On October 6, as the "Chenggong No. 16" shield machine broke through the pile wall, the left line of the Tiantou–Tianxin section (i.e., "Tiantou Station to Tianxin Station") of Shenzhen Metro Line 16 was successfully holed through. With this, the section has achieved twin-tube breakthrough.

The right line of the Tiantou–Tianxin section is about 1,370 m long, and the left line about 1,326.5 m. The strata are dominated by completely weathered sandstone, slightly weathered limestone, and silty clay. The alignment passes beneath residential buildings, factory buildings, the Shijingling–Tianluokeng fault zone, high-pressure gas pipelines, and the Tiantou River, posing great construction difficulty and high risk.

The shield machine was launched from Tiantou Station on July 21, 2020. When tunneling reached the Shijingling–Tianluokeng fault zone, affected by the geological structure, the rock mass in this area was relatively broken, with obvious lithological changes, abrupt karst development, and abundant groundwater, causing great trouble for the shield machine and making tunneling difficult.

To ensure safe and smooth advancement of the shield machine, the project department established the working policy of "careful investigation, multiple point placement, strengthened support, and tracking monitoring." It adopted two approaches in parallel—surface grouting backfill and advanced in-tunnel grouting—and promptly carried out karst cave treatment during the 2021 Spring Festival. During this period, a total of 21 karst caves were filled, 338 grouting holes and material feeding holes were constructed, 868 m³ of mortar and concrete were used, and 23,125 m³ of dual-fluid grout was injected.

Metro Line 16 starts from Dayun Station, runs along Longgang Avenue, Huangge Road, and Longping Road, and ends at Tianxin Station. The line is about 29.2 km long, with 24 stations, including 10 interchange stations, and one parking lot and one depot each.

The line adopts a fully automatic operation mode, with a total of 4 track-laying bases and 12 auxiliary track-laying bases. The total length of track on the entire line is about 86 km, and the goal of full-line track connection is expected to be achieved by the end of 2021.

As of now, 100% of stations on the entire line have been topped out, and 99.5% of sections have been holed through. For ancillary works, 55% of the retaining structures have been completed, 27% of earthwork excavation, 14% of the main structure, and 64% of structural masonry for decoration works. In addition, 25,996 m of track-laying base has been completed on the entire line, accounting for 41%.

Among them, 48 of the 50 single-tube sections have been holed through, and 23 of the 23 stations on the entire line have been topped out.