URUMQI, Feb. 28 -- The longest railway tunnel in northwest China's Xinjiang Uygur Autonomous Region was completed on Friday.

Spanning 22.449 km, the left part of the Zhongtianshan Tunnel was finished on Friday morning, making the tunnel the longest of its kind in Xinjiang and the third-longest in China, according to the Urumqi Railway Bureau (URB).

Undertaken by the URB and the China Railway 18 Bureau Group Co., Ltd, the tunnel took about seven years to build. Its right section, 22.467 km in length, was finished in September 2013.

The tunnel is part of Nanjiang Railway's second trunk that links Turpan with Korla in southern Xinjiang. The 333.864-km-long line, expected to begin operation at the end of the year, will slash train journeys by 122 km.