Beijing has announced opening dates for four subway lines, three of which will be opened before the 2008 Beijing Olympic Games, according to the Beijing Subway Operation Co. Ltd.

The 27.6-km north-south subway Line 5, which was begun in December 2002, will go into operation in September, although the exact date was yet to be fixed.

The 32.9-km west-southeast subway Line 10 and the 28.10-km Airport Extension, stretching from downtown Dongzhimen to the two terminals (T2 and T3) of Beijing Capital International Airport, will be open to traffic on June 30, 2008.

The 28.2-km Line 4, which stretches from Longeicun at the Summer Palace to Majialou in south Beijing, is expected to open on September 30, 2009.

The municipal government also plans to introduce 264 new carriages on the two existing subway lines later this year as it moves to modernize the capital's rapid transit system in advance of the Beijing Olympic Games.

By 2008, there will be nine lines totaling 200 km, and by 2020 the city government plans to have 19 subway lines in operation, totaling 561.5 kilometers, which could make it the largest underground rail system in the world, according to Beijing's city planning authorities.