Unprecedented construction of Beijing's gigantic underground transit network is expected to alleviate traffic problems that have been haunting the metropolis for decades.

A woman takes photos at Nanluoguxiang Station on Line 6 on Sunday. The station's decoration features the traditional folk art of Beijing. Wei Xiaohao / for China Daily

The Beijing Subway has seen unprecedented construction in recent years, greatly easing traffic congestion in the Chinese capital.

Including a new line and extensions to lines, the city boasts a network of 15 lines, covering 11 districts, with 221 stations and 442 km of track.

Wang Renqiang, a leading project official of the subway's Line 6 project department of the China Railway Tunnel Group, said once everything is operational, the updated network will make it easier for people to get around and provide relief to transport services on the ground.

The Beijing Subway is the busiest on the Chinese mainland in terms of passenger volume, and the largest in terms of operational length.

It is estimated the total operational length of the Beijing system will reach 1,050 km by the end of 2020, with 30 lines and some 450 stations, according to the Beijing government.