On December 25, 2019, xiamen metro line 2, the first cross-sea subway in China designed by China railway construction institute (CRCC) and the fourth institute of railway engineering, was put into operation. This is also the second subway line opened by xiamen metro after line 1, marking that xiamen metro has truly entered the "transfer era" from single line to double line.
　　Xiamen metro line 2 is jointly constructed by China railway construction institute, China railway 11th bureau, China railway 12th bureau, China railway construction bridge bureau, China railway 14th bureau, China railway 16th bureau, China railway 17th bureau, China railway 17th bureau, China railway 18th bureau, China railway 22nd bureau and China railway construction. After opening, it will only take 3 minutes to cross the 2,784 meter long channel tunnel from the cruise center station located in the east of the island to haicang bay park station.
　　In the construction of the submarine tunnel, the builders have adopted a number of new technologies and new techniques, including the offshore rock blasting and grouting, the whole process of advanced water exploration, high water pressure crushing rock hengdong mud auxiliary mud shield with pressure tool change, rock crevasse grouting water plugging technology under confined water environment.
　　Aiming at more than ten kinds of complex strata involved in the underground civil engineering construction, the constructors improved and optimized the blasting scheme, adopted shallow hole, digital electronic detonator and multi-stage millisecond delay loose control blasting in the foundation pit blasting to reduce the blasting vibration effect and reduce the impact of blasting on the surrounding buildings. At the same time, they also applied BIM+3D printing technology to the construction and production for the first time, carried out 3D model simulation on the main structure, geological environment and surrounding building environment, carried out construction simulation and optimization, and selected the optimal construction plan.