Work has started on Shenzhen's metro line 7, after a ceremony attended by Wang Rong, Party secretary of the Shenzhen Municipal Committee.

The new line extends 30.2 kilometers from west to east, starting at Lishui Station in Nanshan district, and ending at Tai'an Station in Luohu district.

There will be 28 stations in total connecting the areas of Xili, Longzhu, Futian South, Huaqiang North, Sungang, Tianbei and Buxin, covering the southern half of some of Shenzhen's main residential and business areas. The whole line will be built underground.

The project, costing 20 billion yuan ($3.2 billion), will be undertaken by Shenzhen Metro Group Co Ltd, and Sinohydro Group Ltd. Construction is expected to take 53 months, and the line will be open by the end of 2016.

Shenzhen currently has five subway lines and carries around 2.07 million passengers daily. The city, in Guangdong province, is one of four first-tier cities in the mainland. Located next to Hong Kong, it covers an area of 1,991.64 square kilometers.