Following the crossing of the boundary by the left-line S-623 shield on the Guangzhou-Shenzhen-Hong Kong Express Rail Link Shenzhen-Hong Kong connecting tunnel, China's first cross-border high-speed railway tunnel, at 23:10 on November 25, 2013, the right-line S-624 shield successfully reached the Shenzhen-Hong Kong boundary at 16:00 on March 12, 2014, marking the completion of the entire mainland section of the twin-tube, single-track shield-driven Shenzhen-Hong Kong connecting tunnel.

        The Shenzhen-Hong Kong Tunnel connects Shenzhen and Hong Kong and has a total length of 6.6 kilometers. Its twin-tube, single-track section is 3,346 meters long and is divided into two parts: the 1,856-meter mainland section and the 1,490-meter Hong Kong Section 826 contract. The mainland section was designed by China Railway Siyuan Survey and Design Group Co., Ltd. Two 9.96-meter-diameter slurry shield machines were used for excavation. The left-line S-623 shield was officially launched on July 3, 2012, and the right line was launched on October 31, 2012. The project overcame difficulties including the high construction difficulty of mixed ground that is soft at the top and hard at the bottom, the high risk of passing alongside the existing Jincangli foundation pit, and the strict settlement-control standards amid densely located surface buildings. After the left line set records for a large-diameter slurry shield machine of 16 meters of excavation in a single day and 188 meters in a single month, the right line broke the single-day record with 16 meters and set a new single-month record of 196 meters.