The new subway Line 10, with air-conditioned and spacious compartments, will open this weekend.

A 4.3-km length of the Olympic line and a shuttle train between Dongzhimen and the airport terminals will also open for test runs at the same time. They will extend Beijing's underground railway to 200 km.

"The new lines will directly serve the huge crowds during the Olympics," Zhou Zhengyu, spokesman for the Beijing municipal committee of communications, said Thursday.

Beijing is expecting 21 million commuters each day during the Aug 8-24 Games' period, and up to 5.85 million passengers will use the city's subway during that period, more than one quarter of the total commuters using public transport.

The 15.5 billion yuan ($2.27 billion) Line 10 links Zhongguancun, Beijing's IT hub in the northwest, with the city's central business district in the east. The journey time is 45 minutes.

However, the Olympic subway line, part of the planned Line 8, will not be open to passengers without tickets or accreditation.

Special zones will be set up at each subway station to separate Games ticket holders and accredited personnel, who will enjoy free public transport.

The airport express will operate from 6 am till the last flight arrives at the newly built Terminal 3. The trip from Dongzhimen to the airport will take 20 minutes, with 15-minute intervals.

Six more subway lines are being built, and the next one to open next year is Line 4, which will cross the populated west part of Beijing.

Construction of new lines is on schedule despite the delayed opening of Line 10, which had been scheduled to open early last month, Liu Hongtao, deputy director of the local railway transportation construction corporation, said.

By 2015, Beijing's subway network will stretch more than 561 km and have 420 stations. The cost of developing each kilometer of subway is 500 million yuan.

The municipal government has an annual budget of about 1 billion yuan for public transport.