Beijing's metro system will stretch to 561 kilometres by 2020, surpassing London's underground as the longest subway system in the world, so as to help ease worsening traffic congestion, the state media reported on Monday.
According to the city's latest transportation plan, the 561 kilometres will be laid out along the 19 lines knit together beneath the Chinese capital.
Unlike metro lines 1 and 2 (the loop lines), which encircle the Tian'anmen Square area, the traditional city centre, the new lines are expected to reach all the major corners of the sprawling city.
Fifteen of the new lines will support urban areas, while the remaining four will stretch out to the suburbs, according to the plan drafted by the city's communications commission.
Zhao Hui, a researcher who helped draft the plan, said it represented a long-term vision and was therefore subject to change. The city's Development and Reform Commission still has to approve the plan, China Daily quoted him as saying.
The three lines 4, 5 and 10 that are currently under construction are expected to be operational for the 2008 Olympic Games.
Currently four metro lines serve Beijing. Lines 1 and 2 span 54 kilometres, while Line 13 and Line Batong cover 61 kilometres. Together they carry 1.5 million travellers every day.
Beyond building new subway lines, transportation experts have also been exploring other possibilities for the city's underground space to help ease the traffic pressure.