for underground comprehensive utility tunnel construction, Jiang Yuhua, general manager of Suzhou Urban Underground Comprehensive Utility Tunnel Development Co., Ltd., still finds it somewhat incredible.

　　In January 2015, the General Office of the Ministry of Finance and the General Office of the Ministry of Housing and Urban-Rural Development jointly issued a document to launch the application work for pilot cities of underground comprehensive utility tunnels. After provincial-level selection, 33 cities nationwide were shortlisted, but only 10 could ultimately enter the pilot list.

　　"The competition was fierce. During the preliminary scoring of shortlisted cities, Suzhou did not have outstanding advantages, nor was it certain to win," said Jiang Yuhua.

　　1:1 physical model of the main structure of the Chengbei Road utility tunnel.

　　What to do? Utility tunnel construction is a project that benefits people's livelihood and future generations. Therefore, the Suzhou Municipal Government made up its mind to strive with the utmost effort and carefully prepare for the final "final." The "final" had two parts: expert review and mayor's defense; the total score was the sum of the two. During the two weeks from shortlisting to the formal defense, the applicants worked day and night, carefully organizing, checking, and weighing every word to further solidify the defense materials, and jointly applied for 5 underground comprehensive utility tunnel pilot projects.

　　Ultimately, Suzhou successfully passed the expert review and closed-door defense with a comprehensive and leading planning system, a solid construction foundation, and diverse financing models, and achieved a high score of 94.29, second only to Shenyang's 94.64, ranking second among the first batch of pilot cities.

　　Pioneering trials overcome difficulties; "China's No. 1 Jacking" safely completed

　　On April 10, 2015, the first batch of 10 pilot cities for underground comprehensive utility tunnel construction, including Suzhou, was announced. Jiang Yuhua said that along with joy and excitement came tremendous pressure. At that time, the project was still in the planning stage, and there was no ready-made experience for specific implementation. "We had to get into the river first, then feel for the stones."

　　The first difficulty encountered was time. The Chengbei Road utility tunnel project was the first project implemented and constructed by Suzhou Utility Tunnel Company. According to the original plan, it was to be constructed simultaneously with the Chengbei Road reconstruction. However, due to various reasons, the road reconstruction plan for Chengbei Road was delayed in being determined.

　　But utility tunnel construction could not wait. "We had given a 'military pledge' to the State Council and the two ministries, and we must complete it on schedule," said Jiang Yuhua. At the end of 2016, the Chengbei Road utility tunnel project started before the road project. Facing huge preliminary work such as traffic organization, demolition and relocation, pipeline relocation, and greenery relocation, the builders raced against time and compressed the preliminary procedures that normally take 1 year into half a year.

　　During the utility tunnel construction, a series of highly difficult node projects became new challenges. The Chengbei Road utility tunnel crossing the Yuanhetang node project was one of them. Because there were many buildings and obstacles to be demolished along the alignment, high pressure for traffic relief, and complex distribution of various pipelines, after repeated discussions by experts, the original open-cut plan was adjusted to a rectangular pipe jacking plan. In actual construction, the cross-section of the pipe jacking was 9.1 meters × 5.5 meters, and the total jacking length reached 233.6 meters, creating the longest long-distance large-section rectangular pipe jacking of its kind in China, known in the industry as "China's No. 1 Jacking."

　　At the nodes where the Chengbei Road utility tunnel crosses Renmin Road and Guangji Road, rectangular pipe jacking was also used to ensure the operational safety of Metro Lines 2 and 4. According to the construction party, the rectangular pipe jacking crossing Guangji Road is the world's first rectangular utility tunnel crossing operating tracks.

　　To ensure the safety and quality of the rectangular pipe jacking node projects, Suzhou Utility Tunnel Company established the "Chengbei Road Utility Tunnel Project Major Node Project Control Work Leading Group" and formulated and issued relevant quality and safety risk control management measures. By the end of 2017, a total of 62 various safety inspections had been conducted on the project, 763 hidden dangers were identified and rectified, with a rectification rate of 100%, and no safety accidents occurred in any project.

　　"China's No. 1 Jacking" — Yuanhetang rectangular pipe jacking.

　　Technological innovation sets industry standards; "Suzhou experience" fills domestic gaps

　　Through repeated pioneering trials and technological innovations, Suzhou's utility tunnel builders have reaped fruitful results. In particular, the successful application of rectangular pipe jacking technology broke through multiple high-difficulty construction bottlenecks such as long-distance drag reduction, shallow-buried river crossing, and jacking in unfavorable geology, left a large amount of first-hand data, and summarized and formed a series of related construction process standards, providing valuable experience for future underground comprehensive utility tunnel construction and pipe jacking projects in China.

　　Up to now, the technical team of Suzhou Utility Tunnel Company has successfully applied for 2 municipal-level scientific research projects, 1 provincial-level engineering construction guide, 1 provincial-level engineering construction industry standard, and obtained 2 national patents.

　　Among them, the project "Construction of Intelligent Comprehensive Monitoring and Information Management System for Urban Underground Comprehensive Utility Tunnels" effectively promoted the design and application of intelligent platforms in utility tunnel projects; the project "Technical Standard for Rectangular Pipe Jacking Engineering of Comprehensive Utility Tunnel Projects in Jiangsu Province" filled the current gap in the field of rectangular pipe jacking technical standards in China.

　　The compilation of the "Guidelines for Collaborative Construction of Urban Comprehensive Utility Tunnels and Underground Engineering in Jiangsu Province" provides a basis and technical guide for collaborative cooperation in planning, design, construction, and operation of urban underground comprehensive utility tunnels and underground space construction in the province. In addition, at the end of 2017, two patents applied for by Suzhou Utility Tunnel Company, "A Support Structure Based on Foundation Pit Construction" and "A Force Transmission Carrier Mechanism Based on the Replacement of the Last Support of a Foundation Pit," also successfully passed the approval of the National Patent Office.