On 30 December 2021, an undersea tunnel with 4km length has been opened as part of the 38·3 km southern extension of Qingdao metro Line 1 from Qingdao Bei Railway Station to Wangjiagang.
In advance another 5·4 km sea crossing tunnel on the east-west Line 8 was launched in December 2020, hence this is the city’s second undersea tunnel. The date of construction commencing in the undersea section of Line 1 through 18 fracture zones was September 2015, while the tunneling process was completed in November 2018.
Serving the mainline terminus before heading southwest across the neck of Jiaozhou Bay to Fenghangao and Wangjiagang, the Line 1 development passes beneath the city center. Comprising of 60·1 km length and 41 stations, the intended line is operated by a fleet of 67 six-car Type B trainsets manufactured by CRRC Qingdao Sifang. These are 118 m long and have a maximum speed of 100 km/h and a capacity of 1 900 passengers, including 248 seated.