BEIJING-- Five new subway lines with a total length of nearly 140 kilometers began construction in Beijing on Saturday.

The five lines are Line 6, the second phase of Line 10 and Line 8, Yizhuang and Daxing lines.

The five will all be completed by 2015.

Line 10 starts from Wulu station in western Haidian district and ends in Dongxiaoying in eastern Tongzhou district. It is 41.74 kilometers long with 27 stops.

The second phase of Line 8 will extend the first phase, called the 4.5-km Olympic line, northward and southward separately. The two extensions are 17.46 km long with 12 stops.

Line 10, which is 32.46 km long and has 23 stops, is the second circular line outside the current operational Line 2. The 24.55 km-long first phase of Line 10 started in 2003.

The Yizhuang line is 23.2 km long and has 14 stops. The 22.2-km-long Daxing has 11 stops.

Currently, the first phase of Line 10, Line 8 and a 28-km line linking downtown to Beijing Capital International Airport are under construction.

Line 10, the Olympic line and the airport line will be put into operation before next August's Olympic Games in Beijing.

Currently, the capital has Line 1, Line 2, Line 5, Line 13 and the Batong line in operation carrying about 2.3 million passengers each day. Their combined length is 142 kilometers. The city plans to have 561 kilometers of rail lines by 2015, carrying nine million passengers daily. There are currently 1.2 million private cars on Beijing's roads, and about 1,000 new autos appear on the city's streets each day. The city's population has grown from 12.77 million in 2000 to an estimated 17 million now.